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GeoServices, Ltd.1240 North Mountain Road • Harrisburg, PA 17112

(717)541-0799

COMMENT ON PROPOSEDREMEDIAL ACTION PLAN

ELIZABETHTOWN LANDFILL SUPERFUND SITE

West Donegal Township, Lancaster County, Pennsylvania

September 25, 1995

Prepared for:

The Masonic HomesElizabethtown, Pennsylvania

Prepared by:

GEOSERVICES, LTD.

MepH T. McNally, P.G/Project Director /

Peter G. Robelen, P.O.President

Consulting Geologists and HydrogeologistSj o n 7 -7 Q

TABLE OF CONTENTS

EXECUTIVE SUMMARY ............................................. i

1.0 INTRODUCTION ............................................. I

2.0 COMMENTS ON PREFERRED ALTERNATIVES ..................... 5

3.0 AREAS OF CONCERN ......................................... 9

3.1 Ground Water Flow System ................................. 93.2 Conoy Creek As Impediment To Flow .......................... 133.3 Ground Water Velocity And Transport.......................... 153.4 Fate And Transport Of Contaminants In Ground Water .............. 163.5 Distribution Of VOCs In Ground Water ......................... 193.6 Manganese In Ground Water ................................ 203.7 Sampling Inadequacies ..................................... 24

4.0 ADDITIONAL AREAS OF CONCERN ............................. 28

4.1 Hot Spots .............................................. 284.2 Cattle ................................................. 294.3 PAHs ................................................. 294.4 Pesticides .............................................. 304.5 NPDES Limits .......................................... 30

5.0 RECOMMENDATIONS ........................................ 31

Figure: Masonic Homes Well Locations .................................... 2

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EXECUTIVE SUMMARY

Masonic Homes at Elizabethtown, Pennsylvania, is a continuing care retirement

community and children's home which is dedicated to providing for the physical, social, mentaland spiritual needs of each of its residents. The water supply system for this community provides

potable water to its more than 2,000 residents and for non-irrigation, agricultural and othercommunity needs. Water for the system is provided from a single 500 feet deep well (an

auxiliary 400 feet deep well is not used due to high concentrations of manganese which may beoriginating from the nearby Elizabethtown landfill). The Masonic Homes wells are locatedadjacent to Conoy Creek. The Masonic Homes coristitutes the single largest user of potable water

supplies in the Conoy Valley in the vicinity of the landfill and its concerns for protection of itswater supply must be recognized. Therefore, the assumptions underlying the foundation of theproposed plan must be scrutinized in detail to assure that Masonic Homes interests areconsidered.

Masonic Homes owns property on both the north and south sides of the Conoy CreekValley and includes land adjacent to the Elizabethtown Landfill on the south side. Ground water

beneath and in the vicinity of the landfill, including lands owned by Masonic Homes, has beenshown to be contaminated by various organic compounds and metals. In order to remedy theimpacts of ground water contamination, the United States Environmental Protection Agency(EPA) has directed that Waste Management/SCA complete sufficient studies to assess remedialalternatives which afford protection of ground water supplies, limits air emission, and inhibits soilcontact. As a consequence of years of effort, the EPA has recently published its proposedalternatives for remediation of conditions at the landfill. Essentially, the preferred alternativesconsist of recovery and treatment of ground water, additional landfill capping in the northern andsouthern areas, emission controls and deed restrictions. The preferred remedial alternative isbased on a body of data collected over several years and is summarized in the form of aRemedial Investigation, Feasibility Study and a Risk Assessment. The basis of the preferredalternative, ground water extraction and treatment, is founded on essentially the governing

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assumption that Conoy Creek and, therefore the Conoy Valley, acts to inhibit transport ofcontaminants from the landfill to wells on the north side of Conoy Creek including the watersupply wells on the Masonic Homes property. Indeed, the proposed plan dated July 26, 1995finds it noteworthy to point out that, although contamination exists in a plume extending beyondthe landfill at levels exceeding Maximum Contaminant Levels (MCL) EPA has not detectedcontamination attributable to the landfill above the MCLs in any public or private water supply

wells that have been sampled in the vicinity of the landfill.

Review of the supporting technical documents indicates that the fundamental criteria arein error, and inconsistent with EPA guidance (and the National Contingency Plan). Therefore, theproposed remedy if improperly implemented, will be insufficient to provide for the protection ofthe Masonic Homes water supply wells. Fundamental errors in the foundation of the proposedplan as documented in the supporting documents include:"

• The fundamental data to support the assumption of strong upward head into ConoyCreek which inhibits flow to the Masonic Homes wells is seriously flawed.

• The assertion by EPA that contaminants of concern have not been observed inwells in the vicinity of the landfill at concentrations in excess of MCLs, whiletechnically correct, minimizes the reported concentrations of contaminants and thepotential contamination from the landfill.

• A review of the plan and its supporting documents fails to fully consider theproximity of Masonic Homes wells, both in terms of protection of water qualityand in protection of water availability to these wells. This is particularlyimportant considering the issue of manganese contamination of EM400 givenEPA's expectation in selection of a remedy that ground water be returned tobeneficial use [CFR 300.430(a)(iii)(F)], and given the fact that manganese isrecognized as the major contributor to non-cancer risk at the site.

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• The preferred alternative does not support the primary balancing criteria of long-term effectiveness and permanence [40 CFR 300.430 (f)(i)(B)] in that it does notaddress the potential that Masonic Homes may need to construct additional watersupply wells on the south side of Conby Creek in order to satisfy future needs,

possibly to nor does the plan compensate for ground water withdrawn upgradientby the landfill ground water recovery system and that impact on long-term utilityof existing supply wells.

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• The plan does not identify specific items required to evaluate future needs fortreatment of Masonic Homes water supplies. Therefore, water supply treatmentand assurance of continued water supply to Masonic Homes should be includedas part of the proposed remedy.

Consequently, it is concluded that the proposed remedial action plan published by EPAon July 26, 1995 does not adequately address protection .of Masonic Homes water supplies.

The preferred alternative identified in the proposed remedial action plan provides foralternative water supplies for five downgradient residences. Nowhere in the plan is considerationgiven to protection or replacement of water supplies to the Masonic Homes, the largest single

user of ground water in the vicinity of the landfill. Based on existing data, provision forappropriate treatment of existing and future Masonic Homes supply wells must be added to thepreferred remedial alternative. Depending on the results of new data gathered duringimplementation of the proposed plan, provision for alternate water supplies for Masonic Homesmust be considered. Furthermore, because of apparent deficiencies in the technical support, thefollowing work elements should be included during implementation of the proposed plan:

• Resampling of wells and re-evaluation1 of the downgradient extent of thecontaminant plume based on the historically highest concentrations of volatileorganic compounds and selected metals. [It should be noted that although SCAindicated in 1993 that re-sampling would be completed, such re-sampling has notoccurred.]

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Inclusion of inorganic anions such as chloride, nitrate, sulfate, and bicarbonate infuture sampling protocols.

Evaluation of the relationship of metals to the ground water flow system.

Physical re-evaluation of the burn pit area and re-assessment of the issue of hot

spots in general.

Completion of adequate pumping tests and re-modeling of the ground water flowsystem to include (this time) consideration of pumping from Masonic Homes wells(both EM500 and EM400) and future wells on Masonic Homes property on thesouth side of Conoy Creek.

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1.0 INTRODUCTION

The Masonic Homes at Elizabethtown, Pennsylvania, is a continuing care retirementcommunity and children's home which is dedicated to providing for the physical, social, mentaland spiritual needs of each of its residents. The water supply system for this community providespotable water to its residents consisting of 1,240 full time residents; 75 persons in 30 rental units;and 697 full time equivalent staff for a total of 2,012 persons. Immediate expansion plansinclude addition of 100 cottage units which will add approximately 200 persons to the total

community. In addition to providing residential care Masonic Homes also maintains extensivefarming operations including: dairy and beef cattle, orchards, and grain and livestock feed crops.

The Masonic Homes water supply system consists of two wells (EM400 and EM500shown on the attached figure) and, while it is essentially self-sufficient for water supply, the •

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system includes an emergency interconnect with Elizabethtown Borough's water supply system.In addition to potable supplies, water is supplied for non-irrigation, agricultural purposes and ,

miscellaneous site-wide uses. Total current "withdrawals from Masonic Homes wells averageapproximately 230,000 gallons per day. Based on this withdrawal, the pumping rate averages

160 gallons per minute, but may exceed this rate during peak capacity needs. Currently, due tocontamination of the 400 foot well by high concentrations of manganese, only the 500 foot wellis pumping and is the sole source of potable water supplies to Masonic Homes. Irrigation wateris pumped from spring fed ponds on the property.

The Masonic Homes owns property on both the north and south sides of the Conoy CreekValley, and includes land adjacent to the Elizabethtown Landfill on the south side. The MasonicHomes property (and the adjacent, Elizabethtown Landfill property) is located in the Gettysburg-Newark Lowland Section of the Piedmont Physiographic Province. The property is underlain byTriassic age rocks of the New Oxford formation, consisting of shale, siltstone, sandstone,conglomerate and some limestones. In addition, the ridges on both the north and south sides of

the valley are underlain by Triassic age diabase.

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MASONIC HOMESVKEST DONEGAL TOVKNSHIP, LANCASTER COUNTY, PENNSYLVANIA

WELL LOCATIONSGeoServicea. Ltd

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Ground water generally flows toward Conoy Creek from both sides of the valley. Groundwater flow through the bedrock is controlled by structural features of the bedrock mass includingflow along bedding planes (both downdip and along bedrock strike) and by inhomogeneities in

the bedrock resulting from fractures and other linear structural features. As a consequence,bedding plane flow enhances potential contaminant flow from the Elizabethtown Landfill towardsboth the Conoy Creek and the active Masonic Homes wells. Wells constructed by MasonicHomes on the south side of Conoy Creek would be subject to flow from the landfill along

bedding plane surfaces.

Both Masonic Homes wells are located in close proximity to Conoy Creek and within200 feet. Consequently, given the high yields of the wells, pumping of the wells inducesrecharge from the Conoy Valley. This recharge includes contributions of recharge from thelandfill side of Conoy Creek. Well EM400 is located approximately 500 feet downgradient fromthe limits of the contaminant plume shown in the Remedial Investigation (RI). Under bothpumping and non-pumping conditions, available data document contributions of contaminantsfrom the landfill to Masonic Homes production wells.

The Masonic Homes constitutes the single largest user of potable ground water suppliesin the Conoy Valley in the vicinity of the landfill and its concerns for protection of its watersupply must be recognized. Therefore, evaluation of the preferred remedial alternatives needsto consider the impacts of the remedy on this major ground water user. Fundamentally, the vy f"

I ''preferred alternative is based upon the assumption that the Conoy Creek acts to inhibit ground 'water flow across the Valley. This assumption is based on interpretation of ground water data

which purports to demonstrate a strong upward gradient in the vicinity of Conoy Creek.Unfortunately the data presented do not support this conclusion and data needed to evaluate theimpact to the Masonic Homes wells was not considered. Therefore, in order to assure protectionof Masonic Homes water supply, re-evaluation of the preferred alternatives in light of thedeficiencies in ground water data and the interpretation of that data is warranted. This report

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comments on various aspects of the United States Environmental Protection Agency (EPA)proposed plan of preferred alternatives and the supporting documents, including the RI andFeasibility Study (FS) prepared by Golder Associates (Golder) and ground water modeling effortsby Rust Environmental and Infrastructure (Rust) for Waste Management/SCA relative to SCAactivities at the Elizabethtown Landfill in West Donegal Township, Lancaster County,Pennsylvania.

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2.0 COMMENTS ON PREFERRED ALTERNATIVES!

A Remedial Investigation (RI) and Feasibility Study (FS) was prepared by Colder andsubmitted to EPA by SCA. The RI serves as the basis for development of the proposed plan andprovides the foundation for selection of the preferred alternative. The preferred alternative (#7)listed in the July 26, 1995 Proposed Remedial Action Plan includes the following elements:

• Provision of an alternative water supply for five downgradient residences [Notethat this does not include the Masonic Homes wells];

• Routine inspection and repair of the security fence;

• Maintenance of landfill covers (including annual mowing of vegetation, plus re-grading and re-vegetation of eroded areas;

• Maintenance of storm water management systems, including sediment removalfrom ditches and sedimentation basin, plus erosion repairs;

• Operation and maintenance of the landfill gas management system to activelycollect the gas generated in the landfill, prevent its migration off-site, and burn itat a flare station;

• Operation and maintenance of the leachate collection system which includes drainsand seep collectors;

• Landfill gas monitoring around the perimeter of the site to measure gas migration;

• Ground water and surface water monitoring for organic and inorganiccontaminants;

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• Extraction of contaminated ground water for treatment and disposal;

• Extension of the security fence to surround the entire landfill;

• Establishment of deed restrictions to protect the landfill cap, prevent humanexposure to landfill contents, and prevent use of grounid water both now and in. thefuture; '•

• Sediment monitoring as a measure of remedial effectiveness;

• Shallow ground water level Monitoring to assess ground water extraction impactson wetlands hydrology; ,

* Upgrade northern area landfill cover, install southern area cover, extract groundwater, treat ground water cm+site using air stripping and carbon adsorption, andemissions control.

Review of technical reports supporting selection of the preferred alternatives indicates thatthe preferred alternative does not support the primary balancing criteria of long-term effectiveness ,

.-*-. l< ^and permanence [40 CPR 300.430(f)(i)(B)] in that it does not address the future installation ofadditional wells by Masonic Homes on the sbuth side (landfill side of Conoy Creek) nor providesufficient data to evaluate the degree of certainty that the alternative will be successful.Furthermore, the plan inadequately address long-term impacts to existing Masonic Homes wellsin that predictions of the migration of contaminants from the landfill are not based on sufficientdata..

The preferred alternative in the propo>sed plan states that "contaminated ground waterwould be pumped from a series of extraction wells located a4tacent|o_or downgradtenlfrQm thelandfill." However, the plan does not specifically identify the number or location of proposedrecovery wells including the number and location of wells for the distal recovery system. In

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of the inclusion of the a distal well in the FS Summary of Alternatives, the Proposed Plan

appears vague on the inclusion of this well. In addition, the language in the proposed plandiscusses only "ground water extraction" rather than the use of "source control with migrationmanagement" which was presented in the FS. The FS clearly shows that wells locatedimmediately adjacent to the landfill would .capture only the ground water plume located primarilyon site, and that a distal well is needed to capture the downgradient plume. The location andpumping rate from the distal well is questionable. However, the need to provide for migration

management for protection of the Masonic Homes wells is fundamental. Therefore, the inclusionof distal wells in the preferred remedy should be clearly stated in the proposed plan. As

discussed below further characterization of the hydrogeologic system is required beforeimplementation of the migration management system. This deficiency needs to be addressedbefore the effectiveness of the plan for protection of potable water supplies can be completed.

40 CFR 300.430(a)(iii)(F) states that an expectation in developing remedial alternatives

is "to return usable ground waters to their beneficial uses wherever practicable ..."Contamination of EM400 by manganese, which appears to be migrating from the landfill, has not

been adequately considered in restoring these waters to beneficial use.

Existing testing has not sufficiently characterized the interrelationship between pumpingof Masonic Homes wells and ground water conditions under and immediately surrounding thelandfill or how this interrelationship may impact the proposed remedy in the remedial action plan.

The following issues identified in the FS deserve comment:

• Both of the Masonic Homes wells are downgradient, and characterizationof the hydrogeologic conditions and extent of contamination relative to theMasonic Homes wells is flawed,

• One of the most common site related constituents (1,1-dichloroethane) has beenreported at low concentrations in well EM500,

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• Well EM400 has coxrfirmed elevated concentrations of manganese, which has -""made the well unusable and appear to be related to the landfill, and

• Manganese has been recognized as the major contributor to non-cancer risk at thesire.

In spice of these issues, the FS states (page 6-4) that at present, based on current water qualitydata, there is no need to provide an alterrtativc water supply or well head treatment to theMasonic Homes wells and a provision to prdvide an alternative wafer supply or treatmeint is notincluded in the proposed remedial plan. Wljile the plan includes provisions for alternate watersupplies for five residences, it fails to consider replacement or treatment of existing supplies toa system which provides potable water to more than 2,000 persons. Furthermore, the plan does jnot even consider the potential that wells will be placed on the landfill side of Conoy Creek byMasonic Homes to provide for future demands or the risk associated with wells in this location.In addition, specific items which would be used to evaluate the future need for treatment are notenumerated. Because of the items listed above, well head treatment and assurances of continuedwater supply to Masonic Homes should be included as part of the proposed remedy. Asupplement to the Risk Assessment may also be warranted to establish, based on existing andsupplemental data, the risks associated with'supplies from well EM400.

Sections 3 and 4 of this report (below) detail deficiencies in the technical documents usedto support the proposed plan. The inadequacies found in the technical documents coupled withthe vagueness of the proposed plan relative to protection of the Masonic Homes water supplies(e.g., lack of a provision to provide an alternative water supply to Masonic Homes) warrantsfurther technical evaluation of site conditions and inclusion of the results of the evaluation duringimplementation of the Final Remedial Action Plan in order to protect the Masonic Hordes watersupply.

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3.0 AREAS OF CONCERN

Based on review of the plan and supporting documents, it is apparent that documentationis not provided which demonstrates that the proposed plan will adequately address or protect the

Masonic Homes water supply from the threat of contaminants migrating from the landfill, or fromdiminution of supplies as a result of activation of the proposed remedy. This section details some

of the inadequacies of the technical reports which were used as the foundation to support theplan.

3.1 Ground Water Flow System

Data Gaps Regarding Masonic Homes Wells.

3.1.1 On page 12 of the RI, it is stated that the purpose of the RI was to conduct aseries of tasks involving the collection of data to satisfy the data needs andobjectives described in Section 1.4 and listed in Table 1.2. As stated in Section1.4 these data gaps include determination of the relationship of the MasonicHomes' wells to the ground water flow system and, evaluation of the nature, rate

and extent of any contamination (including the projected extent of leachate( constituents) in the ground water. As addressed in the comments which follow,

the relationship of the Masonic Homes wells to the ground water flow system wasnot adequately described in the RI and this specific objective of the RI was notmet.

Insufficient Data To Support Upward Ground Water Gradient And Flow Barriers.

3.1.2 On page 67 and in other sections of the RI, reference is made to a strong upwardgradient at depth and in the vicinity of the discharge zones represented by ConoyCreek. In addition, the tributaries to Conoy Creek which are located west andnorth of the landfill are also depicted as effective ground water flow barriers. As

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described in detail below, because of the lack of seasonal water level and chemicaldata, and inconsistencies of interpretation of chemical distribution with the conceptof flow barriers, this statement is not supported by the information presented inthe RI and because this concept is pivotal to protection of ground water, needs

further substantiation.

Inappropriate And Incomplete Use Of Water Levels Reported For EM400 And EM500.

3.1.3 Water levels for the Masonic Homes wells EM500 were incorrectly reported andthe water level from EM400 ignored in the interpretation of the hydrogeologicconditions north of Conoy Creek. Figure 3-9 in the RI shows the interpretiveground water phreatic surface contour map and Figures 3-14 and 3-15 the plannedprojections of interpretive equipotential lines at the 300 foot mean sea level and400 foot mean sea level, respectively. The ground water elevations shown for

EM500 on all three figures is 402.84 feet and for EM400 on all three figures is385.61 feet. An asterisk next to EM500 states that this value indicates water levelmeasurements used for this well are other than the December 1, 1992 data andreferences Table 1. On Table I-1 of the RI, the value which is shown next to

EM500 on Figure 3-9 (402.85 feet) is for the elevation of the ground surface anddoes not represent a water level measured in the well. Therefore this value is not

representative of a water level in EM500 and does not support a higher waterlevel or upward gradient north of Conoy Creek. On Figure 3-13, the water levelelevation for EM400 is inconsistent with the equipotential lines shown on Figure3-9. Based on this information, it appears that the information from EM400 wasignored in the preparation of the hydrogeologic cross section C-C' and that waterlevel data reported for EM500 is incorrect. In addition, there is no mention in thetext that the water level at the time of measurement may have been influenced bypumping of EM500.

11Inappropriate Use Of Water Level Measurements And Lack Of Seasonal Data.

3.1.4 The hydrologic projections for the site are based on a single set of water levelmeasurements which were recorded December 1, 1992 and combined with

measurements on May 5, 1993 from the domestic wells and some other locations.As shown on Figure 3-9 the water levels in May of 1993 were generally higher

than those reported in December of 1992 and in the case of ED5R were 16.42 feethigher. In the case of the water levels measured in ED6S, the water level was

lower suggesting that a reversal of gradients at this location had occurred. Thereversal may reflect seasonal fluctuations, which is not adequately defined becausewater levels under different season conditions was not considered. The combiningof such different water level measurements on one map and the use of data fromonly one round of water levels and combining it with limited measurements froma different season to draw significant and basic conclusions regarding thehydrogeologic conditions is incorrect and, given the range of water level

fluctuations, highly suspect. As stated in the Office of Solid Waste andEmergency Response (OSWER) directive 9283.1-2, December 1988 titled"Guidance on Remedial Actions for Contaminated Ground Water at SuperfundSites," pertinent information required to characterized the hydrogeology includesconsideration of seasonal or long-term fluctuations in water levels. In addition,the December 1993, Pennsylvania Department of Environmental Resources (DER),publication "Environmental Contamination, A Handbook for Conducting

Cleanups," (page 13) recognizes that evaluation of changes in the environmentsuch as seasonal water levels may be necessary to determine a relationship tolevels of contaminants. As stated in both the EPA OSWER Guidance Documentand guidance documents prepared by the DER, seasonal fluctuation of groundwater levels is to be considered in hydrogeologic investigations. The lack ofconsideration of seasonal fluctuations, the mixing of two different data setsregarding water levels on one map and ignoring the impacts of pumping from well

EM500 prevent accurate interpretation of the hydrogeologic conditions at the siteand the subsequent prediction of the potential impacts of plume migration.

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Incomplete Understanding Of Rock Aquifer Flow System.

3.1.5 On page 57 of the RI it is stated that interpretation of the site area geologic andhydrogeologic data provided thorough understanding of the rock aquifer flowsystem beneath the landfill and its relationship to the regional flow system.Because of the scarcity and incorrect application of the water level data, thepotential reversal of gradients with seasonal changes, and lack of consideration ofpumping from EM500, it appears that this statement cannot be substantiatedwithout additional measurements of water levelsv under different seasonal

conditions.

Insufficient Data To Support Tributaries As Barriers To Contaminated Ground Water.

3.1.6 In the RI (on page 128 as well as others) it is stated that because shallow groundwater is discharged to the tributaries on either side of the landfill, these tributarieseffectively act as a barrier to ground water flow beyond them. This statementappears to indicate that the tributaries act as a barrier to the migration ofcontaminants not only in the shallow system but also in the deeper ground watersystem. However, a review of the RI sampling results shows that the volatileorganic compounds (VOCs) which were observed near the tributaries east of thelandfill were present only in the deeper well (ED28) and were non-detect in theshallow well (ED22). While a relative upward head was measured in this area(using wells ED22 and ED28) there is no documentation that the contaminants inthe deeper well would also discharge to the adjacent tributaries locatedapproximately 100 feet to the east and not migrate beyond this tributary. Inaddition, there are no deeper wells located east of the tributary to document thatthe barrier is effective for the deeper ground water. Because the VOCs in thisarea are present in the deeper well, the argument that the tributaries act as barrierto shallow flow is not meaningful in that the shallow ground water was belowdetection for VOCs anyway.

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The importance of this clarification regarding tributaries acting as barriersto ground water flow is that the estimated lateral extent of downgradient

contamination which extends in the direction of the Masonic Homes water supplywell appears to have used the "tributaries as barriers" argument even though this

argument is not supported by the data gathered during the RI for the deep groundwater system. Because of the lack of documentation, the inference that the

tributaries act as barriers to flow should be corrected and the possible migrationof contaminants beyond these tributaries in the deeper flow system should be fully

explained or documented through further investigation. Based on these results thelateral extent of downgradient contamination should be re-evaluated.

Impact Of Discharge To Surface Water Is Incomplete.

3.1.7 On page 3-12 of the FS it is stated that by implementation of the chosen remedyfor the site, site-related constituents will no longer discharge to surface water.

Because of deficiencies in the consideration of pumping from EM500 and becausethe proposed plan does not provide details for the number, location or proposedconstruction of the ground water recovery wells, it cannot be assessed whether ornot this statement is correct.

3.2 Conoy Creek As Impediment To Flow

Inappropriate Use Of Water Levels North Of Conoy Creek.

3.2.1 On pages 66 and 67 of "the RI, it is stated that there is a strong upward verticalgradient in the northwest half of the site as shown on cross section AA and Figure3-13. As stated earlier, water level information north of Conoy Creek is notpresented, except for water level measurements collected from residential homesin May of 1993 when water levels were demonstrated to be higher then inDecember 1992. A result of these higher water levels would be to over-estimatethe amount of the upward gradient north of Conoy Creek.

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Inappropriate Use Of Water Levels From Masonic Homes Wells.

3.2.2 On page 57 of the RI (second paragraph) it is stated that strong upward gradientsin the vicinity of the Conoy Creek, caused by higher potential levels on both sidesof the valley ultimately create a vertically upward flow direction and inhibitfurther downdip (northwest) flow. Monitoring well data north of Conoy Creek is

extremely limited and has been collected from only three residential wells andMasonic Homes well EM400. In the case of well EM400 located on the northside of Conoy Creek (opposite side from the landfill), the water level was

measured on December 1, 1992 to be at an elevation of 385.61 feet. The surfaceelevation of EM400 is reported on Table 1-1 to be 406.61 feet which means thatthe water level was 21.0 feet below ground surface. Based on elevation of EM400at 385.61 (as shown on Figure 3-9) and the elevation of Conoy Creek beingapproximately 390 feet (also shown on Figure 3-9), the water level elevation inEM400 north of Conoy Creek is below the creek, not above as would besuggested if a strong upward gradient were present. It is recognized that the waterlevel in EM400 may be a composite water level over the depth of the well boring,however, the information provided does not support an upward gradient in the areaof EM400. These data contradict the interpretation of equipotential lines shownon Figure 3-13 and the statement that higher potentiometric levels exist on bothsides of the valley and that a vertically upward flow is created near Conoy Creekwhich serves to inhibit further downdip (northwest) flow.

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153.3 Ground Water Velocity And Transport

Lack Of Consideration Of Seasonal Data To Evaluate.

3.3.1 On page 65 (in Section 3.5.2.6 Anisotropic Flow System) it is stated that varioussimulations, including a probabilistic approach have been used to estimate ground

water flow velocities. While this information may assist with the development ofthe range of hydraulic conductivities in the aquifer, it appears that thedetermination of gradient (which is one of the most significant factors indetermining velocity) is seriously flawed because it is based upon a single roundof measurements collected in December of 1992 which was incorrectlysupplemented by measurements taken in May of 1993 under different seasonalconditions. Therefore, the impact of seasonal fluctuations, which have shown an

increase in water levels of up to 16 feet as seen between December 1992 and May1993 in well ED5R, is not reflected in the interpretation of the hydrogeologicsystem.

Insufficient Data Used To Develop Hydrogeologic Transport Model.

3.3.2 On page 98 of the RI under Section 4.4 Conceptual Hydrogeologic TransportModel, it is stated that the development and understanding of the hydrogeologicflow system described in Section 3.5 was coupled with ground water quality

analytical results to develop a conceptual model of the hydrogeologic transport ofconstituents via the ground water system. Because the basis for the transportmodel is the hydrogeologic system (described earlier as seriously flawed andincomplete), the results of the hydrogeologic transport model must be consideredsuspect until further documentation supporting the hydrogeologic model isprovided.

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Inability To Assess Effectiveness And Impact Of Distal Pumping Well.

3.3.3 A single distal well was proposed in the conceptual pumping rate and capture

zone of extraction system described the FS. However, because of the lack ofwater level data, and lack of consideration of the pumping from EM500 the long-term effectiveness of this distal well cannot be assessed. In addition the effectsof withdrawal of water from this upgradient distal well on the diminution of thequantity of water (water supply) from the Masonic Homes wells was notconsidered, nor was the possibility of Masonic Homes installing additional wellsto meet its future water supply needs.

3.4 Fate And Transport Of Contaminants In Ground Water

Use Of Dispersion To Estimate Downgradient Extent Of Ground Water Plume Ignores EffectsOf Pumping From Masonic Homes Wells.

3.4.1 On page 103 of the RI, the method used to estimate the potential downgradientextent of ground water impacts along Conoy Creek is discussed. The estimationof the downgradient extent appears to rely only on the dispersion and spatialdistribution of contaminants and does not consider the downgradient impacts frompumping well EM500. In this section it is stated that the data, which may show

dispersion to the northeast and to the southwest of the landfill (upgradient andcross gradient directions), is recognized as having a different flux than thedowngradient ground water flow regime to the northwest. However, thesubsequent dispersion distance estimated was used to provide an order ofmagnitude estimate of the extent of the leading edge of impacts to ground water.The dispersion (which is cross gradient and not downgradient) was estimated tobe approximately 1,000 feet. This 1,000-foot distance was applied to the 200 ug/1isoconcentration line north of the site to estimate the potential downgradient extent

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of impacts to ground water northwest (downgradient) from the landfill. This

estimate ignores the influences of gradient and changes in ground water velocitywhich may result from pumping of Masonic Homes well EM500. In addition, thisapproach uses the concept that the tributaries effectively act as barriers to groundwater flow beyond them which, as discussed in earlier comments, does not appearto be substantiated for the deep ground water flow system.

Lack Of Characterization Of Masonic Homes Wells.

3.4.2 Although the RI recognizes that the estimate of the extent of the plume is not

sufficiently accurate to conclusively determine if the zone of potential impactextends to the Masonic Homes wells EM400 or EM500 (both of which are

downgradient of the landfill) the RI assumes that the regional ground water flowalong Conoy Creek will tend to dilute the concentrations due to mixing withregionally upgradient ground water. Because of the inconclusive characterizationof the ground water flow system, the lack of sampling data, and the lack ofinformation regarding the hydrogeologic conditions at EM400 and EM500 thestatement that dilution will sufficiently reduce contaminant concentrations is notsupported.

Deficiencies And Inadequacies Based On Representation Of Area Of Downgradient GroundWater Degradation.

3.4.3 The remedial actions included in Appendix D of the FS include source control ofground water with migration management. In Section 7.2 of Appendix D it isstated that the area of downgradient ground water degradation includes thecontours presented in Figure 4-1 and 4-2 of the RI which represent the MCL for

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chlorobenzene. As discussed in other sections of these comments, there areseveral deficiencies and inadequacies based on this representation of this area ofdowngradient degradation which include the following:

• The designation of the area of downgradient degradation is based on a

deficient hydrogeologic characterization of the site in that only one roundof water levels (which were supplemented by measurements collected

during different seasonal conditions) were collected; the presence of astrong upward gradient is not supported by water levels measured north ofConoy Creek especially in the area of the Masonic Homes water supplywells; and the effects of pumping from EM500 were not considered in

evaluating the migration management.

• The extent of contamination in the RI is based on the dispersion of

aliphatic volatile organics (such as 1,1-dichloroethane), and not aromaticcompounds such as chlorobenzene. As discussed in the RI (page 104)aliphatic compounds are described as having increased mobility relative tochlorobenzene. However, as show by a comparison of Figure 4-5 of theRI with Figure 23 in Appendix D of the FS, the extent of the plumeconsidered in the FS ground water modeling effort is shown to beapproximately 500 feet closer to the landfill than the extent of the plumedepicted in the RI. In addition, it should be noted that neither the depiction

of the plume in the RI nor the FS fully considers manganeseconcentrations originating from the landfill or the detection of 1,1-

dichloroethane in well EM500.

• Manganese which is considered to be the major contributor to non-cancer

risk (and appears to have elevated concentration in EM400 related to thelandfill) is not considered when estimating this area of downgradientdegradation.

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3.5 Distribution Of VOCs In Ground Water

Inappropriate Use Of Sampling Results To Evaluate Extent Of Contaminant Plume.

3.5.1 Samples from only the Phase 1C sampling round were used to estimate solutetravel distances. Consequently, the sample result of 0.9 ug/1 of 1,1-dichloroethane

from EM500 was excluded in the evaluation since it occurred only in the PhaseIB sampling for EM500 and was not detected in well EM400 sampled 4 months

later. Figure 4-5, "Calculated Solute Travel Distances" for the calculated solutetravel distance, shows the presence of a line designated as U or undetected. Thisline extends only 1,000 feet downgradient of ED24, even though the compound1,1-dichloroethane was detected in EM500 at a concentration of 0.9 ug/L.Because the detection limit for 1,1-dichloroethane is 1 ug/1, and the concentrationsreported was 0.9 ug/L, the undetected line shown on Figure 4-5 would be drawnmuch closer to EM500 if this data point were included. Therefore, selection ofthe Phase 1C sampling results artificially shows the area of the contaminant plumeto be closer to the landfill and not as far downgradient as the results of sampling

from EM500 suggest. The uncertainty of the impacts on EM400 and EM500 isdiscussed on page 118 of the RI where it is clearly stated that SCA will resample

the wells. No resampling has occurred in these wells and was not included in the1995 domestic well sampling thus preventing further interpretation of theseconditions at the site,

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3.6 Manganese In Ground Water

Common Occurrence Of Metals At Recorded Concentrations Is Unsupported.

3.6.1 On page 87 of the RI it is stated that the metals detected in ground water arecommon in Triassic rocks. While this is generally true, the statement isinconclusive and misleading because it suggests that the mere presence of aparticular metal is reason enough to explain the concentrations reported for theground water samples collected during the RI. Without the supporting solubilityand adsorption data, (which is not included in the RI), the presence of a givenmetal in the rock does not provide sufficient indication of its expected groundwater concentration. Because of this, a comparison with historical and/or regionaldata is required to evaluate the ground water sampling results of metals reported

in the RI.

Lack Of Comparison With Historical Data.

3.6.2 Data published by Herbert E. Johnston, (1966), Hydrology of the New OxfordFormation in Lancaster County, Pennsylvania (Pennsylvania Geologic Survey

Ground Water Report W 23) provides an historical summary of metals in groundwater from wells drilled in the Triassic rocks (New Oxford Formation) whichunderlie the site. These results allow for a comparison of sampling results formetals reported during the RI. Although the 1966 publication was cited in thereferences of the RI, quoted on page 56, and reproduced in part as Figure 3-2Regional Geologic Map of the RI, a detailed comparison of the historical groundwater sampling results was not presented in the RI. Furthermore, as discussed

below, the data which was referenced was referenced incorrectly in the RI.

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Incorrect Summary Of Regional Iron And Manganese Concentrations.

3.6.3 Of particular concern for the Masonic Homes is the elevated concentration ofmanganese in well EM400. On page 43 of Johnston (1966) it is stated that

"naturally occurring iron and manganese do not appear to be present in objectionalamounts in ground water throughout most of the area underlain by the New

Oxford Formation" and that only one of the samples of well water contained morethat 0.3 parts per million (ppm) of iron. This statement is incorrectly and

inappropriately restated in the RI on page 56 where it is stated that "Availabledata (Johnston, 1966) indicates that the quality of water from wells in the NewOxford Formation is variable. In particular, high levels of Iron and Manganese

have been reported in some wells." In fact, as shown on page 43 of Johnston(1966), the maximum iron and manganese concentrations were reported to be in

a sample from a spring originating below the Elizabethtown Landfill. Because ofthe frequent use of Johnston (1966) in the RI, it seem unlikely that Colder wasunaware of these conclusions regarding iron and manganese.

Omission Of Results Documenting Elevated Manganese In Ground Water Originating AtElizabethtown Landfill.

3.6.4 Johnston states on page 43 that a sample of water obtained from a spring (Ln-115)which was "contaminated by a refuse burial site" contained 12 ppm (12,000 ug/L)of iron and 6.5 ppm (6,500 ug/L) manganese. The spring was reported to belocated in a draw that headed 1,000 feet upslope at the refuse burial site. The

location of this same spring (Ln-115) is shown on Figure 3-2 of the RI and islocated immediately west of the Elizabethtown Landfill. In spite of the frequent

references in the RI to Johnston and the inclusion of Johnston's geologic mapwhich shows the location of Ln-115, there is no mention of this spring or thehistorical sampling results from Ln-115 in the SCA/Golder Final RI. Johnstonfurther recognized that the water from Ln-115 was "contaminated by a sanitary

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landfill" (Johnston, 1966, p 42) and did not include the results from Ln-l 15 in thepreparation of his Table 2 Summary of Chemical Quality of Ground Water fromthe New Oxford Formation which showed the range of manganese to be 0.0 ppm

(non detect) to 0.24 ppm or (240 ug/L) with a median concentration of 0.1 ppm

(100 ug/L). These data clearly indicate that elevated concentrations of manganesein ground water in the New Oxford Formation are not common except near theElizabethtown landfill and that the representation of the metal results in the RI,especially for manganese, is misleading.

Masonic Homes Well EM400 Unusable Because Of Elevated Manganese.

3.6.5 Masonic Homes is unable to use well EM400 because of elevated manganeseconcentrations in the ground water which results in staining when water from thiswell is used for laundry. The ground water sampling results for manganese duringthe RI have shown that the highest concentration of manganese occurs withinJhefenced portion of the landfill at well ED2R at a concentration of 24,200 ug/L andfar exceeds the secondary MCL of 50 ug/L for manganese. As shown on crosssection C-C of Figure 4-3 in the RI, the next downgradient well in the plume is

___ well ED24 with manganese concentrations of 3,810 and 3,470 reported for the\ --- - - _ ___ _..._

Phase IB and Phase 1C sampling events, respectively. Figure 4-5, "Calculated

Solute Travel Distances" shows that Masonic Homes well EM400 is the nextdown gradient well in the plume. The manganese concentrations in EM400 were656 and 628 ug/L in the Phase IB and Phase 1C sampling. Masonic Homes wellEM500 is downgradient of well EM400 and had a reported manganeseconcentration of 15.6 ug/L in the Phase IB sampling and 5.7 ug/L in the Phase1C sampling. These results clearly show a successive decrease in theconcentration of manganese away from the landfill and along the ground water

migration pathway for Volatile Organic Compounds as depicted in the RI. Thisdistribution of manganese, along with historical reports and regional ground water

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sampling results, provides strong evidence that the elevated manganese

concentration in well EM400 (which exceeds the secondary MCL) is the result ofmigration of manganese from the landfill. The high concentrations of manganese

which are attributable to the landfill clearly demonstrates that Conoy Creek doesnot inhibit flow of contaminants from the landfill, even under static (non-pumping)

conditions.

Risk Assessment Excluded Consideration Of Manganese In Masonic Homes Well EM400.

3.6.6 The Risk Assessment did not consider the sampling results from EM400 as one

of the residential wells even though the RI states that this well is one of two useby Masonic Homes for water supply and it is listed in the sampling resultssummary tables as a residential well. On page 3-7 of the FS (completed after theRisk Assessment) reference is made again jto both wells EM400 and EM500 as

supply wells for Masonic Homes but makes no mention that EM400 was omittedfrom the Risk Assessment. Of the 10 locations identified and sampled in the RIas residential wells, EM400 was the only location to be excluded fromconsideration in the Risk Assessment. Sampling results from well EM500 whichis the other water supply well were included in the Risk Assessment. Ofimportance is that the elevated manganese concentrations reported for EM400were not considered in the Risk Assessment. Although well EM400 is not

currently used for water supply, the reason that it is not used is because of thepresence of manganese.

In the conclusions drawn for one of the residential wells (RES03) wherethe maximum concentration for manganese of 533 ug/L is less than the averagemanganese in EM400 (642 ug/L), the non-cancer health effects for all three age

groups considered in the FS'was due primarily to the presence of manganese. Inaddition, a consideration of the future risks posed by the site also identifiedmanganese as the major contributor to non-cancer risk.

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Although the results from EM400 were not considered, it appears likelythat a non-cancer risk, attributable to manganese, would have also be identified

for EM400 had the calculations been performed. Because this well was identifiedas a water supply well in the RI and a residential well in the summary tables itshould have been included in the Risk Assessment.

3.7 Sampling Inadequacies

Characterization Of Impact To Residential Wells.

3.7.1 Page 7 of the RI states that a private well survey was completed in the areaaround the site and that no VOCs were detected in five residential wells sampled

on December 12, 1988 by Golder. This section continues to state that the absenceof VOCs confirms earlier results of two rounds of sampling conducted by theDER in December of 1986 and June of 1988. However, sampling results collectedas part of the RI have indicated the presence of VOCs in residential wells(RES01) and the preferred remedy includes supplying bottled water to fivedowngradient residences. Although the focus of this section in the RI is historicaldata, the omission of these results on page 7 suggest that off-property impact fromthe landfill is not occurring to residential wells. Such a conclusion is in clearconflict with data provided in the RI.

Ground Water Sampling Conducted During RI Insufficient To Evaluate Seasonal Changes.

3.7.2 Environmental sampling conducted during the RI is described in Section 2.7. Inthis section, the three phases of ground water sampling conducted during the RIare described. The first ground water sampling event (Phase I A) was conductedin mid-August 1992, with Phase IB conducted in mid-November 1992 and Phase1C conducted in late December 1992 through early January 1993. A total of 7

J monitoring wells were designated for ground water sampling in Phase 1A with 35

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monitoring wells and 9 residential wells in both Phase IB and 1C. Although themajority of ground samples were collected only in the Phase IB and the Phase 1C

sampling, the time period covered by the last two sampling events is only frommid-November 1992 to early January 1993 which is a period of approximately 7

weeks. The Pennsylvania Department of Environmental Protection (DEP)protocols generally require that quarterly sampling be conducted in order to

adequately evaluate seasonal fluctuations and potential changes in contaminantlevels. However, because of the timing of the IB and 1C sampling event, the

potential impact resulting from seasonal fluctuations has not been addressed in theRI. Because of the lack of adequate quarterly data, the long-term success of theremedial alternative is uncertain.

Seasonal Limitations Of RI Ground Water Sampling.

3.7.3 Five wells originally intended to be sampled during the Phase IB and 1C were not

sampled because of insufficient water in the wells at the time of sampling. Theseconditions again reflect the limitations of sampling of the IB and 1C samplingevents and do not include different seasonal conditions which may have beenobserved during seasons other than during the winter.

Ground Water Sampling Of EM400.

3.7.4 It is stated on page 25 of the RI that Masonic Homes well EM400 could not besampled during the Phase IB and 1C sampling because repairs on the well werebeing performed. Samples were collected instead on March 22 and April 26,1993. Given the short interval between these sample dates, these results reflectonly a single seasonal event and do not reflect potential seasonal changes whichmay have occurred at this location. Although the lack of sample results wasrecognized as a limitation in the RI, additional sampling at this location has notbeen performed.

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Representation Of Use Of Masonic Homes Wells And Distance From Landfill.

3.7.5 Page 43 of the RI states that the Masonic Homes water supply is provided fromtwo wells, one of which is approximately 400 feet deep and the otherapproximately 500 feet deep. It further states that both wells are located withinone mile of the site. This first statement is incorrect in that because of

contamination by manganese in the 400 foot well, Masonic Homes water supplyis currently provided only from the 500 foot deep well, designated as EM500. Inaddition, while it is correct that the wells are located within one mile of theproperty boundary, Figure 4-5 of the RI shows well EM400 to be within 500 feetof the leading edge of the ground water contaminant plume based on RI samplingresults collected nearly 2'/2 years ago. More recent ground water sample resultshave not been obtained by SCA to further characterize the migration of the VOCground water contaminant plume towards these critical supply wells. Elevatedmanganese results in EM400 and VOC sampling results in EM500 (1,1-dichlorethane) indicate that these wells are currently impacted by contaminatedground water from the landfill. The need for additional data is clearly warrantedand is consistent with EPA Sampling Protocols and OSWER directives.

Insufficient Characterization Of Masonic Homes Water Supply Well EM500.

3.7.6 Although a door-to-door survey was conducted at residential wells locatedsouthwest of the landfill, a similar evaluation was not conducted of the MasonicHomes wells, even though they serve more than 2,000 persons, are located directlydowngradient of the landfill, and contain measurable concentrations of the VOC1,1-dichloroethane which is one of the most prevalent VOCs detected in theground water at the landfill. In addition, the information listed in Table 1-1 of theRI (Borehole and Well Information Summary for Wells Installed Before the Rf),

does not even include accurate information regarding the screen length of the

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wells which was available in previous publications from the PennsylvaniaGeologic Survey (Johnston, 1966). This lack of characterization and the lack of

emphasis given to the hydrogeologic impacts of pumping from well EM500 againdemonstrates that insufficient consideration was given to the impact of pumpingof the Masonic Homes wells on the ground water flow system.

Chlorobenzene Used To Evaluate Extent Of Contaminant Plume.

3.7.7 On page 99 of the RI and under Section 4.4.2 (chlorobenzene and total VOC

isoconcentration contours), it is stated that the isoconcentration contours ofchlorobenzene concentrations were interpreted from the Phase 1C data results andthat this information was used to prepare horizontal projections to define thelateral extent of chlorobenzene within each horizontal projection. It should benoted that the Phase 1C results do not provide the highest concentrations of

chlorobenzene which were reported during the RI sampling in all cases. Forexample, much lower concentrations were observed in sample ED2R (380 ug/1)

for Phase 1C compared with concentrations reported in the 1A sample results (590ug/1). While some locations showed increases in chlorobenzene, other locationswhich showed large decreases included: ED-101, at 1,300 ug/1 in Phase 1Acompared to 410 ug/1 in Phase 1C; and ED6R at 150 ug/1 in Phase IB but 18 ug/1in Phase 1C. This variation in chlorobenzene concentrations (both decreases aswell as increases) between the Phase 1A, IB and 1C sampling rounds do notsupport the use of only the 1C sampling results for estimation of transportconditions. Because of this variation, reevaluation of the transport mechanismsusing the highest concentrations reported during at least the RI investigationshould be conducted to evaluate the extent of the contaminant plume.

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4.0 ADDITIONAL AREAS OF CONCERN

4.1 Hot Spots

• On page 48 of the RI it is stated that there is no indication of concentrations of

contaminants or hot spots at the Elizabethtown Landfill. This conclusion is basedon:

• Maximum detection concentration of VOCs in ground water;

• Evaluation of temporal trends of VOCs in ground water; I

• Air monitoring data conducted within the exploration trenches.

Information provided in Appendix G of the RI however, providesinformation regarding the previous use of an on-site burn area where 55-gallondrums of liquid material were emptied to ignite excess brush and trees.Comparison of the location of the bum pit with the RI sampling locations showsthat there were no soil samples or ground water samples collected in theimmediate vicinity of the burn area. Furthermore, while it is stated on page 49that air monitoring previously carried out within the exploratory trenches at thesite and at the surface of the site did not reveal the presence of VOCs in the air,the log for test pit T-6 (which is located approximately 150 feet south of the burnarea) described the refuse at the bottom of pit as having a creosote odor. Theabsence of sampling results and description of a creosote odor in T-6 does notsupport the absence of hot spots on the site. Because of this, the proposed remedy

should include consideration of possible hot spots in design of the treatmentsystem as well as consideration for conduct of further evaluation in the burn areafor the purposes of source removal.

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4.2 Cattle

• On page 46 of the RI it is stated that Masonic Homes graze cattle on its property,

but that these cattle generally do not have access to the Conoy Creek for drinkingwater. This statement is incorrect. Masonic Homes cattle have access to Conoy

Creek upstream and downstream of the landfill, cross Conoy Creek (except in alimited restricted area), and utilize Conoy Creek water as their primary source ofdrinking water.

4.3 PAHs

On page 92 of the RI, it is stated that polycyclic aromatic hydrocarbon compounds

(PAHs) associated with coal tars or petroleum tar such as asphalt were detected

upstream of the landfill in stream sediments. Later discussion on page 93

attributes the presence of these PAHs to possible transport to the stream bed via

runoff from West Bainbridge Road (which had supposedly been recently

resurfaced near the time of collection) or from "runoff from coal and coke

stockpiles at the Masonic Homes power house located upstream of the site near

where Conoy Creek passes under the Conrail embankment". The statement

regarding the stockpiles at the Masonic Homes power house is incorrect in that

there is no coke stored at this location. Furthermore, review of the storage

methods and distance from the stock piles to Conoy Creek make this scenario

highly unlikely.

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4,4 Pesticides

• Page 97 of the report refers to a telephone conversation on September 30, 1992

and interview in October of 1992 regarding use of pesticides with Masonic

Homes. The paragraph as written is misleading in that it suggests that unspecified

pesticides were used for agricultural purposes on the Masonic Homes farm land

located immediately west of the landfill. This is incorrect, as shown by specific

listing of chemicals recently applied included in Appendix U. In addition, as

shown in Appendix U, it was specifically stated by a representative of Masonic

Homes that one of the pesticides of interest, dieldrin, was not used by Masonic

Homes in the vicinity of soil sample SS-4 where dieldrin had been detected.

4.5 NPDES Limits

• On page 47 of the RI, it is stated that NPDES discharge permits are held by

Heritage Metals Finishing Company located within Elizabethtown Borough and

the Elizabethtown Borough Water Company. Consideration of the influence of

these upstream discharge is needed in determining the appropriate discharge

requirements for the treatment system.

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5.0 RECOMMENDATIONS

Based on the data presented, the technical documents supporting the proposed plan do not

sufficiently explain the hydrogeologic system, the distribution of analytes in the ground water,

and the potential extent of the ground water contaminant plume. Because of this it! is

recommended that the following items be included in the implementation of the-proposed plant

5.1 Re-sampling of Masonic Homes wells. [Although SCA stated in 1993 that

resampling would be perform :d, said resampling has not occurred.]

5.2 Re-evaluation of the downgtadient extent of the jlume based on the highest

concentrations of volatile org mics and selected metals.

53 A ground water model to assc >s contaminant transport and the likely effectiveness

of ground water capture was conducted by Rust. ; However, the ground water

modeling effort did not include, as part of the assumptions or limiting parameters,

pumping from Masonic Homes welts. Consequently, reliance on the model to1 t I 'predict the future impact of; the remedy from, the. Masonic Homes is! withouti

foundation. Given that ground water flow to Masonic Homes wells has not been

adequately characterized, completion of adequate pumping tests and an appropriate

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ground water model which includes consideration of pumping from both existing

• • Masonic Homes wells and future wells on the south side of Conoy Creek is

needed before final design is completed and before Masonic Homes can bei

satisfied that its water supply is protected.

5.4 If warranted based on new data collected during the re-sampling of wells,

completion of a supplemental risk assessment to characterize risks associated with

use of Masonic Homes wells may be required.

5.5 Treatment or replacement of Masonic Homes water supplies must be considered

during implementation of the proposed remedy.

ii

5.6 Because manganese has been recognized as the major contributor to non-cancer

risk at the site, a risk characterization for the sampling results from EM400 should

be completed as part of the evaluation of the proposed remedial plan.

5.7 Inorganic anions such as chloride, nitrate, sulfate, add bicarbonate have hot qeent;

included in previous sampling events. These constituents should be included in

future sampling results to assist with the evaluation of the relationship of metals

to the ground water flow sysfcra.

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5.3 Because of the lack of sampling data in the former bum area, tbe conclusion that

hot spots related to previous' activities is unsubstantiated. In the event that

residual material is present (as suggested by the presence of a creosote odor in T-

6) then source removal may be' warranted. To document that the bum area is not

a hot spot, samples from the farmer bum area should be collected.

WW-2U779.DOC

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