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CH2M HILL REPORT EVALUATION OF THE CENTRAL LANDFILL AND FTS POTENTIAL
IMPACTS ON THE SCITUATE RESERVOIR
RHODE ISLAND SOLID WASTE MANAGEMENT CORPORATION Central Landfill 65 Shun Pike Johnston Rhode island 02919 401 942-1430
1
FAX 401 946-5174
JERROLD L LAVINE Chairman THOMAS E WRIGHT Executive Director
J I
cr q shy ji 1992
shy
February 3 1992
Mr Ed Summerly GZA GeoEnvironmental Inc 14 0 Broadway Providence RI 02903
Dear Mr Summerly
Per your request enclosed is a copy of Evaluation of the Central Landfill and Its Potential Impacts of the Scituate Reservoir prepared for Providence Water Supply Board
If you have any questions please do not hesitate to contact me
Very truly yours
Julie A Jaglowski Environment Engineer
JAJeap
Enclosure
cc Dennis aRusso
100 Recycled Paper
EVALUATION OF THE CENTRAL LANDFILL
AND ITS POTENTIAL IMPACTS ON THE SCITUATE RESERVOIR
Prepared For PROVIDENCE WATER SUPPLY BOARD
Providence Rhode Island
Prepared By CH2M HILL
28 State Street Boston Massachusetts 02109
October 1988 WDC26416A0
BSR03007
Engineers Planners
j T g ^ g Economists ^ i l i i S l S Scientists
October 17 1988
WDC26416AO
Mr Domenic J Mainelli Chief EngineerGeneral Manager Providence Water Supply Board 552 Academy Avenue Providence Rhode Island 02908-2792
Subject Evaluation of the Central Landfill CH2M HILL Project No WDC26416AO
Dear Mr Mainelli
Please find enclosed ten copies of our revised report entitled Evaluation of the Central Landfill and Its Potential Impacts on the Scituate Reservoir
In direct response to your initial questions we offer the following
1 Is there seepage from the [Central] landfill
Yes Because the existing landfill is unlined seepage from the landfill doesoccur This seepage is referred to as leachate
2 What is contained in the seepage
Based on the analyses of water samples obtained from monitoring wells located in and around the landfill the landfill leachate has been found to contain a variety of contaminants including chloride nitrate and sulfate dissolved metals volatile organic compounds and semivolatile organic compounds
3 Is the seepage moving toward the reservoir
Although the existing data are inconclusive the presence of both a surface-water divide and a shallow groundwater divide suggest that movement of groundwater and hence landfill ]oachate from
CH2MHliL Boston Office 28 Stale Sfreet 18th Floor Boston Massachusetts 02109 6175232260
I I Doinenic J M a i n e l l i
4| Page 2 O c t o b e r 17 1988 WDC2 6n6AO
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Pl
the landfill area is not toward either the Scituate Reservoir or the Aqueduct
4 Is the seepage moving toward any other facilities of the board
See response to Question 3
5 If there is seepage what kind of threat does it represent
a To water quality b In what time frame
It is unlikely that seepage from the Central Landshyfill poses any threat to the Scituate Reservoir The landfill does however pose an immediate threat to water quality in the vicinity of the landfill and the receiving bodies of watermdashCedar Swamp Brook Alray Reservoir and Upper Simmons Reservoir
6 If there is no seepage what further actions can be taken to monitor the situation
The existing data are now and will most likely remain inconclusive However deeper wells located between the landfill and the surface-water divide could establish the direction of groundwater movement with greater certainty It is recoirmiended that this additional information be requested of either the Rhode Island Solid Waste Management Corporation or the US EPA the latter of which is conducting the Remedial Investigation Feasibility Study (RIFS) of the Central Landfill Sources of contamination other than the landfill may be posing an even greater threat to the water quality of the Scituate Reservoir Land usage around and within the watershed should be evaluated and consideration should be given to routine groundwater monitoring at selected locations
HI
Mainelli
Page 3 October 17 1988 WDC2 6116AO
D ome n i c
What effect will the current expansion plans of the Solid Waste Management Corporation have on the current situation
The current expansion plans will keep a major portion of the existing landfill open to infiltrashytion throughout the expansion period Unless measures are taken to reduce the amount of infilshytration to the existing fill the discharge cf landfill leachate will continue unabated
Please do not hesitate to contact me if we can be of any further assistance It has been our pleasure to work with you on this project
Very truly yours
rd W Bowers PE esident Manager
BSCG5001
SUMMARY
Significant groundwater contamination has been observed in
monitoring wells located both within the Central Landfill
area and downgradient of the existing fill Piezometric
data suggest that most if not all of the contaminated
groundwater discharges to the following areas Cedar Swamp
Brook which drains to Upper Simmons Reservoir Upper
Simmons Reservoir and Almy Reservoir The vertical and
lateral extent of groundwater contamination has not yet been
completely defined The rates and directions of groundwater
movement can only be inferred from the data that are
currently available
Fracture studies indicate a potential pathway for tlie
migration of groundwater contaminants from the Central
Landfill to Scituate Reservoir At elevation 284 the
spillway elevation of the Scituate Reservoir is well below
the piezometric level of wells located within the Central
Landfill which is at elevations 310 to 380 This
difference in head provides a potential driving mechanism
for the migration of contaminants from the Central Landfill
to Scituate Reservoir However both a surface-water divide
and a shallow groundwater divide are located between the
landfill and Scituate Reservoir Although the existing data
remain inconclusive the presence of these surface and
near-surface features suggests that even at greater depths
movement of groundwater from the landfill area is not toward
the Scituate Reservoir If the movement of groundvater is
away from the landfill it is unlikely that the Central
Landfill has any significant impact on the Scituate
Reservoir
BSR03022
Tlie existing unlined landfill poses a threat to groundvater
quality at the landfill site The proposed landfill
expansion would delay the installation of a final cover over
the entire area By leaving a major portion of the existing
fill uncovered the landfill would generate uncontrolled
leachate throughout the projected expansion
periodmdashapproximately 20 years Other design flaws have
been identified Certain aspects of the expansion plans
require further clarification
Groundwater contamination also has been identified in areas
unrelated to the Central Landfill Contamination probably
also occurs in other areas yet to be identified
Considering the variety of land uses within the watershed
the Providence Water Supply Boards current program of
surface water monitoring should be reevaluated for the
possible inclusion of groundwater monitoring
BSR03022 ii
CONTENTS
Page
Summary i
1 Introduction 1-1
2 Physiography and Drainage 2-1
3 Geology 3-1
4 Geophysical Investigations 4-1 41 Gravity 4-1 42 Electrical Resistivity 4-3 43 Seismic Refraction 4-4 44 Downhole Geophysical Logging
and Vertical Seismic Profiling 4-5
5 Groundwater 5-1 51 Groundwater Occurrence and 5-1
Movement 52 Water Quality 5-3
6 Proposed Landfill Expansion 6-1 61 General Comments on
Overall Design 6-1 62 Specific Comments on Design
Report and Drawings 6-3
7 Conclusions and Recommendations 7-1 71 Hydrogeology 7-1 72 Geophysics 7-4 73 Landfill Design 7-5 74 Groundwater Quality 7-5
A p p e n d i x L i s t of Documents Reviewed
FIGURES
1 Location of Project Within the State of 1-2 Rhode Island
2 Site Map of the Central Landfill 1-3
3 Generalized Cross-Section Along 7-3 NE-SW Trending Lineament 1
BSR03003 iii
INTRODUCTION
The Solid Waste Management Corporation (SWMC) currently
operates the Central Landfill in Johnston Rhode Island
located approximately 2-12 miles east of the Scituate
Reservoir The location of the landfill is shown in the map
presented in Figure 1 The Scituate Reservoir serves as a
water supply for over 60 percent of the population of Rhode
Island The Central Landfill is an unlined municipal
landfill that in the past has received industrial wastes
A permit application for construction of an expansion of the
existing landfill has been submitted to the Rhode Island
Department of Environmental Management (RIDEM) Discharge
of contaminants to groundwater immediately surrounding the
landfill has been documented However the extent of
offsite migration of contaminants is not known
Studies have been conducted to identify the existing and
potsntial impacts of seepage from the landfill on surface
water and groundwater in the vicinity Concern has been
expressed that seepage from the landfill may be endangering
the Scituate Reservoir There is further concern that
expansion of the landfill also may have an impact on the
water supply A site map of the Central Landfill showing
the approximate limit of existing fill and the locations of
all previously installed monitoring wells is presented in
Figure 2
BSR03008 1-1
0 10 M l bull raquo I t I I
Approxiniale Scale
Central Landf i l l
Alrny Reservoir
Simmons Reservoir
Scituate Reservoir
1 Location oT Proiect r^ifiMUIII n Figure I AVlthlnThe State of RhodiJlslana v^fJiVJnU
1-9
Figure 2 Aoproximattt Scale
Slta-Miip 3t i - Cjnt-al Lancrflil cyihL
Ill Tlie Providence Water Supply Board has contracted with CH2M
HILL to perform an evaluation of the data pertaining to the
Central LancJfill The objectives of this study are
Provide an independent review of reports data
drawings and other available information
concerning existing or potential impacts of the
landfill on surface water and groundwater in Using existing data assess whether there is
indeed seepage from the existing landfill and if
so what its impact is on water in the vicinity of
the landfill 111 Assess whether the proposed landfill expansion
will have further impact on surface water and
groundwater
Determine whether seepage from the landfill could m have an impact on Scituate Reservoir
11
mi
m m BSR03008 1-4
li
PHYSIOGRAPHY AND DRAINAGE
Surface topography in the North Scituate Quadrangle is
characterized by northwest-southeast trending uplands and
in intervening valleys The orientation of these surface
features reflects the direction of glacial advance and
concomitant erosion of preglacial soils The orientations
of Oak Swamp Almy and Simmons Reservoirs and portions of
i] Scituate Reservoir are examples of this general
northwest-southeast valley orientation
The active portion of the Central Landfill is located
approximately 2-12 miles east of the Scituate Reservoir
The Central Landfill also occupies an elongate valley The
area has been modified by extensive borrowing and filling
Surface drainage is primarily from the northwest and
southwest The area drains to the east and southeast A
topographic divide which defines the limit of the
watershed lies between the active landfill and the
reservoir A small yet inactive portion of the landfill
property lies within the watershed of the Scituate
Reservoir The active landfill is approximately 5100 feet
from the portion of the watershed boundary that crosses
landfill property
BSR03009 2-1
GEOLOGY
Bedrock in the vicinity of the Central Landfill consists of
granite and granite gneiss and is referenced in the
literature as the Scituate granite Soils overlying the
Scituate granite predominantly consist of glacial till and
glacial outwash The till is an unsorted ground moraine
composed of fine-grained to boulder-sized particles The
outwash varies from poorly sorted materials to well-sorted
ice-contact sands and gravels The soils vary in thickness
from 0 feet in areas that have been excavated to over
60 feet southvest of Cedar Swamp Brook Within the existing
landfill refuse ranges in thickness from 50 feet at Well E
to 135 feet at Well WE87-3 Refuse is in direct contact
with the bedrock over the northern portion of tlie landfill
and is within 5 feet of bedrock over its southern part
Bedrock topography at the landfill is defined by subsurface
investigations associated with the landfill design and the
ongoing remedial investigationfeasibility study (RIFS)
Bedrock topography has been mapped regionally by the
US Geological Survey (USGS) The Central Landfill lies on
the north slope of a bedrock valley with a northwest to
southeast general trend The Upper reach of the bedrock
valley is two prongedmdashnorthwest to southeast and north to
southeast The active landfill overlies most of the latter
Rock quarrying has modified the area along the western slope
of the landfill and in the vicinity of the portion of the
landfill (near Well J) that received industrial wastes
The degree of weathering and Rock Quality Designations
(RQDs) observed in rock core were evaluated with respect to
depth below the top of rock and proximity to fracture
traces The RQD is a measure of the degree to which rock is
BSR03010 3-1
fractured as reflected in the lengths of rock core
reioveries A highly fractured rock will exhibit a low RQD
In general the RQD increased with depth--57 percent for
0 to 10 feet below the top of rock and 77 percent for
10 to 30 feet below the top of rock At boreholes located
in fracture traces however the RQDs were 40 percent and
62 percent respectively indicating a correlation between
the fracture traces observed on both aerial photographs and
satellite imagery and the degree to which the bedrock is
friictured Similarly the degree of weathering was found to
be a function of both depth and proximity to fracture
tl ces Severe veathering was noted throughout
B(U-ehole WE87-13 and to a depth of 45 feet in
Borehole WE85-6 both of which lie along northeast-southwest
trending features It should be noted that observations of
rock weathering and RQDs apply only to boreholes from vhich
rock core was available These boreholes tended to be
relatively shallow extending approximately 30 feet below
the top of rock
Deeper explorations (124 to 247 feet below the top of rock)
were performed in the multilevel wellsmdashWE87-ML1 through
WE87-ML5 The Fracture Trace Analysis (FTA) was used to
position the multilevel wells Each multilevel well was
pllt3ced on or proximal to an observed fracture trace The
degree of fracturing and the orientation of fractures were
evaluated by borehole televiewer The ability of the
observed fractures to transmit water was evaluated by packer
tests
The May 198 8 Interim Remedial Investigation Report by
Goldberg-Zoino amp Associates Inc (GZA) (Appendix
Document 38) indicates that the orientations of fractures
indicated on televiewer logs were compiled into a ccmposite
plotted on a stereonet and contoured The contouring
BSR03010 3-2
yielded four preferred fracture orientations thiat -bullere in
agreement with the orientations of lineaments identified jn
the FTA The dominant group had a strike and dip of
N20deg-40degE 60deg-80degNW The lesser groups were at nearly
horizontal N10deg-20degW 50deg-60degSW and N80deg-85degE 65deg-70NW
Because the stereonet plots were not included in the GZA
May 1988 report (Doc 38) CH2M HILL plotted the fracture
orientations provided on the boring log for Borehole
KE87-ML3 This borehole lies near the intersection of
Lineainents 1 and 2 with Lineament 24 Borehole WE87-ML3 is
of particular significance because Lineaments 1 and 2
represent potential pathways for the migration of
containinants to the Scituate Reservoir The orieiitations of
fractures in Borehole WE87-ML3 correspond reasonably vell
with the trends of Lineaments 1 2 and 24
Barbed on televiewer data the average fracture frequency
reported for the five multilevel wells was 072 fractures
per foot Only a very slight decrease in fracture frequency
was noted with depth--08 fractures per foot for the top
30 feet of bedrock 07 fractures per foot for the tpp
100 feet of bedrock and 06 fractures per foot for depths
greater than 100 feet below the top of rock An exception
to this trend that was noted in the GZA May 1988 report
(Doc 38) was Borehole WE87-ML1 in which fracture frequency
increased with depth Equally significant are above-average
fracture frequencies and significant flow measurements over
deep rock intervals (more than 100 feet in each borehole
extending deeper than 100 feet and more than 200 feet in
each borehole extending deeper than 200 feet) The data
suggest that rock fractures and associated water-bearing
zones extend to some unknown distance below the depth
reached by the five multilevel wells
BSR03010 3-3
GEOPHYSICAL INVESTIGATIONS
Geophysical investigations are described in both the
August 1987 report prepared by Geotech Enterprises Inc
(Appendix Document 35) and GZAs May 1988 report (Doc 38)
Thiree geophysical survey methods were used by Geotech to
investigate the vicinity of the Central Landfill The
objectives of the investigations were to locate areas of
rock fracturing and to recommend locations for three
multilevel wells The survey methods investigated gravity
e]ectrical resi^tivity and seismic refraction Each method
vas targeted at a different physical property of the rock
any of which could indicate fracturing
GZAs May 1988 report (Doc 38) summarizes the results of
the geophysical surveys discussed in the Geotech report
(Doc 35) In addition GZAs May 1988 report describes the
results of downhole geophysical logging performed by the
USGS and vertical seismic profiling performed by Weston
Geophysical Corporation
41 GRAVITY
The gravity investigation method measures minute differences
in the Earths gravitational field resulting from rock
density differences Fracturing can result in lover
densities which can often be identified as gravity lovs
Different rock types with different densities also can
result in gravity lows
Regional data indicate a gravity low in the vicinity of the
landfill but it is uncertain whether the low results from a
fracture zone or from the presence of different rock types
BSR03011 4-1
III
of higher donsity on either side of the landfill
Additional gravity measurements obtained in tho vicinity of
the landfill confirm the gravity low and suggest a
northeast-southwest trend to the low that corresponds with
Lincainent 1
The gravity data are dominated by the regional effects of
the denser metamorphic sediments to the east and the buried
pluton to the west In order to minimize the gravity
effects of these features and to emphasize the ]oca]ized
effects of fracture zones CH2M JIILL removed a fourth-order
surface from the data The residual values reflect the
smaller (shorter wavelength) features that are likely to
include fracture zones The resulting residual data were
tlien plotted on a map
Tlie central part of the residual data map showed a gravity
hiyli with sides oriented northeast-southwest The southeast
side of this feature is coincident with Lineament 1 on the
fracture trace map in GZAs May 1988 report (Doc 38)
Central Landfill is located on this feature The residual
gravity high is breached in the vicinity of the landfill
The breach may be associated with other fracture traces
The results of the residual gravity evaluation suggest that
Lineament 1 may be related to a geologic contact
Alternatively Lineament 1 may be at the contact between
fractured rock to the southeast (the gravity low) and
unfractured rock to the northwest The data support the
fracture trace interpretation in the vicinity of the
landfill
BSR0 3011 4-2
42 ELECTRICAL RESISTIVITY
Electrical soundings are used to estimate subsurface
resistivities Fracture zones can affect the resistivities
by increasing hydraulic conductivity In most cases rock
resistivity is controlled by pore fluid conductivity and
porosity
The soundings in the vicinity of the landfill indicated
areas of resistive bedrock (indicating competent rock) and
areas of less resistive bedrock (possibly fractured rock)
For i he most part the more resistive areas are northwest of
Lineltiment 1 and the less resistive bedrock is southeast of
the lineament
The interpreted bedrock resistivities were used with
groundwater specific conductance to calculate a formation
factor A high formation factor suggests competent rock
The variability of groundwater conductivity over short
distances in general and some uncertainty in the estimated
bedrock conductivity in the vicinity of the landfill may
make use of these formation factors questionable
There are no comments in either the GZA May 1988 report
(Doc 38) or the Geotech report (Doc 35) about cultural
conductors such as fences and power lines that may have
affected the data Either there are no cultural conductors
in the area or this potential problem was overlooked
Soundings 4 and 9 may have been affected by nearby cultural
conductors
The observed bedrock resistivities appear lower on the
southeast side of Lineament 1 and higher on the nort)ivest
side This is consistent with Lineament 1 being a geologic
BSR03011 4-3
I
contact or with the fracture density being higher on the
southeast side
43 SEISMIC REFRACTION
Seismic refraction surveys were performed to measure bedrock
velocities in the vicinity of the landfill Bedrock
veJricities may be reduced in areas of fracturing compared
witli the velocities in unfractured areas Refraction
surveys generally were run in the same areas as those in
which the electrical soundings were run Low velocity
bidrock wliich may be related to rock fracturing vas
idntified by the refraction surveys
Because seismic data are very noisy the first arrivals were
not identified properly in some instances Estimated
bedrock velocities are correspondingly uncertain The
bedrock velocity calculated by CH2M HILL for Line S-4
(12100 fps) is approximately 15 percent higher than the
velocity given in the Geotech and GZA reports (10380 fps)
(Doc 35 38) The data for Line S-4 are relatively good
an uncertainty of 15 percent or worse might be typical for
data of this quality
Some of the seismic spreads did not include a shot at each
end of a spread Without data from shots at both ends it
is impossible to determine true bedrock velocities where
dipping beds are present Although seismic refraction is a
valid metliod for identifying fracture zones better-quality
data than those presented in the Geotech and GZA reports
(Doc 35 38) are required
BSR03011 4-4
44 DOWNHOLE GEOPHYSICAL LOGGINC
AND VERTICAL SEISMIC PROFILING
The downhole geophysical logging was performed by the USGS
Division of Water Resources The logging methods and their
associated functions are listed below
Acoustic Borehole Televiewer
Formation Resistivity
Borehole Caliper
Neutron-Gamma
Natural Gamma
Spontaneous Potential
Maps rock fractures using
sonar transmissions
Maps areas of lower
resistivity lhat may be
the result of fracturing
Measures borehole
diameter
Measures formation
porosity but readings are
affected by clay
Measures formation
natural radioactive
emmissions can be
used to identify clay and
was used with the
neutron-gamma data
Used to identify different
strata such as clay and
shale
BSR03011 4-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
RHODE ISLAND SOLID WASTE MANAGEMENT CORPORATION Central Landfill 65 Shun Pike Johnston Rhode island 02919 401 942-1430
1
FAX 401 946-5174
JERROLD L LAVINE Chairman THOMAS E WRIGHT Executive Director
J I
cr q shy ji 1992
shy
February 3 1992
Mr Ed Summerly GZA GeoEnvironmental Inc 14 0 Broadway Providence RI 02903
Dear Mr Summerly
Per your request enclosed is a copy of Evaluation of the Central Landfill and Its Potential Impacts of the Scituate Reservoir prepared for Providence Water Supply Board
If you have any questions please do not hesitate to contact me
Very truly yours
Julie A Jaglowski Environment Engineer
JAJeap
Enclosure
cc Dennis aRusso
100 Recycled Paper
EVALUATION OF THE CENTRAL LANDFILL
AND ITS POTENTIAL IMPACTS ON THE SCITUATE RESERVOIR
Prepared For PROVIDENCE WATER SUPPLY BOARD
Providence Rhode Island
Prepared By CH2M HILL
28 State Street Boston Massachusetts 02109
October 1988 WDC26416A0
BSR03007
Engineers Planners
j T g ^ g Economists ^ i l i i S l S Scientists
October 17 1988
WDC26416AO
Mr Domenic J Mainelli Chief EngineerGeneral Manager Providence Water Supply Board 552 Academy Avenue Providence Rhode Island 02908-2792
Subject Evaluation of the Central Landfill CH2M HILL Project No WDC26416AO
Dear Mr Mainelli
Please find enclosed ten copies of our revised report entitled Evaluation of the Central Landfill and Its Potential Impacts on the Scituate Reservoir
In direct response to your initial questions we offer the following
1 Is there seepage from the [Central] landfill
Yes Because the existing landfill is unlined seepage from the landfill doesoccur This seepage is referred to as leachate
2 What is contained in the seepage
Based on the analyses of water samples obtained from monitoring wells located in and around the landfill the landfill leachate has been found to contain a variety of contaminants including chloride nitrate and sulfate dissolved metals volatile organic compounds and semivolatile organic compounds
3 Is the seepage moving toward the reservoir
Although the existing data are inconclusive the presence of both a surface-water divide and a shallow groundwater divide suggest that movement of groundwater and hence landfill ]oachate from
CH2MHliL Boston Office 28 Stale Sfreet 18th Floor Boston Massachusetts 02109 6175232260
I I Doinenic J M a i n e l l i
4| Page 2 O c t o b e r 17 1988 WDC2 6n6AO
i
m
Pl
the landfill area is not toward either the Scituate Reservoir or the Aqueduct
4 Is the seepage moving toward any other facilities of the board
See response to Question 3
5 If there is seepage what kind of threat does it represent
a To water quality b In what time frame
It is unlikely that seepage from the Central Landshyfill poses any threat to the Scituate Reservoir The landfill does however pose an immediate threat to water quality in the vicinity of the landfill and the receiving bodies of watermdashCedar Swamp Brook Alray Reservoir and Upper Simmons Reservoir
6 If there is no seepage what further actions can be taken to monitor the situation
The existing data are now and will most likely remain inconclusive However deeper wells located between the landfill and the surface-water divide could establish the direction of groundwater movement with greater certainty It is recoirmiended that this additional information be requested of either the Rhode Island Solid Waste Management Corporation or the US EPA the latter of which is conducting the Remedial Investigation Feasibility Study (RIFS) of the Central Landfill Sources of contamination other than the landfill may be posing an even greater threat to the water quality of the Scituate Reservoir Land usage around and within the watershed should be evaluated and consideration should be given to routine groundwater monitoring at selected locations
HI
Mainelli
Page 3 October 17 1988 WDC2 6116AO
D ome n i c
What effect will the current expansion plans of the Solid Waste Management Corporation have on the current situation
The current expansion plans will keep a major portion of the existing landfill open to infiltrashytion throughout the expansion period Unless measures are taken to reduce the amount of infilshytration to the existing fill the discharge cf landfill leachate will continue unabated
Please do not hesitate to contact me if we can be of any further assistance It has been our pleasure to work with you on this project
Very truly yours
rd W Bowers PE esident Manager
BSCG5001
SUMMARY
Significant groundwater contamination has been observed in
monitoring wells located both within the Central Landfill
area and downgradient of the existing fill Piezometric
data suggest that most if not all of the contaminated
groundwater discharges to the following areas Cedar Swamp
Brook which drains to Upper Simmons Reservoir Upper
Simmons Reservoir and Almy Reservoir The vertical and
lateral extent of groundwater contamination has not yet been
completely defined The rates and directions of groundwater
movement can only be inferred from the data that are
currently available
Fracture studies indicate a potential pathway for tlie
migration of groundwater contaminants from the Central
Landfill to Scituate Reservoir At elevation 284 the
spillway elevation of the Scituate Reservoir is well below
the piezometric level of wells located within the Central
Landfill which is at elevations 310 to 380 This
difference in head provides a potential driving mechanism
for the migration of contaminants from the Central Landfill
to Scituate Reservoir However both a surface-water divide
and a shallow groundwater divide are located between the
landfill and Scituate Reservoir Although the existing data
remain inconclusive the presence of these surface and
near-surface features suggests that even at greater depths
movement of groundwater from the landfill area is not toward
the Scituate Reservoir If the movement of groundvater is
away from the landfill it is unlikely that the Central
Landfill has any significant impact on the Scituate
Reservoir
BSR03022
Tlie existing unlined landfill poses a threat to groundvater
quality at the landfill site The proposed landfill
expansion would delay the installation of a final cover over
the entire area By leaving a major portion of the existing
fill uncovered the landfill would generate uncontrolled
leachate throughout the projected expansion
periodmdashapproximately 20 years Other design flaws have
been identified Certain aspects of the expansion plans
require further clarification
Groundwater contamination also has been identified in areas
unrelated to the Central Landfill Contamination probably
also occurs in other areas yet to be identified
Considering the variety of land uses within the watershed
the Providence Water Supply Boards current program of
surface water monitoring should be reevaluated for the
possible inclusion of groundwater monitoring
BSR03022 ii
CONTENTS
Page
Summary i
1 Introduction 1-1
2 Physiography and Drainage 2-1
3 Geology 3-1
4 Geophysical Investigations 4-1 41 Gravity 4-1 42 Electrical Resistivity 4-3 43 Seismic Refraction 4-4 44 Downhole Geophysical Logging
and Vertical Seismic Profiling 4-5
5 Groundwater 5-1 51 Groundwater Occurrence and 5-1
Movement 52 Water Quality 5-3
6 Proposed Landfill Expansion 6-1 61 General Comments on
Overall Design 6-1 62 Specific Comments on Design
Report and Drawings 6-3
7 Conclusions and Recommendations 7-1 71 Hydrogeology 7-1 72 Geophysics 7-4 73 Landfill Design 7-5 74 Groundwater Quality 7-5
A p p e n d i x L i s t of Documents Reviewed
FIGURES
1 Location of Project Within the State of 1-2 Rhode Island
2 Site Map of the Central Landfill 1-3
3 Generalized Cross-Section Along 7-3 NE-SW Trending Lineament 1
BSR03003 iii
INTRODUCTION
The Solid Waste Management Corporation (SWMC) currently
operates the Central Landfill in Johnston Rhode Island
located approximately 2-12 miles east of the Scituate
Reservoir The location of the landfill is shown in the map
presented in Figure 1 The Scituate Reservoir serves as a
water supply for over 60 percent of the population of Rhode
Island The Central Landfill is an unlined municipal
landfill that in the past has received industrial wastes
A permit application for construction of an expansion of the
existing landfill has been submitted to the Rhode Island
Department of Environmental Management (RIDEM) Discharge
of contaminants to groundwater immediately surrounding the
landfill has been documented However the extent of
offsite migration of contaminants is not known
Studies have been conducted to identify the existing and
potsntial impacts of seepage from the landfill on surface
water and groundwater in the vicinity Concern has been
expressed that seepage from the landfill may be endangering
the Scituate Reservoir There is further concern that
expansion of the landfill also may have an impact on the
water supply A site map of the Central Landfill showing
the approximate limit of existing fill and the locations of
all previously installed monitoring wells is presented in
Figure 2
BSR03008 1-1
0 10 M l bull raquo I t I I
Approxiniale Scale
Central Landf i l l
Alrny Reservoir
Simmons Reservoir
Scituate Reservoir
1 Location oT Proiect r^ifiMUIII n Figure I AVlthlnThe State of RhodiJlslana v^fJiVJnU
1-9
Figure 2 Aoproximattt Scale
Slta-Miip 3t i - Cjnt-al Lancrflil cyihL
Ill Tlie Providence Water Supply Board has contracted with CH2M
HILL to perform an evaluation of the data pertaining to the
Central LancJfill The objectives of this study are
Provide an independent review of reports data
drawings and other available information
concerning existing or potential impacts of the
landfill on surface water and groundwater in Using existing data assess whether there is
indeed seepage from the existing landfill and if
so what its impact is on water in the vicinity of
the landfill 111 Assess whether the proposed landfill expansion
will have further impact on surface water and
groundwater
Determine whether seepage from the landfill could m have an impact on Scituate Reservoir
11
mi
m m BSR03008 1-4
li
PHYSIOGRAPHY AND DRAINAGE
Surface topography in the North Scituate Quadrangle is
characterized by northwest-southeast trending uplands and
in intervening valleys The orientation of these surface
features reflects the direction of glacial advance and
concomitant erosion of preglacial soils The orientations
of Oak Swamp Almy and Simmons Reservoirs and portions of
i] Scituate Reservoir are examples of this general
northwest-southeast valley orientation
The active portion of the Central Landfill is located
approximately 2-12 miles east of the Scituate Reservoir
The Central Landfill also occupies an elongate valley The
area has been modified by extensive borrowing and filling
Surface drainage is primarily from the northwest and
southwest The area drains to the east and southeast A
topographic divide which defines the limit of the
watershed lies between the active landfill and the
reservoir A small yet inactive portion of the landfill
property lies within the watershed of the Scituate
Reservoir The active landfill is approximately 5100 feet
from the portion of the watershed boundary that crosses
landfill property
BSR03009 2-1
GEOLOGY
Bedrock in the vicinity of the Central Landfill consists of
granite and granite gneiss and is referenced in the
literature as the Scituate granite Soils overlying the
Scituate granite predominantly consist of glacial till and
glacial outwash The till is an unsorted ground moraine
composed of fine-grained to boulder-sized particles The
outwash varies from poorly sorted materials to well-sorted
ice-contact sands and gravels The soils vary in thickness
from 0 feet in areas that have been excavated to over
60 feet southvest of Cedar Swamp Brook Within the existing
landfill refuse ranges in thickness from 50 feet at Well E
to 135 feet at Well WE87-3 Refuse is in direct contact
with the bedrock over the northern portion of tlie landfill
and is within 5 feet of bedrock over its southern part
Bedrock topography at the landfill is defined by subsurface
investigations associated with the landfill design and the
ongoing remedial investigationfeasibility study (RIFS)
Bedrock topography has been mapped regionally by the
US Geological Survey (USGS) The Central Landfill lies on
the north slope of a bedrock valley with a northwest to
southeast general trend The Upper reach of the bedrock
valley is two prongedmdashnorthwest to southeast and north to
southeast The active landfill overlies most of the latter
Rock quarrying has modified the area along the western slope
of the landfill and in the vicinity of the portion of the
landfill (near Well J) that received industrial wastes
The degree of weathering and Rock Quality Designations
(RQDs) observed in rock core were evaluated with respect to
depth below the top of rock and proximity to fracture
traces The RQD is a measure of the degree to which rock is
BSR03010 3-1
fractured as reflected in the lengths of rock core
reioveries A highly fractured rock will exhibit a low RQD
In general the RQD increased with depth--57 percent for
0 to 10 feet below the top of rock and 77 percent for
10 to 30 feet below the top of rock At boreholes located
in fracture traces however the RQDs were 40 percent and
62 percent respectively indicating a correlation between
the fracture traces observed on both aerial photographs and
satellite imagery and the degree to which the bedrock is
friictured Similarly the degree of weathering was found to
be a function of both depth and proximity to fracture
tl ces Severe veathering was noted throughout
B(U-ehole WE87-13 and to a depth of 45 feet in
Borehole WE85-6 both of which lie along northeast-southwest
trending features It should be noted that observations of
rock weathering and RQDs apply only to boreholes from vhich
rock core was available These boreholes tended to be
relatively shallow extending approximately 30 feet below
the top of rock
Deeper explorations (124 to 247 feet below the top of rock)
were performed in the multilevel wellsmdashWE87-ML1 through
WE87-ML5 The Fracture Trace Analysis (FTA) was used to
position the multilevel wells Each multilevel well was
pllt3ced on or proximal to an observed fracture trace The
degree of fracturing and the orientation of fractures were
evaluated by borehole televiewer The ability of the
observed fractures to transmit water was evaluated by packer
tests
The May 198 8 Interim Remedial Investigation Report by
Goldberg-Zoino amp Associates Inc (GZA) (Appendix
Document 38) indicates that the orientations of fractures
indicated on televiewer logs were compiled into a ccmposite
plotted on a stereonet and contoured The contouring
BSR03010 3-2
yielded four preferred fracture orientations thiat -bullere in
agreement with the orientations of lineaments identified jn
the FTA The dominant group had a strike and dip of
N20deg-40degE 60deg-80degNW The lesser groups were at nearly
horizontal N10deg-20degW 50deg-60degSW and N80deg-85degE 65deg-70NW
Because the stereonet plots were not included in the GZA
May 1988 report (Doc 38) CH2M HILL plotted the fracture
orientations provided on the boring log for Borehole
KE87-ML3 This borehole lies near the intersection of
Lineainents 1 and 2 with Lineament 24 Borehole WE87-ML3 is
of particular significance because Lineaments 1 and 2
represent potential pathways for the migration of
containinants to the Scituate Reservoir The orieiitations of
fractures in Borehole WE87-ML3 correspond reasonably vell
with the trends of Lineaments 1 2 and 24
Barbed on televiewer data the average fracture frequency
reported for the five multilevel wells was 072 fractures
per foot Only a very slight decrease in fracture frequency
was noted with depth--08 fractures per foot for the top
30 feet of bedrock 07 fractures per foot for the tpp
100 feet of bedrock and 06 fractures per foot for depths
greater than 100 feet below the top of rock An exception
to this trend that was noted in the GZA May 1988 report
(Doc 38) was Borehole WE87-ML1 in which fracture frequency
increased with depth Equally significant are above-average
fracture frequencies and significant flow measurements over
deep rock intervals (more than 100 feet in each borehole
extending deeper than 100 feet and more than 200 feet in
each borehole extending deeper than 200 feet) The data
suggest that rock fractures and associated water-bearing
zones extend to some unknown distance below the depth
reached by the five multilevel wells
BSR03010 3-3
GEOPHYSICAL INVESTIGATIONS
Geophysical investigations are described in both the
August 1987 report prepared by Geotech Enterprises Inc
(Appendix Document 35) and GZAs May 1988 report (Doc 38)
Thiree geophysical survey methods were used by Geotech to
investigate the vicinity of the Central Landfill The
objectives of the investigations were to locate areas of
rock fracturing and to recommend locations for three
multilevel wells The survey methods investigated gravity
e]ectrical resi^tivity and seismic refraction Each method
vas targeted at a different physical property of the rock
any of which could indicate fracturing
GZAs May 1988 report (Doc 38) summarizes the results of
the geophysical surveys discussed in the Geotech report
(Doc 35) In addition GZAs May 1988 report describes the
results of downhole geophysical logging performed by the
USGS and vertical seismic profiling performed by Weston
Geophysical Corporation
41 GRAVITY
The gravity investigation method measures minute differences
in the Earths gravitational field resulting from rock
density differences Fracturing can result in lover
densities which can often be identified as gravity lovs
Different rock types with different densities also can
result in gravity lows
Regional data indicate a gravity low in the vicinity of the
landfill but it is uncertain whether the low results from a
fracture zone or from the presence of different rock types
BSR03011 4-1
III
of higher donsity on either side of the landfill
Additional gravity measurements obtained in tho vicinity of
the landfill confirm the gravity low and suggest a
northeast-southwest trend to the low that corresponds with
Lincainent 1
The gravity data are dominated by the regional effects of
the denser metamorphic sediments to the east and the buried
pluton to the west In order to minimize the gravity
effects of these features and to emphasize the ]oca]ized
effects of fracture zones CH2M JIILL removed a fourth-order
surface from the data The residual values reflect the
smaller (shorter wavelength) features that are likely to
include fracture zones The resulting residual data were
tlien plotted on a map
Tlie central part of the residual data map showed a gravity
hiyli with sides oriented northeast-southwest The southeast
side of this feature is coincident with Lineament 1 on the
fracture trace map in GZAs May 1988 report (Doc 38)
Central Landfill is located on this feature The residual
gravity high is breached in the vicinity of the landfill
The breach may be associated with other fracture traces
The results of the residual gravity evaluation suggest that
Lineament 1 may be related to a geologic contact
Alternatively Lineament 1 may be at the contact between
fractured rock to the southeast (the gravity low) and
unfractured rock to the northwest The data support the
fracture trace interpretation in the vicinity of the
landfill
BSR0 3011 4-2
42 ELECTRICAL RESISTIVITY
Electrical soundings are used to estimate subsurface
resistivities Fracture zones can affect the resistivities
by increasing hydraulic conductivity In most cases rock
resistivity is controlled by pore fluid conductivity and
porosity
The soundings in the vicinity of the landfill indicated
areas of resistive bedrock (indicating competent rock) and
areas of less resistive bedrock (possibly fractured rock)
For i he most part the more resistive areas are northwest of
Lineltiment 1 and the less resistive bedrock is southeast of
the lineament
The interpreted bedrock resistivities were used with
groundwater specific conductance to calculate a formation
factor A high formation factor suggests competent rock
The variability of groundwater conductivity over short
distances in general and some uncertainty in the estimated
bedrock conductivity in the vicinity of the landfill may
make use of these formation factors questionable
There are no comments in either the GZA May 1988 report
(Doc 38) or the Geotech report (Doc 35) about cultural
conductors such as fences and power lines that may have
affected the data Either there are no cultural conductors
in the area or this potential problem was overlooked
Soundings 4 and 9 may have been affected by nearby cultural
conductors
The observed bedrock resistivities appear lower on the
southeast side of Lineament 1 and higher on the nort)ivest
side This is consistent with Lineament 1 being a geologic
BSR03011 4-3
I
contact or with the fracture density being higher on the
southeast side
43 SEISMIC REFRACTION
Seismic refraction surveys were performed to measure bedrock
velocities in the vicinity of the landfill Bedrock
veJricities may be reduced in areas of fracturing compared
witli the velocities in unfractured areas Refraction
surveys generally were run in the same areas as those in
which the electrical soundings were run Low velocity
bidrock wliich may be related to rock fracturing vas
idntified by the refraction surveys
Because seismic data are very noisy the first arrivals were
not identified properly in some instances Estimated
bedrock velocities are correspondingly uncertain The
bedrock velocity calculated by CH2M HILL for Line S-4
(12100 fps) is approximately 15 percent higher than the
velocity given in the Geotech and GZA reports (10380 fps)
(Doc 35 38) The data for Line S-4 are relatively good
an uncertainty of 15 percent or worse might be typical for
data of this quality
Some of the seismic spreads did not include a shot at each
end of a spread Without data from shots at both ends it
is impossible to determine true bedrock velocities where
dipping beds are present Although seismic refraction is a
valid metliod for identifying fracture zones better-quality
data than those presented in the Geotech and GZA reports
(Doc 35 38) are required
BSR03011 4-4
44 DOWNHOLE GEOPHYSICAL LOGGINC
AND VERTICAL SEISMIC PROFILING
The downhole geophysical logging was performed by the USGS
Division of Water Resources The logging methods and their
associated functions are listed below
Acoustic Borehole Televiewer
Formation Resistivity
Borehole Caliper
Neutron-Gamma
Natural Gamma
Spontaneous Potential
Maps rock fractures using
sonar transmissions
Maps areas of lower
resistivity lhat may be
the result of fracturing
Measures borehole
diameter
Measures formation
porosity but readings are
affected by clay
Measures formation
natural radioactive
emmissions can be
used to identify clay and
was used with the
neutron-gamma data
Used to identify different
strata such as clay and
shale
BSR03011 4-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
EVALUATION OF THE CENTRAL LANDFILL
AND ITS POTENTIAL IMPACTS ON THE SCITUATE RESERVOIR
Prepared For PROVIDENCE WATER SUPPLY BOARD
Providence Rhode Island
Prepared By CH2M HILL
28 State Street Boston Massachusetts 02109
October 1988 WDC26416A0
BSR03007
Engineers Planners
j T g ^ g Economists ^ i l i i S l S Scientists
October 17 1988
WDC26416AO
Mr Domenic J Mainelli Chief EngineerGeneral Manager Providence Water Supply Board 552 Academy Avenue Providence Rhode Island 02908-2792
Subject Evaluation of the Central Landfill CH2M HILL Project No WDC26416AO
Dear Mr Mainelli
Please find enclosed ten copies of our revised report entitled Evaluation of the Central Landfill and Its Potential Impacts on the Scituate Reservoir
In direct response to your initial questions we offer the following
1 Is there seepage from the [Central] landfill
Yes Because the existing landfill is unlined seepage from the landfill doesoccur This seepage is referred to as leachate
2 What is contained in the seepage
Based on the analyses of water samples obtained from monitoring wells located in and around the landfill the landfill leachate has been found to contain a variety of contaminants including chloride nitrate and sulfate dissolved metals volatile organic compounds and semivolatile organic compounds
3 Is the seepage moving toward the reservoir
Although the existing data are inconclusive the presence of both a surface-water divide and a shallow groundwater divide suggest that movement of groundwater and hence landfill ]oachate from
CH2MHliL Boston Office 28 Stale Sfreet 18th Floor Boston Massachusetts 02109 6175232260
I I Doinenic J M a i n e l l i
4| Page 2 O c t o b e r 17 1988 WDC2 6n6AO
i
m
Pl
the landfill area is not toward either the Scituate Reservoir or the Aqueduct
4 Is the seepage moving toward any other facilities of the board
See response to Question 3
5 If there is seepage what kind of threat does it represent
a To water quality b In what time frame
It is unlikely that seepage from the Central Landshyfill poses any threat to the Scituate Reservoir The landfill does however pose an immediate threat to water quality in the vicinity of the landfill and the receiving bodies of watermdashCedar Swamp Brook Alray Reservoir and Upper Simmons Reservoir
6 If there is no seepage what further actions can be taken to monitor the situation
The existing data are now and will most likely remain inconclusive However deeper wells located between the landfill and the surface-water divide could establish the direction of groundwater movement with greater certainty It is recoirmiended that this additional information be requested of either the Rhode Island Solid Waste Management Corporation or the US EPA the latter of which is conducting the Remedial Investigation Feasibility Study (RIFS) of the Central Landfill Sources of contamination other than the landfill may be posing an even greater threat to the water quality of the Scituate Reservoir Land usage around and within the watershed should be evaluated and consideration should be given to routine groundwater monitoring at selected locations
HI
Mainelli
Page 3 October 17 1988 WDC2 6116AO
D ome n i c
What effect will the current expansion plans of the Solid Waste Management Corporation have on the current situation
The current expansion plans will keep a major portion of the existing landfill open to infiltrashytion throughout the expansion period Unless measures are taken to reduce the amount of infilshytration to the existing fill the discharge cf landfill leachate will continue unabated
Please do not hesitate to contact me if we can be of any further assistance It has been our pleasure to work with you on this project
Very truly yours
rd W Bowers PE esident Manager
BSCG5001
SUMMARY
Significant groundwater contamination has been observed in
monitoring wells located both within the Central Landfill
area and downgradient of the existing fill Piezometric
data suggest that most if not all of the contaminated
groundwater discharges to the following areas Cedar Swamp
Brook which drains to Upper Simmons Reservoir Upper
Simmons Reservoir and Almy Reservoir The vertical and
lateral extent of groundwater contamination has not yet been
completely defined The rates and directions of groundwater
movement can only be inferred from the data that are
currently available
Fracture studies indicate a potential pathway for tlie
migration of groundwater contaminants from the Central
Landfill to Scituate Reservoir At elevation 284 the
spillway elevation of the Scituate Reservoir is well below
the piezometric level of wells located within the Central
Landfill which is at elevations 310 to 380 This
difference in head provides a potential driving mechanism
for the migration of contaminants from the Central Landfill
to Scituate Reservoir However both a surface-water divide
and a shallow groundwater divide are located between the
landfill and Scituate Reservoir Although the existing data
remain inconclusive the presence of these surface and
near-surface features suggests that even at greater depths
movement of groundwater from the landfill area is not toward
the Scituate Reservoir If the movement of groundvater is
away from the landfill it is unlikely that the Central
Landfill has any significant impact on the Scituate
Reservoir
BSR03022
Tlie existing unlined landfill poses a threat to groundvater
quality at the landfill site The proposed landfill
expansion would delay the installation of a final cover over
the entire area By leaving a major portion of the existing
fill uncovered the landfill would generate uncontrolled
leachate throughout the projected expansion
periodmdashapproximately 20 years Other design flaws have
been identified Certain aspects of the expansion plans
require further clarification
Groundwater contamination also has been identified in areas
unrelated to the Central Landfill Contamination probably
also occurs in other areas yet to be identified
Considering the variety of land uses within the watershed
the Providence Water Supply Boards current program of
surface water monitoring should be reevaluated for the
possible inclusion of groundwater monitoring
BSR03022 ii
CONTENTS
Page
Summary i
1 Introduction 1-1
2 Physiography and Drainage 2-1
3 Geology 3-1
4 Geophysical Investigations 4-1 41 Gravity 4-1 42 Electrical Resistivity 4-3 43 Seismic Refraction 4-4 44 Downhole Geophysical Logging
and Vertical Seismic Profiling 4-5
5 Groundwater 5-1 51 Groundwater Occurrence and 5-1
Movement 52 Water Quality 5-3
6 Proposed Landfill Expansion 6-1 61 General Comments on
Overall Design 6-1 62 Specific Comments on Design
Report and Drawings 6-3
7 Conclusions and Recommendations 7-1 71 Hydrogeology 7-1 72 Geophysics 7-4 73 Landfill Design 7-5 74 Groundwater Quality 7-5
A p p e n d i x L i s t of Documents Reviewed
FIGURES
1 Location of Project Within the State of 1-2 Rhode Island
2 Site Map of the Central Landfill 1-3
3 Generalized Cross-Section Along 7-3 NE-SW Trending Lineament 1
BSR03003 iii
INTRODUCTION
The Solid Waste Management Corporation (SWMC) currently
operates the Central Landfill in Johnston Rhode Island
located approximately 2-12 miles east of the Scituate
Reservoir The location of the landfill is shown in the map
presented in Figure 1 The Scituate Reservoir serves as a
water supply for over 60 percent of the population of Rhode
Island The Central Landfill is an unlined municipal
landfill that in the past has received industrial wastes
A permit application for construction of an expansion of the
existing landfill has been submitted to the Rhode Island
Department of Environmental Management (RIDEM) Discharge
of contaminants to groundwater immediately surrounding the
landfill has been documented However the extent of
offsite migration of contaminants is not known
Studies have been conducted to identify the existing and
potsntial impacts of seepage from the landfill on surface
water and groundwater in the vicinity Concern has been
expressed that seepage from the landfill may be endangering
the Scituate Reservoir There is further concern that
expansion of the landfill also may have an impact on the
water supply A site map of the Central Landfill showing
the approximate limit of existing fill and the locations of
all previously installed monitoring wells is presented in
Figure 2
BSR03008 1-1
0 10 M l bull raquo I t I I
Approxiniale Scale
Central Landf i l l
Alrny Reservoir
Simmons Reservoir
Scituate Reservoir
1 Location oT Proiect r^ifiMUIII n Figure I AVlthlnThe State of RhodiJlslana v^fJiVJnU
1-9
Figure 2 Aoproximattt Scale
Slta-Miip 3t i - Cjnt-al Lancrflil cyihL
Ill Tlie Providence Water Supply Board has contracted with CH2M
HILL to perform an evaluation of the data pertaining to the
Central LancJfill The objectives of this study are
Provide an independent review of reports data
drawings and other available information
concerning existing or potential impacts of the
landfill on surface water and groundwater in Using existing data assess whether there is
indeed seepage from the existing landfill and if
so what its impact is on water in the vicinity of
the landfill 111 Assess whether the proposed landfill expansion
will have further impact on surface water and
groundwater
Determine whether seepage from the landfill could m have an impact on Scituate Reservoir
11
mi
m m BSR03008 1-4
li
PHYSIOGRAPHY AND DRAINAGE
Surface topography in the North Scituate Quadrangle is
characterized by northwest-southeast trending uplands and
in intervening valleys The orientation of these surface
features reflects the direction of glacial advance and
concomitant erosion of preglacial soils The orientations
of Oak Swamp Almy and Simmons Reservoirs and portions of
i] Scituate Reservoir are examples of this general
northwest-southeast valley orientation
The active portion of the Central Landfill is located
approximately 2-12 miles east of the Scituate Reservoir
The Central Landfill also occupies an elongate valley The
area has been modified by extensive borrowing and filling
Surface drainage is primarily from the northwest and
southwest The area drains to the east and southeast A
topographic divide which defines the limit of the
watershed lies between the active landfill and the
reservoir A small yet inactive portion of the landfill
property lies within the watershed of the Scituate
Reservoir The active landfill is approximately 5100 feet
from the portion of the watershed boundary that crosses
landfill property
BSR03009 2-1
GEOLOGY
Bedrock in the vicinity of the Central Landfill consists of
granite and granite gneiss and is referenced in the
literature as the Scituate granite Soils overlying the
Scituate granite predominantly consist of glacial till and
glacial outwash The till is an unsorted ground moraine
composed of fine-grained to boulder-sized particles The
outwash varies from poorly sorted materials to well-sorted
ice-contact sands and gravels The soils vary in thickness
from 0 feet in areas that have been excavated to over
60 feet southvest of Cedar Swamp Brook Within the existing
landfill refuse ranges in thickness from 50 feet at Well E
to 135 feet at Well WE87-3 Refuse is in direct contact
with the bedrock over the northern portion of tlie landfill
and is within 5 feet of bedrock over its southern part
Bedrock topography at the landfill is defined by subsurface
investigations associated with the landfill design and the
ongoing remedial investigationfeasibility study (RIFS)
Bedrock topography has been mapped regionally by the
US Geological Survey (USGS) The Central Landfill lies on
the north slope of a bedrock valley with a northwest to
southeast general trend The Upper reach of the bedrock
valley is two prongedmdashnorthwest to southeast and north to
southeast The active landfill overlies most of the latter
Rock quarrying has modified the area along the western slope
of the landfill and in the vicinity of the portion of the
landfill (near Well J) that received industrial wastes
The degree of weathering and Rock Quality Designations
(RQDs) observed in rock core were evaluated with respect to
depth below the top of rock and proximity to fracture
traces The RQD is a measure of the degree to which rock is
BSR03010 3-1
fractured as reflected in the lengths of rock core
reioveries A highly fractured rock will exhibit a low RQD
In general the RQD increased with depth--57 percent for
0 to 10 feet below the top of rock and 77 percent for
10 to 30 feet below the top of rock At boreholes located
in fracture traces however the RQDs were 40 percent and
62 percent respectively indicating a correlation between
the fracture traces observed on both aerial photographs and
satellite imagery and the degree to which the bedrock is
friictured Similarly the degree of weathering was found to
be a function of both depth and proximity to fracture
tl ces Severe veathering was noted throughout
B(U-ehole WE87-13 and to a depth of 45 feet in
Borehole WE85-6 both of which lie along northeast-southwest
trending features It should be noted that observations of
rock weathering and RQDs apply only to boreholes from vhich
rock core was available These boreholes tended to be
relatively shallow extending approximately 30 feet below
the top of rock
Deeper explorations (124 to 247 feet below the top of rock)
were performed in the multilevel wellsmdashWE87-ML1 through
WE87-ML5 The Fracture Trace Analysis (FTA) was used to
position the multilevel wells Each multilevel well was
pllt3ced on or proximal to an observed fracture trace The
degree of fracturing and the orientation of fractures were
evaluated by borehole televiewer The ability of the
observed fractures to transmit water was evaluated by packer
tests
The May 198 8 Interim Remedial Investigation Report by
Goldberg-Zoino amp Associates Inc (GZA) (Appendix
Document 38) indicates that the orientations of fractures
indicated on televiewer logs were compiled into a ccmposite
plotted on a stereonet and contoured The contouring
BSR03010 3-2
yielded four preferred fracture orientations thiat -bullere in
agreement with the orientations of lineaments identified jn
the FTA The dominant group had a strike and dip of
N20deg-40degE 60deg-80degNW The lesser groups were at nearly
horizontal N10deg-20degW 50deg-60degSW and N80deg-85degE 65deg-70NW
Because the stereonet plots were not included in the GZA
May 1988 report (Doc 38) CH2M HILL plotted the fracture
orientations provided on the boring log for Borehole
KE87-ML3 This borehole lies near the intersection of
Lineainents 1 and 2 with Lineament 24 Borehole WE87-ML3 is
of particular significance because Lineaments 1 and 2
represent potential pathways for the migration of
containinants to the Scituate Reservoir The orieiitations of
fractures in Borehole WE87-ML3 correspond reasonably vell
with the trends of Lineaments 1 2 and 24
Barbed on televiewer data the average fracture frequency
reported for the five multilevel wells was 072 fractures
per foot Only a very slight decrease in fracture frequency
was noted with depth--08 fractures per foot for the top
30 feet of bedrock 07 fractures per foot for the tpp
100 feet of bedrock and 06 fractures per foot for depths
greater than 100 feet below the top of rock An exception
to this trend that was noted in the GZA May 1988 report
(Doc 38) was Borehole WE87-ML1 in which fracture frequency
increased with depth Equally significant are above-average
fracture frequencies and significant flow measurements over
deep rock intervals (more than 100 feet in each borehole
extending deeper than 100 feet and more than 200 feet in
each borehole extending deeper than 200 feet) The data
suggest that rock fractures and associated water-bearing
zones extend to some unknown distance below the depth
reached by the five multilevel wells
BSR03010 3-3
GEOPHYSICAL INVESTIGATIONS
Geophysical investigations are described in both the
August 1987 report prepared by Geotech Enterprises Inc
(Appendix Document 35) and GZAs May 1988 report (Doc 38)
Thiree geophysical survey methods were used by Geotech to
investigate the vicinity of the Central Landfill The
objectives of the investigations were to locate areas of
rock fracturing and to recommend locations for three
multilevel wells The survey methods investigated gravity
e]ectrical resi^tivity and seismic refraction Each method
vas targeted at a different physical property of the rock
any of which could indicate fracturing
GZAs May 1988 report (Doc 38) summarizes the results of
the geophysical surveys discussed in the Geotech report
(Doc 35) In addition GZAs May 1988 report describes the
results of downhole geophysical logging performed by the
USGS and vertical seismic profiling performed by Weston
Geophysical Corporation
41 GRAVITY
The gravity investigation method measures minute differences
in the Earths gravitational field resulting from rock
density differences Fracturing can result in lover
densities which can often be identified as gravity lovs
Different rock types with different densities also can
result in gravity lows
Regional data indicate a gravity low in the vicinity of the
landfill but it is uncertain whether the low results from a
fracture zone or from the presence of different rock types
BSR03011 4-1
III
of higher donsity on either side of the landfill
Additional gravity measurements obtained in tho vicinity of
the landfill confirm the gravity low and suggest a
northeast-southwest trend to the low that corresponds with
Lincainent 1
The gravity data are dominated by the regional effects of
the denser metamorphic sediments to the east and the buried
pluton to the west In order to minimize the gravity
effects of these features and to emphasize the ]oca]ized
effects of fracture zones CH2M JIILL removed a fourth-order
surface from the data The residual values reflect the
smaller (shorter wavelength) features that are likely to
include fracture zones The resulting residual data were
tlien plotted on a map
Tlie central part of the residual data map showed a gravity
hiyli with sides oriented northeast-southwest The southeast
side of this feature is coincident with Lineament 1 on the
fracture trace map in GZAs May 1988 report (Doc 38)
Central Landfill is located on this feature The residual
gravity high is breached in the vicinity of the landfill
The breach may be associated with other fracture traces
The results of the residual gravity evaluation suggest that
Lineament 1 may be related to a geologic contact
Alternatively Lineament 1 may be at the contact between
fractured rock to the southeast (the gravity low) and
unfractured rock to the northwest The data support the
fracture trace interpretation in the vicinity of the
landfill
BSR0 3011 4-2
42 ELECTRICAL RESISTIVITY
Electrical soundings are used to estimate subsurface
resistivities Fracture zones can affect the resistivities
by increasing hydraulic conductivity In most cases rock
resistivity is controlled by pore fluid conductivity and
porosity
The soundings in the vicinity of the landfill indicated
areas of resistive bedrock (indicating competent rock) and
areas of less resistive bedrock (possibly fractured rock)
For i he most part the more resistive areas are northwest of
Lineltiment 1 and the less resistive bedrock is southeast of
the lineament
The interpreted bedrock resistivities were used with
groundwater specific conductance to calculate a formation
factor A high formation factor suggests competent rock
The variability of groundwater conductivity over short
distances in general and some uncertainty in the estimated
bedrock conductivity in the vicinity of the landfill may
make use of these formation factors questionable
There are no comments in either the GZA May 1988 report
(Doc 38) or the Geotech report (Doc 35) about cultural
conductors such as fences and power lines that may have
affected the data Either there are no cultural conductors
in the area or this potential problem was overlooked
Soundings 4 and 9 may have been affected by nearby cultural
conductors
The observed bedrock resistivities appear lower on the
southeast side of Lineament 1 and higher on the nort)ivest
side This is consistent with Lineament 1 being a geologic
BSR03011 4-3
I
contact or with the fracture density being higher on the
southeast side
43 SEISMIC REFRACTION
Seismic refraction surveys were performed to measure bedrock
velocities in the vicinity of the landfill Bedrock
veJricities may be reduced in areas of fracturing compared
witli the velocities in unfractured areas Refraction
surveys generally were run in the same areas as those in
which the electrical soundings were run Low velocity
bidrock wliich may be related to rock fracturing vas
idntified by the refraction surveys
Because seismic data are very noisy the first arrivals were
not identified properly in some instances Estimated
bedrock velocities are correspondingly uncertain The
bedrock velocity calculated by CH2M HILL for Line S-4
(12100 fps) is approximately 15 percent higher than the
velocity given in the Geotech and GZA reports (10380 fps)
(Doc 35 38) The data for Line S-4 are relatively good
an uncertainty of 15 percent or worse might be typical for
data of this quality
Some of the seismic spreads did not include a shot at each
end of a spread Without data from shots at both ends it
is impossible to determine true bedrock velocities where
dipping beds are present Although seismic refraction is a
valid metliod for identifying fracture zones better-quality
data than those presented in the Geotech and GZA reports
(Doc 35 38) are required
BSR03011 4-4
44 DOWNHOLE GEOPHYSICAL LOGGINC
AND VERTICAL SEISMIC PROFILING
The downhole geophysical logging was performed by the USGS
Division of Water Resources The logging methods and their
associated functions are listed below
Acoustic Borehole Televiewer
Formation Resistivity
Borehole Caliper
Neutron-Gamma
Natural Gamma
Spontaneous Potential
Maps rock fractures using
sonar transmissions
Maps areas of lower
resistivity lhat may be
the result of fracturing
Measures borehole
diameter
Measures formation
porosity but readings are
affected by clay
Measures formation
natural radioactive
emmissions can be
used to identify clay and
was used with the
neutron-gamma data
Used to identify different
strata such as clay and
shale
BSR03011 4-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
Engineers Planners
j T g ^ g Economists ^ i l i i S l S Scientists
October 17 1988
WDC26416AO
Mr Domenic J Mainelli Chief EngineerGeneral Manager Providence Water Supply Board 552 Academy Avenue Providence Rhode Island 02908-2792
Subject Evaluation of the Central Landfill CH2M HILL Project No WDC26416AO
Dear Mr Mainelli
Please find enclosed ten copies of our revised report entitled Evaluation of the Central Landfill and Its Potential Impacts on the Scituate Reservoir
In direct response to your initial questions we offer the following
1 Is there seepage from the [Central] landfill
Yes Because the existing landfill is unlined seepage from the landfill doesoccur This seepage is referred to as leachate
2 What is contained in the seepage
Based on the analyses of water samples obtained from monitoring wells located in and around the landfill the landfill leachate has been found to contain a variety of contaminants including chloride nitrate and sulfate dissolved metals volatile organic compounds and semivolatile organic compounds
3 Is the seepage moving toward the reservoir
Although the existing data are inconclusive the presence of both a surface-water divide and a shallow groundwater divide suggest that movement of groundwater and hence landfill ]oachate from
CH2MHliL Boston Office 28 Stale Sfreet 18th Floor Boston Massachusetts 02109 6175232260
I I Doinenic J M a i n e l l i
4| Page 2 O c t o b e r 17 1988 WDC2 6n6AO
i
m
Pl
the landfill area is not toward either the Scituate Reservoir or the Aqueduct
4 Is the seepage moving toward any other facilities of the board
See response to Question 3
5 If there is seepage what kind of threat does it represent
a To water quality b In what time frame
It is unlikely that seepage from the Central Landshyfill poses any threat to the Scituate Reservoir The landfill does however pose an immediate threat to water quality in the vicinity of the landfill and the receiving bodies of watermdashCedar Swamp Brook Alray Reservoir and Upper Simmons Reservoir
6 If there is no seepage what further actions can be taken to monitor the situation
The existing data are now and will most likely remain inconclusive However deeper wells located between the landfill and the surface-water divide could establish the direction of groundwater movement with greater certainty It is recoirmiended that this additional information be requested of either the Rhode Island Solid Waste Management Corporation or the US EPA the latter of which is conducting the Remedial Investigation Feasibility Study (RIFS) of the Central Landfill Sources of contamination other than the landfill may be posing an even greater threat to the water quality of the Scituate Reservoir Land usage around and within the watershed should be evaluated and consideration should be given to routine groundwater monitoring at selected locations
HI
Mainelli
Page 3 October 17 1988 WDC2 6116AO
D ome n i c
What effect will the current expansion plans of the Solid Waste Management Corporation have on the current situation
The current expansion plans will keep a major portion of the existing landfill open to infiltrashytion throughout the expansion period Unless measures are taken to reduce the amount of infilshytration to the existing fill the discharge cf landfill leachate will continue unabated
Please do not hesitate to contact me if we can be of any further assistance It has been our pleasure to work with you on this project
Very truly yours
rd W Bowers PE esident Manager
BSCG5001
SUMMARY
Significant groundwater contamination has been observed in
monitoring wells located both within the Central Landfill
area and downgradient of the existing fill Piezometric
data suggest that most if not all of the contaminated
groundwater discharges to the following areas Cedar Swamp
Brook which drains to Upper Simmons Reservoir Upper
Simmons Reservoir and Almy Reservoir The vertical and
lateral extent of groundwater contamination has not yet been
completely defined The rates and directions of groundwater
movement can only be inferred from the data that are
currently available
Fracture studies indicate a potential pathway for tlie
migration of groundwater contaminants from the Central
Landfill to Scituate Reservoir At elevation 284 the
spillway elevation of the Scituate Reservoir is well below
the piezometric level of wells located within the Central
Landfill which is at elevations 310 to 380 This
difference in head provides a potential driving mechanism
for the migration of contaminants from the Central Landfill
to Scituate Reservoir However both a surface-water divide
and a shallow groundwater divide are located between the
landfill and Scituate Reservoir Although the existing data
remain inconclusive the presence of these surface and
near-surface features suggests that even at greater depths
movement of groundwater from the landfill area is not toward
the Scituate Reservoir If the movement of groundvater is
away from the landfill it is unlikely that the Central
Landfill has any significant impact on the Scituate
Reservoir
BSR03022
Tlie existing unlined landfill poses a threat to groundvater
quality at the landfill site The proposed landfill
expansion would delay the installation of a final cover over
the entire area By leaving a major portion of the existing
fill uncovered the landfill would generate uncontrolled
leachate throughout the projected expansion
periodmdashapproximately 20 years Other design flaws have
been identified Certain aspects of the expansion plans
require further clarification
Groundwater contamination also has been identified in areas
unrelated to the Central Landfill Contamination probably
also occurs in other areas yet to be identified
Considering the variety of land uses within the watershed
the Providence Water Supply Boards current program of
surface water monitoring should be reevaluated for the
possible inclusion of groundwater monitoring
BSR03022 ii
CONTENTS
Page
Summary i
1 Introduction 1-1
2 Physiography and Drainage 2-1
3 Geology 3-1
4 Geophysical Investigations 4-1 41 Gravity 4-1 42 Electrical Resistivity 4-3 43 Seismic Refraction 4-4 44 Downhole Geophysical Logging
and Vertical Seismic Profiling 4-5
5 Groundwater 5-1 51 Groundwater Occurrence and 5-1
Movement 52 Water Quality 5-3
6 Proposed Landfill Expansion 6-1 61 General Comments on
Overall Design 6-1 62 Specific Comments on Design
Report and Drawings 6-3
7 Conclusions and Recommendations 7-1 71 Hydrogeology 7-1 72 Geophysics 7-4 73 Landfill Design 7-5 74 Groundwater Quality 7-5
A p p e n d i x L i s t of Documents Reviewed
FIGURES
1 Location of Project Within the State of 1-2 Rhode Island
2 Site Map of the Central Landfill 1-3
3 Generalized Cross-Section Along 7-3 NE-SW Trending Lineament 1
BSR03003 iii
INTRODUCTION
The Solid Waste Management Corporation (SWMC) currently
operates the Central Landfill in Johnston Rhode Island
located approximately 2-12 miles east of the Scituate
Reservoir The location of the landfill is shown in the map
presented in Figure 1 The Scituate Reservoir serves as a
water supply for over 60 percent of the population of Rhode
Island The Central Landfill is an unlined municipal
landfill that in the past has received industrial wastes
A permit application for construction of an expansion of the
existing landfill has been submitted to the Rhode Island
Department of Environmental Management (RIDEM) Discharge
of contaminants to groundwater immediately surrounding the
landfill has been documented However the extent of
offsite migration of contaminants is not known
Studies have been conducted to identify the existing and
potsntial impacts of seepage from the landfill on surface
water and groundwater in the vicinity Concern has been
expressed that seepage from the landfill may be endangering
the Scituate Reservoir There is further concern that
expansion of the landfill also may have an impact on the
water supply A site map of the Central Landfill showing
the approximate limit of existing fill and the locations of
all previously installed monitoring wells is presented in
Figure 2
BSR03008 1-1
0 10 M l bull raquo I t I I
Approxiniale Scale
Central Landf i l l
Alrny Reservoir
Simmons Reservoir
Scituate Reservoir
1 Location oT Proiect r^ifiMUIII n Figure I AVlthlnThe State of RhodiJlslana v^fJiVJnU
1-9
Figure 2 Aoproximattt Scale
Slta-Miip 3t i - Cjnt-al Lancrflil cyihL
Ill Tlie Providence Water Supply Board has contracted with CH2M
HILL to perform an evaluation of the data pertaining to the
Central LancJfill The objectives of this study are
Provide an independent review of reports data
drawings and other available information
concerning existing or potential impacts of the
landfill on surface water and groundwater in Using existing data assess whether there is
indeed seepage from the existing landfill and if
so what its impact is on water in the vicinity of
the landfill 111 Assess whether the proposed landfill expansion
will have further impact on surface water and
groundwater
Determine whether seepage from the landfill could m have an impact on Scituate Reservoir
11
mi
m m BSR03008 1-4
li
PHYSIOGRAPHY AND DRAINAGE
Surface topography in the North Scituate Quadrangle is
characterized by northwest-southeast trending uplands and
in intervening valleys The orientation of these surface
features reflects the direction of glacial advance and
concomitant erosion of preglacial soils The orientations
of Oak Swamp Almy and Simmons Reservoirs and portions of
i] Scituate Reservoir are examples of this general
northwest-southeast valley orientation
The active portion of the Central Landfill is located
approximately 2-12 miles east of the Scituate Reservoir
The Central Landfill also occupies an elongate valley The
area has been modified by extensive borrowing and filling
Surface drainage is primarily from the northwest and
southwest The area drains to the east and southeast A
topographic divide which defines the limit of the
watershed lies between the active landfill and the
reservoir A small yet inactive portion of the landfill
property lies within the watershed of the Scituate
Reservoir The active landfill is approximately 5100 feet
from the portion of the watershed boundary that crosses
landfill property
BSR03009 2-1
GEOLOGY
Bedrock in the vicinity of the Central Landfill consists of
granite and granite gneiss and is referenced in the
literature as the Scituate granite Soils overlying the
Scituate granite predominantly consist of glacial till and
glacial outwash The till is an unsorted ground moraine
composed of fine-grained to boulder-sized particles The
outwash varies from poorly sorted materials to well-sorted
ice-contact sands and gravels The soils vary in thickness
from 0 feet in areas that have been excavated to over
60 feet southvest of Cedar Swamp Brook Within the existing
landfill refuse ranges in thickness from 50 feet at Well E
to 135 feet at Well WE87-3 Refuse is in direct contact
with the bedrock over the northern portion of tlie landfill
and is within 5 feet of bedrock over its southern part
Bedrock topography at the landfill is defined by subsurface
investigations associated with the landfill design and the
ongoing remedial investigationfeasibility study (RIFS)
Bedrock topography has been mapped regionally by the
US Geological Survey (USGS) The Central Landfill lies on
the north slope of a bedrock valley with a northwest to
southeast general trend The Upper reach of the bedrock
valley is two prongedmdashnorthwest to southeast and north to
southeast The active landfill overlies most of the latter
Rock quarrying has modified the area along the western slope
of the landfill and in the vicinity of the portion of the
landfill (near Well J) that received industrial wastes
The degree of weathering and Rock Quality Designations
(RQDs) observed in rock core were evaluated with respect to
depth below the top of rock and proximity to fracture
traces The RQD is a measure of the degree to which rock is
BSR03010 3-1
fractured as reflected in the lengths of rock core
reioveries A highly fractured rock will exhibit a low RQD
In general the RQD increased with depth--57 percent for
0 to 10 feet below the top of rock and 77 percent for
10 to 30 feet below the top of rock At boreholes located
in fracture traces however the RQDs were 40 percent and
62 percent respectively indicating a correlation between
the fracture traces observed on both aerial photographs and
satellite imagery and the degree to which the bedrock is
friictured Similarly the degree of weathering was found to
be a function of both depth and proximity to fracture
tl ces Severe veathering was noted throughout
B(U-ehole WE87-13 and to a depth of 45 feet in
Borehole WE85-6 both of which lie along northeast-southwest
trending features It should be noted that observations of
rock weathering and RQDs apply only to boreholes from vhich
rock core was available These boreholes tended to be
relatively shallow extending approximately 30 feet below
the top of rock
Deeper explorations (124 to 247 feet below the top of rock)
were performed in the multilevel wellsmdashWE87-ML1 through
WE87-ML5 The Fracture Trace Analysis (FTA) was used to
position the multilevel wells Each multilevel well was
pllt3ced on or proximal to an observed fracture trace The
degree of fracturing and the orientation of fractures were
evaluated by borehole televiewer The ability of the
observed fractures to transmit water was evaluated by packer
tests
The May 198 8 Interim Remedial Investigation Report by
Goldberg-Zoino amp Associates Inc (GZA) (Appendix
Document 38) indicates that the orientations of fractures
indicated on televiewer logs were compiled into a ccmposite
plotted on a stereonet and contoured The contouring
BSR03010 3-2
yielded four preferred fracture orientations thiat -bullere in
agreement with the orientations of lineaments identified jn
the FTA The dominant group had a strike and dip of
N20deg-40degE 60deg-80degNW The lesser groups were at nearly
horizontal N10deg-20degW 50deg-60degSW and N80deg-85degE 65deg-70NW
Because the stereonet plots were not included in the GZA
May 1988 report (Doc 38) CH2M HILL plotted the fracture
orientations provided on the boring log for Borehole
KE87-ML3 This borehole lies near the intersection of
Lineainents 1 and 2 with Lineament 24 Borehole WE87-ML3 is
of particular significance because Lineaments 1 and 2
represent potential pathways for the migration of
containinants to the Scituate Reservoir The orieiitations of
fractures in Borehole WE87-ML3 correspond reasonably vell
with the trends of Lineaments 1 2 and 24
Barbed on televiewer data the average fracture frequency
reported for the five multilevel wells was 072 fractures
per foot Only a very slight decrease in fracture frequency
was noted with depth--08 fractures per foot for the top
30 feet of bedrock 07 fractures per foot for the tpp
100 feet of bedrock and 06 fractures per foot for depths
greater than 100 feet below the top of rock An exception
to this trend that was noted in the GZA May 1988 report
(Doc 38) was Borehole WE87-ML1 in which fracture frequency
increased with depth Equally significant are above-average
fracture frequencies and significant flow measurements over
deep rock intervals (more than 100 feet in each borehole
extending deeper than 100 feet and more than 200 feet in
each borehole extending deeper than 200 feet) The data
suggest that rock fractures and associated water-bearing
zones extend to some unknown distance below the depth
reached by the five multilevel wells
BSR03010 3-3
GEOPHYSICAL INVESTIGATIONS
Geophysical investigations are described in both the
August 1987 report prepared by Geotech Enterprises Inc
(Appendix Document 35) and GZAs May 1988 report (Doc 38)
Thiree geophysical survey methods were used by Geotech to
investigate the vicinity of the Central Landfill The
objectives of the investigations were to locate areas of
rock fracturing and to recommend locations for three
multilevel wells The survey methods investigated gravity
e]ectrical resi^tivity and seismic refraction Each method
vas targeted at a different physical property of the rock
any of which could indicate fracturing
GZAs May 1988 report (Doc 38) summarizes the results of
the geophysical surveys discussed in the Geotech report
(Doc 35) In addition GZAs May 1988 report describes the
results of downhole geophysical logging performed by the
USGS and vertical seismic profiling performed by Weston
Geophysical Corporation
41 GRAVITY
The gravity investigation method measures minute differences
in the Earths gravitational field resulting from rock
density differences Fracturing can result in lover
densities which can often be identified as gravity lovs
Different rock types with different densities also can
result in gravity lows
Regional data indicate a gravity low in the vicinity of the
landfill but it is uncertain whether the low results from a
fracture zone or from the presence of different rock types
BSR03011 4-1
III
of higher donsity on either side of the landfill
Additional gravity measurements obtained in tho vicinity of
the landfill confirm the gravity low and suggest a
northeast-southwest trend to the low that corresponds with
Lincainent 1
The gravity data are dominated by the regional effects of
the denser metamorphic sediments to the east and the buried
pluton to the west In order to minimize the gravity
effects of these features and to emphasize the ]oca]ized
effects of fracture zones CH2M JIILL removed a fourth-order
surface from the data The residual values reflect the
smaller (shorter wavelength) features that are likely to
include fracture zones The resulting residual data were
tlien plotted on a map
Tlie central part of the residual data map showed a gravity
hiyli with sides oriented northeast-southwest The southeast
side of this feature is coincident with Lineament 1 on the
fracture trace map in GZAs May 1988 report (Doc 38)
Central Landfill is located on this feature The residual
gravity high is breached in the vicinity of the landfill
The breach may be associated with other fracture traces
The results of the residual gravity evaluation suggest that
Lineament 1 may be related to a geologic contact
Alternatively Lineament 1 may be at the contact between
fractured rock to the southeast (the gravity low) and
unfractured rock to the northwest The data support the
fracture trace interpretation in the vicinity of the
landfill
BSR0 3011 4-2
42 ELECTRICAL RESISTIVITY
Electrical soundings are used to estimate subsurface
resistivities Fracture zones can affect the resistivities
by increasing hydraulic conductivity In most cases rock
resistivity is controlled by pore fluid conductivity and
porosity
The soundings in the vicinity of the landfill indicated
areas of resistive bedrock (indicating competent rock) and
areas of less resistive bedrock (possibly fractured rock)
For i he most part the more resistive areas are northwest of
Lineltiment 1 and the less resistive bedrock is southeast of
the lineament
The interpreted bedrock resistivities were used with
groundwater specific conductance to calculate a formation
factor A high formation factor suggests competent rock
The variability of groundwater conductivity over short
distances in general and some uncertainty in the estimated
bedrock conductivity in the vicinity of the landfill may
make use of these formation factors questionable
There are no comments in either the GZA May 1988 report
(Doc 38) or the Geotech report (Doc 35) about cultural
conductors such as fences and power lines that may have
affected the data Either there are no cultural conductors
in the area or this potential problem was overlooked
Soundings 4 and 9 may have been affected by nearby cultural
conductors
The observed bedrock resistivities appear lower on the
southeast side of Lineament 1 and higher on the nort)ivest
side This is consistent with Lineament 1 being a geologic
BSR03011 4-3
I
contact or with the fracture density being higher on the
southeast side
43 SEISMIC REFRACTION
Seismic refraction surveys were performed to measure bedrock
velocities in the vicinity of the landfill Bedrock
veJricities may be reduced in areas of fracturing compared
witli the velocities in unfractured areas Refraction
surveys generally were run in the same areas as those in
which the electrical soundings were run Low velocity
bidrock wliich may be related to rock fracturing vas
idntified by the refraction surveys
Because seismic data are very noisy the first arrivals were
not identified properly in some instances Estimated
bedrock velocities are correspondingly uncertain The
bedrock velocity calculated by CH2M HILL for Line S-4
(12100 fps) is approximately 15 percent higher than the
velocity given in the Geotech and GZA reports (10380 fps)
(Doc 35 38) The data for Line S-4 are relatively good
an uncertainty of 15 percent or worse might be typical for
data of this quality
Some of the seismic spreads did not include a shot at each
end of a spread Without data from shots at both ends it
is impossible to determine true bedrock velocities where
dipping beds are present Although seismic refraction is a
valid metliod for identifying fracture zones better-quality
data than those presented in the Geotech and GZA reports
(Doc 35 38) are required
BSR03011 4-4
44 DOWNHOLE GEOPHYSICAL LOGGINC
AND VERTICAL SEISMIC PROFILING
The downhole geophysical logging was performed by the USGS
Division of Water Resources The logging methods and their
associated functions are listed below
Acoustic Borehole Televiewer
Formation Resistivity
Borehole Caliper
Neutron-Gamma
Natural Gamma
Spontaneous Potential
Maps rock fractures using
sonar transmissions
Maps areas of lower
resistivity lhat may be
the result of fracturing
Measures borehole
diameter
Measures formation
porosity but readings are
affected by clay
Measures formation
natural radioactive
emmissions can be
used to identify clay and
was used with the
neutron-gamma data
Used to identify different
strata such as clay and
shale
BSR03011 4-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
I I Doinenic J M a i n e l l i
4| Page 2 O c t o b e r 17 1988 WDC2 6n6AO
i
m
Pl
the landfill area is not toward either the Scituate Reservoir or the Aqueduct
4 Is the seepage moving toward any other facilities of the board
See response to Question 3
5 If there is seepage what kind of threat does it represent
a To water quality b In what time frame
It is unlikely that seepage from the Central Landshyfill poses any threat to the Scituate Reservoir The landfill does however pose an immediate threat to water quality in the vicinity of the landfill and the receiving bodies of watermdashCedar Swamp Brook Alray Reservoir and Upper Simmons Reservoir
6 If there is no seepage what further actions can be taken to monitor the situation
The existing data are now and will most likely remain inconclusive However deeper wells located between the landfill and the surface-water divide could establish the direction of groundwater movement with greater certainty It is recoirmiended that this additional information be requested of either the Rhode Island Solid Waste Management Corporation or the US EPA the latter of which is conducting the Remedial Investigation Feasibility Study (RIFS) of the Central Landfill Sources of contamination other than the landfill may be posing an even greater threat to the water quality of the Scituate Reservoir Land usage around and within the watershed should be evaluated and consideration should be given to routine groundwater monitoring at selected locations
HI
Mainelli
Page 3 October 17 1988 WDC2 6116AO
D ome n i c
What effect will the current expansion plans of the Solid Waste Management Corporation have on the current situation
The current expansion plans will keep a major portion of the existing landfill open to infiltrashytion throughout the expansion period Unless measures are taken to reduce the amount of infilshytration to the existing fill the discharge cf landfill leachate will continue unabated
Please do not hesitate to contact me if we can be of any further assistance It has been our pleasure to work with you on this project
Very truly yours
rd W Bowers PE esident Manager
BSCG5001
SUMMARY
Significant groundwater contamination has been observed in
monitoring wells located both within the Central Landfill
area and downgradient of the existing fill Piezometric
data suggest that most if not all of the contaminated
groundwater discharges to the following areas Cedar Swamp
Brook which drains to Upper Simmons Reservoir Upper
Simmons Reservoir and Almy Reservoir The vertical and
lateral extent of groundwater contamination has not yet been
completely defined The rates and directions of groundwater
movement can only be inferred from the data that are
currently available
Fracture studies indicate a potential pathway for tlie
migration of groundwater contaminants from the Central
Landfill to Scituate Reservoir At elevation 284 the
spillway elevation of the Scituate Reservoir is well below
the piezometric level of wells located within the Central
Landfill which is at elevations 310 to 380 This
difference in head provides a potential driving mechanism
for the migration of contaminants from the Central Landfill
to Scituate Reservoir However both a surface-water divide
and a shallow groundwater divide are located between the
landfill and Scituate Reservoir Although the existing data
remain inconclusive the presence of these surface and
near-surface features suggests that even at greater depths
movement of groundwater from the landfill area is not toward
the Scituate Reservoir If the movement of groundvater is
away from the landfill it is unlikely that the Central
Landfill has any significant impact on the Scituate
Reservoir
BSR03022
Tlie existing unlined landfill poses a threat to groundvater
quality at the landfill site The proposed landfill
expansion would delay the installation of a final cover over
the entire area By leaving a major portion of the existing
fill uncovered the landfill would generate uncontrolled
leachate throughout the projected expansion
periodmdashapproximately 20 years Other design flaws have
been identified Certain aspects of the expansion plans
require further clarification
Groundwater contamination also has been identified in areas
unrelated to the Central Landfill Contamination probably
also occurs in other areas yet to be identified
Considering the variety of land uses within the watershed
the Providence Water Supply Boards current program of
surface water monitoring should be reevaluated for the
possible inclusion of groundwater monitoring
BSR03022 ii
CONTENTS
Page
Summary i
1 Introduction 1-1
2 Physiography and Drainage 2-1
3 Geology 3-1
4 Geophysical Investigations 4-1 41 Gravity 4-1 42 Electrical Resistivity 4-3 43 Seismic Refraction 4-4 44 Downhole Geophysical Logging
and Vertical Seismic Profiling 4-5
5 Groundwater 5-1 51 Groundwater Occurrence and 5-1
Movement 52 Water Quality 5-3
6 Proposed Landfill Expansion 6-1 61 General Comments on
Overall Design 6-1 62 Specific Comments on Design
Report and Drawings 6-3
7 Conclusions and Recommendations 7-1 71 Hydrogeology 7-1 72 Geophysics 7-4 73 Landfill Design 7-5 74 Groundwater Quality 7-5
A p p e n d i x L i s t of Documents Reviewed
FIGURES
1 Location of Project Within the State of 1-2 Rhode Island
2 Site Map of the Central Landfill 1-3
3 Generalized Cross-Section Along 7-3 NE-SW Trending Lineament 1
BSR03003 iii
INTRODUCTION
The Solid Waste Management Corporation (SWMC) currently
operates the Central Landfill in Johnston Rhode Island
located approximately 2-12 miles east of the Scituate
Reservoir The location of the landfill is shown in the map
presented in Figure 1 The Scituate Reservoir serves as a
water supply for over 60 percent of the population of Rhode
Island The Central Landfill is an unlined municipal
landfill that in the past has received industrial wastes
A permit application for construction of an expansion of the
existing landfill has been submitted to the Rhode Island
Department of Environmental Management (RIDEM) Discharge
of contaminants to groundwater immediately surrounding the
landfill has been documented However the extent of
offsite migration of contaminants is not known
Studies have been conducted to identify the existing and
potsntial impacts of seepage from the landfill on surface
water and groundwater in the vicinity Concern has been
expressed that seepage from the landfill may be endangering
the Scituate Reservoir There is further concern that
expansion of the landfill also may have an impact on the
water supply A site map of the Central Landfill showing
the approximate limit of existing fill and the locations of
all previously installed monitoring wells is presented in
Figure 2
BSR03008 1-1
0 10 M l bull raquo I t I I
Approxiniale Scale
Central Landf i l l
Alrny Reservoir
Simmons Reservoir
Scituate Reservoir
1 Location oT Proiect r^ifiMUIII n Figure I AVlthlnThe State of RhodiJlslana v^fJiVJnU
1-9
Figure 2 Aoproximattt Scale
Slta-Miip 3t i - Cjnt-al Lancrflil cyihL
Ill Tlie Providence Water Supply Board has contracted with CH2M
HILL to perform an evaluation of the data pertaining to the
Central LancJfill The objectives of this study are
Provide an independent review of reports data
drawings and other available information
concerning existing or potential impacts of the
landfill on surface water and groundwater in Using existing data assess whether there is
indeed seepage from the existing landfill and if
so what its impact is on water in the vicinity of
the landfill 111 Assess whether the proposed landfill expansion
will have further impact on surface water and
groundwater
Determine whether seepage from the landfill could m have an impact on Scituate Reservoir
11
mi
m m BSR03008 1-4
li
PHYSIOGRAPHY AND DRAINAGE
Surface topography in the North Scituate Quadrangle is
characterized by northwest-southeast trending uplands and
in intervening valleys The orientation of these surface
features reflects the direction of glacial advance and
concomitant erosion of preglacial soils The orientations
of Oak Swamp Almy and Simmons Reservoirs and portions of
i] Scituate Reservoir are examples of this general
northwest-southeast valley orientation
The active portion of the Central Landfill is located
approximately 2-12 miles east of the Scituate Reservoir
The Central Landfill also occupies an elongate valley The
area has been modified by extensive borrowing and filling
Surface drainage is primarily from the northwest and
southwest The area drains to the east and southeast A
topographic divide which defines the limit of the
watershed lies between the active landfill and the
reservoir A small yet inactive portion of the landfill
property lies within the watershed of the Scituate
Reservoir The active landfill is approximately 5100 feet
from the portion of the watershed boundary that crosses
landfill property
BSR03009 2-1
GEOLOGY
Bedrock in the vicinity of the Central Landfill consists of
granite and granite gneiss and is referenced in the
literature as the Scituate granite Soils overlying the
Scituate granite predominantly consist of glacial till and
glacial outwash The till is an unsorted ground moraine
composed of fine-grained to boulder-sized particles The
outwash varies from poorly sorted materials to well-sorted
ice-contact sands and gravels The soils vary in thickness
from 0 feet in areas that have been excavated to over
60 feet southvest of Cedar Swamp Brook Within the existing
landfill refuse ranges in thickness from 50 feet at Well E
to 135 feet at Well WE87-3 Refuse is in direct contact
with the bedrock over the northern portion of tlie landfill
and is within 5 feet of bedrock over its southern part
Bedrock topography at the landfill is defined by subsurface
investigations associated with the landfill design and the
ongoing remedial investigationfeasibility study (RIFS)
Bedrock topography has been mapped regionally by the
US Geological Survey (USGS) The Central Landfill lies on
the north slope of a bedrock valley with a northwest to
southeast general trend The Upper reach of the bedrock
valley is two prongedmdashnorthwest to southeast and north to
southeast The active landfill overlies most of the latter
Rock quarrying has modified the area along the western slope
of the landfill and in the vicinity of the portion of the
landfill (near Well J) that received industrial wastes
The degree of weathering and Rock Quality Designations
(RQDs) observed in rock core were evaluated with respect to
depth below the top of rock and proximity to fracture
traces The RQD is a measure of the degree to which rock is
BSR03010 3-1
fractured as reflected in the lengths of rock core
reioveries A highly fractured rock will exhibit a low RQD
In general the RQD increased with depth--57 percent for
0 to 10 feet below the top of rock and 77 percent for
10 to 30 feet below the top of rock At boreholes located
in fracture traces however the RQDs were 40 percent and
62 percent respectively indicating a correlation between
the fracture traces observed on both aerial photographs and
satellite imagery and the degree to which the bedrock is
friictured Similarly the degree of weathering was found to
be a function of both depth and proximity to fracture
tl ces Severe veathering was noted throughout
B(U-ehole WE87-13 and to a depth of 45 feet in
Borehole WE85-6 both of which lie along northeast-southwest
trending features It should be noted that observations of
rock weathering and RQDs apply only to boreholes from vhich
rock core was available These boreholes tended to be
relatively shallow extending approximately 30 feet below
the top of rock
Deeper explorations (124 to 247 feet below the top of rock)
were performed in the multilevel wellsmdashWE87-ML1 through
WE87-ML5 The Fracture Trace Analysis (FTA) was used to
position the multilevel wells Each multilevel well was
pllt3ced on or proximal to an observed fracture trace The
degree of fracturing and the orientation of fractures were
evaluated by borehole televiewer The ability of the
observed fractures to transmit water was evaluated by packer
tests
The May 198 8 Interim Remedial Investigation Report by
Goldberg-Zoino amp Associates Inc (GZA) (Appendix
Document 38) indicates that the orientations of fractures
indicated on televiewer logs were compiled into a ccmposite
plotted on a stereonet and contoured The contouring
BSR03010 3-2
yielded four preferred fracture orientations thiat -bullere in
agreement with the orientations of lineaments identified jn
the FTA The dominant group had a strike and dip of
N20deg-40degE 60deg-80degNW The lesser groups were at nearly
horizontal N10deg-20degW 50deg-60degSW and N80deg-85degE 65deg-70NW
Because the stereonet plots were not included in the GZA
May 1988 report (Doc 38) CH2M HILL plotted the fracture
orientations provided on the boring log for Borehole
KE87-ML3 This borehole lies near the intersection of
Lineainents 1 and 2 with Lineament 24 Borehole WE87-ML3 is
of particular significance because Lineaments 1 and 2
represent potential pathways for the migration of
containinants to the Scituate Reservoir The orieiitations of
fractures in Borehole WE87-ML3 correspond reasonably vell
with the trends of Lineaments 1 2 and 24
Barbed on televiewer data the average fracture frequency
reported for the five multilevel wells was 072 fractures
per foot Only a very slight decrease in fracture frequency
was noted with depth--08 fractures per foot for the top
30 feet of bedrock 07 fractures per foot for the tpp
100 feet of bedrock and 06 fractures per foot for depths
greater than 100 feet below the top of rock An exception
to this trend that was noted in the GZA May 1988 report
(Doc 38) was Borehole WE87-ML1 in which fracture frequency
increased with depth Equally significant are above-average
fracture frequencies and significant flow measurements over
deep rock intervals (more than 100 feet in each borehole
extending deeper than 100 feet and more than 200 feet in
each borehole extending deeper than 200 feet) The data
suggest that rock fractures and associated water-bearing
zones extend to some unknown distance below the depth
reached by the five multilevel wells
BSR03010 3-3
GEOPHYSICAL INVESTIGATIONS
Geophysical investigations are described in both the
August 1987 report prepared by Geotech Enterprises Inc
(Appendix Document 35) and GZAs May 1988 report (Doc 38)
Thiree geophysical survey methods were used by Geotech to
investigate the vicinity of the Central Landfill The
objectives of the investigations were to locate areas of
rock fracturing and to recommend locations for three
multilevel wells The survey methods investigated gravity
e]ectrical resi^tivity and seismic refraction Each method
vas targeted at a different physical property of the rock
any of which could indicate fracturing
GZAs May 1988 report (Doc 38) summarizes the results of
the geophysical surveys discussed in the Geotech report
(Doc 35) In addition GZAs May 1988 report describes the
results of downhole geophysical logging performed by the
USGS and vertical seismic profiling performed by Weston
Geophysical Corporation
41 GRAVITY
The gravity investigation method measures minute differences
in the Earths gravitational field resulting from rock
density differences Fracturing can result in lover
densities which can often be identified as gravity lovs
Different rock types with different densities also can
result in gravity lows
Regional data indicate a gravity low in the vicinity of the
landfill but it is uncertain whether the low results from a
fracture zone or from the presence of different rock types
BSR03011 4-1
III
of higher donsity on either side of the landfill
Additional gravity measurements obtained in tho vicinity of
the landfill confirm the gravity low and suggest a
northeast-southwest trend to the low that corresponds with
Lincainent 1
The gravity data are dominated by the regional effects of
the denser metamorphic sediments to the east and the buried
pluton to the west In order to minimize the gravity
effects of these features and to emphasize the ]oca]ized
effects of fracture zones CH2M JIILL removed a fourth-order
surface from the data The residual values reflect the
smaller (shorter wavelength) features that are likely to
include fracture zones The resulting residual data were
tlien plotted on a map
Tlie central part of the residual data map showed a gravity
hiyli with sides oriented northeast-southwest The southeast
side of this feature is coincident with Lineament 1 on the
fracture trace map in GZAs May 1988 report (Doc 38)
Central Landfill is located on this feature The residual
gravity high is breached in the vicinity of the landfill
The breach may be associated with other fracture traces
The results of the residual gravity evaluation suggest that
Lineament 1 may be related to a geologic contact
Alternatively Lineament 1 may be at the contact between
fractured rock to the southeast (the gravity low) and
unfractured rock to the northwest The data support the
fracture trace interpretation in the vicinity of the
landfill
BSR0 3011 4-2
42 ELECTRICAL RESISTIVITY
Electrical soundings are used to estimate subsurface
resistivities Fracture zones can affect the resistivities
by increasing hydraulic conductivity In most cases rock
resistivity is controlled by pore fluid conductivity and
porosity
The soundings in the vicinity of the landfill indicated
areas of resistive bedrock (indicating competent rock) and
areas of less resistive bedrock (possibly fractured rock)
For i he most part the more resistive areas are northwest of
Lineltiment 1 and the less resistive bedrock is southeast of
the lineament
The interpreted bedrock resistivities were used with
groundwater specific conductance to calculate a formation
factor A high formation factor suggests competent rock
The variability of groundwater conductivity over short
distances in general and some uncertainty in the estimated
bedrock conductivity in the vicinity of the landfill may
make use of these formation factors questionable
There are no comments in either the GZA May 1988 report
(Doc 38) or the Geotech report (Doc 35) about cultural
conductors such as fences and power lines that may have
affected the data Either there are no cultural conductors
in the area or this potential problem was overlooked
Soundings 4 and 9 may have been affected by nearby cultural
conductors
The observed bedrock resistivities appear lower on the
southeast side of Lineament 1 and higher on the nort)ivest
side This is consistent with Lineament 1 being a geologic
BSR03011 4-3
I
contact or with the fracture density being higher on the
southeast side
43 SEISMIC REFRACTION
Seismic refraction surveys were performed to measure bedrock
velocities in the vicinity of the landfill Bedrock
veJricities may be reduced in areas of fracturing compared
witli the velocities in unfractured areas Refraction
surveys generally were run in the same areas as those in
which the electrical soundings were run Low velocity
bidrock wliich may be related to rock fracturing vas
idntified by the refraction surveys
Because seismic data are very noisy the first arrivals were
not identified properly in some instances Estimated
bedrock velocities are correspondingly uncertain The
bedrock velocity calculated by CH2M HILL for Line S-4
(12100 fps) is approximately 15 percent higher than the
velocity given in the Geotech and GZA reports (10380 fps)
(Doc 35 38) The data for Line S-4 are relatively good
an uncertainty of 15 percent or worse might be typical for
data of this quality
Some of the seismic spreads did not include a shot at each
end of a spread Without data from shots at both ends it
is impossible to determine true bedrock velocities where
dipping beds are present Although seismic refraction is a
valid metliod for identifying fracture zones better-quality
data than those presented in the Geotech and GZA reports
(Doc 35 38) are required
BSR03011 4-4
44 DOWNHOLE GEOPHYSICAL LOGGINC
AND VERTICAL SEISMIC PROFILING
The downhole geophysical logging was performed by the USGS
Division of Water Resources The logging methods and their
associated functions are listed below
Acoustic Borehole Televiewer
Formation Resistivity
Borehole Caliper
Neutron-Gamma
Natural Gamma
Spontaneous Potential
Maps rock fractures using
sonar transmissions
Maps areas of lower
resistivity lhat may be
the result of fracturing
Measures borehole
diameter
Measures formation
porosity but readings are
affected by clay
Measures formation
natural radioactive
emmissions can be
used to identify clay and
was used with the
neutron-gamma data
Used to identify different
strata such as clay and
shale
BSR03011 4-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
Mainelli
Page 3 October 17 1988 WDC2 6116AO
D ome n i c
What effect will the current expansion plans of the Solid Waste Management Corporation have on the current situation
The current expansion plans will keep a major portion of the existing landfill open to infiltrashytion throughout the expansion period Unless measures are taken to reduce the amount of infilshytration to the existing fill the discharge cf landfill leachate will continue unabated
Please do not hesitate to contact me if we can be of any further assistance It has been our pleasure to work with you on this project
Very truly yours
rd W Bowers PE esident Manager
BSCG5001
SUMMARY
Significant groundwater contamination has been observed in
monitoring wells located both within the Central Landfill
area and downgradient of the existing fill Piezometric
data suggest that most if not all of the contaminated
groundwater discharges to the following areas Cedar Swamp
Brook which drains to Upper Simmons Reservoir Upper
Simmons Reservoir and Almy Reservoir The vertical and
lateral extent of groundwater contamination has not yet been
completely defined The rates and directions of groundwater
movement can only be inferred from the data that are
currently available
Fracture studies indicate a potential pathway for tlie
migration of groundwater contaminants from the Central
Landfill to Scituate Reservoir At elevation 284 the
spillway elevation of the Scituate Reservoir is well below
the piezometric level of wells located within the Central
Landfill which is at elevations 310 to 380 This
difference in head provides a potential driving mechanism
for the migration of contaminants from the Central Landfill
to Scituate Reservoir However both a surface-water divide
and a shallow groundwater divide are located between the
landfill and Scituate Reservoir Although the existing data
remain inconclusive the presence of these surface and
near-surface features suggests that even at greater depths
movement of groundwater from the landfill area is not toward
the Scituate Reservoir If the movement of groundvater is
away from the landfill it is unlikely that the Central
Landfill has any significant impact on the Scituate
Reservoir
BSR03022
Tlie existing unlined landfill poses a threat to groundvater
quality at the landfill site The proposed landfill
expansion would delay the installation of a final cover over
the entire area By leaving a major portion of the existing
fill uncovered the landfill would generate uncontrolled
leachate throughout the projected expansion
periodmdashapproximately 20 years Other design flaws have
been identified Certain aspects of the expansion plans
require further clarification
Groundwater contamination also has been identified in areas
unrelated to the Central Landfill Contamination probably
also occurs in other areas yet to be identified
Considering the variety of land uses within the watershed
the Providence Water Supply Boards current program of
surface water monitoring should be reevaluated for the
possible inclusion of groundwater monitoring
BSR03022 ii
CONTENTS
Page
Summary i
1 Introduction 1-1
2 Physiography and Drainage 2-1
3 Geology 3-1
4 Geophysical Investigations 4-1 41 Gravity 4-1 42 Electrical Resistivity 4-3 43 Seismic Refraction 4-4 44 Downhole Geophysical Logging
and Vertical Seismic Profiling 4-5
5 Groundwater 5-1 51 Groundwater Occurrence and 5-1
Movement 52 Water Quality 5-3
6 Proposed Landfill Expansion 6-1 61 General Comments on
Overall Design 6-1 62 Specific Comments on Design
Report and Drawings 6-3
7 Conclusions and Recommendations 7-1 71 Hydrogeology 7-1 72 Geophysics 7-4 73 Landfill Design 7-5 74 Groundwater Quality 7-5
A p p e n d i x L i s t of Documents Reviewed
FIGURES
1 Location of Project Within the State of 1-2 Rhode Island
2 Site Map of the Central Landfill 1-3
3 Generalized Cross-Section Along 7-3 NE-SW Trending Lineament 1
BSR03003 iii
INTRODUCTION
The Solid Waste Management Corporation (SWMC) currently
operates the Central Landfill in Johnston Rhode Island
located approximately 2-12 miles east of the Scituate
Reservoir The location of the landfill is shown in the map
presented in Figure 1 The Scituate Reservoir serves as a
water supply for over 60 percent of the population of Rhode
Island The Central Landfill is an unlined municipal
landfill that in the past has received industrial wastes
A permit application for construction of an expansion of the
existing landfill has been submitted to the Rhode Island
Department of Environmental Management (RIDEM) Discharge
of contaminants to groundwater immediately surrounding the
landfill has been documented However the extent of
offsite migration of contaminants is not known
Studies have been conducted to identify the existing and
potsntial impacts of seepage from the landfill on surface
water and groundwater in the vicinity Concern has been
expressed that seepage from the landfill may be endangering
the Scituate Reservoir There is further concern that
expansion of the landfill also may have an impact on the
water supply A site map of the Central Landfill showing
the approximate limit of existing fill and the locations of
all previously installed monitoring wells is presented in
Figure 2
BSR03008 1-1
0 10 M l bull raquo I t I I
Approxiniale Scale
Central Landf i l l
Alrny Reservoir
Simmons Reservoir
Scituate Reservoir
1 Location oT Proiect r^ifiMUIII n Figure I AVlthlnThe State of RhodiJlslana v^fJiVJnU
1-9
Figure 2 Aoproximattt Scale
Slta-Miip 3t i - Cjnt-al Lancrflil cyihL
Ill Tlie Providence Water Supply Board has contracted with CH2M
HILL to perform an evaluation of the data pertaining to the
Central LancJfill The objectives of this study are
Provide an independent review of reports data
drawings and other available information
concerning existing or potential impacts of the
landfill on surface water and groundwater in Using existing data assess whether there is
indeed seepage from the existing landfill and if
so what its impact is on water in the vicinity of
the landfill 111 Assess whether the proposed landfill expansion
will have further impact on surface water and
groundwater
Determine whether seepage from the landfill could m have an impact on Scituate Reservoir
11
mi
m m BSR03008 1-4
li
PHYSIOGRAPHY AND DRAINAGE
Surface topography in the North Scituate Quadrangle is
characterized by northwest-southeast trending uplands and
in intervening valleys The orientation of these surface
features reflects the direction of glacial advance and
concomitant erosion of preglacial soils The orientations
of Oak Swamp Almy and Simmons Reservoirs and portions of
i] Scituate Reservoir are examples of this general
northwest-southeast valley orientation
The active portion of the Central Landfill is located
approximately 2-12 miles east of the Scituate Reservoir
The Central Landfill also occupies an elongate valley The
area has been modified by extensive borrowing and filling
Surface drainage is primarily from the northwest and
southwest The area drains to the east and southeast A
topographic divide which defines the limit of the
watershed lies between the active landfill and the
reservoir A small yet inactive portion of the landfill
property lies within the watershed of the Scituate
Reservoir The active landfill is approximately 5100 feet
from the portion of the watershed boundary that crosses
landfill property
BSR03009 2-1
GEOLOGY
Bedrock in the vicinity of the Central Landfill consists of
granite and granite gneiss and is referenced in the
literature as the Scituate granite Soils overlying the
Scituate granite predominantly consist of glacial till and
glacial outwash The till is an unsorted ground moraine
composed of fine-grained to boulder-sized particles The
outwash varies from poorly sorted materials to well-sorted
ice-contact sands and gravels The soils vary in thickness
from 0 feet in areas that have been excavated to over
60 feet southvest of Cedar Swamp Brook Within the existing
landfill refuse ranges in thickness from 50 feet at Well E
to 135 feet at Well WE87-3 Refuse is in direct contact
with the bedrock over the northern portion of tlie landfill
and is within 5 feet of bedrock over its southern part
Bedrock topography at the landfill is defined by subsurface
investigations associated with the landfill design and the
ongoing remedial investigationfeasibility study (RIFS)
Bedrock topography has been mapped regionally by the
US Geological Survey (USGS) The Central Landfill lies on
the north slope of a bedrock valley with a northwest to
southeast general trend The Upper reach of the bedrock
valley is two prongedmdashnorthwest to southeast and north to
southeast The active landfill overlies most of the latter
Rock quarrying has modified the area along the western slope
of the landfill and in the vicinity of the portion of the
landfill (near Well J) that received industrial wastes
The degree of weathering and Rock Quality Designations
(RQDs) observed in rock core were evaluated with respect to
depth below the top of rock and proximity to fracture
traces The RQD is a measure of the degree to which rock is
BSR03010 3-1
fractured as reflected in the lengths of rock core
reioveries A highly fractured rock will exhibit a low RQD
In general the RQD increased with depth--57 percent for
0 to 10 feet below the top of rock and 77 percent for
10 to 30 feet below the top of rock At boreholes located
in fracture traces however the RQDs were 40 percent and
62 percent respectively indicating a correlation between
the fracture traces observed on both aerial photographs and
satellite imagery and the degree to which the bedrock is
friictured Similarly the degree of weathering was found to
be a function of both depth and proximity to fracture
tl ces Severe veathering was noted throughout
B(U-ehole WE87-13 and to a depth of 45 feet in
Borehole WE85-6 both of which lie along northeast-southwest
trending features It should be noted that observations of
rock weathering and RQDs apply only to boreholes from vhich
rock core was available These boreholes tended to be
relatively shallow extending approximately 30 feet below
the top of rock
Deeper explorations (124 to 247 feet below the top of rock)
were performed in the multilevel wellsmdashWE87-ML1 through
WE87-ML5 The Fracture Trace Analysis (FTA) was used to
position the multilevel wells Each multilevel well was
pllt3ced on or proximal to an observed fracture trace The
degree of fracturing and the orientation of fractures were
evaluated by borehole televiewer The ability of the
observed fractures to transmit water was evaluated by packer
tests
The May 198 8 Interim Remedial Investigation Report by
Goldberg-Zoino amp Associates Inc (GZA) (Appendix
Document 38) indicates that the orientations of fractures
indicated on televiewer logs were compiled into a ccmposite
plotted on a stereonet and contoured The contouring
BSR03010 3-2
yielded four preferred fracture orientations thiat -bullere in
agreement with the orientations of lineaments identified jn
the FTA The dominant group had a strike and dip of
N20deg-40degE 60deg-80degNW The lesser groups were at nearly
horizontal N10deg-20degW 50deg-60degSW and N80deg-85degE 65deg-70NW
Because the stereonet plots were not included in the GZA
May 1988 report (Doc 38) CH2M HILL plotted the fracture
orientations provided on the boring log for Borehole
KE87-ML3 This borehole lies near the intersection of
Lineainents 1 and 2 with Lineament 24 Borehole WE87-ML3 is
of particular significance because Lineaments 1 and 2
represent potential pathways for the migration of
containinants to the Scituate Reservoir The orieiitations of
fractures in Borehole WE87-ML3 correspond reasonably vell
with the trends of Lineaments 1 2 and 24
Barbed on televiewer data the average fracture frequency
reported for the five multilevel wells was 072 fractures
per foot Only a very slight decrease in fracture frequency
was noted with depth--08 fractures per foot for the top
30 feet of bedrock 07 fractures per foot for the tpp
100 feet of bedrock and 06 fractures per foot for depths
greater than 100 feet below the top of rock An exception
to this trend that was noted in the GZA May 1988 report
(Doc 38) was Borehole WE87-ML1 in which fracture frequency
increased with depth Equally significant are above-average
fracture frequencies and significant flow measurements over
deep rock intervals (more than 100 feet in each borehole
extending deeper than 100 feet and more than 200 feet in
each borehole extending deeper than 200 feet) The data
suggest that rock fractures and associated water-bearing
zones extend to some unknown distance below the depth
reached by the five multilevel wells
BSR03010 3-3
GEOPHYSICAL INVESTIGATIONS
Geophysical investigations are described in both the
August 1987 report prepared by Geotech Enterprises Inc
(Appendix Document 35) and GZAs May 1988 report (Doc 38)
Thiree geophysical survey methods were used by Geotech to
investigate the vicinity of the Central Landfill The
objectives of the investigations were to locate areas of
rock fracturing and to recommend locations for three
multilevel wells The survey methods investigated gravity
e]ectrical resi^tivity and seismic refraction Each method
vas targeted at a different physical property of the rock
any of which could indicate fracturing
GZAs May 1988 report (Doc 38) summarizes the results of
the geophysical surveys discussed in the Geotech report
(Doc 35) In addition GZAs May 1988 report describes the
results of downhole geophysical logging performed by the
USGS and vertical seismic profiling performed by Weston
Geophysical Corporation
41 GRAVITY
The gravity investigation method measures minute differences
in the Earths gravitational field resulting from rock
density differences Fracturing can result in lover
densities which can often be identified as gravity lovs
Different rock types with different densities also can
result in gravity lows
Regional data indicate a gravity low in the vicinity of the
landfill but it is uncertain whether the low results from a
fracture zone or from the presence of different rock types
BSR03011 4-1
III
of higher donsity on either side of the landfill
Additional gravity measurements obtained in tho vicinity of
the landfill confirm the gravity low and suggest a
northeast-southwest trend to the low that corresponds with
Lincainent 1
The gravity data are dominated by the regional effects of
the denser metamorphic sediments to the east and the buried
pluton to the west In order to minimize the gravity
effects of these features and to emphasize the ]oca]ized
effects of fracture zones CH2M JIILL removed a fourth-order
surface from the data The residual values reflect the
smaller (shorter wavelength) features that are likely to
include fracture zones The resulting residual data were
tlien plotted on a map
Tlie central part of the residual data map showed a gravity
hiyli with sides oriented northeast-southwest The southeast
side of this feature is coincident with Lineament 1 on the
fracture trace map in GZAs May 1988 report (Doc 38)
Central Landfill is located on this feature The residual
gravity high is breached in the vicinity of the landfill
The breach may be associated with other fracture traces
The results of the residual gravity evaluation suggest that
Lineament 1 may be related to a geologic contact
Alternatively Lineament 1 may be at the contact between
fractured rock to the southeast (the gravity low) and
unfractured rock to the northwest The data support the
fracture trace interpretation in the vicinity of the
landfill
BSR0 3011 4-2
42 ELECTRICAL RESISTIVITY
Electrical soundings are used to estimate subsurface
resistivities Fracture zones can affect the resistivities
by increasing hydraulic conductivity In most cases rock
resistivity is controlled by pore fluid conductivity and
porosity
The soundings in the vicinity of the landfill indicated
areas of resistive bedrock (indicating competent rock) and
areas of less resistive bedrock (possibly fractured rock)
For i he most part the more resistive areas are northwest of
Lineltiment 1 and the less resistive bedrock is southeast of
the lineament
The interpreted bedrock resistivities were used with
groundwater specific conductance to calculate a formation
factor A high formation factor suggests competent rock
The variability of groundwater conductivity over short
distances in general and some uncertainty in the estimated
bedrock conductivity in the vicinity of the landfill may
make use of these formation factors questionable
There are no comments in either the GZA May 1988 report
(Doc 38) or the Geotech report (Doc 35) about cultural
conductors such as fences and power lines that may have
affected the data Either there are no cultural conductors
in the area or this potential problem was overlooked
Soundings 4 and 9 may have been affected by nearby cultural
conductors
The observed bedrock resistivities appear lower on the
southeast side of Lineament 1 and higher on the nort)ivest
side This is consistent with Lineament 1 being a geologic
BSR03011 4-3
I
contact or with the fracture density being higher on the
southeast side
43 SEISMIC REFRACTION
Seismic refraction surveys were performed to measure bedrock
velocities in the vicinity of the landfill Bedrock
veJricities may be reduced in areas of fracturing compared
witli the velocities in unfractured areas Refraction
surveys generally were run in the same areas as those in
which the electrical soundings were run Low velocity
bidrock wliich may be related to rock fracturing vas
idntified by the refraction surveys
Because seismic data are very noisy the first arrivals were
not identified properly in some instances Estimated
bedrock velocities are correspondingly uncertain The
bedrock velocity calculated by CH2M HILL for Line S-4
(12100 fps) is approximately 15 percent higher than the
velocity given in the Geotech and GZA reports (10380 fps)
(Doc 35 38) The data for Line S-4 are relatively good
an uncertainty of 15 percent or worse might be typical for
data of this quality
Some of the seismic spreads did not include a shot at each
end of a spread Without data from shots at both ends it
is impossible to determine true bedrock velocities where
dipping beds are present Although seismic refraction is a
valid metliod for identifying fracture zones better-quality
data than those presented in the Geotech and GZA reports
(Doc 35 38) are required
BSR03011 4-4
44 DOWNHOLE GEOPHYSICAL LOGGINC
AND VERTICAL SEISMIC PROFILING
The downhole geophysical logging was performed by the USGS
Division of Water Resources The logging methods and their
associated functions are listed below
Acoustic Borehole Televiewer
Formation Resistivity
Borehole Caliper
Neutron-Gamma
Natural Gamma
Spontaneous Potential
Maps rock fractures using
sonar transmissions
Maps areas of lower
resistivity lhat may be
the result of fracturing
Measures borehole
diameter
Measures formation
porosity but readings are
affected by clay
Measures formation
natural radioactive
emmissions can be
used to identify clay and
was used with the
neutron-gamma data
Used to identify different
strata such as clay and
shale
BSR03011 4-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
SUMMARY
Significant groundwater contamination has been observed in
monitoring wells located both within the Central Landfill
area and downgradient of the existing fill Piezometric
data suggest that most if not all of the contaminated
groundwater discharges to the following areas Cedar Swamp
Brook which drains to Upper Simmons Reservoir Upper
Simmons Reservoir and Almy Reservoir The vertical and
lateral extent of groundwater contamination has not yet been
completely defined The rates and directions of groundwater
movement can only be inferred from the data that are
currently available
Fracture studies indicate a potential pathway for tlie
migration of groundwater contaminants from the Central
Landfill to Scituate Reservoir At elevation 284 the
spillway elevation of the Scituate Reservoir is well below
the piezometric level of wells located within the Central
Landfill which is at elevations 310 to 380 This
difference in head provides a potential driving mechanism
for the migration of contaminants from the Central Landfill
to Scituate Reservoir However both a surface-water divide
and a shallow groundwater divide are located between the
landfill and Scituate Reservoir Although the existing data
remain inconclusive the presence of these surface and
near-surface features suggests that even at greater depths
movement of groundwater from the landfill area is not toward
the Scituate Reservoir If the movement of groundvater is
away from the landfill it is unlikely that the Central
Landfill has any significant impact on the Scituate
Reservoir
BSR03022
Tlie existing unlined landfill poses a threat to groundvater
quality at the landfill site The proposed landfill
expansion would delay the installation of a final cover over
the entire area By leaving a major portion of the existing
fill uncovered the landfill would generate uncontrolled
leachate throughout the projected expansion
periodmdashapproximately 20 years Other design flaws have
been identified Certain aspects of the expansion plans
require further clarification
Groundwater contamination also has been identified in areas
unrelated to the Central Landfill Contamination probably
also occurs in other areas yet to be identified
Considering the variety of land uses within the watershed
the Providence Water Supply Boards current program of
surface water monitoring should be reevaluated for the
possible inclusion of groundwater monitoring
BSR03022 ii
CONTENTS
Page
Summary i
1 Introduction 1-1
2 Physiography and Drainage 2-1
3 Geology 3-1
4 Geophysical Investigations 4-1 41 Gravity 4-1 42 Electrical Resistivity 4-3 43 Seismic Refraction 4-4 44 Downhole Geophysical Logging
and Vertical Seismic Profiling 4-5
5 Groundwater 5-1 51 Groundwater Occurrence and 5-1
Movement 52 Water Quality 5-3
6 Proposed Landfill Expansion 6-1 61 General Comments on
Overall Design 6-1 62 Specific Comments on Design
Report and Drawings 6-3
7 Conclusions and Recommendations 7-1 71 Hydrogeology 7-1 72 Geophysics 7-4 73 Landfill Design 7-5 74 Groundwater Quality 7-5
A p p e n d i x L i s t of Documents Reviewed
FIGURES
1 Location of Project Within the State of 1-2 Rhode Island
2 Site Map of the Central Landfill 1-3
3 Generalized Cross-Section Along 7-3 NE-SW Trending Lineament 1
BSR03003 iii
INTRODUCTION
The Solid Waste Management Corporation (SWMC) currently
operates the Central Landfill in Johnston Rhode Island
located approximately 2-12 miles east of the Scituate
Reservoir The location of the landfill is shown in the map
presented in Figure 1 The Scituate Reservoir serves as a
water supply for over 60 percent of the population of Rhode
Island The Central Landfill is an unlined municipal
landfill that in the past has received industrial wastes
A permit application for construction of an expansion of the
existing landfill has been submitted to the Rhode Island
Department of Environmental Management (RIDEM) Discharge
of contaminants to groundwater immediately surrounding the
landfill has been documented However the extent of
offsite migration of contaminants is not known
Studies have been conducted to identify the existing and
potsntial impacts of seepage from the landfill on surface
water and groundwater in the vicinity Concern has been
expressed that seepage from the landfill may be endangering
the Scituate Reservoir There is further concern that
expansion of the landfill also may have an impact on the
water supply A site map of the Central Landfill showing
the approximate limit of existing fill and the locations of
all previously installed monitoring wells is presented in
Figure 2
BSR03008 1-1
0 10 M l bull raquo I t I I
Approxiniale Scale
Central Landf i l l
Alrny Reservoir
Simmons Reservoir
Scituate Reservoir
1 Location oT Proiect r^ifiMUIII n Figure I AVlthlnThe State of RhodiJlslana v^fJiVJnU
1-9
Figure 2 Aoproximattt Scale
Slta-Miip 3t i - Cjnt-al Lancrflil cyihL
Ill Tlie Providence Water Supply Board has contracted with CH2M
HILL to perform an evaluation of the data pertaining to the
Central LancJfill The objectives of this study are
Provide an independent review of reports data
drawings and other available information
concerning existing or potential impacts of the
landfill on surface water and groundwater in Using existing data assess whether there is
indeed seepage from the existing landfill and if
so what its impact is on water in the vicinity of
the landfill 111 Assess whether the proposed landfill expansion
will have further impact on surface water and
groundwater
Determine whether seepage from the landfill could m have an impact on Scituate Reservoir
11
mi
m m BSR03008 1-4
li
PHYSIOGRAPHY AND DRAINAGE
Surface topography in the North Scituate Quadrangle is
characterized by northwest-southeast trending uplands and
in intervening valleys The orientation of these surface
features reflects the direction of glacial advance and
concomitant erosion of preglacial soils The orientations
of Oak Swamp Almy and Simmons Reservoirs and portions of
i] Scituate Reservoir are examples of this general
northwest-southeast valley orientation
The active portion of the Central Landfill is located
approximately 2-12 miles east of the Scituate Reservoir
The Central Landfill also occupies an elongate valley The
area has been modified by extensive borrowing and filling
Surface drainage is primarily from the northwest and
southwest The area drains to the east and southeast A
topographic divide which defines the limit of the
watershed lies between the active landfill and the
reservoir A small yet inactive portion of the landfill
property lies within the watershed of the Scituate
Reservoir The active landfill is approximately 5100 feet
from the portion of the watershed boundary that crosses
landfill property
BSR03009 2-1
GEOLOGY
Bedrock in the vicinity of the Central Landfill consists of
granite and granite gneiss and is referenced in the
literature as the Scituate granite Soils overlying the
Scituate granite predominantly consist of glacial till and
glacial outwash The till is an unsorted ground moraine
composed of fine-grained to boulder-sized particles The
outwash varies from poorly sorted materials to well-sorted
ice-contact sands and gravels The soils vary in thickness
from 0 feet in areas that have been excavated to over
60 feet southvest of Cedar Swamp Brook Within the existing
landfill refuse ranges in thickness from 50 feet at Well E
to 135 feet at Well WE87-3 Refuse is in direct contact
with the bedrock over the northern portion of tlie landfill
and is within 5 feet of bedrock over its southern part
Bedrock topography at the landfill is defined by subsurface
investigations associated with the landfill design and the
ongoing remedial investigationfeasibility study (RIFS)
Bedrock topography has been mapped regionally by the
US Geological Survey (USGS) The Central Landfill lies on
the north slope of a bedrock valley with a northwest to
southeast general trend The Upper reach of the bedrock
valley is two prongedmdashnorthwest to southeast and north to
southeast The active landfill overlies most of the latter
Rock quarrying has modified the area along the western slope
of the landfill and in the vicinity of the portion of the
landfill (near Well J) that received industrial wastes
The degree of weathering and Rock Quality Designations
(RQDs) observed in rock core were evaluated with respect to
depth below the top of rock and proximity to fracture
traces The RQD is a measure of the degree to which rock is
BSR03010 3-1
fractured as reflected in the lengths of rock core
reioveries A highly fractured rock will exhibit a low RQD
In general the RQD increased with depth--57 percent for
0 to 10 feet below the top of rock and 77 percent for
10 to 30 feet below the top of rock At boreholes located
in fracture traces however the RQDs were 40 percent and
62 percent respectively indicating a correlation between
the fracture traces observed on both aerial photographs and
satellite imagery and the degree to which the bedrock is
friictured Similarly the degree of weathering was found to
be a function of both depth and proximity to fracture
tl ces Severe veathering was noted throughout
B(U-ehole WE87-13 and to a depth of 45 feet in
Borehole WE85-6 both of which lie along northeast-southwest
trending features It should be noted that observations of
rock weathering and RQDs apply only to boreholes from vhich
rock core was available These boreholes tended to be
relatively shallow extending approximately 30 feet below
the top of rock
Deeper explorations (124 to 247 feet below the top of rock)
were performed in the multilevel wellsmdashWE87-ML1 through
WE87-ML5 The Fracture Trace Analysis (FTA) was used to
position the multilevel wells Each multilevel well was
pllt3ced on or proximal to an observed fracture trace The
degree of fracturing and the orientation of fractures were
evaluated by borehole televiewer The ability of the
observed fractures to transmit water was evaluated by packer
tests
The May 198 8 Interim Remedial Investigation Report by
Goldberg-Zoino amp Associates Inc (GZA) (Appendix
Document 38) indicates that the orientations of fractures
indicated on televiewer logs were compiled into a ccmposite
plotted on a stereonet and contoured The contouring
BSR03010 3-2
yielded four preferred fracture orientations thiat -bullere in
agreement with the orientations of lineaments identified jn
the FTA The dominant group had a strike and dip of
N20deg-40degE 60deg-80degNW The lesser groups were at nearly
horizontal N10deg-20degW 50deg-60degSW and N80deg-85degE 65deg-70NW
Because the stereonet plots were not included in the GZA
May 1988 report (Doc 38) CH2M HILL plotted the fracture
orientations provided on the boring log for Borehole
KE87-ML3 This borehole lies near the intersection of
Lineainents 1 and 2 with Lineament 24 Borehole WE87-ML3 is
of particular significance because Lineaments 1 and 2
represent potential pathways for the migration of
containinants to the Scituate Reservoir The orieiitations of
fractures in Borehole WE87-ML3 correspond reasonably vell
with the trends of Lineaments 1 2 and 24
Barbed on televiewer data the average fracture frequency
reported for the five multilevel wells was 072 fractures
per foot Only a very slight decrease in fracture frequency
was noted with depth--08 fractures per foot for the top
30 feet of bedrock 07 fractures per foot for the tpp
100 feet of bedrock and 06 fractures per foot for depths
greater than 100 feet below the top of rock An exception
to this trend that was noted in the GZA May 1988 report
(Doc 38) was Borehole WE87-ML1 in which fracture frequency
increased with depth Equally significant are above-average
fracture frequencies and significant flow measurements over
deep rock intervals (more than 100 feet in each borehole
extending deeper than 100 feet and more than 200 feet in
each borehole extending deeper than 200 feet) The data
suggest that rock fractures and associated water-bearing
zones extend to some unknown distance below the depth
reached by the five multilevel wells
BSR03010 3-3
GEOPHYSICAL INVESTIGATIONS
Geophysical investigations are described in both the
August 1987 report prepared by Geotech Enterprises Inc
(Appendix Document 35) and GZAs May 1988 report (Doc 38)
Thiree geophysical survey methods were used by Geotech to
investigate the vicinity of the Central Landfill The
objectives of the investigations were to locate areas of
rock fracturing and to recommend locations for three
multilevel wells The survey methods investigated gravity
e]ectrical resi^tivity and seismic refraction Each method
vas targeted at a different physical property of the rock
any of which could indicate fracturing
GZAs May 1988 report (Doc 38) summarizes the results of
the geophysical surveys discussed in the Geotech report
(Doc 35) In addition GZAs May 1988 report describes the
results of downhole geophysical logging performed by the
USGS and vertical seismic profiling performed by Weston
Geophysical Corporation
41 GRAVITY
The gravity investigation method measures minute differences
in the Earths gravitational field resulting from rock
density differences Fracturing can result in lover
densities which can often be identified as gravity lovs
Different rock types with different densities also can
result in gravity lows
Regional data indicate a gravity low in the vicinity of the
landfill but it is uncertain whether the low results from a
fracture zone or from the presence of different rock types
BSR03011 4-1
III
of higher donsity on either side of the landfill
Additional gravity measurements obtained in tho vicinity of
the landfill confirm the gravity low and suggest a
northeast-southwest trend to the low that corresponds with
Lincainent 1
The gravity data are dominated by the regional effects of
the denser metamorphic sediments to the east and the buried
pluton to the west In order to minimize the gravity
effects of these features and to emphasize the ]oca]ized
effects of fracture zones CH2M JIILL removed a fourth-order
surface from the data The residual values reflect the
smaller (shorter wavelength) features that are likely to
include fracture zones The resulting residual data were
tlien plotted on a map
Tlie central part of the residual data map showed a gravity
hiyli with sides oriented northeast-southwest The southeast
side of this feature is coincident with Lineament 1 on the
fracture trace map in GZAs May 1988 report (Doc 38)
Central Landfill is located on this feature The residual
gravity high is breached in the vicinity of the landfill
The breach may be associated with other fracture traces
The results of the residual gravity evaluation suggest that
Lineament 1 may be related to a geologic contact
Alternatively Lineament 1 may be at the contact between
fractured rock to the southeast (the gravity low) and
unfractured rock to the northwest The data support the
fracture trace interpretation in the vicinity of the
landfill
BSR0 3011 4-2
42 ELECTRICAL RESISTIVITY
Electrical soundings are used to estimate subsurface
resistivities Fracture zones can affect the resistivities
by increasing hydraulic conductivity In most cases rock
resistivity is controlled by pore fluid conductivity and
porosity
The soundings in the vicinity of the landfill indicated
areas of resistive bedrock (indicating competent rock) and
areas of less resistive bedrock (possibly fractured rock)
For i he most part the more resistive areas are northwest of
Lineltiment 1 and the less resistive bedrock is southeast of
the lineament
The interpreted bedrock resistivities were used with
groundwater specific conductance to calculate a formation
factor A high formation factor suggests competent rock
The variability of groundwater conductivity over short
distances in general and some uncertainty in the estimated
bedrock conductivity in the vicinity of the landfill may
make use of these formation factors questionable
There are no comments in either the GZA May 1988 report
(Doc 38) or the Geotech report (Doc 35) about cultural
conductors such as fences and power lines that may have
affected the data Either there are no cultural conductors
in the area or this potential problem was overlooked
Soundings 4 and 9 may have been affected by nearby cultural
conductors
The observed bedrock resistivities appear lower on the
southeast side of Lineament 1 and higher on the nort)ivest
side This is consistent with Lineament 1 being a geologic
BSR03011 4-3
I
contact or with the fracture density being higher on the
southeast side
43 SEISMIC REFRACTION
Seismic refraction surveys were performed to measure bedrock
velocities in the vicinity of the landfill Bedrock
veJricities may be reduced in areas of fracturing compared
witli the velocities in unfractured areas Refraction
surveys generally were run in the same areas as those in
which the electrical soundings were run Low velocity
bidrock wliich may be related to rock fracturing vas
idntified by the refraction surveys
Because seismic data are very noisy the first arrivals were
not identified properly in some instances Estimated
bedrock velocities are correspondingly uncertain The
bedrock velocity calculated by CH2M HILL for Line S-4
(12100 fps) is approximately 15 percent higher than the
velocity given in the Geotech and GZA reports (10380 fps)
(Doc 35 38) The data for Line S-4 are relatively good
an uncertainty of 15 percent or worse might be typical for
data of this quality
Some of the seismic spreads did not include a shot at each
end of a spread Without data from shots at both ends it
is impossible to determine true bedrock velocities where
dipping beds are present Although seismic refraction is a
valid metliod for identifying fracture zones better-quality
data than those presented in the Geotech and GZA reports
(Doc 35 38) are required
BSR03011 4-4
44 DOWNHOLE GEOPHYSICAL LOGGINC
AND VERTICAL SEISMIC PROFILING
The downhole geophysical logging was performed by the USGS
Division of Water Resources The logging methods and their
associated functions are listed below
Acoustic Borehole Televiewer
Formation Resistivity
Borehole Caliper
Neutron-Gamma
Natural Gamma
Spontaneous Potential
Maps rock fractures using
sonar transmissions
Maps areas of lower
resistivity lhat may be
the result of fracturing
Measures borehole
diameter
Measures formation
porosity but readings are
affected by clay
Measures formation
natural radioactive
emmissions can be
used to identify clay and
was used with the
neutron-gamma data
Used to identify different
strata such as clay and
shale
BSR03011 4-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
Tlie existing unlined landfill poses a threat to groundvater
quality at the landfill site The proposed landfill
expansion would delay the installation of a final cover over
the entire area By leaving a major portion of the existing
fill uncovered the landfill would generate uncontrolled
leachate throughout the projected expansion
periodmdashapproximately 20 years Other design flaws have
been identified Certain aspects of the expansion plans
require further clarification
Groundwater contamination also has been identified in areas
unrelated to the Central Landfill Contamination probably
also occurs in other areas yet to be identified
Considering the variety of land uses within the watershed
the Providence Water Supply Boards current program of
surface water monitoring should be reevaluated for the
possible inclusion of groundwater monitoring
BSR03022 ii
CONTENTS
Page
Summary i
1 Introduction 1-1
2 Physiography and Drainage 2-1
3 Geology 3-1
4 Geophysical Investigations 4-1 41 Gravity 4-1 42 Electrical Resistivity 4-3 43 Seismic Refraction 4-4 44 Downhole Geophysical Logging
and Vertical Seismic Profiling 4-5
5 Groundwater 5-1 51 Groundwater Occurrence and 5-1
Movement 52 Water Quality 5-3
6 Proposed Landfill Expansion 6-1 61 General Comments on
Overall Design 6-1 62 Specific Comments on Design
Report and Drawings 6-3
7 Conclusions and Recommendations 7-1 71 Hydrogeology 7-1 72 Geophysics 7-4 73 Landfill Design 7-5 74 Groundwater Quality 7-5
A p p e n d i x L i s t of Documents Reviewed
FIGURES
1 Location of Project Within the State of 1-2 Rhode Island
2 Site Map of the Central Landfill 1-3
3 Generalized Cross-Section Along 7-3 NE-SW Trending Lineament 1
BSR03003 iii
INTRODUCTION
The Solid Waste Management Corporation (SWMC) currently
operates the Central Landfill in Johnston Rhode Island
located approximately 2-12 miles east of the Scituate
Reservoir The location of the landfill is shown in the map
presented in Figure 1 The Scituate Reservoir serves as a
water supply for over 60 percent of the population of Rhode
Island The Central Landfill is an unlined municipal
landfill that in the past has received industrial wastes
A permit application for construction of an expansion of the
existing landfill has been submitted to the Rhode Island
Department of Environmental Management (RIDEM) Discharge
of contaminants to groundwater immediately surrounding the
landfill has been documented However the extent of
offsite migration of contaminants is not known
Studies have been conducted to identify the existing and
potsntial impacts of seepage from the landfill on surface
water and groundwater in the vicinity Concern has been
expressed that seepage from the landfill may be endangering
the Scituate Reservoir There is further concern that
expansion of the landfill also may have an impact on the
water supply A site map of the Central Landfill showing
the approximate limit of existing fill and the locations of
all previously installed monitoring wells is presented in
Figure 2
BSR03008 1-1
0 10 M l bull raquo I t I I
Approxiniale Scale
Central Landf i l l
Alrny Reservoir
Simmons Reservoir
Scituate Reservoir
1 Location oT Proiect r^ifiMUIII n Figure I AVlthlnThe State of RhodiJlslana v^fJiVJnU
1-9
Figure 2 Aoproximattt Scale
Slta-Miip 3t i - Cjnt-al Lancrflil cyihL
Ill Tlie Providence Water Supply Board has contracted with CH2M
HILL to perform an evaluation of the data pertaining to the
Central LancJfill The objectives of this study are
Provide an independent review of reports data
drawings and other available information
concerning existing or potential impacts of the
landfill on surface water and groundwater in Using existing data assess whether there is
indeed seepage from the existing landfill and if
so what its impact is on water in the vicinity of
the landfill 111 Assess whether the proposed landfill expansion
will have further impact on surface water and
groundwater
Determine whether seepage from the landfill could m have an impact on Scituate Reservoir
11
mi
m m BSR03008 1-4
li
PHYSIOGRAPHY AND DRAINAGE
Surface topography in the North Scituate Quadrangle is
characterized by northwest-southeast trending uplands and
in intervening valleys The orientation of these surface
features reflects the direction of glacial advance and
concomitant erosion of preglacial soils The orientations
of Oak Swamp Almy and Simmons Reservoirs and portions of
i] Scituate Reservoir are examples of this general
northwest-southeast valley orientation
The active portion of the Central Landfill is located
approximately 2-12 miles east of the Scituate Reservoir
The Central Landfill also occupies an elongate valley The
area has been modified by extensive borrowing and filling
Surface drainage is primarily from the northwest and
southwest The area drains to the east and southeast A
topographic divide which defines the limit of the
watershed lies between the active landfill and the
reservoir A small yet inactive portion of the landfill
property lies within the watershed of the Scituate
Reservoir The active landfill is approximately 5100 feet
from the portion of the watershed boundary that crosses
landfill property
BSR03009 2-1
GEOLOGY
Bedrock in the vicinity of the Central Landfill consists of
granite and granite gneiss and is referenced in the
literature as the Scituate granite Soils overlying the
Scituate granite predominantly consist of glacial till and
glacial outwash The till is an unsorted ground moraine
composed of fine-grained to boulder-sized particles The
outwash varies from poorly sorted materials to well-sorted
ice-contact sands and gravels The soils vary in thickness
from 0 feet in areas that have been excavated to over
60 feet southvest of Cedar Swamp Brook Within the existing
landfill refuse ranges in thickness from 50 feet at Well E
to 135 feet at Well WE87-3 Refuse is in direct contact
with the bedrock over the northern portion of tlie landfill
and is within 5 feet of bedrock over its southern part
Bedrock topography at the landfill is defined by subsurface
investigations associated with the landfill design and the
ongoing remedial investigationfeasibility study (RIFS)
Bedrock topography has been mapped regionally by the
US Geological Survey (USGS) The Central Landfill lies on
the north slope of a bedrock valley with a northwest to
southeast general trend The Upper reach of the bedrock
valley is two prongedmdashnorthwest to southeast and north to
southeast The active landfill overlies most of the latter
Rock quarrying has modified the area along the western slope
of the landfill and in the vicinity of the portion of the
landfill (near Well J) that received industrial wastes
The degree of weathering and Rock Quality Designations
(RQDs) observed in rock core were evaluated with respect to
depth below the top of rock and proximity to fracture
traces The RQD is a measure of the degree to which rock is
BSR03010 3-1
fractured as reflected in the lengths of rock core
reioveries A highly fractured rock will exhibit a low RQD
In general the RQD increased with depth--57 percent for
0 to 10 feet below the top of rock and 77 percent for
10 to 30 feet below the top of rock At boreholes located
in fracture traces however the RQDs were 40 percent and
62 percent respectively indicating a correlation between
the fracture traces observed on both aerial photographs and
satellite imagery and the degree to which the bedrock is
friictured Similarly the degree of weathering was found to
be a function of both depth and proximity to fracture
tl ces Severe veathering was noted throughout
B(U-ehole WE87-13 and to a depth of 45 feet in
Borehole WE85-6 both of which lie along northeast-southwest
trending features It should be noted that observations of
rock weathering and RQDs apply only to boreholes from vhich
rock core was available These boreholes tended to be
relatively shallow extending approximately 30 feet below
the top of rock
Deeper explorations (124 to 247 feet below the top of rock)
were performed in the multilevel wellsmdashWE87-ML1 through
WE87-ML5 The Fracture Trace Analysis (FTA) was used to
position the multilevel wells Each multilevel well was
pllt3ced on or proximal to an observed fracture trace The
degree of fracturing and the orientation of fractures were
evaluated by borehole televiewer The ability of the
observed fractures to transmit water was evaluated by packer
tests
The May 198 8 Interim Remedial Investigation Report by
Goldberg-Zoino amp Associates Inc (GZA) (Appendix
Document 38) indicates that the orientations of fractures
indicated on televiewer logs were compiled into a ccmposite
plotted on a stereonet and contoured The contouring
BSR03010 3-2
yielded four preferred fracture orientations thiat -bullere in
agreement with the orientations of lineaments identified jn
the FTA The dominant group had a strike and dip of
N20deg-40degE 60deg-80degNW The lesser groups were at nearly
horizontal N10deg-20degW 50deg-60degSW and N80deg-85degE 65deg-70NW
Because the stereonet plots were not included in the GZA
May 1988 report (Doc 38) CH2M HILL plotted the fracture
orientations provided on the boring log for Borehole
KE87-ML3 This borehole lies near the intersection of
Lineainents 1 and 2 with Lineament 24 Borehole WE87-ML3 is
of particular significance because Lineaments 1 and 2
represent potential pathways for the migration of
containinants to the Scituate Reservoir The orieiitations of
fractures in Borehole WE87-ML3 correspond reasonably vell
with the trends of Lineaments 1 2 and 24
Barbed on televiewer data the average fracture frequency
reported for the five multilevel wells was 072 fractures
per foot Only a very slight decrease in fracture frequency
was noted with depth--08 fractures per foot for the top
30 feet of bedrock 07 fractures per foot for the tpp
100 feet of bedrock and 06 fractures per foot for depths
greater than 100 feet below the top of rock An exception
to this trend that was noted in the GZA May 1988 report
(Doc 38) was Borehole WE87-ML1 in which fracture frequency
increased with depth Equally significant are above-average
fracture frequencies and significant flow measurements over
deep rock intervals (more than 100 feet in each borehole
extending deeper than 100 feet and more than 200 feet in
each borehole extending deeper than 200 feet) The data
suggest that rock fractures and associated water-bearing
zones extend to some unknown distance below the depth
reached by the five multilevel wells
BSR03010 3-3
GEOPHYSICAL INVESTIGATIONS
Geophysical investigations are described in both the
August 1987 report prepared by Geotech Enterprises Inc
(Appendix Document 35) and GZAs May 1988 report (Doc 38)
Thiree geophysical survey methods were used by Geotech to
investigate the vicinity of the Central Landfill The
objectives of the investigations were to locate areas of
rock fracturing and to recommend locations for three
multilevel wells The survey methods investigated gravity
e]ectrical resi^tivity and seismic refraction Each method
vas targeted at a different physical property of the rock
any of which could indicate fracturing
GZAs May 1988 report (Doc 38) summarizes the results of
the geophysical surveys discussed in the Geotech report
(Doc 35) In addition GZAs May 1988 report describes the
results of downhole geophysical logging performed by the
USGS and vertical seismic profiling performed by Weston
Geophysical Corporation
41 GRAVITY
The gravity investigation method measures minute differences
in the Earths gravitational field resulting from rock
density differences Fracturing can result in lover
densities which can often be identified as gravity lovs
Different rock types with different densities also can
result in gravity lows
Regional data indicate a gravity low in the vicinity of the
landfill but it is uncertain whether the low results from a
fracture zone or from the presence of different rock types
BSR03011 4-1
III
of higher donsity on either side of the landfill
Additional gravity measurements obtained in tho vicinity of
the landfill confirm the gravity low and suggest a
northeast-southwest trend to the low that corresponds with
Lincainent 1
The gravity data are dominated by the regional effects of
the denser metamorphic sediments to the east and the buried
pluton to the west In order to minimize the gravity
effects of these features and to emphasize the ]oca]ized
effects of fracture zones CH2M JIILL removed a fourth-order
surface from the data The residual values reflect the
smaller (shorter wavelength) features that are likely to
include fracture zones The resulting residual data were
tlien plotted on a map
Tlie central part of the residual data map showed a gravity
hiyli with sides oriented northeast-southwest The southeast
side of this feature is coincident with Lineament 1 on the
fracture trace map in GZAs May 1988 report (Doc 38)
Central Landfill is located on this feature The residual
gravity high is breached in the vicinity of the landfill
The breach may be associated with other fracture traces
The results of the residual gravity evaluation suggest that
Lineament 1 may be related to a geologic contact
Alternatively Lineament 1 may be at the contact between
fractured rock to the southeast (the gravity low) and
unfractured rock to the northwest The data support the
fracture trace interpretation in the vicinity of the
landfill
BSR0 3011 4-2
42 ELECTRICAL RESISTIVITY
Electrical soundings are used to estimate subsurface
resistivities Fracture zones can affect the resistivities
by increasing hydraulic conductivity In most cases rock
resistivity is controlled by pore fluid conductivity and
porosity
The soundings in the vicinity of the landfill indicated
areas of resistive bedrock (indicating competent rock) and
areas of less resistive bedrock (possibly fractured rock)
For i he most part the more resistive areas are northwest of
Lineltiment 1 and the less resistive bedrock is southeast of
the lineament
The interpreted bedrock resistivities were used with
groundwater specific conductance to calculate a formation
factor A high formation factor suggests competent rock
The variability of groundwater conductivity over short
distances in general and some uncertainty in the estimated
bedrock conductivity in the vicinity of the landfill may
make use of these formation factors questionable
There are no comments in either the GZA May 1988 report
(Doc 38) or the Geotech report (Doc 35) about cultural
conductors such as fences and power lines that may have
affected the data Either there are no cultural conductors
in the area or this potential problem was overlooked
Soundings 4 and 9 may have been affected by nearby cultural
conductors
The observed bedrock resistivities appear lower on the
southeast side of Lineament 1 and higher on the nort)ivest
side This is consistent with Lineament 1 being a geologic
BSR03011 4-3
I
contact or with the fracture density being higher on the
southeast side
43 SEISMIC REFRACTION
Seismic refraction surveys were performed to measure bedrock
velocities in the vicinity of the landfill Bedrock
veJricities may be reduced in areas of fracturing compared
witli the velocities in unfractured areas Refraction
surveys generally were run in the same areas as those in
which the electrical soundings were run Low velocity
bidrock wliich may be related to rock fracturing vas
idntified by the refraction surveys
Because seismic data are very noisy the first arrivals were
not identified properly in some instances Estimated
bedrock velocities are correspondingly uncertain The
bedrock velocity calculated by CH2M HILL for Line S-4
(12100 fps) is approximately 15 percent higher than the
velocity given in the Geotech and GZA reports (10380 fps)
(Doc 35 38) The data for Line S-4 are relatively good
an uncertainty of 15 percent or worse might be typical for
data of this quality
Some of the seismic spreads did not include a shot at each
end of a spread Without data from shots at both ends it
is impossible to determine true bedrock velocities where
dipping beds are present Although seismic refraction is a
valid metliod for identifying fracture zones better-quality
data than those presented in the Geotech and GZA reports
(Doc 35 38) are required
BSR03011 4-4
44 DOWNHOLE GEOPHYSICAL LOGGINC
AND VERTICAL SEISMIC PROFILING
The downhole geophysical logging was performed by the USGS
Division of Water Resources The logging methods and their
associated functions are listed below
Acoustic Borehole Televiewer
Formation Resistivity
Borehole Caliper
Neutron-Gamma
Natural Gamma
Spontaneous Potential
Maps rock fractures using
sonar transmissions
Maps areas of lower
resistivity lhat may be
the result of fracturing
Measures borehole
diameter
Measures formation
porosity but readings are
affected by clay
Measures formation
natural radioactive
emmissions can be
used to identify clay and
was used with the
neutron-gamma data
Used to identify different
strata such as clay and
shale
BSR03011 4-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
CONTENTS
Page
Summary i
1 Introduction 1-1
2 Physiography and Drainage 2-1
3 Geology 3-1
4 Geophysical Investigations 4-1 41 Gravity 4-1 42 Electrical Resistivity 4-3 43 Seismic Refraction 4-4 44 Downhole Geophysical Logging
and Vertical Seismic Profiling 4-5
5 Groundwater 5-1 51 Groundwater Occurrence and 5-1
Movement 52 Water Quality 5-3
6 Proposed Landfill Expansion 6-1 61 General Comments on
Overall Design 6-1 62 Specific Comments on Design
Report and Drawings 6-3
7 Conclusions and Recommendations 7-1 71 Hydrogeology 7-1 72 Geophysics 7-4 73 Landfill Design 7-5 74 Groundwater Quality 7-5
A p p e n d i x L i s t of Documents Reviewed
FIGURES
1 Location of Project Within the State of 1-2 Rhode Island
2 Site Map of the Central Landfill 1-3
3 Generalized Cross-Section Along 7-3 NE-SW Trending Lineament 1
BSR03003 iii
INTRODUCTION
The Solid Waste Management Corporation (SWMC) currently
operates the Central Landfill in Johnston Rhode Island
located approximately 2-12 miles east of the Scituate
Reservoir The location of the landfill is shown in the map
presented in Figure 1 The Scituate Reservoir serves as a
water supply for over 60 percent of the population of Rhode
Island The Central Landfill is an unlined municipal
landfill that in the past has received industrial wastes
A permit application for construction of an expansion of the
existing landfill has been submitted to the Rhode Island
Department of Environmental Management (RIDEM) Discharge
of contaminants to groundwater immediately surrounding the
landfill has been documented However the extent of
offsite migration of contaminants is not known
Studies have been conducted to identify the existing and
potsntial impacts of seepage from the landfill on surface
water and groundwater in the vicinity Concern has been
expressed that seepage from the landfill may be endangering
the Scituate Reservoir There is further concern that
expansion of the landfill also may have an impact on the
water supply A site map of the Central Landfill showing
the approximate limit of existing fill and the locations of
all previously installed monitoring wells is presented in
Figure 2
BSR03008 1-1
0 10 M l bull raquo I t I I
Approxiniale Scale
Central Landf i l l
Alrny Reservoir
Simmons Reservoir
Scituate Reservoir
1 Location oT Proiect r^ifiMUIII n Figure I AVlthlnThe State of RhodiJlslana v^fJiVJnU
1-9
Figure 2 Aoproximattt Scale
Slta-Miip 3t i - Cjnt-al Lancrflil cyihL
Ill Tlie Providence Water Supply Board has contracted with CH2M
HILL to perform an evaluation of the data pertaining to the
Central LancJfill The objectives of this study are
Provide an independent review of reports data
drawings and other available information
concerning existing or potential impacts of the
landfill on surface water and groundwater in Using existing data assess whether there is
indeed seepage from the existing landfill and if
so what its impact is on water in the vicinity of
the landfill 111 Assess whether the proposed landfill expansion
will have further impact on surface water and
groundwater
Determine whether seepage from the landfill could m have an impact on Scituate Reservoir
11
mi
m m BSR03008 1-4
li
PHYSIOGRAPHY AND DRAINAGE
Surface topography in the North Scituate Quadrangle is
characterized by northwest-southeast trending uplands and
in intervening valleys The orientation of these surface
features reflects the direction of glacial advance and
concomitant erosion of preglacial soils The orientations
of Oak Swamp Almy and Simmons Reservoirs and portions of
i] Scituate Reservoir are examples of this general
northwest-southeast valley orientation
The active portion of the Central Landfill is located
approximately 2-12 miles east of the Scituate Reservoir
The Central Landfill also occupies an elongate valley The
area has been modified by extensive borrowing and filling
Surface drainage is primarily from the northwest and
southwest The area drains to the east and southeast A
topographic divide which defines the limit of the
watershed lies between the active landfill and the
reservoir A small yet inactive portion of the landfill
property lies within the watershed of the Scituate
Reservoir The active landfill is approximately 5100 feet
from the portion of the watershed boundary that crosses
landfill property
BSR03009 2-1
GEOLOGY
Bedrock in the vicinity of the Central Landfill consists of
granite and granite gneiss and is referenced in the
literature as the Scituate granite Soils overlying the
Scituate granite predominantly consist of glacial till and
glacial outwash The till is an unsorted ground moraine
composed of fine-grained to boulder-sized particles The
outwash varies from poorly sorted materials to well-sorted
ice-contact sands and gravels The soils vary in thickness
from 0 feet in areas that have been excavated to over
60 feet southvest of Cedar Swamp Brook Within the existing
landfill refuse ranges in thickness from 50 feet at Well E
to 135 feet at Well WE87-3 Refuse is in direct contact
with the bedrock over the northern portion of tlie landfill
and is within 5 feet of bedrock over its southern part
Bedrock topography at the landfill is defined by subsurface
investigations associated with the landfill design and the
ongoing remedial investigationfeasibility study (RIFS)
Bedrock topography has been mapped regionally by the
US Geological Survey (USGS) The Central Landfill lies on
the north slope of a bedrock valley with a northwest to
southeast general trend The Upper reach of the bedrock
valley is two prongedmdashnorthwest to southeast and north to
southeast The active landfill overlies most of the latter
Rock quarrying has modified the area along the western slope
of the landfill and in the vicinity of the portion of the
landfill (near Well J) that received industrial wastes
The degree of weathering and Rock Quality Designations
(RQDs) observed in rock core were evaluated with respect to
depth below the top of rock and proximity to fracture
traces The RQD is a measure of the degree to which rock is
BSR03010 3-1
fractured as reflected in the lengths of rock core
reioveries A highly fractured rock will exhibit a low RQD
In general the RQD increased with depth--57 percent for
0 to 10 feet below the top of rock and 77 percent for
10 to 30 feet below the top of rock At boreholes located
in fracture traces however the RQDs were 40 percent and
62 percent respectively indicating a correlation between
the fracture traces observed on both aerial photographs and
satellite imagery and the degree to which the bedrock is
friictured Similarly the degree of weathering was found to
be a function of both depth and proximity to fracture
tl ces Severe veathering was noted throughout
B(U-ehole WE87-13 and to a depth of 45 feet in
Borehole WE85-6 both of which lie along northeast-southwest
trending features It should be noted that observations of
rock weathering and RQDs apply only to boreholes from vhich
rock core was available These boreholes tended to be
relatively shallow extending approximately 30 feet below
the top of rock
Deeper explorations (124 to 247 feet below the top of rock)
were performed in the multilevel wellsmdashWE87-ML1 through
WE87-ML5 The Fracture Trace Analysis (FTA) was used to
position the multilevel wells Each multilevel well was
pllt3ced on or proximal to an observed fracture trace The
degree of fracturing and the orientation of fractures were
evaluated by borehole televiewer The ability of the
observed fractures to transmit water was evaluated by packer
tests
The May 198 8 Interim Remedial Investigation Report by
Goldberg-Zoino amp Associates Inc (GZA) (Appendix
Document 38) indicates that the orientations of fractures
indicated on televiewer logs were compiled into a ccmposite
plotted on a stereonet and contoured The contouring
BSR03010 3-2
yielded four preferred fracture orientations thiat -bullere in
agreement with the orientations of lineaments identified jn
the FTA The dominant group had a strike and dip of
N20deg-40degE 60deg-80degNW The lesser groups were at nearly
horizontal N10deg-20degW 50deg-60degSW and N80deg-85degE 65deg-70NW
Because the stereonet plots were not included in the GZA
May 1988 report (Doc 38) CH2M HILL plotted the fracture
orientations provided on the boring log for Borehole
KE87-ML3 This borehole lies near the intersection of
Lineainents 1 and 2 with Lineament 24 Borehole WE87-ML3 is
of particular significance because Lineaments 1 and 2
represent potential pathways for the migration of
containinants to the Scituate Reservoir The orieiitations of
fractures in Borehole WE87-ML3 correspond reasonably vell
with the trends of Lineaments 1 2 and 24
Barbed on televiewer data the average fracture frequency
reported for the five multilevel wells was 072 fractures
per foot Only a very slight decrease in fracture frequency
was noted with depth--08 fractures per foot for the top
30 feet of bedrock 07 fractures per foot for the tpp
100 feet of bedrock and 06 fractures per foot for depths
greater than 100 feet below the top of rock An exception
to this trend that was noted in the GZA May 1988 report
(Doc 38) was Borehole WE87-ML1 in which fracture frequency
increased with depth Equally significant are above-average
fracture frequencies and significant flow measurements over
deep rock intervals (more than 100 feet in each borehole
extending deeper than 100 feet and more than 200 feet in
each borehole extending deeper than 200 feet) The data
suggest that rock fractures and associated water-bearing
zones extend to some unknown distance below the depth
reached by the five multilevel wells
BSR03010 3-3
GEOPHYSICAL INVESTIGATIONS
Geophysical investigations are described in both the
August 1987 report prepared by Geotech Enterprises Inc
(Appendix Document 35) and GZAs May 1988 report (Doc 38)
Thiree geophysical survey methods were used by Geotech to
investigate the vicinity of the Central Landfill The
objectives of the investigations were to locate areas of
rock fracturing and to recommend locations for three
multilevel wells The survey methods investigated gravity
e]ectrical resi^tivity and seismic refraction Each method
vas targeted at a different physical property of the rock
any of which could indicate fracturing
GZAs May 1988 report (Doc 38) summarizes the results of
the geophysical surveys discussed in the Geotech report
(Doc 35) In addition GZAs May 1988 report describes the
results of downhole geophysical logging performed by the
USGS and vertical seismic profiling performed by Weston
Geophysical Corporation
41 GRAVITY
The gravity investigation method measures minute differences
in the Earths gravitational field resulting from rock
density differences Fracturing can result in lover
densities which can often be identified as gravity lovs
Different rock types with different densities also can
result in gravity lows
Regional data indicate a gravity low in the vicinity of the
landfill but it is uncertain whether the low results from a
fracture zone or from the presence of different rock types
BSR03011 4-1
III
of higher donsity on either side of the landfill
Additional gravity measurements obtained in tho vicinity of
the landfill confirm the gravity low and suggest a
northeast-southwest trend to the low that corresponds with
Lincainent 1
The gravity data are dominated by the regional effects of
the denser metamorphic sediments to the east and the buried
pluton to the west In order to minimize the gravity
effects of these features and to emphasize the ]oca]ized
effects of fracture zones CH2M JIILL removed a fourth-order
surface from the data The residual values reflect the
smaller (shorter wavelength) features that are likely to
include fracture zones The resulting residual data were
tlien plotted on a map
Tlie central part of the residual data map showed a gravity
hiyli with sides oriented northeast-southwest The southeast
side of this feature is coincident with Lineament 1 on the
fracture trace map in GZAs May 1988 report (Doc 38)
Central Landfill is located on this feature The residual
gravity high is breached in the vicinity of the landfill
The breach may be associated with other fracture traces
The results of the residual gravity evaluation suggest that
Lineament 1 may be related to a geologic contact
Alternatively Lineament 1 may be at the contact between
fractured rock to the southeast (the gravity low) and
unfractured rock to the northwest The data support the
fracture trace interpretation in the vicinity of the
landfill
BSR0 3011 4-2
42 ELECTRICAL RESISTIVITY
Electrical soundings are used to estimate subsurface
resistivities Fracture zones can affect the resistivities
by increasing hydraulic conductivity In most cases rock
resistivity is controlled by pore fluid conductivity and
porosity
The soundings in the vicinity of the landfill indicated
areas of resistive bedrock (indicating competent rock) and
areas of less resistive bedrock (possibly fractured rock)
For i he most part the more resistive areas are northwest of
Lineltiment 1 and the less resistive bedrock is southeast of
the lineament
The interpreted bedrock resistivities were used with
groundwater specific conductance to calculate a formation
factor A high formation factor suggests competent rock
The variability of groundwater conductivity over short
distances in general and some uncertainty in the estimated
bedrock conductivity in the vicinity of the landfill may
make use of these formation factors questionable
There are no comments in either the GZA May 1988 report
(Doc 38) or the Geotech report (Doc 35) about cultural
conductors such as fences and power lines that may have
affected the data Either there are no cultural conductors
in the area or this potential problem was overlooked
Soundings 4 and 9 may have been affected by nearby cultural
conductors
The observed bedrock resistivities appear lower on the
southeast side of Lineament 1 and higher on the nort)ivest
side This is consistent with Lineament 1 being a geologic
BSR03011 4-3
I
contact or with the fracture density being higher on the
southeast side
43 SEISMIC REFRACTION
Seismic refraction surveys were performed to measure bedrock
velocities in the vicinity of the landfill Bedrock
veJricities may be reduced in areas of fracturing compared
witli the velocities in unfractured areas Refraction
surveys generally were run in the same areas as those in
which the electrical soundings were run Low velocity
bidrock wliich may be related to rock fracturing vas
idntified by the refraction surveys
Because seismic data are very noisy the first arrivals were
not identified properly in some instances Estimated
bedrock velocities are correspondingly uncertain The
bedrock velocity calculated by CH2M HILL for Line S-4
(12100 fps) is approximately 15 percent higher than the
velocity given in the Geotech and GZA reports (10380 fps)
(Doc 35 38) The data for Line S-4 are relatively good
an uncertainty of 15 percent or worse might be typical for
data of this quality
Some of the seismic spreads did not include a shot at each
end of a spread Without data from shots at both ends it
is impossible to determine true bedrock velocities where
dipping beds are present Although seismic refraction is a
valid metliod for identifying fracture zones better-quality
data than those presented in the Geotech and GZA reports
(Doc 35 38) are required
BSR03011 4-4
44 DOWNHOLE GEOPHYSICAL LOGGINC
AND VERTICAL SEISMIC PROFILING
The downhole geophysical logging was performed by the USGS
Division of Water Resources The logging methods and their
associated functions are listed below
Acoustic Borehole Televiewer
Formation Resistivity
Borehole Caliper
Neutron-Gamma
Natural Gamma
Spontaneous Potential
Maps rock fractures using
sonar transmissions
Maps areas of lower
resistivity lhat may be
the result of fracturing
Measures borehole
diameter
Measures formation
porosity but readings are
affected by clay
Measures formation
natural radioactive
emmissions can be
used to identify clay and
was used with the
neutron-gamma data
Used to identify different
strata such as clay and
shale
BSR03011 4-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
INTRODUCTION
The Solid Waste Management Corporation (SWMC) currently
operates the Central Landfill in Johnston Rhode Island
located approximately 2-12 miles east of the Scituate
Reservoir The location of the landfill is shown in the map
presented in Figure 1 The Scituate Reservoir serves as a
water supply for over 60 percent of the population of Rhode
Island The Central Landfill is an unlined municipal
landfill that in the past has received industrial wastes
A permit application for construction of an expansion of the
existing landfill has been submitted to the Rhode Island
Department of Environmental Management (RIDEM) Discharge
of contaminants to groundwater immediately surrounding the
landfill has been documented However the extent of
offsite migration of contaminants is not known
Studies have been conducted to identify the existing and
potsntial impacts of seepage from the landfill on surface
water and groundwater in the vicinity Concern has been
expressed that seepage from the landfill may be endangering
the Scituate Reservoir There is further concern that
expansion of the landfill also may have an impact on the
water supply A site map of the Central Landfill showing
the approximate limit of existing fill and the locations of
all previously installed monitoring wells is presented in
Figure 2
BSR03008 1-1
0 10 M l bull raquo I t I I
Approxiniale Scale
Central Landf i l l
Alrny Reservoir
Simmons Reservoir
Scituate Reservoir
1 Location oT Proiect r^ifiMUIII n Figure I AVlthlnThe State of RhodiJlslana v^fJiVJnU
1-9
Figure 2 Aoproximattt Scale
Slta-Miip 3t i - Cjnt-al Lancrflil cyihL
Ill Tlie Providence Water Supply Board has contracted with CH2M
HILL to perform an evaluation of the data pertaining to the
Central LancJfill The objectives of this study are
Provide an independent review of reports data
drawings and other available information
concerning existing or potential impacts of the
landfill on surface water and groundwater in Using existing data assess whether there is
indeed seepage from the existing landfill and if
so what its impact is on water in the vicinity of
the landfill 111 Assess whether the proposed landfill expansion
will have further impact on surface water and
groundwater
Determine whether seepage from the landfill could m have an impact on Scituate Reservoir
11
mi
m m BSR03008 1-4
li
PHYSIOGRAPHY AND DRAINAGE
Surface topography in the North Scituate Quadrangle is
characterized by northwest-southeast trending uplands and
in intervening valleys The orientation of these surface
features reflects the direction of glacial advance and
concomitant erosion of preglacial soils The orientations
of Oak Swamp Almy and Simmons Reservoirs and portions of
i] Scituate Reservoir are examples of this general
northwest-southeast valley orientation
The active portion of the Central Landfill is located
approximately 2-12 miles east of the Scituate Reservoir
The Central Landfill also occupies an elongate valley The
area has been modified by extensive borrowing and filling
Surface drainage is primarily from the northwest and
southwest The area drains to the east and southeast A
topographic divide which defines the limit of the
watershed lies between the active landfill and the
reservoir A small yet inactive portion of the landfill
property lies within the watershed of the Scituate
Reservoir The active landfill is approximately 5100 feet
from the portion of the watershed boundary that crosses
landfill property
BSR03009 2-1
GEOLOGY
Bedrock in the vicinity of the Central Landfill consists of
granite and granite gneiss and is referenced in the
literature as the Scituate granite Soils overlying the
Scituate granite predominantly consist of glacial till and
glacial outwash The till is an unsorted ground moraine
composed of fine-grained to boulder-sized particles The
outwash varies from poorly sorted materials to well-sorted
ice-contact sands and gravels The soils vary in thickness
from 0 feet in areas that have been excavated to over
60 feet southvest of Cedar Swamp Brook Within the existing
landfill refuse ranges in thickness from 50 feet at Well E
to 135 feet at Well WE87-3 Refuse is in direct contact
with the bedrock over the northern portion of tlie landfill
and is within 5 feet of bedrock over its southern part
Bedrock topography at the landfill is defined by subsurface
investigations associated with the landfill design and the
ongoing remedial investigationfeasibility study (RIFS)
Bedrock topography has been mapped regionally by the
US Geological Survey (USGS) The Central Landfill lies on
the north slope of a bedrock valley with a northwest to
southeast general trend The Upper reach of the bedrock
valley is two prongedmdashnorthwest to southeast and north to
southeast The active landfill overlies most of the latter
Rock quarrying has modified the area along the western slope
of the landfill and in the vicinity of the portion of the
landfill (near Well J) that received industrial wastes
The degree of weathering and Rock Quality Designations
(RQDs) observed in rock core were evaluated with respect to
depth below the top of rock and proximity to fracture
traces The RQD is a measure of the degree to which rock is
BSR03010 3-1
fractured as reflected in the lengths of rock core
reioveries A highly fractured rock will exhibit a low RQD
In general the RQD increased with depth--57 percent for
0 to 10 feet below the top of rock and 77 percent for
10 to 30 feet below the top of rock At boreholes located
in fracture traces however the RQDs were 40 percent and
62 percent respectively indicating a correlation between
the fracture traces observed on both aerial photographs and
satellite imagery and the degree to which the bedrock is
friictured Similarly the degree of weathering was found to
be a function of both depth and proximity to fracture
tl ces Severe veathering was noted throughout
B(U-ehole WE87-13 and to a depth of 45 feet in
Borehole WE85-6 both of which lie along northeast-southwest
trending features It should be noted that observations of
rock weathering and RQDs apply only to boreholes from vhich
rock core was available These boreholes tended to be
relatively shallow extending approximately 30 feet below
the top of rock
Deeper explorations (124 to 247 feet below the top of rock)
were performed in the multilevel wellsmdashWE87-ML1 through
WE87-ML5 The Fracture Trace Analysis (FTA) was used to
position the multilevel wells Each multilevel well was
pllt3ced on or proximal to an observed fracture trace The
degree of fracturing and the orientation of fractures were
evaluated by borehole televiewer The ability of the
observed fractures to transmit water was evaluated by packer
tests
The May 198 8 Interim Remedial Investigation Report by
Goldberg-Zoino amp Associates Inc (GZA) (Appendix
Document 38) indicates that the orientations of fractures
indicated on televiewer logs were compiled into a ccmposite
plotted on a stereonet and contoured The contouring
BSR03010 3-2
yielded four preferred fracture orientations thiat -bullere in
agreement with the orientations of lineaments identified jn
the FTA The dominant group had a strike and dip of
N20deg-40degE 60deg-80degNW The lesser groups were at nearly
horizontal N10deg-20degW 50deg-60degSW and N80deg-85degE 65deg-70NW
Because the stereonet plots were not included in the GZA
May 1988 report (Doc 38) CH2M HILL plotted the fracture
orientations provided on the boring log for Borehole
KE87-ML3 This borehole lies near the intersection of
Lineainents 1 and 2 with Lineament 24 Borehole WE87-ML3 is
of particular significance because Lineaments 1 and 2
represent potential pathways for the migration of
containinants to the Scituate Reservoir The orieiitations of
fractures in Borehole WE87-ML3 correspond reasonably vell
with the trends of Lineaments 1 2 and 24
Barbed on televiewer data the average fracture frequency
reported for the five multilevel wells was 072 fractures
per foot Only a very slight decrease in fracture frequency
was noted with depth--08 fractures per foot for the top
30 feet of bedrock 07 fractures per foot for the tpp
100 feet of bedrock and 06 fractures per foot for depths
greater than 100 feet below the top of rock An exception
to this trend that was noted in the GZA May 1988 report
(Doc 38) was Borehole WE87-ML1 in which fracture frequency
increased with depth Equally significant are above-average
fracture frequencies and significant flow measurements over
deep rock intervals (more than 100 feet in each borehole
extending deeper than 100 feet and more than 200 feet in
each borehole extending deeper than 200 feet) The data
suggest that rock fractures and associated water-bearing
zones extend to some unknown distance below the depth
reached by the five multilevel wells
BSR03010 3-3
GEOPHYSICAL INVESTIGATIONS
Geophysical investigations are described in both the
August 1987 report prepared by Geotech Enterprises Inc
(Appendix Document 35) and GZAs May 1988 report (Doc 38)
Thiree geophysical survey methods were used by Geotech to
investigate the vicinity of the Central Landfill The
objectives of the investigations were to locate areas of
rock fracturing and to recommend locations for three
multilevel wells The survey methods investigated gravity
e]ectrical resi^tivity and seismic refraction Each method
vas targeted at a different physical property of the rock
any of which could indicate fracturing
GZAs May 1988 report (Doc 38) summarizes the results of
the geophysical surveys discussed in the Geotech report
(Doc 35) In addition GZAs May 1988 report describes the
results of downhole geophysical logging performed by the
USGS and vertical seismic profiling performed by Weston
Geophysical Corporation
41 GRAVITY
The gravity investigation method measures minute differences
in the Earths gravitational field resulting from rock
density differences Fracturing can result in lover
densities which can often be identified as gravity lovs
Different rock types with different densities also can
result in gravity lows
Regional data indicate a gravity low in the vicinity of the
landfill but it is uncertain whether the low results from a
fracture zone or from the presence of different rock types
BSR03011 4-1
III
of higher donsity on either side of the landfill
Additional gravity measurements obtained in tho vicinity of
the landfill confirm the gravity low and suggest a
northeast-southwest trend to the low that corresponds with
Lincainent 1
The gravity data are dominated by the regional effects of
the denser metamorphic sediments to the east and the buried
pluton to the west In order to minimize the gravity
effects of these features and to emphasize the ]oca]ized
effects of fracture zones CH2M JIILL removed a fourth-order
surface from the data The residual values reflect the
smaller (shorter wavelength) features that are likely to
include fracture zones The resulting residual data were
tlien plotted on a map
Tlie central part of the residual data map showed a gravity
hiyli with sides oriented northeast-southwest The southeast
side of this feature is coincident with Lineament 1 on the
fracture trace map in GZAs May 1988 report (Doc 38)
Central Landfill is located on this feature The residual
gravity high is breached in the vicinity of the landfill
The breach may be associated with other fracture traces
The results of the residual gravity evaluation suggest that
Lineament 1 may be related to a geologic contact
Alternatively Lineament 1 may be at the contact between
fractured rock to the southeast (the gravity low) and
unfractured rock to the northwest The data support the
fracture trace interpretation in the vicinity of the
landfill
BSR0 3011 4-2
42 ELECTRICAL RESISTIVITY
Electrical soundings are used to estimate subsurface
resistivities Fracture zones can affect the resistivities
by increasing hydraulic conductivity In most cases rock
resistivity is controlled by pore fluid conductivity and
porosity
The soundings in the vicinity of the landfill indicated
areas of resistive bedrock (indicating competent rock) and
areas of less resistive bedrock (possibly fractured rock)
For i he most part the more resistive areas are northwest of
Lineltiment 1 and the less resistive bedrock is southeast of
the lineament
The interpreted bedrock resistivities were used with
groundwater specific conductance to calculate a formation
factor A high formation factor suggests competent rock
The variability of groundwater conductivity over short
distances in general and some uncertainty in the estimated
bedrock conductivity in the vicinity of the landfill may
make use of these formation factors questionable
There are no comments in either the GZA May 1988 report
(Doc 38) or the Geotech report (Doc 35) about cultural
conductors such as fences and power lines that may have
affected the data Either there are no cultural conductors
in the area or this potential problem was overlooked
Soundings 4 and 9 may have been affected by nearby cultural
conductors
The observed bedrock resistivities appear lower on the
southeast side of Lineament 1 and higher on the nort)ivest
side This is consistent with Lineament 1 being a geologic
BSR03011 4-3
I
contact or with the fracture density being higher on the
southeast side
43 SEISMIC REFRACTION
Seismic refraction surveys were performed to measure bedrock
velocities in the vicinity of the landfill Bedrock
veJricities may be reduced in areas of fracturing compared
witli the velocities in unfractured areas Refraction
surveys generally were run in the same areas as those in
which the electrical soundings were run Low velocity
bidrock wliich may be related to rock fracturing vas
idntified by the refraction surveys
Because seismic data are very noisy the first arrivals were
not identified properly in some instances Estimated
bedrock velocities are correspondingly uncertain The
bedrock velocity calculated by CH2M HILL for Line S-4
(12100 fps) is approximately 15 percent higher than the
velocity given in the Geotech and GZA reports (10380 fps)
(Doc 35 38) The data for Line S-4 are relatively good
an uncertainty of 15 percent or worse might be typical for
data of this quality
Some of the seismic spreads did not include a shot at each
end of a spread Without data from shots at both ends it
is impossible to determine true bedrock velocities where
dipping beds are present Although seismic refraction is a
valid metliod for identifying fracture zones better-quality
data than those presented in the Geotech and GZA reports
(Doc 35 38) are required
BSR03011 4-4
44 DOWNHOLE GEOPHYSICAL LOGGINC
AND VERTICAL SEISMIC PROFILING
The downhole geophysical logging was performed by the USGS
Division of Water Resources The logging methods and their
associated functions are listed below
Acoustic Borehole Televiewer
Formation Resistivity
Borehole Caliper
Neutron-Gamma
Natural Gamma
Spontaneous Potential
Maps rock fractures using
sonar transmissions
Maps areas of lower
resistivity lhat may be
the result of fracturing
Measures borehole
diameter
Measures formation
porosity but readings are
affected by clay
Measures formation
natural radioactive
emmissions can be
used to identify clay and
was used with the
neutron-gamma data
Used to identify different
strata such as clay and
shale
BSR03011 4-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
0 10 M l bull raquo I t I I
Approxiniale Scale
Central Landf i l l
Alrny Reservoir
Simmons Reservoir
Scituate Reservoir
1 Location oT Proiect r^ifiMUIII n Figure I AVlthlnThe State of RhodiJlslana v^fJiVJnU
1-9
Figure 2 Aoproximattt Scale
Slta-Miip 3t i - Cjnt-al Lancrflil cyihL
Ill Tlie Providence Water Supply Board has contracted with CH2M
HILL to perform an evaluation of the data pertaining to the
Central LancJfill The objectives of this study are
Provide an independent review of reports data
drawings and other available information
concerning existing or potential impacts of the
landfill on surface water and groundwater in Using existing data assess whether there is
indeed seepage from the existing landfill and if
so what its impact is on water in the vicinity of
the landfill 111 Assess whether the proposed landfill expansion
will have further impact on surface water and
groundwater
Determine whether seepage from the landfill could m have an impact on Scituate Reservoir
11
mi
m m BSR03008 1-4
li
PHYSIOGRAPHY AND DRAINAGE
Surface topography in the North Scituate Quadrangle is
characterized by northwest-southeast trending uplands and
in intervening valleys The orientation of these surface
features reflects the direction of glacial advance and
concomitant erosion of preglacial soils The orientations
of Oak Swamp Almy and Simmons Reservoirs and portions of
i] Scituate Reservoir are examples of this general
northwest-southeast valley orientation
The active portion of the Central Landfill is located
approximately 2-12 miles east of the Scituate Reservoir
The Central Landfill also occupies an elongate valley The
area has been modified by extensive borrowing and filling
Surface drainage is primarily from the northwest and
southwest The area drains to the east and southeast A
topographic divide which defines the limit of the
watershed lies between the active landfill and the
reservoir A small yet inactive portion of the landfill
property lies within the watershed of the Scituate
Reservoir The active landfill is approximately 5100 feet
from the portion of the watershed boundary that crosses
landfill property
BSR03009 2-1
GEOLOGY
Bedrock in the vicinity of the Central Landfill consists of
granite and granite gneiss and is referenced in the
literature as the Scituate granite Soils overlying the
Scituate granite predominantly consist of glacial till and
glacial outwash The till is an unsorted ground moraine
composed of fine-grained to boulder-sized particles The
outwash varies from poorly sorted materials to well-sorted
ice-contact sands and gravels The soils vary in thickness
from 0 feet in areas that have been excavated to over
60 feet southvest of Cedar Swamp Brook Within the existing
landfill refuse ranges in thickness from 50 feet at Well E
to 135 feet at Well WE87-3 Refuse is in direct contact
with the bedrock over the northern portion of tlie landfill
and is within 5 feet of bedrock over its southern part
Bedrock topography at the landfill is defined by subsurface
investigations associated with the landfill design and the
ongoing remedial investigationfeasibility study (RIFS)
Bedrock topography has been mapped regionally by the
US Geological Survey (USGS) The Central Landfill lies on
the north slope of a bedrock valley with a northwest to
southeast general trend The Upper reach of the bedrock
valley is two prongedmdashnorthwest to southeast and north to
southeast The active landfill overlies most of the latter
Rock quarrying has modified the area along the western slope
of the landfill and in the vicinity of the portion of the
landfill (near Well J) that received industrial wastes
The degree of weathering and Rock Quality Designations
(RQDs) observed in rock core were evaluated with respect to
depth below the top of rock and proximity to fracture
traces The RQD is a measure of the degree to which rock is
BSR03010 3-1
fractured as reflected in the lengths of rock core
reioveries A highly fractured rock will exhibit a low RQD
In general the RQD increased with depth--57 percent for
0 to 10 feet below the top of rock and 77 percent for
10 to 30 feet below the top of rock At boreholes located
in fracture traces however the RQDs were 40 percent and
62 percent respectively indicating a correlation between
the fracture traces observed on both aerial photographs and
satellite imagery and the degree to which the bedrock is
friictured Similarly the degree of weathering was found to
be a function of both depth and proximity to fracture
tl ces Severe veathering was noted throughout
B(U-ehole WE87-13 and to a depth of 45 feet in
Borehole WE85-6 both of which lie along northeast-southwest
trending features It should be noted that observations of
rock weathering and RQDs apply only to boreholes from vhich
rock core was available These boreholes tended to be
relatively shallow extending approximately 30 feet below
the top of rock
Deeper explorations (124 to 247 feet below the top of rock)
were performed in the multilevel wellsmdashWE87-ML1 through
WE87-ML5 The Fracture Trace Analysis (FTA) was used to
position the multilevel wells Each multilevel well was
pllt3ced on or proximal to an observed fracture trace The
degree of fracturing and the orientation of fractures were
evaluated by borehole televiewer The ability of the
observed fractures to transmit water was evaluated by packer
tests
The May 198 8 Interim Remedial Investigation Report by
Goldberg-Zoino amp Associates Inc (GZA) (Appendix
Document 38) indicates that the orientations of fractures
indicated on televiewer logs were compiled into a ccmposite
plotted on a stereonet and contoured The contouring
BSR03010 3-2
yielded four preferred fracture orientations thiat -bullere in
agreement with the orientations of lineaments identified jn
the FTA The dominant group had a strike and dip of
N20deg-40degE 60deg-80degNW The lesser groups were at nearly
horizontal N10deg-20degW 50deg-60degSW and N80deg-85degE 65deg-70NW
Because the stereonet plots were not included in the GZA
May 1988 report (Doc 38) CH2M HILL plotted the fracture
orientations provided on the boring log for Borehole
KE87-ML3 This borehole lies near the intersection of
Lineainents 1 and 2 with Lineament 24 Borehole WE87-ML3 is
of particular significance because Lineaments 1 and 2
represent potential pathways for the migration of
containinants to the Scituate Reservoir The orieiitations of
fractures in Borehole WE87-ML3 correspond reasonably vell
with the trends of Lineaments 1 2 and 24
Barbed on televiewer data the average fracture frequency
reported for the five multilevel wells was 072 fractures
per foot Only a very slight decrease in fracture frequency
was noted with depth--08 fractures per foot for the top
30 feet of bedrock 07 fractures per foot for the tpp
100 feet of bedrock and 06 fractures per foot for depths
greater than 100 feet below the top of rock An exception
to this trend that was noted in the GZA May 1988 report
(Doc 38) was Borehole WE87-ML1 in which fracture frequency
increased with depth Equally significant are above-average
fracture frequencies and significant flow measurements over
deep rock intervals (more than 100 feet in each borehole
extending deeper than 100 feet and more than 200 feet in
each borehole extending deeper than 200 feet) The data
suggest that rock fractures and associated water-bearing
zones extend to some unknown distance below the depth
reached by the five multilevel wells
BSR03010 3-3
GEOPHYSICAL INVESTIGATIONS
Geophysical investigations are described in both the
August 1987 report prepared by Geotech Enterprises Inc
(Appendix Document 35) and GZAs May 1988 report (Doc 38)
Thiree geophysical survey methods were used by Geotech to
investigate the vicinity of the Central Landfill The
objectives of the investigations were to locate areas of
rock fracturing and to recommend locations for three
multilevel wells The survey methods investigated gravity
e]ectrical resi^tivity and seismic refraction Each method
vas targeted at a different physical property of the rock
any of which could indicate fracturing
GZAs May 1988 report (Doc 38) summarizes the results of
the geophysical surveys discussed in the Geotech report
(Doc 35) In addition GZAs May 1988 report describes the
results of downhole geophysical logging performed by the
USGS and vertical seismic profiling performed by Weston
Geophysical Corporation
41 GRAVITY
The gravity investigation method measures minute differences
in the Earths gravitational field resulting from rock
density differences Fracturing can result in lover
densities which can often be identified as gravity lovs
Different rock types with different densities also can
result in gravity lows
Regional data indicate a gravity low in the vicinity of the
landfill but it is uncertain whether the low results from a
fracture zone or from the presence of different rock types
BSR03011 4-1
III
of higher donsity on either side of the landfill
Additional gravity measurements obtained in tho vicinity of
the landfill confirm the gravity low and suggest a
northeast-southwest trend to the low that corresponds with
Lincainent 1
The gravity data are dominated by the regional effects of
the denser metamorphic sediments to the east and the buried
pluton to the west In order to minimize the gravity
effects of these features and to emphasize the ]oca]ized
effects of fracture zones CH2M JIILL removed a fourth-order
surface from the data The residual values reflect the
smaller (shorter wavelength) features that are likely to
include fracture zones The resulting residual data were
tlien plotted on a map
Tlie central part of the residual data map showed a gravity
hiyli with sides oriented northeast-southwest The southeast
side of this feature is coincident with Lineament 1 on the
fracture trace map in GZAs May 1988 report (Doc 38)
Central Landfill is located on this feature The residual
gravity high is breached in the vicinity of the landfill
The breach may be associated with other fracture traces
The results of the residual gravity evaluation suggest that
Lineament 1 may be related to a geologic contact
Alternatively Lineament 1 may be at the contact between
fractured rock to the southeast (the gravity low) and
unfractured rock to the northwest The data support the
fracture trace interpretation in the vicinity of the
landfill
BSR0 3011 4-2
42 ELECTRICAL RESISTIVITY
Electrical soundings are used to estimate subsurface
resistivities Fracture zones can affect the resistivities
by increasing hydraulic conductivity In most cases rock
resistivity is controlled by pore fluid conductivity and
porosity
The soundings in the vicinity of the landfill indicated
areas of resistive bedrock (indicating competent rock) and
areas of less resistive bedrock (possibly fractured rock)
For i he most part the more resistive areas are northwest of
Lineltiment 1 and the less resistive bedrock is southeast of
the lineament
The interpreted bedrock resistivities were used with
groundwater specific conductance to calculate a formation
factor A high formation factor suggests competent rock
The variability of groundwater conductivity over short
distances in general and some uncertainty in the estimated
bedrock conductivity in the vicinity of the landfill may
make use of these formation factors questionable
There are no comments in either the GZA May 1988 report
(Doc 38) or the Geotech report (Doc 35) about cultural
conductors such as fences and power lines that may have
affected the data Either there are no cultural conductors
in the area or this potential problem was overlooked
Soundings 4 and 9 may have been affected by nearby cultural
conductors
The observed bedrock resistivities appear lower on the
southeast side of Lineament 1 and higher on the nort)ivest
side This is consistent with Lineament 1 being a geologic
BSR03011 4-3
I
contact or with the fracture density being higher on the
southeast side
43 SEISMIC REFRACTION
Seismic refraction surveys were performed to measure bedrock
velocities in the vicinity of the landfill Bedrock
veJricities may be reduced in areas of fracturing compared
witli the velocities in unfractured areas Refraction
surveys generally were run in the same areas as those in
which the electrical soundings were run Low velocity
bidrock wliich may be related to rock fracturing vas
idntified by the refraction surveys
Because seismic data are very noisy the first arrivals were
not identified properly in some instances Estimated
bedrock velocities are correspondingly uncertain The
bedrock velocity calculated by CH2M HILL for Line S-4
(12100 fps) is approximately 15 percent higher than the
velocity given in the Geotech and GZA reports (10380 fps)
(Doc 35 38) The data for Line S-4 are relatively good
an uncertainty of 15 percent or worse might be typical for
data of this quality
Some of the seismic spreads did not include a shot at each
end of a spread Without data from shots at both ends it
is impossible to determine true bedrock velocities where
dipping beds are present Although seismic refraction is a
valid metliod for identifying fracture zones better-quality
data than those presented in the Geotech and GZA reports
(Doc 35 38) are required
BSR03011 4-4
44 DOWNHOLE GEOPHYSICAL LOGGINC
AND VERTICAL SEISMIC PROFILING
The downhole geophysical logging was performed by the USGS
Division of Water Resources The logging methods and their
associated functions are listed below
Acoustic Borehole Televiewer
Formation Resistivity
Borehole Caliper
Neutron-Gamma
Natural Gamma
Spontaneous Potential
Maps rock fractures using
sonar transmissions
Maps areas of lower
resistivity lhat may be
the result of fracturing
Measures borehole
diameter
Measures formation
porosity but readings are
affected by clay
Measures formation
natural radioactive
emmissions can be
used to identify clay and
was used with the
neutron-gamma data
Used to identify different
strata such as clay and
shale
BSR03011 4-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
Figure 2 Aoproximattt Scale
Slta-Miip 3t i - Cjnt-al Lancrflil cyihL
Ill Tlie Providence Water Supply Board has contracted with CH2M
HILL to perform an evaluation of the data pertaining to the
Central LancJfill The objectives of this study are
Provide an independent review of reports data
drawings and other available information
concerning existing or potential impacts of the
landfill on surface water and groundwater in Using existing data assess whether there is
indeed seepage from the existing landfill and if
so what its impact is on water in the vicinity of
the landfill 111 Assess whether the proposed landfill expansion
will have further impact on surface water and
groundwater
Determine whether seepage from the landfill could m have an impact on Scituate Reservoir
11
mi
m m BSR03008 1-4
li
PHYSIOGRAPHY AND DRAINAGE
Surface topography in the North Scituate Quadrangle is
characterized by northwest-southeast trending uplands and
in intervening valleys The orientation of these surface
features reflects the direction of glacial advance and
concomitant erosion of preglacial soils The orientations
of Oak Swamp Almy and Simmons Reservoirs and portions of
i] Scituate Reservoir are examples of this general
northwest-southeast valley orientation
The active portion of the Central Landfill is located
approximately 2-12 miles east of the Scituate Reservoir
The Central Landfill also occupies an elongate valley The
area has been modified by extensive borrowing and filling
Surface drainage is primarily from the northwest and
southwest The area drains to the east and southeast A
topographic divide which defines the limit of the
watershed lies between the active landfill and the
reservoir A small yet inactive portion of the landfill
property lies within the watershed of the Scituate
Reservoir The active landfill is approximately 5100 feet
from the portion of the watershed boundary that crosses
landfill property
BSR03009 2-1
GEOLOGY
Bedrock in the vicinity of the Central Landfill consists of
granite and granite gneiss and is referenced in the
literature as the Scituate granite Soils overlying the
Scituate granite predominantly consist of glacial till and
glacial outwash The till is an unsorted ground moraine
composed of fine-grained to boulder-sized particles The
outwash varies from poorly sorted materials to well-sorted
ice-contact sands and gravels The soils vary in thickness
from 0 feet in areas that have been excavated to over
60 feet southvest of Cedar Swamp Brook Within the existing
landfill refuse ranges in thickness from 50 feet at Well E
to 135 feet at Well WE87-3 Refuse is in direct contact
with the bedrock over the northern portion of tlie landfill
and is within 5 feet of bedrock over its southern part
Bedrock topography at the landfill is defined by subsurface
investigations associated with the landfill design and the
ongoing remedial investigationfeasibility study (RIFS)
Bedrock topography has been mapped regionally by the
US Geological Survey (USGS) The Central Landfill lies on
the north slope of a bedrock valley with a northwest to
southeast general trend The Upper reach of the bedrock
valley is two prongedmdashnorthwest to southeast and north to
southeast The active landfill overlies most of the latter
Rock quarrying has modified the area along the western slope
of the landfill and in the vicinity of the portion of the
landfill (near Well J) that received industrial wastes
The degree of weathering and Rock Quality Designations
(RQDs) observed in rock core were evaluated with respect to
depth below the top of rock and proximity to fracture
traces The RQD is a measure of the degree to which rock is
BSR03010 3-1
fractured as reflected in the lengths of rock core
reioveries A highly fractured rock will exhibit a low RQD
In general the RQD increased with depth--57 percent for
0 to 10 feet below the top of rock and 77 percent for
10 to 30 feet below the top of rock At boreholes located
in fracture traces however the RQDs were 40 percent and
62 percent respectively indicating a correlation between
the fracture traces observed on both aerial photographs and
satellite imagery and the degree to which the bedrock is
friictured Similarly the degree of weathering was found to
be a function of both depth and proximity to fracture
tl ces Severe veathering was noted throughout
B(U-ehole WE87-13 and to a depth of 45 feet in
Borehole WE85-6 both of which lie along northeast-southwest
trending features It should be noted that observations of
rock weathering and RQDs apply only to boreholes from vhich
rock core was available These boreholes tended to be
relatively shallow extending approximately 30 feet below
the top of rock
Deeper explorations (124 to 247 feet below the top of rock)
were performed in the multilevel wellsmdashWE87-ML1 through
WE87-ML5 The Fracture Trace Analysis (FTA) was used to
position the multilevel wells Each multilevel well was
pllt3ced on or proximal to an observed fracture trace The
degree of fracturing and the orientation of fractures were
evaluated by borehole televiewer The ability of the
observed fractures to transmit water was evaluated by packer
tests
The May 198 8 Interim Remedial Investigation Report by
Goldberg-Zoino amp Associates Inc (GZA) (Appendix
Document 38) indicates that the orientations of fractures
indicated on televiewer logs were compiled into a ccmposite
plotted on a stereonet and contoured The contouring
BSR03010 3-2
yielded four preferred fracture orientations thiat -bullere in
agreement with the orientations of lineaments identified jn
the FTA The dominant group had a strike and dip of
N20deg-40degE 60deg-80degNW The lesser groups were at nearly
horizontal N10deg-20degW 50deg-60degSW and N80deg-85degE 65deg-70NW
Because the stereonet plots were not included in the GZA
May 1988 report (Doc 38) CH2M HILL plotted the fracture
orientations provided on the boring log for Borehole
KE87-ML3 This borehole lies near the intersection of
Lineainents 1 and 2 with Lineament 24 Borehole WE87-ML3 is
of particular significance because Lineaments 1 and 2
represent potential pathways for the migration of
containinants to the Scituate Reservoir The orieiitations of
fractures in Borehole WE87-ML3 correspond reasonably vell
with the trends of Lineaments 1 2 and 24
Barbed on televiewer data the average fracture frequency
reported for the five multilevel wells was 072 fractures
per foot Only a very slight decrease in fracture frequency
was noted with depth--08 fractures per foot for the top
30 feet of bedrock 07 fractures per foot for the tpp
100 feet of bedrock and 06 fractures per foot for depths
greater than 100 feet below the top of rock An exception
to this trend that was noted in the GZA May 1988 report
(Doc 38) was Borehole WE87-ML1 in which fracture frequency
increased with depth Equally significant are above-average
fracture frequencies and significant flow measurements over
deep rock intervals (more than 100 feet in each borehole
extending deeper than 100 feet and more than 200 feet in
each borehole extending deeper than 200 feet) The data
suggest that rock fractures and associated water-bearing
zones extend to some unknown distance below the depth
reached by the five multilevel wells
BSR03010 3-3
GEOPHYSICAL INVESTIGATIONS
Geophysical investigations are described in both the
August 1987 report prepared by Geotech Enterprises Inc
(Appendix Document 35) and GZAs May 1988 report (Doc 38)
Thiree geophysical survey methods were used by Geotech to
investigate the vicinity of the Central Landfill The
objectives of the investigations were to locate areas of
rock fracturing and to recommend locations for three
multilevel wells The survey methods investigated gravity
e]ectrical resi^tivity and seismic refraction Each method
vas targeted at a different physical property of the rock
any of which could indicate fracturing
GZAs May 1988 report (Doc 38) summarizes the results of
the geophysical surveys discussed in the Geotech report
(Doc 35) In addition GZAs May 1988 report describes the
results of downhole geophysical logging performed by the
USGS and vertical seismic profiling performed by Weston
Geophysical Corporation
41 GRAVITY
The gravity investigation method measures minute differences
in the Earths gravitational field resulting from rock
density differences Fracturing can result in lover
densities which can often be identified as gravity lovs
Different rock types with different densities also can
result in gravity lows
Regional data indicate a gravity low in the vicinity of the
landfill but it is uncertain whether the low results from a
fracture zone or from the presence of different rock types
BSR03011 4-1
III
of higher donsity on either side of the landfill
Additional gravity measurements obtained in tho vicinity of
the landfill confirm the gravity low and suggest a
northeast-southwest trend to the low that corresponds with
Lincainent 1
The gravity data are dominated by the regional effects of
the denser metamorphic sediments to the east and the buried
pluton to the west In order to minimize the gravity
effects of these features and to emphasize the ]oca]ized
effects of fracture zones CH2M JIILL removed a fourth-order
surface from the data The residual values reflect the
smaller (shorter wavelength) features that are likely to
include fracture zones The resulting residual data were
tlien plotted on a map
Tlie central part of the residual data map showed a gravity
hiyli with sides oriented northeast-southwest The southeast
side of this feature is coincident with Lineament 1 on the
fracture trace map in GZAs May 1988 report (Doc 38)
Central Landfill is located on this feature The residual
gravity high is breached in the vicinity of the landfill
The breach may be associated with other fracture traces
The results of the residual gravity evaluation suggest that
Lineament 1 may be related to a geologic contact
Alternatively Lineament 1 may be at the contact between
fractured rock to the southeast (the gravity low) and
unfractured rock to the northwest The data support the
fracture trace interpretation in the vicinity of the
landfill
BSR0 3011 4-2
42 ELECTRICAL RESISTIVITY
Electrical soundings are used to estimate subsurface
resistivities Fracture zones can affect the resistivities
by increasing hydraulic conductivity In most cases rock
resistivity is controlled by pore fluid conductivity and
porosity
The soundings in the vicinity of the landfill indicated
areas of resistive bedrock (indicating competent rock) and
areas of less resistive bedrock (possibly fractured rock)
For i he most part the more resistive areas are northwest of
Lineltiment 1 and the less resistive bedrock is southeast of
the lineament
The interpreted bedrock resistivities were used with
groundwater specific conductance to calculate a formation
factor A high formation factor suggests competent rock
The variability of groundwater conductivity over short
distances in general and some uncertainty in the estimated
bedrock conductivity in the vicinity of the landfill may
make use of these formation factors questionable
There are no comments in either the GZA May 1988 report
(Doc 38) or the Geotech report (Doc 35) about cultural
conductors such as fences and power lines that may have
affected the data Either there are no cultural conductors
in the area or this potential problem was overlooked
Soundings 4 and 9 may have been affected by nearby cultural
conductors
The observed bedrock resistivities appear lower on the
southeast side of Lineament 1 and higher on the nort)ivest
side This is consistent with Lineament 1 being a geologic
BSR03011 4-3
I
contact or with the fracture density being higher on the
southeast side
43 SEISMIC REFRACTION
Seismic refraction surveys were performed to measure bedrock
velocities in the vicinity of the landfill Bedrock
veJricities may be reduced in areas of fracturing compared
witli the velocities in unfractured areas Refraction
surveys generally were run in the same areas as those in
which the electrical soundings were run Low velocity
bidrock wliich may be related to rock fracturing vas
idntified by the refraction surveys
Because seismic data are very noisy the first arrivals were
not identified properly in some instances Estimated
bedrock velocities are correspondingly uncertain The
bedrock velocity calculated by CH2M HILL for Line S-4
(12100 fps) is approximately 15 percent higher than the
velocity given in the Geotech and GZA reports (10380 fps)
(Doc 35 38) The data for Line S-4 are relatively good
an uncertainty of 15 percent or worse might be typical for
data of this quality
Some of the seismic spreads did not include a shot at each
end of a spread Without data from shots at both ends it
is impossible to determine true bedrock velocities where
dipping beds are present Although seismic refraction is a
valid metliod for identifying fracture zones better-quality
data than those presented in the Geotech and GZA reports
(Doc 35 38) are required
BSR03011 4-4
44 DOWNHOLE GEOPHYSICAL LOGGINC
AND VERTICAL SEISMIC PROFILING
The downhole geophysical logging was performed by the USGS
Division of Water Resources The logging methods and their
associated functions are listed below
Acoustic Borehole Televiewer
Formation Resistivity
Borehole Caliper
Neutron-Gamma
Natural Gamma
Spontaneous Potential
Maps rock fractures using
sonar transmissions
Maps areas of lower
resistivity lhat may be
the result of fracturing
Measures borehole
diameter
Measures formation
porosity but readings are
affected by clay
Measures formation
natural radioactive
emmissions can be
used to identify clay and
was used with the
neutron-gamma data
Used to identify different
strata such as clay and
shale
BSR03011 4-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
Ill Tlie Providence Water Supply Board has contracted with CH2M
HILL to perform an evaluation of the data pertaining to the
Central LancJfill The objectives of this study are
Provide an independent review of reports data
drawings and other available information
concerning existing or potential impacts of the
landfill on surface water and groundwater in Using existing data assess whether there is
indeed seepage from the existing landfill and if
so what its impact is on water in the vicinity of
the landfill 111 Assess whether the proposed landfill expansion
will have further impact on surface water and
groundwater
Determine whether seepage from the landfill could m have an impact on Scituate Reservoir
11
mi
m m BSR03008 1-4
li
PHYSIOGRAPHY AND DRAINAGE
Surface topography in the North Scituate Quadrangle is
characterized by northwest-southeast trending uplands and
in intervening valleys The orientation of these surface
features reflects the direction of glacial advance and
concomitant erosion of preglacial soils The orientations
of Oak Swamp Almy and Simmons Reservoirs and portions of
i] Scituate Reservoir are examples of this general
northwest-southeast valley orientation
The active portion of the Central Landfill is located
approximately 2-12 miles east of the Scituate Reservoir
The Central Landfill also occupies an elongate valley The
area has been modified by extensive borrowing and filling
Surface drainage is primarily from the northwest and
southwest The area drains to the east and southeast A
topographic divide which defines the limit of the
watershed lies between the active landfill and the
reservoir A small yet inactive portion of the landfill
property lies within the watershed of the Scituate
Reservoir The active landfill is approximately 5100 feet
from the portion of the watershed boundary that crosses
landfill property
BSR03009 2-1
GEOLOGY
Bedrock in the vicinity of the Central Landfill consists of
granite and granite gneiss and is referenced in the
literature as the Scituate granite Soils overlying the
Scituate granite predominantly consist of glacial till and
glacial outwash The till is an unsorted ground moraine
composed of fine-grained to boulder-sized particles The
outwash varies from poorly sorted materials to well-sorted
ice-contact sands and gravels The soils vary in thickness
from 0 feet in areas that have been excavated to over
60 feet southvest of Cedar Swamp Brook Within the existing
landfill refuse ranges in thickness from 50 feet at Well E
to 135 feet at Well WE87-3 Refuse is in direct contact
with the bedrock over the northern portion of tlie landfill
and is within 5 feet of bedrock over its southern part
Bedrock topography at the landfill is defined by subsurface
investigations associated with the landfill design and the
ongoing remedial investigationfeasibility study (RIFS)
Bedrock topography has been mapped regionally by the
US Geological Survey (USGS) The Central Landfill lies on
the north slope of a bedrock valley with a northwest to
southeast general trend The Upper reach of the bedrock
valley is two prongedmdashnorthwest to southeast and north to
southeast The active landfill overlies most of the latter
Rock quarrying has modified the area along the western slope
of the landfill and in the vicinity of the portion of the
landfill (near Well J) that received industrial wastes
The degree of weathering and Rock Quality Designations
(RQDs) observed in rock core were evaluated with respect to
depth below the top of rock and proximity to fracture
traces The RQD is a measure of the degree to which rock is
BSR03010 3-1
fractured as reflected in the lengths of rock core
reioveries A highly fractured rock will exhibit a low RQD
In general the RQD increased with depth--57 percent for
0 to 10 feet below the top of rock and 77 percent for
10 to 30 feet below the top of rock At boreholes located
in fracture traces however the RQDs were 40 percent and
62 percent respectively indicating a correlation between
the fracture traces observed on both aerial photographs and
satellite imagery and the degree to which the bedrock is
friictured Similarly the degree of weathering was found to
be a function of both depth and proximity to fracture
tl ces Severe veathering was noted throughout
B(U-ehole WE87-13 and to a depth of 45 feet in
Borehole WE85-6 both of which lie along northeast-southwest
trending features It should be noted that observations of
rock weathering and RQDs apply only to boreholes from vhich
rock core was available These boreholes tended to be
relatively shallow extending approximately 30 feet below
the top of rock
Deeper explorations (124 to 247 feet below the top of rock)
were performed in the multilevel wellsmdashWE87-ML1 through
WE87-ML5 The Fracture Trace Analysis (FTA) was used to
position the multilevel wells Each multilevel well was
pllt3ced on or proximal to an observed fracture trace The
degree of fracturing and the orientation of fractures were
evaluated by borehole televiewer The ability of the
observed fractures to transmit water was evaluated by packer
tests
The May 198 8 Interim Remedial Investigation Report by
Goldberg-Zoino amp Associates Inc (GZA) (Appendix
Document 38) indicates that the orientations of fractures
indicated on televiewer logs were compiled into a ccmposite
plotted on a stereonet and contoured The contouring
BSR03010 3-2
yielded four preferred fracture orientations thiat -bullere in
agreement with the orientations of lineaments identified jn
the FTA The dominant group had a strike and dip of
N20deg-40degE 60deg-80degNW The lesser groups were at nearly
horizontal N10deg-20degW 50deg-60degSW and N80deg-85degE 65deg-70NW
Because the stereonet plots were not included in the GZA
May 1988 report (Doc 38) CH2M HILL plotted the fracture
orientations provided on the boring log for Borehole
KE87-ML3 This borehole lies near the intersection of
Lineainents 1 and 2 with Lineament 24 Borehole WE87-ML3 is
of particular significance because Lineaments 1 and 2
represent potential pathways for the migration of
containinants to the Scituate Reservoir The orieiitations of
fractures in Borehole WE87-ML3 correspond reasonably vell
with the trends of Lineaments 1 2 and 24
Barbed on televiewer data the average fracture frequency
reported for the five multilevel wells was 072 fractures
per foot Only a very slight decrease in fracture frequency
was noted with depth--08 fractures per foot for the top
30 feet of bedrock 07 fractures per foot for the tpp
100 feet of bedrock and 06 fractures per foot for depths
greater than 100 feet below the top of rock An exception
to this trend that was noted in the GZA May 1988 report
(Doc 38) was Borehole WE87-ML1 in which fracture frequency
increased with depth Equally significant are above-average
fracture frequencies and significant flow measurements over
deep rock intervals (more than 100 feet in each borehole
extending deeper than 100 feet and more than 200 feet in
each borehole extending deeper than 200 feet) The data
suggest that rock fractures and associated water-bearing
zones extend to some unknown distance below the depth
reached by the five multilevel wells
BSR03010 3-3
GEOPHYSICAL INVESTIGATIONS
Geophysical investigations are described in both the
August 1987 report prepared by Geotech Enterprises Inc
(Appendix Document 35) and GZAs May 1988 report (Doc 38)
Thiree geophysical survey methods were used by Geotech to
investigate the vicinity of the Central Landfill The
objectives of the investigations were to locate areas of
rock fracturing and to recommend locations for three
multilevel wells The survey methods investigated gravity
e]ectrical resi^tivity and seismic refraction Each method
vas targeted at a different physical property of the rock
any of which could indicate fracturing
GZAs May 1988 report (Doc 38) summarizes the results of
the geophysical surveys discussed in the Geotech report
(Doc 35) In addition GZAs May 1988 report describes the
results of downhole geophysical logging performed by the
USGS and vertical seismic profiling performed by Weston
Geophysical Corporation
41 GRAVITY
The gravity investigation method measures minute differences
in the Earths gravitational field resulting from rock
density differences Fracturing can result in lover
densities which can often be identified as gravity lovs
Different rock types with different densities also can
result in gravity lows
Regional data indicate a gravity low in the vicinity of the
landfill but it is uncertain whether the low results from a
fracture zone or from the presence of different rock types
BSR03011 4-1
III
of higher donsity on either side of the landfill
Additional gravity measurements obtained in tho vicinity of
the landfill confirm the gravity low and suggest a
northeast-southwest trend to the low that corresponds with
Lincainent 1
The gravity data are dominated by the regional effects of
the denser metamorphic sediments to the east and the buried
pluton to the west In order to minimize the gravity
effects of these features and to emphasize the ]oca]ized
effects of fracture zones CH2M JIILL removed a fourth-order
surface from the data The residual values reflect the
smaller (shorter wavelength) features that are likely to
include fracture zones The resulting residual data were
tlien plotted on a map
Tlie central part of the residual data map showed a gravity
hiyli with sides oriented northeast-southwest The southeast
side of this feature is coincident with Lineament 1 on the
fracture trace map in GZAs May 1988 report (Doc 38)
Central Landfill is located on this feature The residual
gravity high is breached in the vicinity of the landfill
The breach may be associated with other fracture traces
The results of the residual gravity evaluation suggest that
Lineament 1 may be related to a geologic contact
Alternatively Lineament 1 may be at the contact between
fractured rock to the southeast (the gravity low) and
unfractured rock to the northwest The data support the
fracture trace interpretation in the vicinity of the
landfill
BSR0 3011 4-2
42 ELECTRICAL RESISTIVITY
Electrical soundings are used to estimate subsurface
resistivities Fracture zones can affect the resistivities
by increasing hydraulic conductivity In most cases rock
resistivity is controlled by pore fluid conductivity and
porosity
The soundings in the vicinity of the landfill indicated
areas of resistive bedrock (indicating competent rock) and
areas of less resistive bedrock (possibly fractured rock)
For i he most part the more resistive areas are northwest of
Lineltiment 1 and the less resistive bedrock is southeast of
the lineament
The interpreted bedrock resistivities were used with
groundwater specific conductance to calculate a formation
factor A high formation factor suggests competent rock
The variability of groundwater conductivity over short
distances in general and some uncertainty in the estimated
bedrock conductivity in the vicinity of the landfill may
make use of these formation factors questionable
There are no comments in either the GZA May 1988 report
(Doc 38) or the Geotech report (Doc 35) about cultural
conductors such as fences and power lines that may have
affected the data Either there are no cultural conductors
in the area or this potential problem was overlooked
Soundings 4 and 9 may have been affected by nearby cultural
conductors
The observed bedrock resistivities appear lower on the
southeast side of Lineament 1 and higher on the nort)ivest
side This is consistent with Lineament 1 being a geologic
BSR03011 4-3
I
contact or with the fracture density being higher on the
southeast side
43 SEISMIC REFRACTION
Seismic refraction surveys were performed to measure bedrock
velocities in the vicinity of the landfill Bedrock
veJricities may be reduced in areas of fracturing compared
witli the velocities in unfractured areas Refraction
surveys generally were run in the same areas as those in
which the electrical soundings were run Low velocity
bidrock wliich may be related to rock fracturing vas
idntified by the refraction surveys
Because seismic data are very noisy the first arrivals were
not identified properly in some instances Estimated
bedrock velocities are correspondingly uncertain The
bedrock velocity calculated by CH2M HILL for Line S-4
(12100 fps) is approximately 15 percent higher than the
velocity given in the Geotech and GZA reports (10380 fps)
(Doc 35 38) The data for Line S-4 are relatively good
an uncertainty of 15 percent or worse might be typical for
data of this quality
Some of the seismic spreads did not include a shot at each
end of a spread Without data from shots at both ends it
is impossible to determine true bedrock velocities where
dipping beds are present Although seismic refraction is a
valid metliod for identifying fracture zones better-quality
data than those presented in the Geotech and GZA reports
(Doc 35 38) are required
BSR03011 4-4
44 DOWNHOLE GEOPHYSICAL LOGGINC
AND VERTICAL SEISMIC PROFILING
The downhole geophysical logging was performed by the USGS
Division of Water Resources The logging methods and their
associated functions are listed below
Acoustic Borehole Televiewer
Formation Resistivity
Borehole Caliper
Neutron-Gamma
Natural Gamma
Spontaneous Potential
Maps rock fractures using
sonar transmissions
Maps areas of lower
resistivity lhat may be
the result of fracturing
Measures borehole
diameter
Measures formation
porosity but readings are
affected by clay
Measures formation
natural radioactive
emmissions can be
used to identify clay and
was used with the
neutron-gamma data
Used to identify different
strata such as clay and
shale
BSR03011 4-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
li
PHYSIOGRAPHY AND DRAINAGE
Surface topography in the North Scituate Quadrangle is
characterized by northwest-southeast trending uplands and
in intervening valleys The orientation of these surface
features reflects the direction of glacial advance and
concomitant erosion of preglacial soils The orientations
of Oak Swamp Almy and Simmons Reservoirs and portions of
i] Scituate Reservoir are examples of this general
northwest-southeast valley orientation
The active portion of the Central Landfill is located
approximately 2-12 miles east of the Scituate Reservoir
The Central Landfill also occupies an elongate valley The
area has been modified by extensive borrowing and filling
Surface drainage is primarily from the northwest and
southwest The area drains to the east and southeast A
topographic divide which defines the limit of the
watershed lies between the active landfill and the
reservoir A small yet inactive portion of the landfill
property lies within the watershed of the Scituate
Reservoir The active landfill is approximately 5100 feet
from the portion of the watershed boundary that crosses
landfill property
BSR03009 2-1
GEOLOGY
Bedrock in the vicinity of the Central Landfill consists of
granite and granite gneiss and is referenced in the
literature as the Scituate granite Soils overlying the
Scituate granite predominantly consist of glacial till and
glacial outwash The till is an unsorted ground moraine
composed of fine-grained to boulder-sized particles The
outwash varies from poorly sorted materials to well-sorted
ice-contact sands and gravels The soils vary in thickness
from 0 feet in areas that have been excavated to over
60 feet southvest of Cedar Swamp Brook Within the existing
landfill refuse ranges in thickness from 50 feet at Well E
to 135 feet at Well WE87-3 Refuse is in direct contact
with the bedrock over the northern portion of tlie landfill
and is within 5 feet of bedrock over its southern part
Bedrock topography at the landfill is defined by subsurface
investigations associated with the landfill design and the
ongoing remedial investigationfeasibility study (RIFS)
Bedrock topography has been mapped regionally by the
US Geological Survey (USGS) The Central Landfill lies on
the north slope of a bedrock valley with a northwest to
southeast general trend The Upper reach of the bedrock
valley is two prongedmdashnorthwest to southeast and north to
southeast The active landfill overlies most of the latter
Rock quarrying has modified the area along the western slope
of the landfill and in the vicinity of the portion of the
landfill (near Well J) that received industrial wastes
The degree of weathering and Rock Quality Designations
(RQDs) observed in rock core were evaluated with respect to
depth below the top of rock and proximity to fracture
traces The RQD is a measure of the degree to which rock is
BSR03010 3-1
fractured as reflected in the lengths of rock core
reioveries A highly fractured rock will exhibit a low RQD
In general the RQD increased with depth--57 percent for
0 to 10 feet below the top of rock and 77 percent for
10 to 30 feet below the top of rock At boreholes located
in fracture traces however the RQDs were 40 percent and
62 percent respectively indicating a correlation between
the fracture traces observed on both aerial photographs and
satellite imagery and the degree to which the bedrock is
friictured Similarly the degree of weathering was found to
be a function of both depth and proximity to fracture
tl ces Severe veathering was noted throughout
B(U-ehole WE87-13 and to a depth of 45 feet in
Borehole WE85-6 both of which lie along northeast-southwest
trending features It should be noted that observations of
rock weathering and RQDs apply only to boreholes from vhich
rock core was available These boreholes tended to be
relatively shallow extending approximately 30 feet below
the top of rock
Deeper explorations (124 to 247 feet below the top of rock)
were performed in the multilevel wellsmdashWE87-ML1 through
WE87-ML5 The Fracture Trace Analysis (FTA) was used to
position the multilevel wells Each multilevel well was
pllt3ced on or proximal to an observed fracture trace The
degree of fracturing and the orientation of fractures were
evaluated by borehole televiewer The ability of the
observed fractures to transmit water was evaluated by packer
tests
The May 198 8 Interim Remedial Investigation Report by
Goldberg-Zoino amp Associates Inc (GZA) (Appendix
Document 38) indicates that the orientations of fractures
indicated on televiewer logs were compiled into a ccmposite
plotted on a stereonet and contoured The contouring
BSR03010 3-2
yielded four preferred fracture orientations thiat -bullere in
agreement with the orientations of lineaments identified jn
the FTA The dominant group had a strike and dip of
N20deg-40degE 60deg-80degNW The lesser groups were at nearly
horizontal N10deg-20degW 50deg-60degSW and N80deg-85degE 65deg-70NW
Because the stereonet plots were not included in the GZA
May 1988 report (Doc 38) CH2M HILL plotted the fracture
orientations provided on the boring log for Borehole
KE87-ML3 This borehole lies near the intersection of
Lineainents 1 and 2 with Lineament 24 Borehole WE87-ML3 is
of particular significance because Lineaments 1 and 2
represent potential pathways for the migration of
containinants to the Scituate Reservoir The orieiitations of
fractures in Borehole WE87-ML3 correspond reasonably vell
with the trends of Lineaments 1 2 and 24
Barbed on televiewer data the average fracture frequency
reported for the five multilevel wells was 072 fractures
per foot Only a very slight decrease in fracture frequency
was noted with depth--08 fractures per foot for the top
30 feet of bedrock 07 fractures per foot for the tpp
100 feet of bedrock and 06 fractures per foot for depths
greater than 100 feet below the top of rock An exception
to this trend that was noted in the GZA May 1988 report
(Doc 38) was Borehole WE87-ML1 in which fracture frequency
increased with depth Equally significant are above-average
fracture frequencies and significant flow measurements over
deep rock intervals (more than 100 feet in each borehole
extending deeper than 100 feet and more than 200 feet in
each borehole extending deeper than 200 feet) The data
suggest that rock fractures and associated water-bearing
zones extend to some unknown distance below the depth
reached by the five multilevel wells
BSR03010 3-3
GEOPHYSICAL INVESTIGATIONS
Geophysical investigations are described in both the
August 1987 report prepared by Geotech Enterprises Inc
(Appendix Document 35) and GZAs May 1988 report (Doc 38)
Thiree geophysical survey methods were used by Geotech to
investigate the vicinity of the Central Landfill The
objectives of the investigations were to locate areas of
rock fracturing and to recommend locations for three
multilevel wells The survey methods investigated gravity
e]ectrical resi^tivity and seismic refraction Each method
vas targeted at a different physical property of the rock
any of which could indicate fracturing
GZAs May 1988 report (Doc 38) summarizes the results of
the geophysical surveys discussed in the Geotech report
(Doc 35) In addition GZAs May 1988 report describes the
results of downhole geophysical logging performed by the
USGS and vertical seismic profiling performed by Weston
Geophysical Corporation
41 GRAVITY
The gravity investigation method measures minute differences
in the Earths gravitational field resulting from rock
density differences Fracturing can result in lover
densities which can often be identified as gravity lovs
Different rock types with different densities also can
result in gravity lows
Regional data indicate a gravity low in the vicinity of the
landfill but it is uncertain whether the low results from a
fracture zone or from the presence of different rock types
BSR03011 4-1
III
of higher donsity on either side of the landfill
Additional gravity measurements obtained in tho vicinity of
the landfill confirm the gravity low and suggest a
northeast-southwest trend to the low that corresponds with
Lincainent 1
The gravity data are dominated by the regional effects of
the denser metamorphic sediments to the east and the buried
pluton to the west In order to minimize the gravity
effects of these features and to emphasize the ]oca]ized
effects of fracture zones CH2M JIILL removed a fourth-order
surface from the data The residual values reflect the
smaller (shorter wavelength) features that are likely to
include fracture zones The resulting residual data were
tlien plotted on a map
Tlie central part of the residual data map showed a gravity
hiyli with sides oriented northeast-southwest The southeast
side of this feature is coincident with Lineament 1 on the
fracture trace map in GZAs May 1988 report (Doc 38)
Central Landfill is located on this feature The residual
gravity high is breached in the vicinity of the landfill
The breach may be associated with other fracture traces
The results of the residual gravity evaluation suggest that
Lineament 1 may be related to a geologic contact
Alternatively Lineament 1 may be at the contact between
fractured rock to the southeast (the gravity low) and
unfractured rock to the northwest The data support the
fracture trace interpretation in the vicinity of the
landfill
BSR0 3011 4-2
42 ELECTRICAL RESISTIVITY
Electrical soundings are used to estimate subsurface
resistivities Fracture zones can affect the resistivities
by increasing hydraulic conductivity In most cases rock
resistivity is controlled by pore fluid conductivity and
porosity
The soundings in the vicinity of the landfill indicated
areas of resistive bedrock (indicating competent rock) and
areas of less resistive bedrock (possibly fractured rock)
For i he most part the more resistive areas are northwest of
Lineltiment 1 and the less resistive bedrock is southeast of
the lineament
The interpreted bedrock resistivities were used with
groundwater specific conductance to calculate a formation
factor A high formation factor suggests competent rock
The variability of groundwater conductivity over short
distances in general and some uncertainty in the estimated
bedrock conductivity in the vicinity of the landfill may
make use of these formation factors questionable
There are no comments in either the GZA May 1988 report
(Doc 38) or the Geotech report (Doc 35) about cultural
conductors such as fences and power lines that may have
affected the data Either there are no cultural conductors
in the area or this potential problem was overlooked
Soundings 4 and 9 may have been affected by nearby cultural
conductors
The observed bedrock resistivities appear lower on the
southeast side of Lineament 1 and higher on the nort)ivest
side This is consistent with Lineament 1 being a geologic
BSR03011 4-3
I
contact or with the fracture density being higher on the
southeast side
43 SEISMIC REFRACTION
Seismic refraction surveys were performed to measure bedrock
velocities in the vicinity of the landfill Bedrock
veJricities may be reduced in areas of fracturing compared
witli the velocities in unfractured areas Refraction
surveys generally were run in the same areas as those in
which the electrical soundings were run Low velocity
bidrock wliich may be related to rock fracturing vas
idntified by the refraction surveys
Because seismic data are very noisy the first arrivals were
not identified properly in some instances Estimated
bedrock velocities are correspondingly uncertain The
bedrock velocity calculated by CH2M HILL for Line S-4
(12100 fps) is approximately 15 percent higher than the
velocity given in the Geotech and GZA reports (10380 fps)
(Doc 35 38) The data for Line S-4 are relatively good
an uncertainty of 15 percent or worse might be typical for
data of this quality
Some of the seismic spreads did not include a shot at each
end of a spread Without data from shots at both ends it
is impossible to determine true bedrock velocities where
dipping beds are present Although seismic refraction is a
valid metliod for identifying fracture zones better-quality
data than those presented in the Geotech and GZA reports
(Doc 35 38) are required
BSR03011 4-4
44 DOWNHOLE GEOPHYSICAL LOGGINC
AND VERTICAL SEISMIC PROFILING
The downhole geophysical logging was performed by the USGS
Division of Water Resources The logging methods and their
associated functions are listed below
Acoustic Borehole Televiewer
Formation Resistivity
Borehole Caliper
Neutron-Gamma
Natural Gamma
Spontaneous Potential
Maps rock fractures using
sonar transmissions
Maps areas of lower
resistivity lhat may be
the result of fracturing
Measures borehole
diameter
Measures formation
porosity but readings are
affected by clay
Measures formation
natural radioactive
emmissions can be
used to identify clay and
was used with the
neutron-gamma data
Used to identify different
strata such as clay and
shale
BSR03011 4-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
GEOLOGY
Bedrock in the vicinity of the Central Landfill consists of
granite and granite gneiss and is referenced in the
literature as the Scituate granite Soils overlying the
Scituate granite predominantly consist of glacial till and
glacial outwash The till is an unsorted ground moraine
composed of fine-grained to boulder-sized particles The
outwash varies from poorly sorted materials to well-sorted
ice-contact sands and gravels The soils vary in thickness
from 0 feet in areas that have been excavated to over
60 feet southvest of Cedar Swamp Brook Within the existing
landfill refuse ranges in thickness from 50 feet at Well E
to 135 feet at Well WE87-3 Refuse is in direct contact
with the bedrock over the northern portion of tlie landfill
and is within 5 feet of bedrock over its southern part
Bedrock topography at the landfill is defined by subsurface
investigations associated with the landfill design and the
ongoing remedial investigationfeasibility study (RIFS)
Bedrock topography has been mapped regionally by the
US Geological Survey (USGS) The Central Landfill lies on
the north slope of a bedrock valley with a northwest to
southeast general trend The Upper reach of the bedrock
valley is two prongedmdashnorthwest to southeast and north to
southeast The active landfill overlies most of the latter
Rock quarrying has modified the area along the western slope
of the landfill and in the vicinity of the portion of the
landfill (near Well J) that received industrial wastes
The degree of weathering and Rock Quality Designations
(RQDs) observed in rock core were evaluated with respect to
depth below the top of rock and proximity to fracture
traces The RQD is a measure of the degree to which rock is
BSR03010 3-1
fractured as reflected in the lengths of rock core
reioveries A highly fractured rock will exhibit a low RQD
In general the RQD increased with depth--57 percent for
0 to 10 feet below the top of rock and 77 percent for
10 to 30 feet below the top of rock At boreholes located
in fracture traces however the RQDs were 40 percent and
62 percent respectively indicating a correlation between
the fracture traces observed on both aerial photographs and
satellite imagery and the degree to which the bedrock is
friictured Similarly the degree of weathering was found to
be a function of both depth and proximity to fracture
tl ces Severe veathering was noted throughout
B(U-ehole WE87-13 and to a depth of 45 feet in
Borehole WE85-6 both of which lie along northeast-southwest
trending features It should be noted that observations of
rock weathering and RQDs apply only to boreholes from vhich
rock core was available These boreholes tended to be
relatively shallow extending approximately 30 feet below
the top of rock
Deeper explorations (124 to 247 feet below the top of rock)
were performed in the multilevel wellsmdashWE87-ML1 through
WE87-ML5 The Fracture Trace Analysis (FTA) was used to
position the multilevel wells Each multilevel well was
pllt3ced on or proximal to an observed fracture trace The
degree of fracturing and the orientation of fractures were
evaluated by borehole televiewer The ability of the
observed fractures to transmit water was evaluated by packer
tests
The May 198 8 Interim Remedial Investigation Report by
Goldberg-Zoino amp Associates Inc (GZA) (Appendix
Document 38) indicates that the orientations of fractures
indicated on televiewer logs were compiled into a ccmposite
plotted on a stereonet and contoured The contouring
BSR03010 3-2
yielded four preferred fracture orientations thiat -bullere in
agreement with the orientations of lineaments identified jn
the FTA The dominant group had a strike and dip of
N20deg-40degE 60deg-80degNW The lesser groups were at nearly
horizontal N10deg-20degW 50deg-60degSW and N80deg-85degE 65deg-70NW
Because the stereonet plots were not included in the GZA
May 1988 report (Doc 38) CH2M HILL plotted the fracture
orientations provided on the boring log for Borehole
KE87-ML3 This borehole lies near the intersection of
Lineainents 1 and 2 with Lineament 24 Borehole WE87-ML3 is
of particular significance because Lineaments 1 and 2
represent potential pathways for the migration of
containinants to the Scituate Reservoir The orieiitations of
fractures in Borehole WE87-ML3 correspond reasonably vell
with the trends of Lineaments 1 2 and 24
Barbed on televiewer data the average fracture frequency
reported for the five multilevel wells was 072 fractures
per foot Only a very slight decrease in fracture frequency
was noted with depth--08 fractures per foot for the top
30 feet of bedrock 07 fractures per foot for the tpp
100 feet of bedrock and 06 fractures per foot for depths
greater than 100 feet below the top of rock An exception
to this trend that was noted in the GZA May 1988 report
(Doc 38) was Borehole WE87-ML1 in which fracture frequency
increased with depth Equally significant are above-average
fracture frequencies and significant flow measurements over
deep rock intervals (more than 100 feet in each borehole
extending deeper than 100 feet and more than 200 feet in
each borehole extending deeper than 200 feet) The data
suggest that rock fractures and associated water-bearing
zones extend to some unknown distance below the depth
reached by the five multilevel wells
BSR03010 3-3
GEOPHYSICAL INVESTIGATIONS
Geophysical investigations are described in both the
August 1987 report prepared by Geotech Enterprises Inc
(Appendix Document 35) and GZAs May 1988 report (Doc 38)
Thiree geophysical survey methods were used by Geotech to
investigate the vicinity of the Central Landfill The
objectives of the investigations were to locate areas of
rock fracturing and to recommend locations for three
multilevel wells The survey methods investigated gravity
e]ectrical resi^tivity and seismic refraction Each method
vas targeted at a different physical property of the rock
any of which could indicate fracturing
GZAs May 1988 report (Doc 38) summarizes the results of
the geophysical surveys discussed in the Geotech report
(Doc 35) In addition GZAs May 1988 report describes the
results of downhole geophysical logging performed by the
USGS and vertical seismic profiling performed by Weston
Geophysical Corporation
41 GRAVITY
The gravity investigation method measures minute differences
in the Earths gravitational field resulting from rock
density differences Fracturing can result in lover
densities which can often be identified as gravity lovs
Different rock types with different densities also can
result in gravity lows
Regional data indicate a gravity low in the vicinity of the
landfill but it is uncertain whether the low results from a
fracture zone or from the presence of different rock types
BSR03011 4-1
III
of higher donsity on either side of the landfill
Additional gravity measurements obtained in tho vicinity of
the landfill confirm the gravity low and suggest a
northeast-southwest trend to the low that corresponds with
Lincainent 1
The gravity data are dominated by the regional effects of
the denser metamorphic sediments to the east and the buried
pluton to the west In order to minimize the gravity
effects of these features and to emphasize the ]oca]ized
effects of fracture zones CH2M JIILL removed a fourth-order
surface from the data The residual values reflect the
smaller (shorter wavelength) features that are likely to
include fracture zones The resulting residual data were
tlien plotted on a map
Tlie central part of the residual data map showed a gravity
hiyli with sides oriented northeast-southwest The southeast
side of this feature is coincident with Lineament 1 on the
fracture trace map in GZAs May 1988 report (Doc 38)
Central Landfill is located on this feature The residual
gravity high is breached in the vicinity of the landfill
The breach may be associated with other fracture traces
The results of the residual gravity evaluation suggest that
Lineament 1 may be related to a geologic contact
Alternatively Lineament 1 may be at the contact between
fractured rock to the southeast (the gravity low) and
unfractured rock to the northwest The data support the
fracture trace interpretation in the vicinity of the
landfill
BSR0 3011 4-2
42 ELECTRICAL RESISTIVITY
Electrical soundings are used to estimate subsurface
resistivities Fracture zones can affect the resistivities
by increasing hydraulic conductivity In most cases rock
resistivity is controlled by pore fluid conductivity and
porosity
The soundings in the vicinity of the landfill indicated
areas of resistive bedrock (indicating competent rock) and
areas of less resistive bedrock (possibly fractured rock)
For i he most part the more resistive areas are northwest of
Lineltiment 1 and the less resistive bedrock is southeast of
the lineament
The interpreted bedrock resistivities were used with
groundwater specific conductance to calculate a formation
factor A high formation factor suggests competent rock
The variability of groundwater conductivity over short
distances in general and some uncertainty in the estimated
bedrock conductivity in the vicinity of the landfill may
make use of these formation factors questionable
There are no comments in either the GZA May 1988 report
(Doc 38) or the Geotech report (Doc 35) about cultural
conductors such as fences and power lines that may have
affected the data Either there are no cultural conductors
in the area or this potential problem was overlooked
Soundings 4 and 9 may have been affected by nearby cultural
conductors
The observed bedrock resistivities appear lower on the
southeast side of Lineament 1 and higher on the nort)ivest
side This is consistent with Lineament 1 being a geologic
BSR03011 4-3
I
contact or with the fracture density being higher on the
southeast side
43 SEISMIC REFRACTION
Seismic refraction surveys were performed to measure bedrock
velocities in the vicinity of the landfill Bedrock
veJricities may be reduced in areas of fracturing compared
witli the velocities in unfractured areas Refraction
surveys generally were run in the same areas as those in
which the electrical soundings were run Low velocity
bidrock wliich may be related to rock fracturing vas
idntified by the refraction surveys
Because seismic data are very noisy the first arrivals were
not identified properly in some instances Estimated
bedrock velocities are correspondingly uncertain The
bedrock velocity calculated by CH2M HILL for Line S-4
(12100 fps) is approximately 15 percent higher than the
velocity given in the Geotech and GZA reports (10380 fps)
(Doc 35 38) The data for Line S-4 are relatively good
an uncertainty of 15 percent or worse might be typical for
data of this quality
Some of the seismic spreads did not include a shot at each
end of a spread Without data from shots at both ends it
is impossible to determine true bedrock velocities where
dipping beds are present Although seismic refraction is a
valid metliod for identifying fracture zones better-quality
data than those presented in the Geotech and GZA reports
(Doc 35 38) are required
BSR03011 4-4
44 DOWNHOLE GEOPHYSICAL LOGGINC
AND VERTICAL SEISMIC PROFILING
The downhole geophysical logging was performed by the USGS
Division of Water Resources The logging methods and their
associated functions are listed below
Acoustic Borehole Televiewer
Formation Resistivity
Borehole Caliper
Neutron-Gamma
Natural Gamma
Spontaneous Potential
Maps rock fractures using
sonar transmissions
Maps areas of lower
resistivity lhat may be
the result of fracturing
Measures borehole
diameter
Measures formation
porosity but readings are
affected by clay
Measures formation
natural radioactive
emmissions can be
used to identify clay and
was used with the
neutron-gamma data
Used to identify different
strata such as clay and
shale
BSR03011 4-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
fractured as reflected in the lengths of rock core
reioveries A highly fractured rock will exhibit a low RQD
In general the RQD increased with depth--57 percent for
0 to 10 feet below the top of rock and 77 percent for
10 to 30 feet below the top of rock At boreholes located
in fracture traces however the RQDs were 40 percent and
62 percent respectively indicating a correlation between
the fracture traces observed on both aerial photographs and
satellite imagery and the degree to which the bedrock is
friictured Similarly the degree of weathering was found to
be a function of both depth and proximity to fracture
tl ces Severe veathering was noted throughout
B(U-ehole WE87-13 and to a depth of 45 feet in
Borehole WE85-6 both of which lie along northeast-southwest
trending features It should be noted that observations of
rock weathering and RQDs apply only to boreholes from vhich
rock core was available These boreholes tended to be
relatively shallow extending approximately 30 feet below
the top of rock
Deeper explorations (124 to 247 feet below the top of rock)
were performed in the multilevel wellsmdashWE87-ML1 through
WE87-ML5 The Fracture Trace Analysis (FTA) was used to
position the multilevel wells Each multilevel well was
pllt3ced on or proximal to an observed fracture trace The
degree of fracturing and the orientation of fractures were
evaluated by borehole televiewer The ability of the
observed fractures to transmit water was evaluated by packer
tests
The May 198 8 Interim Remedial Investigation Report by
Goldberg-Zoino amp Associates Inc (GZA) (Appendix
Document 38) indicates that the orientations of fractures
indicated on televiewer logs were compiled into a ccmposite
plotted on a stereonet and contoured The contouring
BSR03010 3-2
yielded four preferred fracture orientations thiat -bullere in
agreement with the orientations of lineaments identified jn
the FTA The dominant group had a strike and dip of
N20deg-40degE 60deg-80degNW The lesser groups were at nearly
horizontal N10deg-20degW 50deg-60degSW and N80deg-85degE 65deg-70NW
Because the stereonet plots were not included in the GZA
May 1988 report (Doc 38) CH2M HILL plotted the fracture
orientations provided on the boring log for Borehole
KE87-ML3 This borehole lies near the intersection of
Lineainents 1 and 2 with Lineament 24 Borehole WE87-ML3 is
of particular significance because Lineaments 1 and 2
represent potential pathways for the migration of
containinants to the Scituate Reservoir The orieiitations of
fractures in Borehole WE87-ML3 correspond reasonably vell
with the trends of Lineaments 1 2 and 24
Barbed on televiewer data the average fracture frequency
reported for the five multilevel wells was 072 fractures
per foot Only a very slight decrease in fracture frequency
was noted with depth--08 fractures per foot for the top
30 feet of bedrock 07 fractures per foot for the tpp
100 feet of bedrock and 06 fractures per foot for depths
greater than 100 feet below the top of rock An exception
to this trend that was noted in the GZA May 1988 report
(Doc 38) was Borehole WE87-ML1 in which fracture frequency
increased with depth Equally significant are above-average
fracture frequencies and significant flow measurements over
deep rock intervals (more than 100 feet in each borehole
extending deeper than 100 feet and more than 200 feet in
each borehole extending deeper than 200 feet) The data
suggest that rock fractures and associated water-bearing
zones extend to some unknown distance below the depth
reached by the five multilevel wells
BSR03010 3-3
GEOPHYSICAL INVESTIGATIONS
Geophysical investigations are described in both the
August 1987 report prepared by Geotech Enterprises Inc
(Appendix Document 35) and GZAs May 1988 report (Doc 38)
Thiree geophysical survey methods were used by Geotech to
investigate the vicinity of the Central Landfill The
objectives of the investigations were to locate areas of
rock fracturing and to recommend locations for three
multilevel wells The survey methods investigated gravity
e]ectrical resi^tivity and seismic refraction Each method
vas targeted at a different physical property of the rock
any of which could indicate fracturing
GZAs May 1988 report (Doc 38) summarizes the results of
the geophysical surveys discussed in the Geotech report
(Doc 35) In addition GZAs May 1988 report describes the
results of downhole geophysical logging performed by the
USGS and vertical seismic profiling performed by Weston
Geophysical Corporation
41 GRAVITY
The gravity investigation method measures minute differences
in the Earths gravitational field resulting from rock
density differences Fracturing can result in lover
densities which can often be identified as gravity lovs
Different rock types with different densities also can
result in gravity lows
Regional data indicate a gravity low in the vicinity of the
landfill but it is uncertain whether the low results from a
fracture zone or from the presence of different rock types
BSR03011 4-1
III
of higher donsity on either side of the landfill
Additional gravity measurements obtained in tho vicinity of
the landfill confirm the gravity low and suggest a
northeast-southwest trend to the low that corresponds with
Lincainent 1
The gravity data are dominated by the regional effects of
the denser metamorphic sediments to the east and the buried
pluton to the west In order to minimize the gravity
effects of these features and to emphasize the ]oca]ized
effects of fracture zones CH2M JIILL removed a fourth-order
surface from the data The residual values reflect the
smaller (shorter wavelength) features that are likely to
include fracture zones The resulting residual data were
tlien plotted on a map
Tlie central part of the residual data map showed a gravity
hiyli with sides oriented northeast-southwest The southeast
side of this feature is coincident with Lineament 1 on the
fracture trace map in GZAs May 1988 report (Doc 38)
Central Landfill is located on this feature The residual
gravity high is breached in the vicinity of the landfill
The breach may be associated with other fracture traces
The results of the residual gravity evaluation suggest that
Lineament 1 may be related to a geologic contact
Alternatively Lineament 1 may be at the contact between
fractured rock to the southeast (the gravity low) and
unfractured rock to the northwest The data support the
fracture trace interpretation in the vicinity of the
landfill
BSR0 3011 4-2
42 ELECTRICAL RESISTIVITY
Electrical soundings are used to estimate subsurface
resistivities Fracture zones can affect the resistivities
by increasing hydraulic conductivity In most cases rock
resistivity is controlled by pore fluid conductivity and
porosity
The soundings in the vicinity of the landfill indicated
areas of resistive bedrock (indicating competent rock) and
areas of less resistive bedrock (possibly fractured rock)
For i he most part the more resistive areas are northwest of
Lineltiment 1 and the less resistive bedrock is southeast of
the lineament
The interpreted bedrock resistivities were used with
groundwater specific conductance to calculate a formation
factor A high formation factor suggests competent rock
The variability of groundwater conductivity over short
distances in general and some uncertainty in the estimated
bedrock conductivity in the vicinity of the landfill may
make use of these formation factors questionable
There are no comments in either the GZA May 1988 report
(Doc 38) or the Geotech report (Doc 35) about cultural
conductors such as fences and power lines that may have
affected the data Either there are no cultural conductors
in the area or this potential problem was overlooked
Soundings 4 and 9 may have been affected by nearby cultural
conductors
The observed bedrock resistivities appear lower on the
southeast side of Lineament 1 and higher on the nort)ivest
side This is consistent with Lineament 1 being a geologic
BSR03011 4-3
I
contact or with the fracture density being higher on the
southeast side
43 SEISMIC REFRACTION
Seismic refraction surveys were performed to measure bedrock
velocities in the vicinity of the landfill Bedrock
veJricities may be reduced in areas of fracturing compared
witli the velocities in unfractured areas Refraction
surveys generally were run in the same areas as those in
which the electrical soundings were run Low velocity
bidrock wliich may be related to rock fracturing vas
idntified by the refraction surveys
Because seismic data are very noisy the first arrivals were
not identified properly in some instances Estimated
bedrock velocities are correspondingly uncertain The
bedrock velocity calculated by CH2M HILL for Line S-4
(12100 fps) is approximately 15 percent higher than the
velocity given in the Geotech and GZA reports (10380 fps)
(Doc 35 38) The data for Line S-4 are relatively good
an uncertainty of 15 percent or worse might be typical for
data of this quality
Some of the seismic spreads did not include a shot at each
end of a spread Without data from shots at both ends it
is impossible to determine true bedrock velocities where
dipping beds are present Although seismic refraction is a
valid metliod for identifying fracture zones better-quality
data than those presented in the Geotech and GZA reports
(Doc 35 38) are required
BSR03011 4-4
44 DOWNHOLE GEOPHYSICAL LOGGINC
AND VERTICAL SEISMIC PROFILING
The downhole geophysical logging was performed by the USGS
Division of Water Resources The logging methods and their
associated functions are listed below
Acoustic Borehole Televiewer
Formation Resistivity
Borehole Caliper
Neutron-Gamma
Natural Gamma
Spontaneous Potential
Maps rock fractures using
sonar transmissions
Maps areas of lower
resistivity lhat may be
the result of fracturing
Measures borehole
diameter
Measures formation
porosity but readings are
affected by clay
Measures formation
natural radioactive
emmissions can be
used to identify clay and
was used with the
neutron-gamma data
Used to identify different
strata such as clay and
shale
BSR03011 4-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
yielded four preferred fracture orientations thiat -bullere in
agreement with the orientations of lineaments identified jn
the FTA The dominant group had a strike and dip of
N20deg-40degE 60deg-80degNW The lesser groups were at nearly
horizontal N10deg-20degW 50deg-60degSW and N80deg-85degE 65deg-70NW
Because the stereonet plots were not included in the GZA
May 1988 report (Doc 38) CH2M HILL plotted the fracture
orientations provided on the boring log for Borehole
KE87-ML3 This borehole lies near the intersection of
Lineainents 1 and 2 with Lineament 24 Borehole WE87-ML3 is
of particular significance because Lineaments 1 and 2
represent potential pathways for the migration of
containinants to the Scituate Reservoir The orieiitations of
fractures in Borehole WE87-ML3 correspond reasonably vell
with the trends of Lineaments 1 2 and 24
Barbed on televiewer data the average fracture frequency
reported for the five multilevel wells was 072 fractures
per foot Only a very slight decrease in fracture frequency
was noted with depth--08 fractures per foot for the top
30 feet of bedrock 07 fractures per foot for the tpp
100 feet of bedrock and 06 fractures per foot for depths
greater than 100 feet below the top of rock An exception
to this trend that was noted in the GZA May 1988 report
(Doc 38) was Borehole WE87-ML1 in which fracture frequency
increased with depth Equally significant are above-average
fracture frequencies and significant flow measurements over
deep rock intervals (more than 100 feet in each borehole
extending deeper than 100 feet and more than 200 feet in
each borehole extending deeper than 200 feet) The data
suggest that rock fractures and associated water-bearing
zones extend to some unknown distance below the depth
reached by the five multilevel wells
BSR03010 3-3
GEOPHYSICAL INVESTIGATIONS
Geophysical investigations are described in both the
August 1987 report prepared by Geotech Enterprises Inc
(Appendix Document 35) and GZAs May 1988 report (Doc 38)
Thiree geophysical survey methods were used by Geotech to
investigate the vicinity of the Central Landfill The
objectives of the investigations were to locate areas of
rock fracturing and to recommend locations for three
multilevel wells The survey methods investigated gravity
e]ectrical resi^tivity and seismic refraction Each method
vas targeted at a different physical property of the rock
any of which could indicate fracturing
GZAs May 1988 report (Doc 38) summarizes the results of
the geophysical surveys discussed in the Geotech report
(Doc 35) In addition GZAs May 1988 report describes the
results of downhole geophysical logging performed by the
USGS and vertical seismic profiling performed by Weston
Geophysical Corporation
41 GRAVITY
The gravity investigation method measures minute differences
in the Earths gravitational field resulting from rock
density differences Fracturing can result in lover
densities which can often be identified as gravity lovs
Different rock types with different densities also can
result in gravity lows
Regional data indicate a gravity low in the vicinity of the
landfill but it is uncertain whether the low results from a
fracture zone or from the presence of different rock types
BSR03011 4-1
III
of higher donsity on either side of the landfill
Additional gravity measurements obtained in tho vicinity of
the landfill confirm the gravity low and suggest a
northeast-southwest trend to the low that corresponds with
Lincainent 1
The gravity data are dominated by the regional effects of
the denser metamorphic sediments to the east and the buried
pluton to the west In order to minimize the gravity
effects of these features and to emphasize the ]oca]ized
effects of fracture zones CH2M JIILL removed a fourth-order
surface from the data The residual values reflect the
smaller (shorter wavelength) features that are likely to
include fracture zones The resulting residual data were
tlien plotted on a map
Tlie central part of the residual data map showed a gravity
hiyli with sides oriented northeast-southwest The southeast
side of this feature is coincident with Lineament 1 on the
fracture trace map in GZAs May 1988 report (Doc 38)
Central Landfill is located on this feature The residual
gravity high is breached in the vicinity of the landfill
The breach may be associated with other fracture traces
The results of the residual gravity evaluation suggest that
Lineament 1 may be related to a geologic contact
Alternatively Lineament 1 may be at the contact between
fractured rock to the southeast (the gravity low) and
unfractured rock to the northwest The data support the
fracture trace interpretation in the vicinity of the
landfill
BSR0 3011 4-2
42 ELECTRICAL RESISTIVITY
Electrical soundings are used to estimate subsurface
resistivities Fracture zones can affect the resistivities
by increasing hydraulic conductivity In most cases rock
resistivity is controlled by pore fluid conductivity and
porosity
The soundings in the vicinity of the landfill indicated
areas of resistive bedrock (indicating competent rock) and
areas of less resistive bedrock (possibly fractured rock)
For i he most part the more resistive areas are northwest of
Lineltiment 1 and the less resistive bedrock is southeast of
the lineament
The interpreted bedrock resistivities were used with
groundwater specific conductance to calculate a formation
factor A high formation factor suggests competent rock
The variability of groundwater conductivity over short
distances in general and some uncertainty in the estimated
bedrock conductivity in the vicinity of the landfill may
make use of these formation factors questionable
There are no comments in either the GZA May 1988 report
(Doc 38) or the Geotech report (Doc 35) about cultural
conductors such as fences and power lines that may have
affected the data Either there are no cultural conductors
in the area or this potential problem was overlooked
Soundings 4 and 9 may have been affected by nearby cultural
conductors
The observed bedrock resistivities appear lower on the
southeast side of Lineament 1 and higher on the nort)ivest
side This is consistent with Lineament 1 being a geologic
BSR03011 4-3
I
contact or with the fracture density being higher on the
southeast side
43 SEISMIC REFRACTION
Seismic refraction surveys were performed to measure bedrock
velocities in the vicinity of the landfill Bedrock
veJricities may be reduced in areas of fracturing compared
witli the velocities in unfractured areas Refraction
surveys generally were run in the same areas as those in
which the electrical soundings were run Low velocity
bidrock wliich may be related to rock fracturing vas
idntified by the refraction surveys
Because seismic data are very noisy the first arrivals were
not identified properly in some instances Estimated
bedrock velocities are correspondingly uncertain The
bedrock velocity calculated by CH2M HILL for Line S-4
(12100 fps) is approximately 15 percent higher than the
velocity given in the Geotech and GZA reports (10380 fps)
(Doc 35 38) The data for Line S-4 are relatively good
an uncertainty of 15 percent or worse might be typical for
data of this quality
Some of the seismic spreads did not include a shot at each
end of a spread Without data from shots at both ends it
is impossible to determine true bedrock velocities where
dipping beds are present Although seismic refraction is a
valid metliod for identifying fracture zones better-quality
data than those presented in the Geotech and GZA reports
(Doc 35 38) are required
BSR03011 4-4
44 DOWNHOLE GEOPHYSICAL LOGGINC
AND VERTICAL SEISMIC PROFILING
The downhole geophysical logging was performed by the USGS
Division of Water Resources The logging methods and their
associated functions are listed below
Acoustic Borehole Televiewer
Formation Resistivity
Borehole Caliper
Neutron-Gamma
Natural Gamma
Spontaneous Potential
Maps rock fractures using
sonar transmissions
Maps areas of lower
resistivity lhat may be
the result of fracturing
Measures borehole
diameter
Measures formation
porosity but readings are
affected by clay
Measures formation
natural radioactive
emmissions can be
used to identify clay and
was used with the
neutron-gamma data
Used to identify different
strata such as clay and
shale
BSR03011 4-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
GEOPHYSICAL INVESTIGATIONS
Geophysical investigations are described in both the
August 1987 report prepared by Geotech Enterprises Inc
(Appendix Document 35) and GZAs May 1988 report (Doc 38)
Thiree geophysical survey methods were used by Geotech to
investigate the vicinity of the Central Landfill The
objectives of the investigations were to locate areas of
rock fracturing and to recommend locations for three
multilevel wells The survey methods investigated gravity
e]ectrical resi^tivity and seismic refraction Each method
vas targeted at a different physical property of the rock
any of which could indicate fracturing
GZAs May 1988 report (Doc 38) summarizes the results of
the geophysical surveys discussed in the Geotech report
(Doc 35) In addition GZAs May 1988 report describes the
results of downhole geophysical logging performed by the
USGS and vertical seismic profiling performed by Weston
Geophysical Corporation
41 GRAVITY
The gravity investigation method measures minute differences
in the Earths gravitational field resulting from rock
density differences Fracturing can result in lover
densities which can often be identified as gravity lovs
Different rock types with different densities also can
result in gravity lows
Regional data indicate a gravity low in the vicinity of the
landfill but it is uncertain whether the low results from a
fracture zone or from the presence of different rock types
BSR03011 4-1
III
of higher donsity on either side of the landfill
Additional gravity measurements obtained in tho vicinity of
the landfill confirm the gravity low and suggest a
northeast-southwest trend to the low that corresponds with
Lincainent 1
The gravity data are dominated by the regional effects of
the denser metamorphic sediments to the east and the buried
pluton to the west In order to minimize the gravity
effects of these features and to emphasize the ]oca]ized
effects of fracture zones CH2M JIILL removed a fourth-order
surface from the data The residual values reflect the
smaller (shorter wavelength) features that are likely to
include fracture zones The resulting residual data were
tlien plotted on a map
Tlie central part of the residual data map showed a gravity
hiyli with sides oriented northeast-southwest The southeast
side of this feature is coincident with Lineament 1 on the
fracture trace map in GZAs May 1988 report (Doc 38)
Central Landfill is located on this feature The residual
gravity high is breached in the vicinity of the landfill
The breach may be associated with other fracture traces
The results of the residual gravity evaluation suggest that
Lineament 1 may be related to a geologic contact
Alternatively Lineament 1 may be at the contact between
fractured rock to the southeast (the gravity low) and
unfractured rock to the northwest The data support the
fracture trace interpretation in the vicinity of the
landfill
BSR0 3011 4-2
42 ELECTRICAL RESISTIVITY
Electrical soundings are used to estimate subsurface
resistivities Fracture zones can affect the resistivities
by increasing hydraulic conductivity In most cases rock
resistivity is controlled by pore fluid conductivity and
porosity
The soundings in the vicinity of the landfill indicated
areas of resistive bedrock (indicating competent rock) and
areas of less resistive bedrock (possibly fractured rock)
For i he most part the more resistive areas are northwest of
Lineltiment 1 and the less resistive bedrock is southeast of
the lineament
The interpreted bedrock resistivities were used with
groundwater specific conductance to calculate a formation
factor A high formation factor suggests competent rock
The variability of groundwater conductivity over short
distances in general and some uncertainty in the estimated
bedrock conductivity in the vicinity of the landfill may
make use of these formation factors questionable
There are no comments in either the GZA May 1988 report
(Doc 38) or the Geotech report (Doc 35) about cultural
conductors such as fences and power lines that may have
affected the data Either there are no cultural conductors
in the area or this potential problem was overlooked
Soundings 4 and 9 may have been affected by nearby cultural
conductors
The observed bedrock resistivities appear lower on the
southeast side of Lineament 1 and higher on the nort)ivest
side This is consistent with Lineament 1 being a geologic
BSR03011 4-3
I
contact or with the fracture density being higher on the
southeast side
43 SEISMIC REFRACTION
Seismic refraction surveys were performed to measure bedrock
velocities in the vicinity of the landfill Bedrock
veJricities may be reduced in areas of fracturing compared
witli the velocities in unfractured areas Refraction
surveys generally were run in the same areas as those in
which the electrical soundings were run Low velocity
bidrock wliich may be related to rock fracturing vas
idntified by the refraction surveys
Because seismic data are very noisy the first arrivals were
not identified properly in some instances Estimated
bedrock velocities are correspondingly uncertain The
bedrock velocity calculated by CH2M HILL for Line S-4
(12100 fps) is approximately 15 percent higher than the
velocity given in the Geotech and GZA reports (10380 fps)
(Doc 35 38) The data for Line S-4 are relatively good
an uncertainty of 15 percent or worse might be typical for
data of this quality
Some of the seismic spreads did not include a shot at each
end of a spread Without data from shots at both ends it
is impossible to determine true bedrock velocities where
dipping beds are present Although seismic refraction is a
valid metliod for identifying fracture zones better-quality
data than those presented in the Geotech and GZA reports
(Doc 35 38) are required
BSR03011 4-4
44 DOWNHOLE GEOPHYSICAL LOGGINC
AND VERTICAL SEISMIC PROFILING
The downhole geophysical logging was performed by the USGS
Division of Water Resources The logging methods and their
associated functions are listed below
Acoustic Borehole Televiewer
Formation Resistivity
Borehole Caliper
Neutron-Gamma
Natural Gamma
Spontaneous Potential
Maps rock fractures using
sonar transmissions
Maps areas of lower
resistivity lhat may be
the result of fracturing
Measures borehole
diameter
Measures formation
porosity but readings are
affected by clay
Measures formation
natural radioactive
emmissions can be
used to identify clay and
was used with the
neutron-gamma data
Used to identify different
strata such as clay and
shale
BSR03011 4-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
of higher donsity on either side of the landfill
Additional gravity measurements obtained in tho vicinity of
the landfill confirm the gravity low and suggest a
northeast-southwest trend to the low that corresponds with
Lincainent 1
The gravity data are dominated by the regional effects of
the denser metamorphic sediments to the east and the buried
pluton to the west In order to minimize the gravity
effects of these features and to emphasize the ]oca]ized
effects of fracture zones CH2M JIILL removed a fourth-order
surface from the data The residual values reflect the
smaller (shorter wavelength) features that are likely to
include fracture zones The resulting residual data were
tlien plotted on a map
Tlie central part of the residual data map showed a gravity
hiyli with sides oriented northeast-southwest The southeast
side of this feature is coincident with Lineament 1 on the
fracture trace map in GZAs May 1988 report (Doc 38)
Central Landfill is located on this feature The residual
gravity high is breached in the vicinity of the landfill
The breach may be associated with other fracture traces
The results of the residual gravity evaluation suggest that
Lineament 1 may be related to a geologic contact
Alternatively Lineament 1 may be at the contact between
fractured rock to the southeast (the gravity low) and
unfractured rock to the northwest The data support the
fracture trace interpretation in the vicinity of the
landfill
BSR0 3011 4-2
42 ELECTRICAL RESISTIVITY
Electrical soundings are used to estimate subsurface
resistivities Fracture zones can affect the resistivities
by increasing hydraulic conductivity In most cases rock
resistivity is controlled by pore fluid conductivity and
porosity
The soundings in the vicinity of the landfill indicated
areas of resistive bedrock (indicating competent rock) and
areas of less resistive bedrock (possibly fractured rock)
For i he most part the more resistive areas are northwest of
Lineltiment 1 and the less resistive bedrock is southeast of
the lineament
The interpreted bedrock resistivities were used with
groundwater specific conductance to calculate a formation
factor A high formation factor suggests competent rock
The variability of groundwater conductivity over short
distances in general and some uncertainty in the estimated
bedrock conductivity in the vicinity of the landfill may
make use of these formation factors questionable
There are no comments in either the GZA May 1988 report
(Doc 38) or the Geotech report (Doc 35) about cultural
conductors such as fences and power lines that may have
affected the data Either there are no cultural conductors
in the area or this potential problem was overlooked
Soundings 4 and 9 may have been affected by nearby cultural
conductors
The observed bedrock resistivities appear lower on the
southeast side of Lineament 1 and higher on the nort)ivest
side This is consistent with Lineament 1 being a geologic
BSR03011 4-3
I
contact or with the fracture density being higher on the
southeast side
43 SEISMIC REFRACTION
Seismic refraction surveys were performed to measure bedrock
velocities in the vicinity of the landfill Bedrock
veJricities may be reduced in areas of fracturing compared
witli the velocities in unfractured areas Refraction
surveys generally were run in the same areas as those in
which the electrical soundings were run Low velocity
bidrock wliich may be related to rock fracturing vas
idntified by the refraction surveys
Because seismic data are very noisy the first arrivals were
not identified properly in some instances Estimated
bedrock velocities are correspondingly uncertain The
bedrock velocity calculated by CH2M HILL for Line S-4
(12100 fps) is approximately 15 percent higher than the
velocity given in the Geotech and GZA reports (10380 fps)
(Doc 35 38) The data for Line S-4 are relatively good
an uncertainty of 15 percent or worse might be typical for
data of this quality
Some of the seismic spreads did not include a shot at each
end of a spread Without data from shots at both ends it
is impossible to determine true bedrock velocities where
dipping beds are present Although seismic refraction is a
valid metliod for identifying fracture zones better-quality
data than those presented in the Geotech and GZA reports
(Doc 35 38) are required
BSR03011 4-4
44 DOWNHOLE GEOPHYSICAL LOGGINC
AND VERTICAL SEISMIC PROFILING
The downhole geophysical logging was performed by the USGS
Division of Water Resources The logging methods and their
associated functions are listed below
Acoustic Borehole Televiewer
Formation Resistivity
Borehole Caliper
Neutron-Gamma
Natural Gamma
Spontaneous Potential
Maps rock fractures using
sonar transmissions
Maps areas of lower
resistivity lhat may be
the result of fracturing
Measures borehole
diameter
Measures formation
porosity but readings are
affected by clay
Measures formation
natural radioactive
emmissions can be
used to identify clay and
was used with the
neutron-gamma data
Used to identify different
strata such as clay and
shale
BSR03011 4-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
42 ELECTRICAL RESISTIVITY
Electrical soundings are used to estimate subsurface
resistivities Fracture zones can affect the resistivities
by increasing hydraulic conductivity In most cases rock
resistivity is controlled by pore fluid conductivity and
porosity
The soundings in the vicinity of the landfill indicated
areas of resistive bedrock (indicating competent rock) and
areas of less resistive bedrock (possibly fractured rock)
For i he most part the more resistive areas are northwest of
Lineltiment 1 and the less resistive bedrock is southeast of
the lineament
The interpreted bedrock resistivities were used with
groundwater specific conductance to calculate a formation
factor A high formation factor suggests competent rock
The variability of groundwater conductivity over short
distances in general and some uncertainty in the estimated
bedrock conductivity in the vicinity of the landfill may
make use of these formation factors questionable
There are no comments in either the GZA May 1988 report
(Doc 38) or the Geotech report (Doc 35) about cultural
conductors such as fences and power lines that may have
affected the data Either there are no cultural conductors
in the area or this potential problem was overlooked
Soundings 4 and 9 may have been affected by nearby cultural
conductors
The observed bedrock resistivities appear lower on the
southeast side of Lineament 1 and higher on the nort)ivest
side This is consistent with Lineament 1 being a geologic
BSR03011 4-3
I
contact or with the fracture density being higher on the
southeast side
43 SEISMIC REFRACTION
Seismic refraction surveys were performed to measure bedrock
velocities in the vicinity of the landfill Bedrock
veJricities may be reduced in areas of fracturing compared
witli the velocities in unfractured areas Refraction
surveys generally were run in the same areas as those in
which the electrical soundings were run Low velocity
bidrock wliich may be related to rock fracturing vas
idntified by the refraction surveys
Because seismic data are very noisy the first arrivals were
not identified properly in some instances Estimated
bedrock velocities are correspondingly uncertain The
bedrock velocity calculated by CH2M HILL for Line S-4
(12100 fps) is approximately 15 percent higher than the
velocity given in the Geotech and GZA reports (10380 fps)
(Doc 35 38) The data for Line S-4 are relatively good
an uncertainty of 15 percent or worse might be typical for
data of this quality
Some of the seismic spreads did not include a shot at each
end of a spread Without data from shots at both ends it
is impossible to determine true bedrock velocities where
dipping beds are present Although seismic refraction is a
valid metliod for identifying fracture zones better-quality
data than those presented in the Geotech and GZA reports
(Doc 35 38) are required
BSR03011 4-4
44 DOWNHOLE GEOPHYSICAL LOGGINC
AND VERTICAL SEISMIC PROFILING
The downhole geophysical logging was performed by the USGS
Division of Water Resources The logging methods and their
associated functions are listed below
Acoustic Borehole Televiewer
Formation Resistivity
Borehole Caliper
Neutron-Gamma
Natural Gamma
Spontaneous Potential
Maps rock fractures using
sonar transmissions
Maps areas of lower
resistivity lhat may be
the result of fracturing
Measures borehole
diameter
Measures formation
porosity but readings are
affected by clay
Measures formation
natural radioactive
emmissions can be
used to identify clay and
was used with the
neutron-gamma data
Used to identify different
strata such as clay and
shale
BSR03011 4-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
contact or with the fracture density being higher on the
southeast side
43 SEISMIC REFRACTION
Seismic refraction surveys were performed to measure bedrock
velocities in the vicinity of the landfill Bedrock
veJricities may be reduced in areas of fracturing compared
witli the velocities in unfractured areas Refraction
surveys generally were run in the same areas as those in
which the electrical soundings were run Low velocity
bidrock wliich may be related to rock fracturing vas
idntified by the refraction surveys
Because seismic data are very noisy the first arrivals were
not identified properly in some instances Estimated
bedrock velocities are correspondingly uncertain The
bedrock velocity calculated by CH2M HILL for Line S-4
(12100 fps) is approximately 15 percent higher than the
velocity given in the Geotech and GZA reports (10380 fps)
(Doc 35 38) The data for Line S-4 are relatively good
an uncertainty of 15 percent or worse might be typical for
data of this quality
Some of the seismic spreads did not include a shot at each
end of a spread Without data from shots at both ends it
is impossible to determine true bedrock velocities where
dipping beds are present Although seismic refraction is a
valid metliod for identifying fracture zones better-quality
data than those presented in the Geotech and GZA reports
(Doc 35 38) are required
BSR03011 4-4
44 DOWNHOLE GEOPHYSICAL LOGGINC
AND VERTICAL SEISMIC PROFILING
The downhole geophysical logging was performed by the USGS
Division of Water Resources The logging methods and their
associated functions are listed below
Acoustic Borehole Televiewer
Formation Resistivity
Borehole Caliper
Neutron-Gamma
Natural Gamma
Spontaneous Potential
Maps rock fractures using
sonar transmissions
Maps areas of lower
resistivity lhat may be
the result of fracturing
Measures borehole
diameter
Measures formation
porosity but readings are
affected by clay
Measures formation
natural radioactive
emmissions can be
used to identify clay and
was used with the
neutron-gamma data
Used to identify different
strata such as clay and
shale
BSR03011 4-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
44 DOWNHOLE GEOPHYSICAL LOGGINC
AND VERTICAL SEISMIC PROFILING
The downhole geophysical logging was performed by the USGS
Division of Water Resources The logging methods and their
associated functions are listed below
Acoustic Borehole Televiewer
Formation Resistivity
Borehole Caliper
Neutron-Gamma
Natural Gamma
Spontaneous Potential
Maps rock fractures using
sonar transmissions
Maps areas of lower
resistivity lhat may be
the result of fracturing
Measures borehole
diameter
Measures formation
porosity but readings are
affected by clay
Measures formation
natural radioactive
emmissions can be
used to identify clay and
was used with the
neutron-gamma data
Used to identify different
strata such as clay and
shale
BSR03011 4-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
Spinning Flow Meter Measures fluid flow
velocities in boreholes
will indicate zones
releasing water irito
boreholes
The vertical seismic profiling is used to identify
fluid-filled fractures in a borehole A series of seismic
sensors (hydrophones) is lowered into the borehole A
seismic source such as a weight drop generates
corapressional waves which are detected by the hydrophones
Fractures are indicated by a distinct pattern in tho seismic
record
The downhole geophysical logging methods can indicate
fractures at each borehole but they cannot indic-ite whetiier
the fractures have any extent or are part of an extensive
fracture zone Whether a borehole is within a fracture zone
can only be inferred by the fracture density The same is
true of the vertical seismic profiling The information
provided by the logging methods however is important in
determining which portion of a well should be screened vhen
constructing the well
BSR03011 4-6
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
I GROUNDWATER
51 GROUNDWATER OCCURRENCE AND MOVEMENT
Groundwater within the North Scituate Quadrangle has been
mapped by the USGS using data obtained in 1958 These data
have been incorporated into Drawing 5 of the GZ May 1988
report (Doc 38) Tlie mapping of well data indicates a
groundwater divide between the Central Landfill and the
Situate Reservoir that is coincident with the topographic
divide
Drawing 4 of the GZA May 1988 report (Doc 38) is a
groundwater content map depicting the lateral movement of
groundwater within the overburden and shallow rot k The map
combines data from both overburden (Water table) wells and
rock wells Some of the rock wells also monitor water table
conditions at some locations the water table occurs within
the top of rock At other locations the potentiometric
level is well above the top of rock and groundwater
probably occurs within the overburden The potentiometric
level recorded by rock Well WE87-13 is approximately 50 feet
above the top of rock
Preparation of the groundwater content map was based on the
assumption that there is little or no change in head over
possibly 50 feet of saturated soils Other liberties taken
in preparation of the map included the use of deep open
boreholes before completion of the multilevel wells and
adjustments to the recorded water levels from several wells
as a correction for the rise in water levels that occurred
since the time of measurement Given the scale of the map
(1 inch = 300 feet) and the 10-foot groundwater contour
interval (neither of which is inappropriate for an area of
DSR03012 5-1
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
It this size) the map probably provides a reasonable
i
in
representation of both the water table and groundweter
occurrence within the shallow bedrock Drawing 4 shows
shallow groundwater flow coming onto the site from the
northwest vest and south Through the area of existing
fill shallow groundwater movement is south toward Cedar
Swamp Brook southwest toward Simmons Upper Reservoir and
east and northeast toward Almy Reservoir
Vertical head distributions in the fractured bedrock aro
less straightforward Water levels taken in each of the
five multilevel wells during April 1988 are shown in Table 5
of the GZA May 1988 report (Doc 38) The water levels
taken in January and February 1988 the latter of wliich were
included in Drawing 4 were taken in deep open boreholes
arni they appear to most closely represent the elevation of
the water table At well couplets and each multilevel well
except Well WE87-ML3 the vertical component of flow is
shown to be either upward or downward as indicated by a
small arrow on Drawing 4 With the exception of Wells
WEB7-ML4 and WE85-6 (and WE87-ML3 for which there is no
arrow) downward components of flow are shown for each vell
pair and multilevel installation
An upward component of flow at Well WE85-6 as indicated by
a higher potentiometric level in the rock well (3481) than
that reported in the overburden well (3477) is not
consistent with the water level measuirements in nearby
multilevel Well WE87-ML1 and therefore it may be erroneous
Unlike Well WE87-ML4 which is adjacent to a m-ajor discharge
point this well pair would not be expected to have as large
a head diffexonce as is indicated between the two v bullells In
GZAs Geohydrologic Study Final Report of October 1986
(Appendix Document 33) both Well WE85-6a and Well WE85-6b
were shown at elevation 3433
PSR03012 5-2
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
Multilevel Well WE87-ML3 was interpreted by GZA as
exhibiting a higher head at both the top and bottom
locations than at the central portion of the well However
the water levels provided in Table 5 of the GIA May 1988
report (Doc 38) indicate a drop in head from elevation
4153 at Zone A to 4151 feet at Zone C to 4137 feet at
Zone E It is true that the head at Zone B is one-tenth of
a foot lower than that at Zone C and the head at Zone D is
one-tenth of a foot lower than that at Zone E However
these minor head differences may not be significant when
comparing two zones along the vertical dimension in a
fractured rock that exhibits no vertical fractures Because n the various sampling zones are not along the same flow path
minor head differences may be more a reflection of lateral
changes in head than a true representation of the vertical
component of groundwater movement
52 WATER QUALITY
The water quality data reviewed include residential well
data from 1983 through 1987 monitoring well data from 1985
and 1986 (contained in GZAs October 1986 final report
Doc 33) monitoring well data from 1987 (split samples
analyzed by WaterTest Corporation Appendix Documents 11 and
18) and monitoring well data contained in GZAs Remedial
Investigation Data Report of August 1988 (Appendix Document
39) The water quality data indicate that the existing
landfill has had an impact on groundwater quality with
respect to selected water quality parameters metals [ | | volatile organic compounds (VOCs) and semivolatile organic
compounds
Monitoring wells located downgradient of the landfill tend
to exceed upgradient monitoring wells with respect to each
BSR03012 5-3
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
parameter group In certain downgradient well including
Well J located near the industrial waste area this
contamination is quite severe On the other hand the
presence of VOCs in upgradient Monitoring Well VJE85-12
suggests that sources of groundwater contamination other
than the landfill also are present Although the precise
locations of many of the domestic wells tested are not clear
from the data reviewed there appears to be a large number
of domestic wells that are not downgradient of the landfill
and yet are contaminated with VOCs This also suggests the
presence of other unrelated sources of groundvater
contamination
Significant grc^undwater contamination has been observed in
rronitoring wells located within the landfill proper in
downgradient wells along the toe of slope and southeast
prcperty line and in one upgradient well southwest of ihe
landfill Wells J 87-2A and B consistently have contained
VOCs in excess of 1000 parts per billion (ppb) or 1 part
per million (ppm) All three wells are located within the
landfill area Well J is located near the former industrial
waste area Well J was found to contain 103 ppm VOCs with
chlorobenzene toluene and total xylenes each at
concentrations of more than 1 ppm
Top of rock Well C located at the toe of slope along the
southeast portion of the property line has ranged from more
than 100 ppb VOCs to more than 1000 ppb VOCs Wells B and
B-l and Wells WE87-1B 3A 3B 4 and 12 have contained VOCs
at concentrations of more than 100 ppb VJells D and B-l
(top of rock and overburden respectively) are located along
the southeast portion of the property line just south of
the existing fill Wells WE87-1B 3A 3B and 4 are all
located within the existing fill All but VJell 3A are
screened within the top of rock
mt
ESR03012 5-4
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
Upgradir-nt Well WE87-1B located southwest of Lhe landfill
and souMiwest of Cedar Swamp Brook has contai tied more than
100 ppb VOCs predominantly trichloroethylene (TCE) Top of
rock Well N located in the landfill approximately 380 feet
downgradient of Well J has ranged from more than 10 ppb
VOCs to more than 100 ppb VOCs Downgradient Well B7-ML2
and Wells 87-15 and 19 both located at the toe of slope
have indicated VOCs concentrations of more than 10 ppb
Ill BSR03012 5-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
PROPOSED LANDFILL EXPANSION
6_J GENERAL COMMENTS ON OVERALL DESIGN
The existing unlined landfill designated as Phase I in the
Fngineerincj Design Report of July 1987 (Appendix Document
34) poses a threat to groundwater quality at the landfill
site Groundwater quality data indicate that the fill is
leaking and a plume is spreading One way to reduce ihe
quantity of the leachate generated would be to install a
low-permeability cap over the area This would
significantly reduce the leaching of pollutants from the
portion of the fill above the water table As described
below the proposed expansion would delay the installation
of a final cover over the entire area for 20 years
Percolation during this time would continue to leach
pollutants to the groundwater as well as provide the
potential for leachate seeps to emerge from the side slopes
of the fill Leachate contaminants could emanate not only
from the municipal waste but also from the industrial wastes
that were disposed of in the facility
A significant deficiency of the expansion plan is that it
would leave a major portion of the existing fill uncovered
allowing it to generate uncontrolled leachate throughout the
projected expansion period (completion in year 2009) In
Stage 1 additional waste would be disposed of in Phase I
for 3 years during this time infiltration into the fill
would remain at current levels In Stage 2 portions of the
existing fill woi-ld be capped but the entire vestern half
would receive only 1 foot of soil cover having a
permeability of 1 x 10 centimeters per second before being
overlaid with additional waste materials (as shown on
Drawings 5 and 7) This area approximately 60 acres would
BSR03013 6-1
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
1 be open to percolation of leachate from the overlying fill
Thu a largo portion of the existing unlined fill vould not
reccive final cover for 20 years
The July 1987 design report (Doc 34) makes several
misleading statements that do not recognize the issue
discussed above
A composite primary baseliner leachate collection
systnm and secondary collection system will be
installed on the entire area of Phase II and
Phase III prior to the placement of waste in those
areas (page 9)
Stage 2 landfilling includes filling over the
baseliner constructed in the Phase II and
Phase III area (page 60)
These statements ignore the fact that most of the filling in
Phase II would be done vertically above the unlined Phase I
area The design does not include the extension of the
liner system up this side slope which actually would
constitute the majority of the Phase II fill footprint
Percolation through this area would impinge on the western
bullfloiie of Phase I and a significant amount of leachate could
infiltrate the unlined Phase I fill
The potential for percolation through the western slope area
could be increased by the buildup of landfill gas pressure
under the intermediate cover layer No provision for
nvlieving this pressure is considered in the July 1987
ciesign report (Doc 34) The potential exists for the
opening of fissures in the layer with a resultant increase
in leachate percolation
BSR03013 6-2
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
The July 1987 design report (Doc 34) does not mention
consideration of or calculations concerning slope stability
for the proposed fill contours Throughout the report
31 slopc=5 are used for final contours for the existing and
expanf^ion fills Guidelines for municipal refuse developed
from actua1 practice dictate the use of 41 slopes as a
conservative measure to ensure stable slopes but 31 slopes
have been employed successfully Because of the extensive
height of the proposed final fillmdashover 250 feet higher than
existing grade in places--slope stability should be
evaluited carefully Shallow surface failures through the
fill as well as deep failures through underlying geologic
strata should be considered
62 SPECIFIC COMMENTS ON DESIGN REPORT AND DRAWINGS
The following specific comments pertain to the Engineering
Design Report and Drawings of July 1987 (Doc 34)
Page 15 362 Final CovermdashControl of final cover slopes to
enhance runoff and to minimize erosion should be addressed
The geomembrare option would have no impervious soil backup
beneath the liner A material more impervious than is sandy
soil should be used
Page 16 Drawing 12mdashFinal cover Alternative 1 vould not
provide a drainage layer overlying the low-permeability
layer A drainage layer should be included to limit the
buildup of head on the cover liner and increased
infiltration potential
BSR03013 6-3
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
There is no mention in the design report concerning
potential freeze-thaw effects on the cover system Final
cover Alternative 1 would provide only 2 feet of soil cover
over the clay layer Frost penetration into the clay layer
could result in its loss of effectiveness as a barrier to
infiltration
Final cover Mternative 2 should include a geotextile
between the topsoil and sand as a filter to prevent clogging
of the drainage layer In addition EPA guidance recommends
that c minimum 2-foot-thick top layer be provided to sustain
vegetative growth Alternative 2 would provide only
12 inches
Table 3-1 and page 18 mdash The maximum area open to pc r cc l a i ion
for Phase II is assumed to be 242 acres This ignores any
contribution from the approximately 60 acres of Phase II
overlying Phase I The leachate collectionstorage system
may be undersized as a result
Page 18 365 Baseliner DesignmdashIt is unclear whether the
groundvater control layer should provide a 5-foot separation
between the groundvater and the top of the primary liner or
between the groundwater and the bottom of the secondary
liner
Page 19--It is not current practice to use a 1-foot-thick
sand bedding for a geomembrane A low-permeability clayey
soil provides suitable bedding and an impervious backup
beneath the geomembrane
Page 20--The groundwater control layer three feet minimum
thickness does not agree with page18 paragraph 365
(see page 18 reference above)
BSR03013 6-4
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
Tlie riopinn l)nsis for the choice of materials for and
til ilt-M ness of tlie groundwater control layer as vell as igtipe
sizes and spacing is not discussed It is unclear how it
was determined that this system would function as intended
to maintain a 5-foot separation between waste and
groundwater
Page 21--The purpose of the additional 30-mil PVC membrane
overlying the HDPE gecnet is not clear The repc^rt states
that its purpose would be to protect the geonet from fines
intmsion a function for which geotextiles are produced
The PVC membrane would prevent leakage from reacliing the
geonet therefore nullifying its traditional function as a
detection medium for any leaks in the primary liner
Page 26--It is not clear how contaminated groundwater from
the Phase I area would be kept from infiltrating the
proposed Phase II groundwater control layer Details of the
proposed control system should be reviewed carefully before
the construction of Phase II Contamination of the control
layer would result in the direct discharge of pollutant
loadings into Cedar Swamp Brook
Page 31--Development plans for the borrow area to the
southwest of the landfill should be evaluated carefully with
regard to potential impacts on surface water and groundwater
quality Dewatering of the area could cause a gradient for
groundwater flow toward the pit necessitating the pumping
of contaminated water
Page 36 43 Secondary Collection System--The 6-inch
depression in the sand bedding (or impervious soil) must
provide for leachate pipe support Lateral pipe supports to
support vertical loads have not been addressed
BSR03013 6-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
Page 37--nirect contact of the stone bedding and the HOPE
membrane could result in puncture
Page 42 Drawing ll--The constructability of the separation
berm l^etween Phases II and III as proposed is questionable
Most soils vill not stand on vertical side slopes as
indicated in the plans Extending the geomembrane
vertically would be difficult
Page 44 Drawings 7 8 9--Side slope diversion swales fr
managing final cover runoff should be provided every 20-foot
drop in elevation as opposed to the 30-foot drop indicated
Page 48 Drawing 11mdashThe proposed construction method for
tho placement of the leachate laterals could damage the
liner if extreme care were not taken Better construction
methods are available
Page 48 Drawing 7--No final cover is indicated to be
installed over the eastern portion of Phase I this area
would be left open to infiltration and continued leachate
generation after final closure
Page 48 Drawing 10 Detail of Pumping Station--The primary
liner thickness is not called out (all other liner
thicknesses are called out) It is unclear what supports
the 4-inch slotted pipe The 2-inch rounded gravel bedltHnq
cannot and the geogrid cannot The 1 foot of compacted
roil beltlding is shown under the pump station The
transition to tho soil under the horizontal liner is not
defined
BSR03013 6-6
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
IlJDPK Liner Penetration Detail
1 It is unclear how pipe boot would be fused to pipe
beneath or at the bottom of the pipe Equipment would
not fit under the pipe
2 Mechanical clamps should be provided to support and
seal the boot to the pipe
3 A concrete pad should be provided to support the pipe
through ihe sand (or impervious soil if the desifin were
modified)
Page 4 8 Drawing 12--A sand layer overlying a siriooth IDPE
membrane on a 31 slope would not be stable and could result
in the sliding of Ihe cover soil and exposure of the liner
it appears that this problem has been addressed in the
May 1988 Preliminary Final Cover Specifications (Appendix
Document 37) by the inclusion of a textured HDPE membrane
BSR03013 6-7
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
CONCLUSIONS AND RECOMMENDATIONS
71 HYDROGEOLOGY
Within the study area soils consisting of glacial till and
glacial outwash overly a granitic bedrock Partly because
of earlier quarrying refuse is in direct contact with the
bedrock over the northern portion of the landfill and
within 5 feet of bedrock over its southern part
Based on features observed on aerial photography and
satellite imagery northwest-southeast trending lineaments
and northeast-southwest trending lineaments were identified
in the vicinity of the landfill A set of lineaments
belonging in the latter group runs from the Central Landfill
to the Scituate Reservoir
The degree of bedrock weathering in shallow core was found
to be a function of depth and proximity to fracture traces
The orientations of fractures observed in boreholes located
near the fracture traces correspond with the trends of the
major lineaments In multilevel wells located near the
fracture trices only a very slight decrease in fracture
frequency was noted with depth During packer testing
significant flow measurements were recorded in the deeper
portions of each multilevel well These data indicate that
the vater-bearing zone within the bedrock extends to some
depth beyond the limit of investigation
Within the overburden and shallow bedrock groundwater has
been shown to move onto the landfill site from the
northwest west and south Groundwater discharges from the
landfill to the drainage areas of Simmons Upper Reservoir
and Almy Reservoir A surface-water divide and shallov
BSR03014 7-1
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
qroumlwater divide occur between tho Scituate Res^rvoi r and
the Central Landf i11 Although the deeper flov regime is
not vell dfjfined it is unlikely that groundwater from
either the existing or proposed areas of fill drains to tlie
Scituate Reservoir The extreme northwest portion of the
landfill property however does lie within the reservoirs
watershed Figure 3 presents a generalized cross-section
showing water table conditions along northeast-southwest
trending Lineament 1
Deeper multilevel wells located between the Central landfill
and Scituate Reservoir could provide more conclusive
evid^Mice on the directions of groundwater movement and the
potential for significant impact of the landfill on
groundwater If either a reversal in vertical gradient
(from a downward component of flow to an upward component of
flow) or significantly reduced bedrock permeability occurs
at depth such deeper multilevel wells would provide useful
data
Water quality data from deeper multilevel wells between the
landfill and reservoir would be unlikely to provide
conclusive evidence Beneath the existing fill however
both water quality and piezometric data from deeper wells
would be useful One aspect of the uncertainty concerning
the impact of the Central Landfill is that the pathways of
contaminant migration from areas of high-level contamination
have not been defined By more thoroughly definingthe
directions of groundwater movement beneath the landfill and
by determining the fate of contaminants released from areas
of high-level contamination the potential impacts of the
landfill on surrounding areas can be determined more
accurately
BSR0 3014 7-2
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
sw 500rshy
450 shy
o Dlt
400
350
300hshy
Sc i tuate Reservoir
r
o o
CQ
c0)
gt -
J t
o o ffl
gtlaquo bull
offl
raquo
2 5 0 -
Marsh
Irferred Vatflf
l-ilprSl jar
TaHe (Tlevaiion at Surface -Vater Location
rn^iij ltvgtilion at Monitcnrg veil iocaiion
1 Mile
_(
Figure 3
G e n e r a l i z e d Cros i -Sect ion AiuTTti ^^ltjr ri^iri - SjuiiWtJST T r e n d i n q L i n e a m e n t 1
i i i j
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
72 GEOPHYSICS
The geophysical investigations have been used successfully
to plan monitoring well locations and to determine the
depths at which to screen the wells The work jDorformed by
Geotech Enterprises Inc (Doc 35) defined areas of
probable fracturing in the vicinity of the landfill The
subsequent downhole investigations determined where in each
hole the fractures were intercepted
The preferred locations of future monitoring wells
presumably would be within fracture zones or fault traces
Geophysical urvey methods and the Fracture Trace Analysis
should be incorporated into the well-placement planning to
establish fracture zone locations Existing data may be
sufficient to determine approximate locations for additional
wells located at the landfill Boreholegeophysical logging
should be used for locating appropriate zones for the well
screens
Additional work may be required to locate fracture traces
more precisely This work would be performed in the
vicinity of the planned wells to ensure that the best
locations for them are selected Recommended methods of
obtaining data include electrical resistivity and seismic
refraction surveys
An induced polarization (IP) survey (a specialized
resistivity survey) may be able to locate fractures from
their resistivity values and from the IP values associated
with clays in zones of weathering IP surveys usually are
performed using a dipole-dipole electrode configuration
which provides both depth and lateral information
BSR03014 7-4
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
Very Low Frequency (VLF) electromagnetic surveys also can be
used lo map fracture zones At the frequencies used for
this type of survey the equipment is sensitive (o
relatively shallow resistivity variations such cis
fractures This method may be appropriate if the bedrock is
not deeply buried The depth of penetration by this method
depen(3s on the conductivity of the ground
A seiijmic refraction survey also can be used to identify
fracture zones by their associated low bedrock velocities
Seismic refraction surveys would be designed specifically to
determine bedrock velocities and may not be particularly
useful to determine depths
73 LANDFILL DESIGN
The existing unlined landfill poses a threat to groundwater
quality at the landfill site A significant deficiency of
the proposal expansion plan is that it would leave a major
portion of the existing fill uncovered allowing it to
generate uncontrolled leachate throughout the projected
expansion period Other potential problems with the
proposed expansion design include slope stability drainage
frost penetration of the final cover sizing of the leachate
collection system isolation of the Phase II groundwater
control layer from contaminated groundwater generated by the
unlined Phase I area and the constructability of the
propc^ed design
74 GROUNDWATER QUALITY
The groundwater monitoring data indicate that the Central
Landfill has had an adverse impact on water quality in the
BSR03014 7-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
vicinity ot tho landfill However the full vertical ond
lateral extent of contamination has not yet been defned
The most severe contamination has been observed in
relatively shallow wells located within the landfill proper
Deeper wells have not yet been installed in the areas
exhibiting the highest levels of contamination
Water quality data also indicate the presence of additional
sources of groundwater contamination other than tlie Central
Landfill Areas of unrelated groundwater contamination
occur within the vicinity of the Central Landfill and at
locations avay from the landfill Still unidentified
sources of contamination may pose an even greater threat to
the quality of water in the Scituate Reservoir than does the
leachate emanating from the Central Landfill
It may be prudent to evaluate land use within the vatershed
identify areas that pose the greatest threat to both surface
water and groundwater and then determine whether the
current program of surface water monitoring provides
adequate protection of the water supply
BSP03014 7-6
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
APPENDIX
List of Documents Reviewed
BSR03015
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
Coir(Ppon(liric(2
Dates
From
I To
Subject
CorrnGpDndiince Date From
11 To Subject
I
Analytical Data Dates of Sampling Laboratory Source
Consent Agrrjement
Date
Correspondence
Date From
I To Subject
Correspondence Date From To Subject
Chain of Custody Dates Lal^oratory
Correspoundiondence Date From To Subject
Corresponr^ence Date From To Subject
February 11 1983 and Janunr- IHI Rhode Island Department of Heoltb Owners of Domestic Wells Results of chemical analyses
August 28 1984 US Department of Interior Goldberg-Zoino s Associates Inc Direction of groundwater movement Central Landfill
783 883 1283 285 and 5P5 WaterTest Corporation Domestic wells
David DelSesto et al vs Rhode Island Solid Waste Management Corporation September 10 1986
February 18 1987 Rhode Island Solid Waste Management Corporation WATER Summary of Goldberg-Zoino amp Associates Incs report
May 21 1987 Rhode Island Solid Waste Management Corporation WATER
Notification of sampling event
May 1987 and June 1987 WaterTest Corporation
May 10 1987 Goldberg-Zoino amp Associates Im Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Refiort 1
June 14 1987 Goldberg-Zoino R Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progresr Report 2
BSR03016 A-1
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
JO AnoJytical Data Date of Sampling raboratory
I Souice
11 Ajialyt ical Data Date of Sampling Laboratory Source
12 Memorandum Undated By Subject
li ]3 Correspondence
Date From To Subject
14 Correspondence
li Date- From To Subject
15 Correspondence Date From
M To Subject
II 16 Correspondence
Date From To Subject
17 Correspondence Date From To Subject
TR Ajialytical Data Dates of Sampling La bora (ory Source
June 1987 WaterTest Corporation Domestic wells
June 9 1987 WaterTest Corporation Central Landfill
WATER Results of private well samples
August 11 1987 Rhode Island Solid Waste Management Cc)r])oration David DelSesto Analytical resuJls of the May sampling
August 13 1987 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Repoit 3
September 15 1987 Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 4
October 15 1987 Goldberg-Zoino S Associates Inc Rhode Island Solid Wast^ Management Corporation Central Landfill RIFS Progress Report 5
October 26 1987 RI Analytical Laboratories Inc Rhode Island Solid Waste Manag(Mnent Corporation Analytical parameters and methods
October 14-16 1987 and Octoler 27 1907 WaterTest Corporation Central Landfill
BSR03016 A-2
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
1 9 Corresprjnd(MiC( D a t o Frdm To S u b j e c t
20 Correspondence Date From To Subject
21 Correspondence Date From To Subject
22 Correspcjidence Date From
To Subject
Corre-^pondence Date From To Subject
24 Corre- piindence Date From To Subject
25 Correspondence Date From To Subject
26 Correspondence Date From To Subject
November 13 1907 Goldberg-Zoino amp Associates I n c Rhode Island Solid Waste Manacemerit igtr[)rrat ion Central Landfill RIFS Progreis Rij-gtrL 6
December 21 1907 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corpcjration Central Landfill RIFS Progress Report 7
January 22 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste ManageTient Corporation Central Landfill RIFS Progress Report 8
February 8 1908 Rhode Island Department of Eir-i ronmr^ntal Management Providence Water Supply Board Well Location Map Central Landfill
February 9 1988 Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation Central Landfill RIFS Progress Report 9
February 24 1988
Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Managenent Corporation Hydrogeologic Information for Central Landfill Interim Area 2
March 10 1988 Goldberg-Zoino s Associates Inc Providence Water Supply Board Status of geohydrological studies at the Central Landfill
March 15 1988 Rhode Island Solid Waste Management Corpojation US EPA Transmittal of GZA Progress Report 10
BSR03016 A-3
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
li^l 2 1 Correspondeiice Date From To Subject
28 Corresponrience Date From To Subject
29 Correspondence Date From To Subject
30 Map
31 Map
32 Newspaper articles Newspaper Dates
33 Report Prepared by Prepared for Date
34 Design Docinnent Prepared by Prepared for Date
35 Report Prepared by Prepared for Date
36 Sampling Plan Prepared by Prepared for Date
March 25 1988 Rhode Island Solid Waste Management C rporation Providence Water Supply Board Transmittal of DEM Decision and Order
April 19 1988 Rhode Island Solid Waste Management Corporation US EPA Central Landfill RIFS Progress Reigtort 11
May 19 1988 Rhode Island Solid Waste Managenont Corporation US EPA Transmittal of GZA Progress Peport 3 2
Rhode Island 1987
Scituate Reservoir showing selected -SMrfice water sampling points and the eastern bull ige of the watershed limit in relation to the active landfill
Providence Journal-Bulletin March 1 March 22 and May~4 1988
Final Report Geohydrologic Study Goldberg-Zoino s Associates Inc Rhode Island Solid Waste Management Corporation October 1986
Engineering Design Report Wehran Engineering Corporation Rhode Island Solid Waste Manageniciit Corporation July 1987
Fracture TraceGeophysical Investigatioji Geotech Enterprises Inc Goldberg-Zoino s Associates Inc August 1987
Air Monitoring Program Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation September 2 1987
BSR03016 A-4
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5
III Ill 37 Tesign Document
P r e p a r e d lgty Preparr- f o r P a t e
18 Report Prepared by Prepared for Date
39 Report Prepared by Prepared ftjr Date
Preliminary Final Cover Speci f i catit Wehran Engineiering Corpora tior Rhode Island Solid Waste Mana L-TmiMil Cnrporation May 1988
Interim Remedial Investigatio Repoit Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Manag^^menl Cojporat ion May 1988
Remedial Investigation Data Report Goldberg-Zoino amp Associates Inc Rhode Island Solid Waste Management Corporation August 1988
bulln BSRO3016 A-5