c

-FMC NORTHERN ORDNANCE DIVISIONMINNEAPOLIS

EVALUATION ofREMEDIAL ACTION ALTERNATIVI

FMC and BNR LandsGroundwater Regime

May 1985Ref. No. 1518 CONESTOGA-ROVERS & ASSOCIATES LIMITED

L

TABLE OF CONTENTS

Page1.0 INTRODUCTION 1

2.0 PRELIMINARY ASSESSMENT OF POTENTIAL REMEDIAL TECHNOLOGY 42.1 GENERAL 42.2 ASSESSMENT CRITERIA 52.3 PRELIMINARY ASSESSMENT RATING SYSTEM 72.4 PRELIMINARY ASSESSMENT OF POTENTIAL

REMEDIAL TECHNOLOGIES 92.4.1 Excavation and Disposal 92.4.1.1 Disposal at an Off-Site RCRA Facility 112.4.1.2 Disposal On Site 122.4.2 Capping 132.4.2.1 Normal Portland Concrete Pavement 152.4.2.2 Asphaltic Concrete Pavement 162.4.2.3 In-situ Soil Admixtures 172.4.2.4 Sprayed on Covers 192.4.2.5 Low Permeability Soil Cover 202.4.2.6 Synthetic Membranes 212.4.2.7 Composite Construction 232.4.3 Physical Containment 252.4.3.1 Slurry Walls 262.4.3.1.1 Soil-bentonite mixtures 282.4.3.1.2 Cement-bentonite mixtures 292.4.3.2 Sheet Piles 312.4.3.3 Injected Screens 322.4.3.4 Grout Curtain 332.4.4. Hydraulic Containment 342.4.5 Groundwater Treatment 372.4.5.1 Biological Treatment 402.4.5.2 Carbon Adsorption 412.4.5.3 Stripping 432.4.6 Groundwater Disposal 442.4.6.1 Discharge to a Surface Fresh Water Body 45

TABLE OF CONTENTS (continued)

Page2.4.6.2 Discharge to a Publicly Owned Treatment Work 452.4.6.3 Disposal at a RCRA Permitted Facility 472.4.6.4 Reinjection 482.4.6.5 Deep Well Injection 482.4.7 Alternate Water Source Supply 492.4.7.1 Providing a Well Outside of the

Contaminated Plume 502.4.7.2 Providing a Potable Water Delivery Service 512.4.7.3 Providing a Water Service from a Municipal

Source 512.5 SELECTED REMEDIAL TECHNOLOGIES 522.5.1 Excavation and Disposal 532.5.2 Capping 542.5.3 Physical Containment 552.5.4 Hydraulic Containment 572.5.5 Groundwater Treatment 582.5.6 Groundwater Disposal 582.5.7 Alternate Water Source Supply 602.6 IN-SITU BIOLOGICAL TREATMENT 60

3.0 PRELIMINARY ASSESSMENT OF POTENTIAL REMEDIAL ALTERNATIVE 623.1 GENERAL 623.2 ASSESSMENT CRITERIA 623.3 ASSEMBLED POTENTIAL REMEDIAL ALTERNATIVES 63

3.4 PRELIMINARY ASSESSMENT OF POTENTIAL REMEDIAL

ALTERNATIVES 65

3.4.1 Preliminary Assessment of General Categories 663.4.1.1 Excavation of Contaminated Soils and

Disposal in a Containment Facility 663.4.1.2 Physical Containment 683.4.1.3 Hydraulic Containment 693.4.1.4 Groundwater Treatment and Groundwater Disposal 703.4.1.5 Alternate Water Source Supply 73

TABLE OF CONTENTS (continued)

3.4.2 Preliminary Cost Assessment of PotentialRemedial Alternatives 73

3.4.2.1 BNR Lands Assembled Potential RemedialAlternatives 75

3.4.2.3 FMC Lands Assembled Potential RemedialAlternatives 82

3.5 SELECTED REMEDIAL ALTERNATIVES 85

4.0 DISCUSSION OF HYDRAULIC CONTAINMENT ALTERNATIVE ATEVALUATION LOCATIONS 884.1 SCOPE 884.2 DESCRIPTION OF HYDRAULIC CONTAINMENT TECHNOLOGY 894.3 EVALUATION LOCATIONS 954.3.1 Site Property Boundary 954.3.2 Anoka County Lands 984.3.3 Mississippi River Shoreline 1004.3.4 Minneapolis Water Works Intake 1014.3.5 Residuals Following System Shutdown 1024.4 PERMITTING REQUIREMENTS 1034.4.1 General 1034.4.2 Fresh Water Body Discharge 1044.4.3 Sanitary Sewer Discharge 1054.4.4 Air Stripping Tower Discharge 106

5.0 CONCLUSIONS 108

APPENDIX A DETAILED RELATIVE COST

ESTIMATES OF REMEDIAL ACTION TECHNOLOGIES

APPENDIX B DETAILED RELATIVE COSTESTIMATE OF SELECTED REMEDIAL ACTION ALTERNATIVES

LIST OF FIGURES

FIGURE 1 ALTERNATIVE CAPPING TECHNOLOGIES

FIGURE 2 PRELIMINARY COST ASSESSMENT FOR TREATMENTAND DISPOSAL OF CONTAMINATED GROUNDWATER

Page

15a

74a

FIGURE 3 EXCAVATION AND DISPOSAL IN A CONTAINMENTTREATMENT FACILITY (ALTERNATIVE BNR 1)

FIGURE 4 PHYSICAL CONTAINMENT(ALTERNATIVES BNR 2 AND FMC 1)

FIGURE 5 HYDRAULIC CONTAINMENT(ALTERNATIVE BNR 3 AND FMC 2)

FIGURE 6 PROPOSED LOCATIONS FOR EXTRACTION WELLS- HYDRAULIC CONTAINMENT

75b

76b

79a

89a

FIGURE 7 ASSUMED RELATIONSHIP BETWEEN TCE REMOVALAND MASS VS PORE VOLUMES

92a

LIST OF TABLES

TABLE 1 EVALUATION OF REMEDIAL TECHNOLOGIES

TABLE 2 SUMMARY OF SELECTED REMEDIAL TECHNOLOGIES

TABLE 3 PREFERRED TREATMENT AND DISPOSAL METHODFOR CONTAMINATED GROUNDWATER

9a

63a

74b

TABLE 4 ESTIMATED COST SUMMARY FOR REMEDIAL ACTIONALTERNATIVES

75a

TABLE 5 SUMMARY OF ESTIMATED COST FOR HYDRAULICCONTAINMENT REMEDIAL ACTION ALTERNATIVESTO ACHIEVE 10-6 AND 1CT5 RISK LEVELSAT STIPULATED EVALUATION LOCATIONS

88a

LIST OF TABLES (continued)

Page

TABLE 6 AVERAGE AQUIFER PROPERTIES 89b

TABLE 7 SUMMARY OF REQUIRED PUMPING RATES FOR 95aEXTRACTION WELLS FOR HYDRAULIC CONTAINMENTPREFERRED REMEDIAL ACTION ALTERNATIVE

1

1

I

L

1.0 INTRODUCTION

I In response to the June 8, 1983

j Administrative Order and Interim Response Order by Consent

(Consent Order) between FMC Corporation (FMC), the Minnesota

I Pollution Control Agency (MPCA) and the United States

Environmental Protection Agency (USEPA), FMC has submitted

\ under separate cover, the report entitled "Feasibility Study

• - FMC and BNR Lands Groundwater Regime", Conestoga-Rovers and

^ Associates Limited, January 1985. The Feasibility Study

I evaluated the impact of volatile organic compound (VOC)

contamination identified in the groundwater beneath the Site,

1 on present and future potential human receptors and concluded

I that a long term groundwater monitoring program was the

appropriate response action for the Site. In the context of

} this report, reference to the Site as discussed herein shall

collectively mean the lands owned by FMC and the lands owned

I ^ by Burlington Northern Railroad (BNR).

In addition to carrying out the evaluation

1 contained in the Feasibility Study, the MPCA and USEPA

(hereafter referred to collectively as the Agencies) further

1 requested that FMC evaluate remedial action alternatives

, which would attain 10~6 and 10~5 excess cancer risk

criteria at defined evaluation locations between the Site and

1 the Mississippi River (MPCA letter dated December 6, 1984;

USEPA letter dated December 7, 1984). The Agencies

l_ identified the evaluation locations to be as follows:

i 1

1 i) the western boundary of the Site,

ii) the eastern boundary of the Anoka County lands,

| iii) the Mississippi River shoreline, and

i iv) the Minneapolis Water Works intake.

In submitting this further evaluation of

remedial action alternatives in accordance with the Agencies'

} request, FMC does not acknowledge or agree that such an

/ evaluation is warranted where the risk assessment contained

— in the Feasibility Study indicates no further response

I actions other than long term monitoring need be considered.

This further report is not required by the provisions or

1 intent of the June 8, 1983 Consent Order or applicable law,

i including the National Contingency Plan, 40 C.F.R. 300.

Remedial action alternatives are considered herein on the

I basis of data and information which are presently available.

Additional data and information collection would be

1 _ necessary, including information on the total cost of any

j particular remedial action, to determine whether a remedial

action would be cost-effective.

iThis remedial action alternative evaluation

I is organized in the following manner:

Section 2 provides a qualitative assessment of potential

{ remedial technologies within each remedial category

previously identified with the Agencies.

Section 3 provides a quantitative evaluation of the

technology chosen under each remedial category and identifies

the selected remedial action alternative which would achieve

a contaminant level equivalent to the 10 excess cancer

risk criterion at the Site property boundary.

Section 4 evaluates the performance standards of the selected

technology identified in Section 3 at each of the evaluation

locations stipulated by the Agencies.

Section 5 provides conclusions generated by the remediation

alternative evaluation.

This report is being submitted as an

accomodation to the Agencies. In light of the Feasibility

Study conclusions and the provisions of the Consent Order,

FMC does not believe the evaluation is warranted or required.

Furthermore, the 10-5 an(j io~6 excess cancer risk

criteria imposed by the Agencies have insufficient scientific

and medical support for their use. Even if FMC accepted such

criteria as valid for use at human receptors, which it does

not, the risk criteria at non-receptors should be

significantly lower.

I

2.0 PRELIMINARY ASSESSMENT OF POTENTIAL REMEDIAL TECHNOLOGIES

I 2.1 GENERAL

This chapter provides a preliminary

J assessment of potential remedial technologies which may be

feasible in achieving 10-6 an(j io~5 excess cancer

1 criteria at the specified evaluation locations.

_ The Feasibility Study concluded that

| contaminant levels in groundwater between the western

property boundary of the Site and the River did not pose a

I significant risk to current or future receptors. Therefore,

j candidate remedial technologies will be those that may be

feasible as source control measures, i.e., those that will

I control or contain the contaminants remaining on or beneath

the Site.

II Potential remedial technology categories

assessed in this chapter include excavation and disposal of

1 contaminated soils below the groundwater table, capping,

physical containment, hydraulic containment, groundwater

{ treatment, groundwater disposal, and alternate water source

i supply. The purpose of this preliminary assessment is to

identify a selected technology within each of the technology

I categories assessed.

II

At this level of assessment, no attempt has

been made to combine technologies within or between

j categories. Technologies have been assessed individually

. with respect to their effectiveness at performing the

' intended purpose for the category and without consideration

I of positive or negative effects when applied in combination

with other technology categories. The preliminary assessment

| process considers only major positive and negative features

. of the technology based on available data. The selected

^ technology for each category has been then identified based

[ on quantifiable and comparative features.

| The preliminary assessment of potential

. remedial technologies therefore allows an evaluation and

methodical reduction of the number of technologies in each of

I the identified categories. This is required in preparation

for assembling and screening remedial action alternatives as

] discussed in Section 3. The discussion presented under

I Section 3 will combine, assess and screen in more detail the

selected remedial technologies identified in this section.

1\ 2.2 ASSESSMENT CRITERIA

The preliminary selection or rejection of

I applicable remedial technologies was based on the following

general factors:

1. the chemical and physical characteristics of the

contaminant(s) that affect the effectiveness of a

I remedial technology,

2. physical site conditions that would preclude, restrict

I or promote a specific technology, and

1 3. the track record of a technology, including

i performance, reliability and operation

— characteristics.

iBased on the above three factors, potential remedial

I technologies were generated under various categories as

presented in Section 2.4. These potential remedial

technologies were then further assessed based on the

| following criteria:

I — 1. Technical Feasibility: Technical feasibility included

j a general assessment of reliability, implementation,

and safety. Effectiveness, durability and track record

| were considered under reliability. Implementation was

concerned with ease of installation, applicability to

1 Site conditions, time to implement and monitoring

j requirements. Safety addressed the relative safety of

a technology during operation and in the event of

I failure of the technology.

2. Environmental, Public Health and Institutional Impacts:

The environmental perspective addressed short- and

J long- term impacts on the natural and man-made

/ environments. These impacts include odor, noise, air

pollution, surface water and/or groundwater pollution,

\ use of natural resources, habitat alterations,

relocation of man-made structures and/or services, and

1 aesthetic changes. Public health addressed short- and

, long-term exposure from Site contaminants.

_ Institutional impacts considered environmental quality

I standards, land use, and federal, state or local laws

and/or policies.

II 3. Cost: The cost comparison involved development of

relative costs for each technology. Elements common

f among each technology assessed within a specific

category were not included in the relative cost

assessment. Costs presented are not, therefore,

, intended to represent actual construction cost

' estimates.

I| 2.3 PRELIMINARY ASSESSMENT RATING SYSTEM

*• Based on the assessment criteria developed in

| the previous section, each technology was individually rated

in accordance with the following scale:

II

L1

Rating Description

-2 Extremely negative effects, even with mitigating

measures. Technology not worth further

consideration in this category.

-1 Negative effects but not strong enough or certain

enough to be sole justification for eliminating

technology in this category.

0 Does not affect existing conditions or of very

little positive or negative affect.

1 A positive benefit.

+2 Extremely positive benefit.

* Inappropriate to draw conclusions at this point in

evaluation process.

8

2.4 PRELIMINARY ASSESSMENT OF POTENTIALREMEDIAL TECHNOLOGIES

This section provides the preliminary

I assessment of potential remedial technologies based on the

criteria stated in Section 2.2 and the preliminary assessment

I rating system identified in Section 2.3.

In order to establish consistent ratings,

I each potential remedial technology was rated according to its

effectiveness at performing its intended purpose within its

I specific category. Each individual remedial technology,

j therefore, does not address all hazards or problems

identified on the Site by itself. It was assumed that

I concern regarding other Site hazards could be potentially

mitigated by implementing or combining technologies from

I other categories. This is discussed in Section 3.

ITable 1 summarizes the preliminary assessment

1 of all potential remedial technologies discussed in the

following sections.

I

2.4.1 Excavation and Disposal

IThe excavation and disposal technology, in

L general, involves the excavation of saturated contaminated

materials from an identified area ("hot spot") with disposal

TABLE I

EVALUATION Of REMEDIAL TECHNOLOGIES

FMC CORPORATIONMINNEAPOLIS, MINNESOTA

SCREENING RATING COMMENTSTECHNOLOGY

Technical EnvironmentalP u b l i cHealth Institutional

CapitalCost Advantages

CATEGORY Excavation and Disposal (Section 4.4.1) (Costs based on a one acre area, contaminated from the 20 foot depth to the 35 foot depth)

Transportation andDisposal ofContaminated Soilsat a Hazardous WasteLandf111 Approvedby USEPA

Disposal ofContaminated SoilsIn a ContainmentFacili t y (CF)ConstructedOn-slte.

preferred technology for remedial category

N/A S 8,335,000

» 15,000 t 1,288,000

- physica l ly removes contaminatedmaterial off site, therebyminimizing future potential ofgroundwater contamination

- minimal site disturbance- restores future usage of entire

site- minimal future maintenance and

mon I tor I ng

- physically removes contaminatedmaterial and secures In CF,thereby reducing futurepotential of groundwatercontamination

- below grade on-sl te CF reducesrequirement for Imported f i l lfor site regradtng

- capital costs are low

Disadvantages

excavated material transportedoff site w i l l requirereplacement wi th Imported f i l lfor gradingdepending on depth and extentof contamination, capital costscan be prohibitivewaters collected throughdewaterlng w i l l requiretreatment and disposal.

extensive site disturbanceduring constructionarea of CF restricts futuresite usagecontinual monitoring andmaintenance of CF requiredwater collected throughdewaterlng w i l l requiretreatment and disposal.

continued....

TABLE 1

EVALUATION OF REMEDIAL TECHNOLOGIES

FMC CORPORATIONMINNEAPOLIS, MINNESOTA

SCREENING RATINGTECHNOLOGY

Public Summation MM Cost CapitalTechnical Environmental Heal th Institutional ol Rating per Year Cost

II. CATEGORY Capping (Section 4.4.2) (Costs based on a one acre area)

I . Normal Portland + t + 1 0 0Concrete Pavement

I 2,000 $ 100,000

COMMENTS

Advantages

minimal slope required,therefore minimal sitepregradlng requiredexcellent water repellencyexcel lent weatheringcharacteristicsdurable, long ternhard surface permits futuresurflclal usage of sitemoderately low maintenance costs

Disadvantages

Increased stormwater managementconcernstypical cap thickness Is 12Inches, may require removal ofexisting material from sitereinforcing and granular baserec 01 mendedmaintenance Involves repair offractureshigh capital cost

2. Asphaltlc ConcretePavement

$ 4,000 t 84,000 minimal slope required,therefore minimal sitepregradlng requiredexcellent water repellencygood weathering characteristicsdurable, long termsemi-rigid structure, thereforemore responsive to minordeflections and movement thannormal port)and concretepavement with minimal crackinghard surface permits futuresurflclal site use

Increased stormwater managementconcernstypical cap thickness Is 16Inches, may require removalof existing material frcm siteweathers more rapidly thanPortland cement concretepavement and Is susceptible toattack by v o l a t l l I zedcon tan I nan tsgranular base recommendedmaintenance Involves occasionalover I ays

• moderately high capital andmaintenance costs

con 11nued....

TABLE t

EVALUATION OF REMEDIAL TECHNOLOGIES

FMC CORPORATIONMINNEAPOLIS, MINNESOTA

TECHNOLOGYSCREENING RATING

Public Summation O&M Cost CapitalTechnical Environmental Health Institutional of Rating per Year Cost

COMMENTS

II. CATEGORY Capping (continued)

3. In-sltu soil 0Admixtures

-1 -2 $ 8.000 $ 41.000

Advantages

does not Increase voluveon-slte, therefore no materialto be removed fro* sitemoderate water repellencyIon capital cost

Disadvantages

moderate slopa required,therefore moderate sitepregradlng requiredmay require off-site materialfor pregradlng

• low durability restricts futuresite usage

• veathers more rapidly thanPortland cement concretepavement and Is susceptible toattack by volatilizedcontonlnants

• hard surfacing sealantrecommended

• Increases stormnater managementconcerns

• maintenance requires frequentsurface reseating

• high maintenance costs

continued*...

TECHNOLOGY

TABLE I

EVALUATION OF REMEDIAL TECHNOLOGIES

FMC CORPORATIONMINNEAPOLIS, MINNESOTA

SCREENING RATING

Public Summation 04M Cost CapitalTechnical Environmental Health Institutional of Rating per Year Cost

COMMENTS

II. CATEGORY Capping (continued)

4. Sprayed an Covers -1 -1 -1 -3 f 8,000 $ 25,000

Advantages

minimal slope required,therefore Minimal siteregradlng requiredtypical thickness Is 1/4Inch, therefore no materialto be removed froi siteexcel lent water repellencyeasy to apply

• low capital costs

Disadvantages

Increases stormwater managementconcernsmay require off-site materialfor pregradlngpoor durabll Ityrestricts future usage of sitemaintenance Involves extensiverecoatlnghigh maintenance costs

5. Low PermeabilitySoil Cover

46" $ 3,000 t 91,000 - minimal effect on existingfirst 2 yrs, stormwater runoff

1,000 - good water repellencythereafter - flexibility allows significant

movement with minimal effectson cap Integrity

- moderate to low maintenancecosts

" - preferred technology for remedial category

surface drainage Important,thereafore significant siteregradlng requiredtopsoll over loon over clayrecommended with vegetativecover for erosion controloverall thickness exceeds 5ft., may require removal ofexisting material from sitecontinual surface maintenancerequiredlimited future site use optionsloam over clay required tomaintain moisture In clay andprevent desslcatlonmoderate capital cost

continued....

TABLE I

EVALUATION OF REMEDIAL TECHNOLOGIES

FMC CORPORATIONMINNEAPOLIS, MINNESOTA

SCREENING RATINGTECHNOLOGY

PublicTechnical Environmental Health Institutional of Rat I

II. CATEGORY Capping Ccontlnued)

6. Synthetic Membranes +1 -H +1 +1 *4

Summation MM Cost Capitalper Year Cost

$ 3,000 $ 74,000first 2 yrs,

1,000thereafteruntilsyntheticlinerreplacementrequired

COMMENTS

Advantages

minimal effect on existingstormwater runoff whenprotective cover usedgood water repellencyflexibility alIons moremovement with minimal effectson leakagemoderately low capital costs

1 moderate maintenance costs

Disadvantages

membrane protection requiredtopsoll over loan protectivecover recommendedvegetative cover recommendedsurface drainage Important,therefore significant sitepregradlng requiredtypical overall membrane andcover thickness Is 2 1/2 ft.,may require removal of existingmaterial from site

7. CompositeConstruction

+2 +8 t 3,000 t 132,000first 2 yrs,

1,000thereafteruntilsyntheticlinerreplacementrequired

minimal effect on existingstormwater runoffgood water repellency,provides double form ofInfiltration protection

• flexibility allowssignificant movement withminimal effects on leakagemoderate maintenance costs

surface drainage Important,therefore significant sitepregradlng required

1 protective cover and vegetationrecommended

> cover thickness exceeds 5 ft.,may require removal of mistingmaterial frcm siterestricts future site useoptionscontinual surface maintenancerequired

• high capital costscontinued....

TABU 1

EVALUATION OF REMEDIAL TECHNOLOGIES

FMC CORPORATIONMINNEAPOLIS, MINNESOTA

SCREENING RATINGTECHNOLOGY

Public Summation MH CostTechnical Environmental Health Institutional of Rating per Year

CapitalCost

COMMENTS

III.

I. Slurry Halls(common to all types)

Advantages

Physical Containment (Section 4.4.3) (Costs based on containing a one acre area to I) 135 foot depth, and II) n foot depth)

See Subparts a, b & c for Rating - provides a continuous barrieragainst groundvater migration

- low maintenance requirements

Disadvantages

- excavated soils may requiretreatment as contaminatedmaterial

- economic feasibility dependanton required depth of slurry•all

- conventional backhoe can reach10 ft. - good production rate

- specially modified backhoe canreach 75 ft. - moderateproduction rate

- clamshelI buckets required over75 ft. depth - slew productionrate

- monitoring required todetermine Integrity of slurrynail

- restricots future site usage- high capital cost

continued....

TABLE I

EVALUATION OF REMEDIAL TECHNOLOGIES

FMC CORPORATIONMINNEAPOLIS, MINNESOTA

SCREENING RATINGTECHNOLOGY

EnvironmentalRib lieHsalth Institutional

Summation 0AM Costof Rating car Year

CapitalCost

COMMENTS

Advantages

III. CATEGORY Physical Containment (continued) (costs based on containing a one acre site to I) 133 ft. depth and II) 3? ft. depth)

I.a Soll-bentonltemixtures

II)

Kb Ceiient-bentonlte I)mixtures

II)

0

+1

+2

+2

+1

+2

+2

+1

+1

+7"

*4

$1.026.000 - provides low permeabilitybarrier for medium to fine

129,000 grained soils- extremely durable- resistant to minor deformations- utilizes excavated material for

backfill, thereby minimizingmaterial to be disposed of

$1,657,000 - suitable for all soilclassifications

229,000 - provides some structuralstability to the containment wall

- requires less site area- durable

Disadvantages

- not suitable for medium coarsegrained soils

- requires significant site areafor mixing of so 11-ben ton I temixture

- containment wall w i l l dry,shrink and crack If notprotected from moisture loss

- disposal required for excavatedmaterial

- Imported material required forbackfi l l

- susceptible to cracking andloss of some Impermeability dueto curing and minordeformations

l.c Syntheticmembranetnstallotion

I)

II)

-2

-1

+2

+2

*• - preferred technology for remedial category.

-I

-I

0

-1

SI,443,000 - leakage detection systemensures effective monitoring

229,000 regarding effectiveness ofbarrier

- applicable for medium to finegrained soils

- permeable material required torbackfill , may require Importedmaterial and disposal ofexcavated material

- Integrity highly dependant onInstallation expertise

- technology In experimentalstage

- Implementation very d i f f i c u l tcontinued....

TABLE I

EVALUATION OF REMEDIAL TECHNOLOGIES

FMC CORPORATIONMINNEAPOLIS, MINNESOTA

SCREENING RATING COMMENTS

PublicHealth

Summation MM CoatRat Ins per Year

CapitalCost

TECHNOLOGY

Technical Environmental Health Institutional o( Rating per Year Cost Advantages

III. CATEGORY Physical Containment (continued) (costs based on containing a one acre site to I) l» ft. depth and II) 35 ft. depth)

2. Sheet Piles I)

0 * 1 * 1 0 t 789,000 - n o excavation o r handling o fIn-sltu material* required

II) -2

- minimal disturbance to site

Disadvantages

- provides a segmented barrieragainst groundxater migration

- Integrity questionable as mayhave window between adjacentpilings, therefore questionableeffectiveness

- depth limited to approximately35 ft. due to plumbness control

- applicable for medium to finegrained soils only

- restricted future site usage- monitoring required to

determine Integrity- extremely high capital cost- limited life span due to

material deterioration

continued....

TABU I

EVALUATION OF REMEDIAL TECHNOLOGIES

FMC CORPORATIONMINNEAPOLIS, MINNESOTA

SCREENING RATING COMMENTSTECHNOLOGY

EnvironmentalPublicHealth Institutional

CapitalCost Advantages

III. CATEGORY Physical Containment (continued) (costs based on containing a one acre site to I) 139 ft. depth and II) 3? foot depth)

I) not technically feasible at this depth range

II) -1 0 0 0 -I t 438,000

3. InjectionScreens

- Minimal disturbance to sitearea

- no excavation or handling ofIn-sltu materials required

- provides a more continuousbarrier than sheet piletechnology

- durable

Disadvantages

- not ensured of continuousbarrier due to potentialwindowing of sheet piling

- depth limited to approximately39 ft* due to piunbness control

- applicable for fine to mediumgrained soils only

- restricted future site usage- monitoring required to

determine Integrity- moderate capital cost

4. Grout Curtain I)

II)

+2

+1

+2

+2

+2

+2

+7"

+6

" - preferred technology for remedial category

$ 676,000 - minimal disturbance to sitearea

S 179,000 -handling of In-sltu materialslimited to drill spoils

- continuity of barrier can beImproved by decreasing spacingof grout holes

- applicable to all material types- durable- no depth limitation- easily modified by Installation

of additional holes.

not ensured of continuousbarrier due to uncontrollabledeflection of d r i l l i n grestricted future site usagemonitoring required todetermine Integritymoderate capital cost

continued...

TABLE 1

EVALUATION OF REMEDIAL TECHNOLOGIES

FMC CORPORATIONMINNEAPOLIS, MINNESOTA

SCREENING RATING COMMENTSTECHNOLOGY

Technical EnvironmentalPublicHealth Institutional

Summationof Rat In

MM CostYear Advantages

IV. CATEGORY Hydraulic Containment (Section 4.4.4) {Costs based on containing a one acre area to I) 13? foot depth and II) 35 foot depth)

Extraction Me)I I) +2System

II) +2

+2

+2

+1

+1

+7"* $ 2,200 * 35,000

+7" $ 2,000 $ 32,000

- removes contmlnants fromsaturated zone, therebyMinimizing potential futuregroundwater contamination

- easily adjusted to compensatefor heterogeneous geologicconditions or groundvaterquality and quantity

- durable- required only for limited

period- ultimately restores full

usage of site- moderately low capital costs

Disadvantages

- additional remedial technologyrequired for disposal ofextracted water

- depletes groundvater resourceduring period of operation

- moderately high operation andmaintenance costs associatedMlth subsequent handlingrequirement of extractedgroundvater

"* - preferred technology for remedial category

continued....

TABLE 1

EVALUATION OF REMEDIAL TECHNOLOGIES

FMC CORPORATIONMINNEAPOLIS, MINNESOTA

SCREENING RATING COMMENTSTECHNOLOGY

Public Simulation O&M Cost CapitalTechnical Environmental Health Institutional of Rating per Year Cost Advantages

IV. CATEGORY Hydraulic Containment (continued) (costs based on containing a one acre area to I) 135 ft. depth and II) 33 foot depth!

2. I)Extraction andInjection Hal ISystem II)

*2

+1

+1

+1

+4 $ 10,900 S 197,000

+4 t 11,200 $ 151,000

reduces contaminants fromsaturated zone, therebyminimizing potential futuregroundwater contamination

> easily adjusted to compensatefor heterogeneous geologicconditions or groundxaterquality and quantitydurable

• required for shorter periodthan extraction only veilsystemIf treated extractedgroundvat«r used for Injection,minimize depletion ofgroundwater resource

• ultimately restores full usageof site

Disadvantages

- additional remedial technologyrequired for treatment ofextracted water prior toInjection, or additionalremedial technology requiredfor disposal of treated waterand supply other water forInjection

- high operation and maintenancecosts associated primarily withsubsequent disposal ofextracted groundwater andsupply of water for Injection

- moderately low capital costs

continued....

TECHNOLOGY

TABLE I

EVALUATION OF REMEDIAL TECHNOLOGIES

FKC CORPORATIONMINNEAPOLIS, MINNESOTA

SCREENING RATING

Public Subnotion MM Cost CapitalTechnical Environmental Health Institutional of Rating per Year Cost

V. CATEGORY GroundNater Treatment (Section 4.4.5)

1. Biological -1 +1Treatment

2. Carbon Adorptlon

3. Air Stripping

* Costs depend on volume and quality of Influent. ** Preferred technology for remedial category

COMMENTS

Advantages

Moderately ION capital costoperation and Maintenancedependent on results of pilottesting, can be Moderately ION

Disadvantages

- May be Insufficient organicMatter In groundNater to sustainbiological activity

- potential for uncontrolledrelease of volatile organiccompounds to atmosphere

- require substantial amount ofpilot testing

- require disposal of biologicalsludge

- operation and Maintenance costscan be extremely highdependent on characteristics ofcontaminated groundNater to betreated and volume

proven technology appl(cablefor both air and water phasesachieves a high level ofcontaminant removallittle potential for emissionof volatile organic compoundsto atmospheremoderately ION capital cost

proven technology for removal of - does not remove contaminants tovolatile organic contaminants same degree as carbon adsorptionfrom groundNater - May require polishing of treatedmoderately ION capital, operation *ater and air emissions fro* theand maintenance costs stripping process

continued....

TABLE I

EVALUATION OF REMEDIAL TECHNOLOGIES

FMC CORPORATIONMINNEAPOLIS, MINNESOTA

SCREENING RATINGTECHNOLOGY

Public Summation CAM Cost CapitalTechnical Environmental Health Institutional of Rating per Year Cost

VI. CATEGORY Groundwater Disposal (Section 4.4.6)

I. Discharge to a +1 -I -1Surface Fresh MaterBody

-1 -2

2. Discharge to aPublicly OwnedTreatment WorksIPOTW)

+1 -I

3. Disposal at a RCRADisposal Facility

-I -I

COMMENTS

Advantages

applicable to both treatedand untreated waterlow capital cost providedallovable receiving waterbody Is nearbyloo operation andmaintenance costs

applicable to both treatedand untreated waterlow capital cost provided a

POTW Is nearby

applicable to both treatedand untreated waterlow capital cost

* Costs depend on quantity and quality of effluent. *• Preferred technology for remedial category

Disadvantages

quality and quantity of waterto be discharged must meetallowable dischargerequirements for fresh waterrequire monitoring to ensuredischarge complies withrequirements

• quality and quantity of waterto be discharged must meetrequirements of MetropolitanWaste Control Commission (MWCC)require monitoring to ensuredischarge compiles withrequirementsoperation and maintenancecosts can be extremely high,depending on MWCC charges

requires transport via publictransportation systems fromsite to disposal facility

• operation and maintenance costsdependent on transport chargesand gate fees per volume ofgroundwater to be disposed of

continued....

TECHNOLOGY

TABU 1

EVALUATION OF REMEDIAL TECHNOLOGIES

FMC CORPORATIONMINNEAPOLIS. MINNESOTA

SCREENING RATING

Public SuMutlon MM Cost CapitalTechnical Environmental Health Institutional of Rating per Year Cost

VI. CATEGORY Oroundnatw Disposal (continued)

4. Relnjectlon +1 -1 -1

Advantages

Ion capital costIon Maintenance cost

COMMENTS

Disadvantages

applicable to treated wateronlyrequire a peralt

5. Deep HellInjection

»1 -2 -2 appl (cable to botti treatedand untreated waterloo capital costs afterIdentification of suitablereceiving aquiferION operation and maintenancecosts

require peewitpotential future exposure Ifreceiving aquifer Is tapped orleaksrequire extensive Investigationto Identify suitable receivingaquiferhigh Initial capital cost,usually only appropriate forlarge Haste vo I IOTAS

• Costs depend on quantity and quality of •fluent. continued...

TECHNOLOGY

TABLE I

EVALUATION OF REMEDIAL TECHNOLOGIES

FMC CORPORATIONMINNEAPOLIS. MINNESOTA

SCREENING RATING

Public Summation 0AM Cost CapitalTechnical Environmental Health Institutional of Rating per Year Cost

COMMENTS

V I I . CATEGORY Alternate Mater Source Supply (Section 4.4.7)

1. Mall Outside +1 +2 +2ContaminatedPlume

2. Portable PotableWater Del(veryService

3. Use ExistingMunicipalService

-2 +2

Advantages

all three alternativessatisfy objective tominimize potential risk tooff-site receptors ofeffects of contaminatedgrounditater

Disadvantages

- all three alternatives requireIdentification of all futurepotential receptors withineffective zone of contaminantplume

- costs depend on water qualityand quantity requirements ofusers and on distance users arefrom supply source point.

* Costs depend on volume and quality of Influent** Preferred technology for remedial technology

of the excavated contaminated material in an approved manner.

Disposal may be at either on-site or off-site facilities.

The purpose of excavation and disposal is to

physically remove the source of contaminants available for

future migration. This technology is, therefore, reliable

and effective in minimizing future groundwater

contamination.

Once the source of contamination has been

removed, imported fill would be required to backfill the site

to the approximate existing site elevations, and surficial

vegetation would be restored. The site would then be

returned to normal usage.

The feasibility of the excavation and

disposal technology is limited by the extent of contamination

and in-situ conditions. Excavation to significant depths and

disposal of extremely large quantities of contaminated

material generally is not feasible since extensive amounts of

earthwork are required. Also the depth of excavation is

usually limited to the unsaturated zone to avoid excessive

dewatering costs. Additional excavation may be limited to a

practical physical depth because of the volume of material to

be moved. If the contaminated zone is not in the upper soil

stratum, excavation and replacement of the uncontaminated

overburden usually renders this technology unacceptable.

Alternatives for disposal of the contaminated

excavated material include:

10

1. transporting off site to a hazardous waste landfill

approved by USEPA, and

2. securing in a newly constructed on-site containment

facility (CF).

A brief discussion of each of these disposal

technologies follows:

2.4.1.1 Disposal at an Off-Site HazardousWaste Landfill

Excavation of contaminated material would be

performed by a backhoe or other mechanical means. Excavated

material would be loaded directly into hazardous waste

licensed haulers and transported to an off-site hazardous

waste landfill approved by USEPA. Imported fill material

would be required to backfill the excavated areas.

The excavation and disposal method results in

minimal long-term disturbance to the site and permits full

future usage of the site. Long-term management of the

contaminated material would become the responsibility of a

third party.

Capital costs for off-site disposal are

extremely high compared to securement of contaminated

materials in an on-site CF due to transport costs and tipping

fees at the disposal facility. The magnitude of this

11

cost differential between off-site disposal and on-site

containment would be dependent on the distance between the

off-site disposal facility and the site. A major constraint

to off-site disposal is that it is doubtful that landfill

capacity exists at current USEPA approved sites within a

reasonable distance of the Site for the volume of material

that would be excavated. Additionally, transport of

hazardous waste by road inherently has a potential for

spillage of contaminants by haulage unit upset, accident or

equipment malfunction.

2.4.1.2 Disposal On Site

A CF for the on-site disposal of contaminated

soil would consist of a base, cap and sidewalls constructed

of low-permeability clay with a second internal synthetic

liner installed to further insure containment of

contaminants. A CF would be constructed either above ground

or below ground and either off-site or on-site.

Construction activities include constructing

the clay and synthetic liner base and sidewalls (above or

below ground), excavating the contaminated material and

placing it in the CF, constructing the synthetic overliner

and clay cover, and site restoration.

12

A below-ground CF is generally more feasible

than above-ground construction since the excavated material

from the CF construction may be used to backfill the

contaminated area excavation. The amount of imported

material required to fill this area of excavation is,

therefore, minimized. On-site construction of a CF would

generally be preferred to off-site construction since items

such as off-site transport, fill material and additional land

aquisition are all minimized.

Construction of an on-site CF would restrict

future site usage in the vicinity of the facility. Long-term

monitoring and maintenance of the CF final cover, and of

groundwater quality adjacent to the CF would also be

required.

Capital costs for the CF are moderately low

compared to off-site disposal when significant volumes of

contaminated material are considered.

2.4.2 Capping

I The capping technology, in general, involves

the construction of a low- to very low-permeability cover

I over an identified area of contamination. The purpose of

this cover is to minimize infiltration of surface waters

I through the contaminated unsaturated soils, thus reducing the

i 13

long-term mass loading rate of contaminants into the

groundwater from the unsaturated zone. The capping

[ technology does not address removal of the contaminants in

r" the soils below the cover and, therefore, does not remove the

potential source of future groundwater contamination. The

I capping technology also does not address containment or

removal of contaminants presently in the groundwater.

1 Capping does provide long-term protection against contact by

humans or wildlife with the contaminated soils, uncontrolled

^ volatilization of contaminants to the atmosphere, migration

of contaminated sediments by surface water runoff, and

migration of contaminants dissolved in surface water runoff

contacting contaminated soils.

Alternatives for provision of a low-

permeability cover over identified areas of contamination

include:

i _i 1. normal portland concrete pavement,

2. asphaltic concrete pavement,

J 3. in-situ soil admixtures,

4. sprayed on covers,

[ 5. low-permeability soil cover,

i 6. synthetic membranes, and

7. composite construction.

LTypical cross-sectional views of each of the

I above low-permeability capping options are presented in

i 14

If

Figure 1. A brief discussion of each of these capping

technologies follows.

2.4.2.1 Normal Portland Concrete Pavement

rThis technology involves removal and disposal

I of the existing organic topsoil, pre-grading the site to

provide contouring for effective surface water runoff,

"~ placement of a 6-inch thick granular base course and

placement of a 6-inch thick concrete slab.

1 The concrete slab would provide a durable

surface which would permit selective future surface use of

the site for storage or parking. The concrete slab has

excellent weathering characteristics and excellent water

repellency.

• ""-—-

j Due to the reduced infiltration rate,

increased precipitation runoff can be anticipated which may

cause stormwater management concerns. Large areas of

concrete pavement may, therefore, require some form of

1 stormwater retention to control peak runoff rates.

Although normal portland concrete is

I susceptable to cracking from settlement, shrinkage and frost

heave, proper design of expansion and contraction joints and

15

mm.

<: 6 CONCRETE%6. GRANULAR BASE

NORMAL PORTLAND CONCRETE PAVEMENT

_____________ 2% mm.

6" TO 12" LIQUID ASPHALT OR PORTLANDCEMENT MIXED WITH INSITU MATERIAL

V'̂ K'̂ -̂ ^V'^blfl-NATIVE^MATERIAL.^rO^x,1

- -•!.">" -.'"I VrV^O r-'ilrV'.Y-.•"-*

IN SITU SOIL ADMIXTURES

-'6" SANii \' H YLENE LINER :

SYNTHETIC MEMBRANE

::::.-:6"SAiy yM& HIGH DENSITY Si:;:;:::;:

' ' ' ' ' ' ' ' ' ' ' ' ' ' '

;^^^vr';''v<:>'^:':-l;v>iV7'^^^:V''c/-,r': NATIVE MATERIAL '''̂ 'x'̂ -'/''x.-.--''.OVooNS^"./!-.''•>-'*--.'f'.A'.."

CRA COMPOSITE MEMBRANE

.-;•• 4'.-ASPHALT •?••:,•:..

• 12 GRANULAR BASE •••-.o : • : • . • : • . • - . .-••:.•: • - - . . . . -p .

o

ASPHALTIC CONCRETE PAVEMENT

'A" THICK SPRAY COATING |O/°min-

•"r,\»j,-NATIVE MATERIAL :!&£;£-

SPRAYED ON COVERS

SEEDED

TOPSOIL

3% mio min.

LOW PERMEABILITY SOIL COVER

figure IALTERNATIVE

CAPPING TECHNOLOGIESFMC Northern Ordnance Plant

ISIS-29/04/89

proper construction methods will ensure control of the

cracking and minimize future maintenance.

The moderately low maintenance costs of the

normal portland concrete pavement technology help to offset

the high initial capital construction cost.

, 2.4.2.2 Asphaltic Concrete Pavement

j This technology involves removal and disposal

of the existing organic topsoil, provision of surface

contouring for effective surface water runoff, placement of a

• 12-inch thick granular base course and placement of a 4-inch

' thick asphaltic concrete surface course.

IAsphaltic concrete specifically designed to

( ^ reduce infiltration is similar to highway paving asphaltic

• concrete except that the percentages of mineral filler and

• asphalt cement are increased. The increased percentage of

j mineral filler and asphalt cement serve to provide an

excellent water repellent surface as well as to decrease thef[ photosensitive weathering characteristics of this asphaltic

concrete pavement when compared with normal asphaltic

'• pavements.

L

16

The asphaltic concrete surface retains enough

flexibility to mould to slight deformations of the subgrade

and is more resistant to surface cracking than normal

Portland concrete pavement. The asphaltic surface, however,

is durable enough to permit selective future surface use of

the site such as a storage or parking area.

The increased precipitation runoff resulting

from reduced infiltration by the asphaltic concrete pavement

may cause stormwater management concerns and may require some

form of stormwater retention to control peak runoff rates.

The asphaltic concrete pavement technology

has lower initial capital cost than normal portland concrete

pavement but generally requires increased maintenance over

the long term, since asphaltic concrete has a shorter

service life than does normal portland concrete.

2.4.2.3 In-situ Soil Admixtures

1This technology involves removal and disposal of

1 the existing organic topsoil, provision of surficial

• contouring for effective surface runoff, and addition and

mixing into the soil of either a liquid asphalt to create

I soil asphalt, or portland cement and water to create soil

cement. In either case, the mixing depth, approximately six

17

LI

to 12 inches, results in soil physical properties greater

than the natural soil. It may be necessary to import

material for contouring to create a minimum one percent

surface grade. Neither admixture will provide a surface as

durable as the normal portland concrete pavement or the

asphaltic concrete pavement technologies.

Soil cement has a tendency to crack and

shrink on drying, and soil asphalt generally retains a high

void content. Therefore, both soil cement and soil asphalt

do not contribute significantly to reducing permeability, and

both require a surface sealent such as epoxy asphalt or epoxy

coal-tar for the soil cement, or a bituminous seal for the

soil asphalt.

As with the normal portland concrete pavement

and the asphaltic concrete pavement, surface precipitation

runoff will be increased over the area where the in-situ

admixture has been placed. This may require further controls

for stormwater runoff management.

The initial low capital cost of the in-situ

soil admixture technology would be offset by high maintenance

costs for periodic surface resealing.

18

I

2.4.2.4 Sprayed on Covers

This technology involves removal and disposal

of the existing organic topsoil, provision of surficial

contouring for effective surface water runoff, compaction and

rolling of the base to obtain a smooth surface and

application of a sprayed surface membrane. The membrane

material generally used is an asphalt; however, more recent

advancements using rubber and plastic latexes are presently

in the experimental stages. The finished sprayed membrane

has a thickness of approximately 1/4 inch. Since minimal

material is imported onto the site to construct the sprayed

on cover, material may have to be imported for surficial

contouring to achieve the required grades to promote surface

water runoff.

Sprayed on membranes generally are not

durable. Without a protective cover future usage of the site

would be severly restricted.

The sprayed on cover has excellent water

repellency. As with the normal portland concrete and

asphaltic concrete pavements this may cause increased

stormwater management concerns.

j The low initial capital cost of the sprayed

on cover technology is offset by high maintenance costs for

( recoating.

1 19

2.4.2.5 Low-Permeability Soil Cover

r This technology involves excavation and

f" stockpiling of the existing topsoil, excavation of the area

to be covered to a depth of six feet below design finished

I grade and stockpiling of excavated native material on site,

placement and compaction of clay to a hydraulic conductivity

1 less than 1 x 10-7 cm/sec to a depth of two feet,

| placement of a 6-inch thick sand blanket over the clay layer,

••—- placement of a 3-foot thick layer of common fill material

| . from the on-site stockpile over the sand blanket,

replacement of the topsoil over the area, and revegetation.

fj The clay layer provides a low-permeability

barrier which minimizes infiltration of surface waters. The

j sand blanket provides a drainage layer above the clay to

intercept and provide a drainage channel for infiltrated

( _. surface water. The layer of common fill serves to protect

f the clay layer from frost penetration and surface erosion.

This layer also retains moisture, thereby preventing

J dessication and fracturing of the clay layer. Replacing the

topsoil promotes revegetation which serves to reduce surface

1 erosion.

This technology has been proven to be

j effective and has longevity assuming proper design,

installation and maintenance. The effectiveness of the

< system is derived from the clay which is least susceptible to

I 20

cracking from settlement or aging, and tends to be

"self-healing". Long-term maintenance of the vegetative

cover and surface erosion is required. The vegetative cover

will reduce surface runoff, and thereby reduce stormwater

management concerns.

The moderate capital cost of the low

permeability soil cover technology is associated with a

moderate to low maintenance cost.

2.4.2.6 Synthetic Membranes

Ii This technology involves excavating and

• stockpiling the existing topsoil, excavating and regrading

j the site area to two feet below design finished grade with

stockpiling of this native material on site, placing the

^ ^ synthetic liner, placing a 6-inch thick sand blanket below

• and above the synthetic membrane, placing a 1-foot thick

layer of common fill from the on-site stockpile over the sand

| layer, replacing the topsoil over the site area, and

revegetation.

I, The initial 6-inch thick sand blanket

provides a cushion for the synthetic membrane which is a

J flexible polymeric material. The 6-inch thick sand blanket

above the synthetic membrane provides a drainage layer for

121

infiltrated surface water. The 12-inch depth of material

above this sand layer provides protection to the synthetic

membrane from surficial activities, and the replacement of

the topsoil permits revegetation for erosion control. Due to

the limited cover over the synthetic membrane, future site

usage would be restricted compared to a low permeability soil

membrane.

The synthetic membrane provides excellent

water repellency provided a good quality control program is

implemented and maintained during construction. Flexibility

makes this technology relatively less susceptible to cracking

from settlement or frost heave than others. Long-term

maintenance of the vegetative cover and prevention of surface

erosion would be required. Long-term replacement of the

synthetic membrane must be anticipated due to the potential

for degradation from biological or chemical agents. The

vegetative cover would reduce surface runoff, and thereby

reduce stormwater management concerns. The long-term

durability of synthetic liners has not been conclusively

demonstrated in the field.

The moderate capital cost of the synthetic

membrane technology is associated with a moderate maintenance

cost.

22

2.4.2.7 Composite Construction

This technology involves excavating and

stockpiling existing topsoil, excavating and regrading the

site area to six feet below design finished grade with

stockpiling of excavated material on-site, placing and

compacting clay to a hydraulic conductivity of less than

1 x 10-7 cm/sec to a depth of two feet, placing a 6-inch

thick sand drainage blanket over the clay liner installing a

synthetic membrane liner and a second 6-inch thick sand

blanket over the liner, placing to a depth of 2-1/2 feet over

the sand blanket common fill material from the on-site

stockpile, replacing the topsoil over the site, and

revegetation.

This technology provides two low-permeability

liners for the minimization of infiltration. The synthetic

membrane would serve to retain moisture in the clay layer,

thus minimizing dessication fracturing of the clay layer.

The 6-inch thick sand blanket below the synthetic membrane

would serve as a cushion while the sand blanket over the

synthetic membrane serves as a drainage layer. The fill

material would provide a protective cover for both the

synthetic membrane and clay layer. Replacing the topsoil

would permit revegetation for runoff and erosion control.

23

J Since the composite cap is constructed of two

materials of significantly different physical properties

' (clay and a synthetic plastic liner), the response of each

( liner to various conditions and stresses will also differ.

This response difference is important to the long- term

| integrity of the cap in that conditions or stresses which may

deteriorate the effectiveness of one of the cap members, may

' not impact the other. As a result, a failure of one of the

| cap members does not necessarily result in a failure of the

"— cap, as the second member acts as a safety net to protect

I against failure of the entire cap.

I This technology is effective in minimizing

I surface water infiltration due to the low permeability of the

synthetic membrane combined with the "self-healing"

I properties of the low-permeability clay. Long-term

maintenance of the vegetative cover and surface erosion would

' -_- be required. It must be anticipated that the synthetic

f membrane liner would require replacement periodically due to

the potential degradation from biological or chemical agents.

I The vegetative cover serves to minimize surface runoff and

stormwater management concerns.

j The high capital cost of the composite

construction technology is associated with a moderate

| maintenance cost.

24

I 2.4.3 Physical Containment

( The physical containment technology, in

f general, involves the securement of contaminated material

either by excavation and placement of the material in a CF or

| by construction of a perimeter barrier wall around the areai

of contamination, effectively securing the contaminated

I material in place. Section 2.4.2 has addressed securement of

I contaminated material in a CF. This section will address

^ securement of the contaminated material in place.

(The purpose of a perimeter containment system

1 would be to provide a relatively impervious barrier

i surrounding an area of known contamination to minimize and

control the migration of contaminants to the groundwater. In

order to effectively control contaminant migration within the

groundwater regime, a perimeter barrier wall must be keyed

into a confining layer of low permeability at its base,

* extend upward to an elevation above the groundwater level,

and completely encompass the contaminated area. A dewatering

( system consisting of either a gravity drainage tile system

connected to a pumped sump or an extraction well system would

j be constructed within the perimeter barrier wall. A minimal

. amount of water would be extracted to lower the natural

groundwater level within the perimeter barrier wall system,

I thereby ensuring an inward hydraulic gradient within the

contaminated area. This extracted groundwater would require

| further collection, treatment and disposal.

I25

The physical containment technology strictly

{ contains the source of groundwater contamination within the

/ perimeter barrier wall and does not address the actual

removal of contaminants except for those removed incidentally

I while maintaining hydraulic control of the system. This

technology, therefore, does not to any extent remove the

\ potential source of future groundwater contamination.

Alternatives for provision of a perimeter

barrier wall to contain a specified defined area of

contamination include:

i) slurry walls,

ii) sheet piles,

iii) injected screens, and

iv) grout curtains

A brief discussion of each of these physical

containment technologies follows:

2.4.3.1 Slurry Walls

This technology involves excavating a trench

to the depth of a confining base layer while adding

bentonite/water slurry to maintain a stable trench face.

26

fI Following excavation, the bentonite/water slurry is displaced

with selective low-permeability backfill materials to produce

{ a low-permeability barrier wall.

The effectiveness of slurry walls is

j dependent on the control of proper excavation procedures and

proper proportioning and placement of the select backfill

1 material. The construction procedure to form a slurry wall

/ provides a continuous rather than a segmented barrier.

| The trench excavation is most commonly and

economically performed with conventional hydraulic backhoes.

1 Specially adapted backhoes for slurry wall construction can

• reach depths in excess of 75 feet. When excavations exceed

this depth range, clamshells which are much less productive

J are usually required and, significantly increase the cost of

the slurry wall. Alternatively, where groundwater conditions

j ^ permit, the alignment of the slurry wall can be benched by

r earth moving equipment to a depth compatible with the reach

of the trenching equipment.

1The addition of bentonite/water slurry during

1 trench excavation, provides trench stability during the

. slurry wall construction. The bentonite has favourable

^ swelling characteristics when combined with water. The

1 slurry forms a filter cake on the trench walls and the

hydrostatic head of the slurry, acting against the

I

low-permeability filter cake, resists inward movement of the

trench walls. The surface of the slurry is maintained at a

higher elevation than the adjacent groundwater. Excavation

of the trench proceeds through the bentonite/water slurry,

with excavated material being replaced by the slurry. The

trench is then backfilled with selected low-permeability

backfill materials. Backfill materials displace the

bentonite slurry during the trench backfilling. The backfill

materials are specially selected or manufactured to create a

low permeability barrier. Various backfill materials used

and their characteristics are described in Sub-Sections

2.4.3.1.1 through 2.4.3.1.3.

2.4.3.1.1 Soil-bentonite mixtures

IBentonite would be added to the excavated

I _^ native soil usually in slurry form, although dry bentonite

/ may be added where larger volumes of bentonite are called for

in the design. The bentonite and soil are mixed by

t windrowing, dozing or blading. The bentonite serves to

increase the fraction of fines in the native material,

\ thereby reducing the permeability. It also serves to provide

. a mix which is viscous so that the soil-bentonite mixture

* will slide slowly into the trench excavation, without

| entrapping pockets of slurry.

ii

Medium to coarse grained soils are not

suitable for soil-bentonite mixtures since low permeabilities

cannot be achieved consistently without massive additions of

bentonite.

The construction procedure requires

significant land area since a bentonite slurry mixing area

and a soil-bentonite mixing area are required. The completed

soil-bentonite barrier is durable and resistant to minor

deformations. The soil-bentonite barrier must retain its

moisture to remain effective since loss of moisture will

cause the bentonite to shrink and crack. The soil-bentonite

backfill material is relatively economical since it utilizes

native material.

2.4.3.1.2 Cement-bentonite mixtures

I „ ——————————. Bentonite is added in small amounts to

water-cement suspensions to extend the range over which the

| system is free from segregation by settlement. This mixture

generally is used in open granular soils and rock fissures,

1 or where some structural stability is required over and above

I that provided by a soil-bentonite wall barrier.

I The construction procedure requires less land

use area than for the soil-bentonite mixture since only

It 29

j imported materials are used for the backfill material. The

completed cement-bentonite barrier is durable but also

j susceptable to cracking due to minor deformations. This

i- cracking would cause the barrier wall to be more permeable

than the soil-bentonite backfill mixture.

rThe cement-bentonite mixture is less

1 economical than the soil-bentonite mixture since imported

/ materials are required and the native materials that are

•— excavated must be disposed.

2.4.3.1.3 Synthetic membrane installation

A synthetic membrane is placed over the

trench and caused to settle into the trench in a U

configuration by filling it with a highly permeable sand

material. Observation wells are then placed within the

permeable sand material to detect infiltration and ensure the

integrity of the synthetic membrane.

This method is still in the experimental

1 stages. Available information indicates that extreme

. difficulty has been experienced to date during construction

and installation of synthetic membranes in the field.

I1I

The use of imported materials as well as the

difficulty in construction lead to a high capital cost for

this form of containment wall.

2.4.3.2 Sheet Piles

1 This technology involves driving H piles,

i with the flanges back to back, around the perimeter of the

^ area to be contained. The piles are driven until the tips

f reach and penetrate an underlying low-permeability layer.

1 Since specifications generally call for a

. vertical variation of one percent or less, the maximum depth

' of installation is restricted to approximately 35 feet. For

I depths greater than 35 feet, deflection can create

unacceptable openings between adjacent piles.

I _, The installation of sheet piles results in

minimal disturbance to the existing site. However, a

I continuous barrier is not created due to the segmental nature

of the construction using H piles. The actual decrease in

I permeability obtained across a sheet pile is generally not

very large. The permeability has actually been found to

* decrease with time due to rusting and possible movement of

I fines. Long-term reliability would be suspect due to

deterioration by corrosion.

1I

Sheet piling is not feasible when the site

soils contain cobbles or larger fragments because of the

potential pile deflections that result during installation.

Sheet piling has a high installed construction capital cost,

and potentially has high maintenance costs.

2.4.3.3 Injected Screens

This technology requires similar construction

procedures as the sheet pile technology except that the piles

are subsequently extracted one at a time and the resultant

void filled with a clay-cement grout injected under pressure.

The extracted piles are redriven in the direction of travel

approximately ten feet from the point of extraction, thereby

minimizing the equipment and material required.

The injected grout produces a low

permeability barrier consisting of a "continuous" core of

relatively impermeable material which occupies the space left

by the extracted piles and is overlapped by a cemented zone

of soil penetrated by the injected grout. The thin fillet of

earth usually trapped between the flanges of adjacent piles

as they are driven, is removed by the pressure of the

injected grout during pile extraction.

This technology is limited to a maximum depth

of approximately 35 feet for reasons similar to the sheet

32

I pile technology. Windowing may cause unanticipated high

permeabilities across the barrier and thus defeat the purpose

J of this technology. As with sheet piles, this method is not

appropriate for use in soils containing cobbles or larger

rock fragments.

rCapital costs are moderate to high for the

| injected screen technology.

I 2.4.3.4 Grout Curtain

} This technology involves drilling holes along

, the perimeter of the area to be contained until an

' underlying low-permeability layer is reached. The drill is

I then extracted and a cement-bentonite grout is injected under

pressure through the drill holes. The grout creates a

/ ^_ cemented zone of soil around each drill hole, the diameter of

which depends on the penetrability of the grout into the

soils. The drill holes are spaced along a line at distances

f such that the cemented zone of each grout hole overlaps the

proceeding zone. Two or three staggered drill lines may be

| constructed such that the zone of each line overlaps the

previous line. This serves to increase the width of the

I grout curtain and effectively lowers its permeability.

J However, the injected grout will tend to flow in the

direction of least resistance and may not form a continuous

{ barrier.

I 33

This technology provides minimal disturbance

to the site during construction and requires disposal of the

drilling spoils only. Although some deflection of the grout

holes will be experienced, the horizontal spacing may be

adjusted to minimize the consequences of this deflection.

The permeability of the existing site soils

and the penetrating characteristics of the grout will

determine the required sequencing and spacing of grout holes,

and thereby significantly affect the initial capital cost

proportionally. Because of variability in soils on-site,

penetration of grout may not be completed in all areas, and

"windows" may exist after installation.

2.4.4 Hydraulic Containment

' v_- The hydraulic containment technology involves

I the use of extraction wells to manipulate the flow pattern of

groundwater. The extraction well system controls the flow

I pattern of groundwater by inducing a flow towards the

installed extraction wells. During the period of operation,

• the system captures contaminated groundwater and the

| contaminants released from both the saturated and unsaturated

soils. The hydraulic containment technology also removes the

source of contaminants in the groundwater and thereby reduces

the long-term impact of the site contamination to the

groundwater.

34

The extracted contaminated groundwater is

replaced at an accelerated rate by water from the surrounding

areas. The flushing of contaminants adsorbed in the aquifer

materials is also accelerated. The extracted contaminated

groundwater will require some form of treatment and disposal.

These are discussed in Section 2.4.6 of this report. Since

groundwater is being extracted and disposed, the technology

does deplete the groundwater resource.

The hydraulic containment technology offers

the flexibility of adjusting extraction rates to compensate

for heterogeneous geologic conditions or changes in

groundwater quality or quantity. The technology also offers

the ability of expansion to address potential problems that

may be identified after the system has been installed.

The extraction well system controls the

contaminant plume and, therefore, allows the continued use of

the aquifer by other users immediately outside of the zone of

contamination. These users may, however, incur some

additional pumping costs, depending on the area of drawdown

created by the remedial extraction wells.

Short-term site usage will be restricted

because of site utilities that will be required to transport

the extracted groundwater from the extraction wells to the

treatment system and subsequently to an approved discharge

outlet. However, long-term site usage will return to normal

35

I after the contaminants have been removed to an acceptable

level from the contaminated area.

f.- Off-site easements may be required during the

' period of operation of the extraction well system. Easements

may be necessary if it is deemed that off-site wells are

required to control the groundwater fl<effluent discharge outlet is off site.

r

required to control the groundwater flow pattern, or if the

j When properly designed, constructed and

maintained, the hydraulic containment technology is extremely

1 reliable, effective and durable as compared to the other

i technologies discussed herein. It is likewise relatively

easy to install and applicable to removal of dissolved

I contaminants especially where contaminants are identified at

a significant depth below the surface.

ICapital costs for this technology are

I ^ comparatively low. The majority of the cost is associated

. with operation and maintenance of the system. The treatment

cost of the extracted groundwater comprises a large| percentage of the operation and maintenance cost.

J The extraction well system discussed above

may be supplemented with an injection well system.

| Simultaneous injection of cleaner water during the extraction

process would further increase the rate of flow through the

I contaminated zone between the injection and extraction wells,

i thereby further accelerating the flushing of contaminants

( 36

adsorbed onto the alluvial materials. The injection wells

would be located such that the entire system creates a

controllable, stable flow pattern between the injection and

extraction wells.

The effect of the injection well system would

be to reduce the total pumping time required to remove the

contaminant source to a stipulated level. If permitted,

reinjection of the treated extracted groundwater could

provide a source of injection water.

The additional capital cost of the injection

well system and associated piping must be compared to present

worth costs of pumping and treating a smaller amount of

groundwater for a longer period of time relative to pumping

and treating larger amounts of water for a shorter period of

time. The reduction in pumping time achieved as a result of

installing an injection well system depends on the in-situ

soil permeability and specific contaminant characteristics

such as water solubility and coefficient of retardation.

12.4.5 Groundwater Treatment

I1

All potential remedial technologies discussed

in the previous sections, with the exception of capping,

. require extraction of groundwater to be effective. This

*" extracted groundwater would be contaminated and would require

I some form of treatment. This section discusses potential

I 37

I remedial technologies for the treatment of extracted

contaminated groundwater and is limited to treatment of

j groundwater contaminated by volatile organic compounds

(VOC's) only.1J Depending on the volume and quality of water

extracted, it may be feasible to dispose of the untreated

j groundwater by one of the technologies discussed in Section

2.4.6. If disposal costs for untreated effluent become

^. unacceptably high, or institutional restrictions are imposed,

j then some form of on-site treatment may be required.

( Treatment processes available for treatment

i of specific hazardous waste contaminant compounds, as listed

' by Shuckrow et al, ("Hazardous Waste Leachate Management

I Manual", Shuckrow; Pajak; and Touhill, 1982) include:

] ^ Biological Treatment Evaporation

( Carbon Adsorption Filtration

Catalysis Flocculation

J Chemical Oxidation Ion Exchange

Chemical Reduction Resin Adsorption

[ Chemical Precipitation Reverse Osmosis

Crystallization Solvent Extraction

' Density Separation Stripping

[ Dialysis/Electrodialysis Ultrafiltration

Distillation Wet Oxidation

138

1

I Of the above unit treatment processes, only

five would potentially have the capability of removing

I and/or degrading the majority of VOC contaminants in

i extracted groundwater. These five are:

( Biological Treatment

Carbon Adsorption

| Resin Adsorption

/ Stripping

— Wet Oxidation

I -Resin adsorption is somewhat similar to

( carbon adsorption. However, it is generally not as effective

, as carbon for treatment of waters which contain VOC

contaminants. For this reason, it appears that resin

J adsorption is probably not a suitable alternative for the

treatment of the groundwaters in question, although should

/ ^_. the need arise, actual testing may be required to confirm

• such a conclusion.

J The wet oxidation process is most applicable

for contaminants which are too refractory for chemical or

[ biological oxidation. Moreover, it is a technology which

i requires close operational control and is much more

' applicable for treating concentrated waste streams rather

[ than dilute concentrations such as those found in

groundwater. Furthermore, there is little to no evidence of

{ experience in the use of wet oxidation for treatment of

39I

groundwater. Therefore, wet oxidation will not be considered

further at this time. The list of treatment alternatives to

be further evaluated will therefore be limited to biological

treatment, carbon adsorption, and stripping.

2.4.5.1 Biological Treatment

j This technology has been applied in numerous

^ processes, including activated sludge, trickling filters,

I . rotating biological contactors and anaerobic treatment, and

has proven to be effective for a wide variety of organic

I compounds. However, this technology also has a number of

f limitations, of which the most significant is that sufficient

organic matter must be present to sustain biological

I activity. Most groundwater has a small amount of organic

material naturally present. Although microorganisms will be

i ^- found in the groundwater they will be insufficient in-situ to

j provide timely degradation of the organic materials.

Classic biological treatment systems require

a substantial organic load, measured in the 100 ppm or

*• greater range for BOD or TOG. Systems usually are designed

j to reduce this organic load to a range of 10 to 30 mg/L.

These systems require supplemental nutrients, oxygen, and pH

J control to sustain the biological activity.

II 40

j A side benefit from biological treatment is

the reduction in specific VOC's. However, to date biological

systems have not been designed to reduce only the

concentration of one or more specific VOC's.I

Some preliminary tests by USEPA have

indicated that reduction of VOC's in a biological system may

be totally or at least partially a result of volatilization

and not biological reduction. This would indicate that a

biological treatment system that was open to the atmosphere

would promote VOC volatilization to the air around it.

Application of this technology would have to

be site specific. Bench- or pilot-scale studies would be

required to demonstrate its applicability and to develop

design factors.

. 2.4.5.2 Carbon Adsorption

j This technology involves pumping extracted

groundwater through an activated carbon bed in which close

[ contact with the surface of the carbon grains promotes the

. adsorption of contaminants. This technology has been

*• extensively developed and proven suitable for the removal of

j a wide range of contaminants from both air and water phases.

Carbon adsorption achieves a high level of contaminant

II

removal and is capable of producing water that is of drinking

water quality.

Carbon adsorption systems are closed systems

and, therefore, unlike biological treatment systems, have a

low potential for emission of VOC's to the atmosphere.

Carbon adsorption systems have moderately low

capital costs and are commercially available. However,

operation costs vary significantly, being dependant upon the

total mass of contaminants and the adsorption characteristics

of the contaminants to be removed. If one contaminant has a

poor adsorption characteristic, breakthrough of this

contaminant would occur through the carbon system long before

the carbon has reached saturation for the other contaminants.

The carbon would, therefore, require replacement or

regeneration based on this one indicator compound. A common

method for improving the effectiveness of carbon adsorption

and lowering the cost for this process is to remove some of

the less easily removed compounds (ie. contaminants with poor

adsorption characteristics) prior to the carbon adsorption

system. This is accomplished by applying a process such as

stripping.

42

2.4.5.3 Stripping

This technology uses a system to mix large

volumes of air and/or steam with the contaminated water

to promote the transfer of VOC's into the air and/or steam.

The system may consist of a packed column, in which water is

pumped into the top of the column and cascades down over the

loosely packed media while air and/or steam is pumped upward

through the column. The steam generally is required only for

the removal of less volatile compounds and requires a

significant amount of energy input to maintain.

The efficiency of the air stripping process

is mainly dependant on the air/steam to water ratio and the

contact time in the tower. Both the ratio and tower length

can be adjusted to optimize the groundwater treatment with

minimal differences in overall capital cost.

If air stripping does not fully satisfy the

treatment objectives, a carbon adsorption system may be used

to further reduce the contaminant levels in the groundwater.

However, the air stripping process will significantly reduce

the carbon required in the carbon adsorption polishing

system.

A major concern of the stripping process is

the potential release of unacceptable concentrations of VOC's

43

to the atmosphere. If discharge from an air stripping tower

exceeds the allowable mass discharge, a vapor-phase carbon

adsorption system may have to be added to the tower

discharge.

2.4.6 Groundwater Disposal

IAlternative methods considered for the

•~— disposal of extracted groundwater include:

\1. discharge to a surface fresh water body,

[ 2. discharge to a Publicly Owned Treatment Works (POTW),

. 3. disposal at an RCRA permitted disposal facility,

' 4. reinjection, and

I 5. deep well injection.

I _ The appropriateness of the listed methods of

. disposal are dependent on whether or not the groundwater to

be disposed of has been treated, and if it has been treated,

I the degree of treatment received.

I A brief discussion of the alternative

• groundwater disposal methods for both treated and untreated

' groundwater and their applicability are as follows:

44

2.4.6.1 Discharge to a Surface Fresh Water Body

This alternative is applicable to both

treated and untreated groundwater provided that both the

quality and quantity of the groundwater being directly

discharged to the surface fresh water body meets the

allowable discharge requirements for fresh water as regulated

under Federal or State standards. The quantity of

groundwater that would be allowed to be discharged would

depend on the capacity of the discharge system and the

receiving water bodies. Groundwater quality sampling of the

waste groundwater to be discharged would be required to

identify its quality and to ensure that it meets the

allowable discharge requirements for fresh water.

The capital cost would depend on the

proximity of the nearest receiving fresh water body and the

available alternatives of conveying the waste groundwater to

this water body. Operation and maintenance costs would be

low, requiring only sampling and maintenance of the discharge

system.

2.4.6.2 Discharge to a Publicly Owned Treatment Works

This alternative is applicable to both

treated and untreated water provided that the quality and

45

quantity of the groundwater being discharged to the

publically owned treatment works (POTW) meets the allowable

discharge requirements of the local regulatory agency. The

quantity of groundwater that would be allowed to be

discharged would depend on the capacity of the discharge

system and the POTW. Sampling and analysis of the waste

groundwater to be discharged would be required to identify

its quality and to ensure that it meets the allowable

discharge requirements of the local POTW.

The capital cost would depend on the

proximity of the nearest conveyance system capable of

receiving the anticipated and allowable quantity of

groundwater to be discharged. A flow measuring device would

be required by the POTW at the point of discharge of waste

groundwater from the site. Operation and maintenance costs

for sampling and maintenance of the discharge system would be

similar to the discharge to a surface fresh water body

alternative. In addition, treatment costs would be charged

by the POTW based on the volume and/or quality of the waste

groundwater being discharged. These treatment charges could

potentially be quite significant and must be compared to the

cost of treatment by one of the technologies discussed in

Section 2.4.5, prior to ultimate disposal.

46

I 2.4.6.3 Disposal at a RCRA Permitted Facility

j This alternative is applicable to both

. treated and untreated groundwater and is limited only by

' cost. Waste groundwater would be transported to a RCRA

j permitted disposal facility that is approved to accept the

quality and quantity of the waste groundwater to be disposed

( of.

' -— Generally, transport costs and gate fees at a

| RCRA permitted disposal facility would limit the economic

feasibility of this alternative to relatively small

[ quantities of waste groundwater. This alternative would,

. therefore, only be considered when the requirements for

' discharge to a surface fresh water body or discharge to a

I POTW cannot be achieved, or when the quantity of waste

groundwater to be discharged is so minimal that on-site

J _. temporary storage and ultimate disposal to a RCRA permitted

I disposal facility would be more economical than an

alternative form of disposal (and treatment).

ICapital costs may be low depending on the

I size of temporary storage required on site. Operation and

• maintenance associated with the storage and transport filling

system would be minimal. The majority of costs would be

J associated with the actual transportation costs and receiving

facility gate fees.

II 47

2.4.6.4 Reinjaction

This alternative is only applicable to treated groundwater as

reinjection of untreated groundwater would not be a means of

disposal but rather a recirculation system. This alternative

would also only be applicable if a variance of the State of

Minnesota regulations could be obtained for subsurface

disposal of the waste groundwater. Reinjection of treated

groundwater would only be considered if all of the above

three alternatives prove not to be feasible.

Capital, operation and maintenance costs

would depend on the volume of waste groundwater to be

disposed of by injection.

2.4.6.5 Deep Well Injection

This alternative may be applicable to both

treated and untreated groundwater, but would require

a permit for subsurface disposal. This technology would

involve the construction of a well into an isolated,

nonpotable deep aquifer, thereby protecting potential

receptors using other aquifers. Future exposure could be

possible however, if the deep aquifer were used.

48

Capital costs for this alternative could be

low to moderately high, depending on the extent of

investigation required to identify an acceptable deep aquifer

disposal unit. Operation and maintenance costs are

relatively low.

2.4.7 Alternate Water Source Supply

The alternate water source supply technology

addresses the provision of alternate water sources to

potential receptors of contaminated groundwater. This

technology does not address containment or removal of

contaminated groundwater and, therefore, has no effect on the

future migration of groundwater contaminants. However, this

technology does satisfy the primary objective which is to

minimize the potential risk to off-site receptors from the

effects of contaminated groundwater.

In order to implement this alternative, all

present and potential future receptors must be identified and

quantified as to water consumption rates/water quality

requirements. Potential future receptors would include all

consumers of the groundwater within an area that may

eventually be impacted by the migration of contaminants from

the present zone of contamination.

49

Alternative methods of providing an alternate

water source supply include the following:

i) providing a well outside of the contaminated plume,

ii) providing a portable water delivery service, and

iiijproviding a water service from a municipal supply.

A brief discussion on each of these technologies follows:

2.4.7.1 Providing a Well Outside of theContaminated Plume

This technology would require the

installation and operation of a well outside of the present

and potential future contaminant plume, with provision and

operation of a distribution piping system from this well to

identified users.

Costs for this technology depend on both the

quality and quantity of water required for the identified

users. Land aquistion costs may also be substantial for the

distribution system, depending on the zone of contamination

which determines the location of the water supply well.

50

2.4.7.2 Providing a Potable Water Delivery Service

This technology would require provision of

all potential future receptors with water storage facilities

and potable water delivery on a regular basis. Water would

be obtained from either a municipal source or a well located

outside of the contaminated groundwater plume.

This technology would only be acceptable to

minor water consumers. Large water consumers could not

depend on a potable water delivery service.

Costs for this technology would depend on

both the quality and quantity of water required for the

potential receptors. Capital costs would be less than the

previous technology since no water distribution system is

required. However, operation costs for transportation would

be greater than operation costs for pumping.

2.4.7.3 Providing a Water Service from a Municipal Source

This technology would require provision of a

water distribution system from an existing municipal system

to potential future receptors. All potential future

receptors and required water consumptions would have to be

identified in order to size the water distribution system.

51

I!

This technology would then provide a reliable source of water

at a reliable quality.

Initial capital costs depend on the proximity

of a municipal source the size of the water distribution

system required and the aquistion of land easements for the

water distribution system. Some compensation may also be

required to the receptors to offset the difference in costs

of pumping water from a private well compared to purchasing

water from a municipal system. Once the water distribution

system is installed, the municipality may assume maintenance

and operation of the system.

2.5 SELECTED REMEDIAL TECHNOLOGIES

Section 2.4 presented potential remedial

alternative technologies in various categories applicable to

reducing the impacts to groundwater users by migrating

groundwater contaminants. Based on the technical,

environmental, public health, institutional and cost issues

presented in Section 2.4 and summarized in Table 1, the most

applicable remedial technology was identified for each

category in specific response to the Site.

52

L

The most applicable remedial technology in

each category may not be the same for the FMC lands as for

the BNR lands, since the vertical and areal distribution of

contamination is different in each of the two areas.

Therefore, the selected remedial technologies identified in

the following sections are based on data collected during the

remedial investigation and outlined in the Feasibility Study.

These concluded that contamination within the lower alluvium

has been identified beneath the FMC lands, and that

contamination within the upper alluvium has been identified

beneath the BNR lands.

2.5.1 Excavation and Disposal

Two technologies were discussed under the

excavation and disposal category, namely disposal in an

off-site hazardous waste landfill approved by USEPA, and

disposal in a newly constructed containment facility located

either on site or off site.

Both technologies become cost prohibitive for

the FMC lands due to the volume of overburden above the

contaminated lower alluvium (approximately 300,000 cubic

yards). No further consideration is therefore given to this

category for the FMC lands.

II 53

Disposal at a hazardous waste landfill

approved by USEPA is very costly (two orders of magnitude

greater) compared to disposal in an on-site CF for the BNR

lands and offers few benefits not shared by the CF option.

The CF option has, therefore, been selected as the excavation

and disposal option for the BNR lands.

2.5.2 Capping

Seven alternative technologies were discussed

under the capping category, namely normal portland

concrete pavement, asphaltic concrete pavement, in-situ soil

admixtures, sprayed on covers, low permeability soil cover,

synthetic membranes, and composite construction.

As previously stated, contamination has been

identified in the lower aquifer beneath the FMC lands. This

aquifer is isolated from the upper alluvium by a clay stratum

approximately 20 feet in depth which provides a natural low

permeability cap over the lower contaminated aquifer.

Providing an additional surface cap over the FMC lands would

therefore provide no benefit in terms of mitigation of

off-site contaminant migration. This category, therefore,

requires no further consideration for the FMC lands.

54

Furthermore, it was concluded in the

Feasibility Study, that no significant contaminant loading

from the unsaturated overburden soil to the saturated

alluvium occurs at the Site. On this basis, placement of a

low-permeability cap over the Site would only be appropriate

in the context of reducing the volume of groundwater required

to be pumped for the physical containment or hydraulic

containment alternatives. This reduction of pumping rates

would therefore affect the evaluation of treatment

alternatives discussed in Section 3.4.2.

2.5.3 Physical Containment

Four technologies were discussed under the

physical containment category, namely slurry walls, sheet

piles, injected screens, and grout curtains. The slurry wall

technology was further divided into three alternatives,

namely soil-bentonite mixtures, cement-bentonite mixtures,

and synthetic membrane installation.

Technical issues such as the depth to the

underlying low-permeability strata preclude the use of the

sheet pile and injected screen technologies for providing

physical containment of the lower aquifer in the FMC lands.

Based on environmental, public health, and cost issues, the

grout curtain is the selected technology for the FMC lands.

55

Based on environmental, public health, and cost issues, the

grout curtain is the selected technology for the FMC lands.

Technically, the slurry wall may be argued to provide a more

consistent continuous barrier than the grout curtain;

however, the grout curtain can easily be expanded to seal off

identified areas of leakage. Areas of leakage would be

identified by a long-term monitoring program which is common

to all forms of physical containment. The savings in capital

costs for the grout curtain as compared to the slurry wall

would allow significant additional expansion of the grout

curtain if it were deemed necessary by monitoring. For these

reasons, the grout curtain is the selected technology in the

physical containment category for providing a barrier to

contaminant migration from the lower aquifer of the FMC

lands.

Based on technical, institutional and cost

considerations, the slurry wall is the most applicable

technology to physically contain the upper aquifer of the

BNR Lands. Public health and environmental disadvantages of

this technology during construction may be alleviated through

the implementation of a safety and health program during

construction and proper post-construction site restoration.

Evaluations indicate the soil-bentonite wall to be the

applicable technology for containment barriers. Therefore,

the soil-bentonite containment wall is identified as the

selected technology in the physical containment category for

56

LI

provision of a barrier to contaminant migration from the

upper aquifer of the BNR lands.

2.5.4 Hydraulic Containment

Hydraulic containment through the use of a

series of groundwater extraction wells provides an

appropriate form of containment based on all issues addressed

for both the FMC lands and the BNR lands. Supplementing the

extraction well system with an injection well system

primarily affects only the cost issue of this technology,

since it provides a partial means of disposal of the

extracted groundwater/ and reduces the overall pumping time

required.

The extraction well system is identified as

the selected technology for the hydraulic containment

category for both the FMC lands and the BNR lands, with

additional consideration to be given to the

extraction/injection well system on a cost effectiveness

basis only.

57

Ifr

2.5.5 Groundwater Treatment

Three primary technologies were discussed

under the groundwater treatment category, namely biological

treatment, carbon adsorption, and air stripping.

Technical factors identified to date cannot

conclude that biological treatment is an effective and

reliable technology for treating VOC contaminated groundwater

and this technology, therefore, warrants no further

consideration. Cost issues identify air stripping as the

selected technology for groundwater treatment, with further

consideration required on carbon adsorption as a polishing

stage for both the treated groundwater effluent and air

emissions for environmental, public health and institutional

issues.

• 2.5.6 Groundwater Disposal

j Five technologies were discussed under the1

groundwater disposal category, namely discharge to a surface

I fresh water body, discharge to a POTW, disposal at a RCRA

j permitted disposal facility, reinjection, and deep well

injection.

L1t 58

1 Institutional issues in the State of

Minnesota preclude groundwater disposal by deep well

j injection. This technology, therefore, warrants no further

I consideration. Disposal at a RCRA permitted disposal

' facility becomes cost prohibitive for any significant volume

j of water requiring disposal. Therefore, this technology

warrants no further consideration unless the volume of water

I to be disposed of is minimal. Reinjection warrants further

, consideration based on cost issues and for treated water

^-- only, as a supplemental technology to hydraulic containment

I which is discussed in Section 2.5.3.

J On-site storm sewers and sanitary sewers

• are cost effective for disposal to a fresh water body and a

POTW, respectively. Proper assessment of these two disposal

i technologies cannot be performed until the quality and

quantity of groundwater requiring disposal is identified,

j x_ Therefore, further consideration of the discharge to a fresh

j water body and the discharge to a POTW technologies is

required under the groundwater disposal category. This will

J be performed in conjunction with the analysis of the

alternatives generated in Section 3.

Ii

59

2.5.7 Alternate Water Source Supply

Three alternative technologies were discussed

under the alternative water source supply category, namely

providing a well outside of the contaminated plume,

providing a potable water delivery service, and providing a

water service from a municipal system.

Environmental, public health and

institutional issues preclude the implementation of this

category in general as a sole means of remedial action.

Further consideration is therefore only warranted as an

interim measure, should it be identified that there is an

immediate risk to a potential receptor.

2.6 IN-SITU BIOLOGICAL TREATMENT

I In-situ biological treatment has been found

effective in some instances involving the remediation of

I hydrocarbon groundwater contamination (for example, oil or

gasoline spills). Evidence also exists which suggests that

I degradation of chlorinated organics by native soil microbes

j occurs naturally, albeit at very slow rates. Theoretical

considerations suggest that the rate of degradation of

I chlorinated organics in groundwater may be enhanced by

providing naturally occuring microbes with both nutrients and

I 60

oxygen (both normally rate limiting). Because apropriate

data were not readily available/ the technology of in-situ

biological treatment could not be evaluated in the context of

the Site.

61

3.0 PRELIMINARY ASSESSMENT OF POTENTIAL REMEDIAL ALTERNATIVES

3.1 GENERAL

This section assembles and combines into

potential remedial alternatives, the selected technologies

identified in Section 2 under each remedial category which

remediate or mitigate the impacts of the off-site migration

of VOC contaminants in the groundwater. On the basis of the

assessment criteria discussed under Section 3.2, an

appropriate remedial alternative will be identified which

will be utilized in evaluating each compliance location at

the 10"̂ an<3 10~6 excess cancer risk criteria.

This final evaluation step is presented in Section 4.

3.2 ASSESSMENT CRITERIA

j1

The initial primary assessment criterion

« which all potential remedial alternatives will address is the

j reduction of trichloroethylene (TCE) contamination in the

groundwater at the Site boundary to concentrations less than

j the 10~6 excess cancer risk criterion (2.8 ppb). The

generation of potential remedial alternatives will therefore

'. be limited to only those alternatives which provide a

J complete remedial action plan to achieve an average

groundwater concentration of TCE less than 2.8 part per

I billion (ppb).

62

I Remedial alternatives satisfying the above

primary criterion are then further assessed and screened

{ using criteria identical to those presented in Section 2.2,

f namely; i) technical feasibility, ii) environmental, public

health and institutional impacts, and iii) cost. The

appropriate remedial alternative selected in this section for

the worst case assumption of the 10~6 excess cancer risk

1 criterion at the Site boundary will be evaluated at each

/ receptor location in Section 4.

3.3 ASSEMBLED POTENTIAL REMEDIAL ALTERNATIVES

i The selected remedial technology for each

remedial category as summarized in Table 2 is identified

I separately for both the BNR lands and the FMC lands. This is

necessary since groundwater contamination in each of these

I ^ two areas has been identified to be in separate alluviums.

| Contamination beneath the BNR lands was identified in the

upper alluvium, which is isolated from the lower alluvium by

| a clay aquitard. Contamination beneath the FMC lands was

identified primarily in the deep alluvium below the clay

L aquitard.

IOn the basis of the assessment of the

I selected remedial technologies and the characteristics of the

actual contaminant source, potential remedial alternatives

I 63

TABLE 2

SUMMARY OF SELECTED REMEDIAL TECHNOLOGIES

FMC CORPORATIONMINNEAPOLIS, MINNESOTA

R E M E D I A L C A T E G O R Y

Area

BNR Lands

Excavationand Disposal

on- sitecontainmentfacility

PhysicalCapping Containment

low soil-bentonitepermeability containmentsoil cover wall

HydraulicContainment

extraction wellsystem withconsideration ofreinjection oncost effective-ness basis only

GroundwaterTreatment

air strippingwith additionaltreatment bycarbonadsorption ifrequired

GroundwaterDisposal

surface freshwater body orpublicly ownedtreatment works.reinjection oncost effective-ness basis only

Alternate WaterSource Supply

interim response onlywhen required forimmediate concernfor a receptor

FMC Lands notapplicable

notapplicable

grout curtaincontainmentwall

same as above same as above same as above same as above

will be assembled separately for the BNR lands and the FMC

lands. The selected remedial alternative for each area may

then be combined to provide an overall selected remedial

alternative for the entire Site.

Using the selected remedial technologies from

the categories summarized in Table 2, the following potential

remedial alternatives are assembled and assessed in respect

to the performance criterion (TCE concentration less than 2.8

— PPt>) at the Site boundary:

Assembled Alternatives - BNR Lands

IBNR-1 excavation of contaminated soils from the saturated

' zone with disposal in a newly constructed on-site

f containment facility,

BNR-2a physical containment utilizing a soil-bentonite

J _, containment wall,

BNR-2b physical containment utilizing a soil-bentonite

' containment wall with a low-permeability soil cap,

j BNR-3a hydraulic containment utilizing extraction wells,

and

| BNR-3b hydraulic containment utilizing extraction wells,

with a low-permeability soil cap.I

64

Assembled Alternatives - FMC Lands

FMC-1 physical containment utilizing a grout curtain wall,

and

FMC-2 hydraulic containment utilizing extraction wells.

The hydraulic containment alternatives will

be further evaluated in combination with reinjection in

Section 3.4.

3.4 PRELIMINARY ASSESSMENT OF POTENTIAL REMEDIALALTERNATIVES

j The potential remedial alternatives assembled

in the proceeding section can be classified into three

I general categories, namely,

( „ i) excavation of soils with disposal in a containment

I facility,

ii) physical containment, and

I iii) hydraulic containment.

IOn the basis of technical feasibility, the

I first category is applicable only to the BNR lands, whereas

the latter two categories are applicable to both the BNR

1-7- and the FMC lands. All three categories may in general be

assessed with respect to technical feasibility, and

65

I environmental, public health and institutional impact

criteria identified in Section 3.2. Only the cost criterion

( is site specific and cost therefore will be assessed

individually for each potential remedial alternative.f

3.4.1 Preliminary Assessment of General Categories

All assembled potential remedial alternatives

satisfy the primary criterion of reducing the concentration

of TCE in the groundwater to less than 2.8 ppb. at the Site

boundary. Therefore, the following discussions are limited

to major differences among the general categories.

3.4.1.1 Excavation of Contaminated Soils andDisposal in a Containment Facility

This alternative involves the dewatering and

I excavation of contaminated materials from a predefined area

of contamination ("hot spot"), with disposal of the excavated

• contaminated material in an on-site CF constructed to RCRA

| standards.

I This alternative does not remove the source

. of contaminants from the Site, but rather relocates the

L contaminated material into a secure facility which may be

I66

I

I monitored to ensure its effectiveness at containing the

contaminated materials. Therefore, the potential for future

groundwater impact is minimized.

' The excavated area would be backfilled with

[ uncontaminated material excavated and stockpiled during the

CF construction, and would be restored to normal site usage.

} The area occupied by the CF would restrict the future use of

that portion of the Site.

{ The large volumes and depth of excavation,

and the extensive dewatering required during the excavation

I would result in a significant time of implementation, during

which adjacent lands and facilities both underground and

' aboveground would be impacted. All water collected during

f dewatering operations potentially would be contaminated and

may require treatment prior to disposal. A stringent health

| and safety program would be instituted due to the potential

of worker exposure and contaminant migration from the Site

' during construction. Impacts to adjacent lands and

j facilities could not be significantly reduced during the

contaminated soil excavation process.

IPotential long-term environmental, public

* health and institutional impacts are mitigated through proper

f monitoring and operation of the CF.

I67

I

I 3.4.1.2 Physical Containment

I Physical containment of contaminated areas

involves securing in place "hot spots" by constructing a

« perimeter barrier wall having low permeability around the

f area of contamination. The barrier wall would be founded in

an underlying low permeability formation. This perimeter

| barrier wall would, therefore, restrict further migration of

contaminants off site.

j This alternative does not address the removal

of the source of contaminants but rather, effectively

1 contains the source of groundwater contamination within the

perimeter barrier wall, and thereby minimizes the potential

< for future migration of contaminated groundwater off site.

f The area within the perimeter barrier wall will be restricted

from future site usage. Monitoring of the barrier wall will

[ be required to ensure maintenance of its low permeability and

its effectiveness at containing the contaminated groundwater.

' Removal of contaminated contained groundwater to the degree

/ necessary to maintain an inward hydraulic gradient would be

accomplished by pumping. Collected waters may require

1 treatment prior to discharge.

* Potential risk of contaminant exposure to

f on-site workers, the general public and the environment would

not be as great as for the soil excavation alternative, sinceii

J the volume of soil excavated during the perimeter barrier

wall construction is substantially reduced. A less stringent

I health, safety and air monitoring program would be required

r in comparison to the excavation alternative.

f Long-term environmental, public health and

institutional impacts would be mitigated through proper

\ monitoring and maintenance of the perimeter barrier wall.

( ̂j 3.4.1.3 Hydraulic Containment

I Hydraulic containment involves the

• installation of a series of extraction wells to manipulate

the flow pattern of the groundwater regime. By extracting

I groundwater from the extraction wells, the groundwater flow

pattern is controlled, and the potential for migration of

1 contaminated groundwater beyond the extraction well system is

I minimized.

f The extracted contaminated groundwater is

replaced by better quality water from the surrounding

I aquifer, and over a period of time the contaminants adsorbed

j to the soils in the aquifer will be flushed out. This

alternative, therefore, physically removes the source of

j contaminants from all areas within the hydraulic influence of

the extraction wells and in turn provides a hydraulic control

1 to prevent off-site migration of contaminants.

69I

This alternative requires the shortest

construction period and results in the least amount of Site

disturbance, thereby mitigating the potential of contaminant

exposure to on-site workers/ the general public and the

environment.

The hydraulic containment alternative

requires implementation for a specific time period only,

after which the entire Site area will be returned to normal

use. Therefore, potential long-term environmental, public

health and institutional impacts are eliminated.

Combining a low-permeability soil cover with

hydraulic containment has the same effect as described for

physical containment in Section 3.4.1.2.

3.4.1.4 Groundwater Treatment and Groundwater Disposal

The following discussions on groundwater

treatment and groundwater disposal are combined since the

degree of treatment determines the alternate methods of

disposal. Considering the technical feasibility and the

environmental, public health and institutional impact

criteria, the potential alternatives for ultimate disposal of

extracted contaminated groundwater include the following:

70

I 1. no treatment with direct discharge to a surface water

body,

j 2. no treatment with direct discharge to a POTW,

. 3. treatment and subsequent discharge to a surface water

' body, and

| 4. treatment and subsequent discharge to a POTW.

1 It is understood that institutional

, guidelines will permit direct discharge to a surface water

^ body if the concentration of TCE in the discharge is less

1 than the 10~5 excess cancer risk criterion (28 ppb).

Therefore, this criterion has been used to determine the

j degree of treatment required prior to discharge to a surface

, water body. Implementation of this alternative would require

a National Pollutant Discharge Elimination System (NPDES)

( permit for the point of discharge of the treated effluent.

1 The Metropolitan Waste Control Commission

/ (MWCC) has permitted direct discharge of VOC contaminated

groundwater into the POTW system during the remedial work

( performed at the Site in 1983. Recent discussions with MWCC

staff indicate, within certain concentration (20 parts per

[ million) and volume limits, that this practice is currently

I acceptable. A formal proposal of the discharge program would

be required to be submitted to the MWCC for approval.

L71

Both discharge to a surface fresh water body

and to a POTW are technically feasible for the Site as both a

storm sewer system and a sanitary sewer system transverses

the Site. Provided the regulated concentration and volume

parameters established by the controlling authority are

adhered to, the environmental, public health and

institutional impacts will be minimal.

Air stripping can effectively reduce

concentrations of TCE contaminantion to less than 28 ppb,

and, therefore, treatment by air stripping alone can satisfy

the treatment and subsequent discharge requirements for a

fresh water body. Discussions with MPCA staff indicate that

the State of Minnesota may not require treatment of the air

emitted from the air stripping treatment system, provided

that the total VOC mass discharged into the atmosphere from

the stripping tower is below one ton per year. If this limit

is exceeded, treatment of the discharged gases by carbon

adsorption may be required. Section 4.4 discusses further

the permitting requirements for the treatment facility.

Treatment prior to direct discharge to a POTW

would be required if the contaminated groundwater exceeds the

direct discharge quality criteria of the POTW. This

condition is not anticipated for the extracted contaminated

groundwater from the Site.

72

3.4.1.5 Alternate Water Source Supply

This alternative is identified for

consideration only as an interim response action if there is

an immediate concern for a potential receptor. No immediate

receptor concern has been identified, and, therefore, this

alternative requires no further consideration at this time.

3.4.2 Preliminary Cost Assessment of PotentialRemedial Alternatives

I This section provides a relative cost

comparison of the assembled potential remedial alternatives.

j Elements common among all alternatives are not included in

this cost assessment. The costs presented in this section,

' therefore, are not intended to represent actual detailed

j construction cost estimates.

| Since all of the assembled potential remedial

alternatives extract contaminated groundwater to some degree,

<- a preliminary relative cost assessment of groundwater

j treatment and disposal alternatives is required to select a

treatment and disposal method which may be applied to each of

I the assembled potential remedial alternatives. Preliminary

relative groundwater treatment and disposal costs have been

*- determined for various flow rates and various time periods,

73

I and are presented in Figure 2. These costs are based on the

following assumptions:

I. i) on-site treatment is provided by air stripping designed

' to achieve an effluent TCE concentration of less than 28

Treated waters are discharged to the Mississippi

River via the existing storm sewer system. An initial

I capital cost has been assigned to the air stripping

treatment facility with subsequent treatment costs

' ^ assessed conservatively at $0.10/1,000 gallons,

Iii) direct discharge is permitted to the on-site sanitary

j sewer system with no pretreatment . Discharge costs are

assessed at $1.00/1,000 gallons as charged by the MWCC,

' and

Iiii) future costs are returned to a 1985 present worth costs

j using a six percent net discount factor.

' Table 3 summarizes the selected method of

j effluent discharge following treatment by air stripping based

on effluent flow rate. The cost assessments of the potential

] remedial alternatives as discussed in Sections 3.4.2.1 and

3.4.2.3 will apply the relative treatment and disposal

* alternatives selected on the basis of analysis of the

| information summarized in Table 3. A summary of all relative

costs estimated for the potential remedial alternatives

iI

PRESENT WORTH RELATIVE COSTS ($ X 10s) 6 % DISCOUNT FACTOR

Cl

o:oo zom

Im

1355Ilia>)I>02:g-\u>rr}§ m>z^ 3)r H

TABLE 3

SELECTED TREATMENT AND DISPOSAL METHOD_____FOR CONTAMINATED GROUNDWATER

FMC CORPORATIONMINNEAPOLIS, MINNESOTA

Pumping Rate BelowWhich Discharge to

POTW With NoTreatment is

Selected, and AboveInitial Design Total Pumping Which Treatment by

Flow Rate for Air Period Required Air Stripping andStripping Treatment for 20 Pore Discharge to Storm

Facility Volume Changes Sewer is Selected_______(GPM)_______ (YEARS) _______(GPM)________

30 2 50

30 4 24

30 11 12

30 20 9

100 2 68

100 4 37

100 11 17

100 20 13

LII

generated is presented in Table 4. Appendix A presents a

detailed cost summary for each of the alternatives summarized

in Table 4.

3.4.2.1 BNR Lands Assembled Potential RemedialAlternatives

i) Alternative BNR 1 - Excavation and Disposalin a Containment Facility_______________

This alternative involves constructing a

below grade, double lined, containment facility (CF) within

the FMC lands with a capacity for approximately 50,300 cubic

yards of contaminated soil; excavating and stockpiling

approximately 66,100 cubic yards of uncontaminated overburden

from the BNR lands; dewatering and excavating the

contaminated saturated soils from the BNR lands and placing

of these soils in the CF; backfilling the excavation in the

BNR lands with uncontaminated material from the BNR lands

overburden excavation and CF excavation stockpiles; obtaining

the balance of required backfill material from off-site

borrow pits; surface restoration of approximately ten acres;

and disposal by discharge to the POTW of approximately 3.1

million gallons of water generated by dewatering. Figure 3

illustrates the identified area of contamination to be

excavated and the proposed location of the CF.

75

TABLE 4

ESTIMATED COST SUMMARY OF REMEDIAL ACTION ALTERNATIVES

FMC CORPORATIONMINNEAPOLIS, MINNESOTA

Total CapitalRemedial Action Alternative Construction Cost

1. Excavation of contaminated soilsfrom BNR lands with disposal inconstructed CF on FMC lands $4,644,880

2. a) Hiyaleal containment of BNRlands with soil-bentonitecontainment wall and no cap 1,003,550

b) Ihysical containment of BNRlands with soil-bentonitecontainment wall and clay cap 1,125,645

3. Hydraulic containment of BNR lands 216,180

4. Ihysical containment of FMC landswith grout curtain wall 5,197,945

491,755

Operation, Maintenance and Monitoring Cost______Total Present

Worth CostCapital Cost

$15,000

18,000

18,000

18,000

48,000

48,000

Annual Cost

$71,840

54,340first 5 years

43,340remaining 15 years

57,818first 5 years

45,818remaining 15 years

72,900

62,144first 5 years

42,144remaining 15 years

77,500

$988,880 for30 yearperiod

536,185 for20 yearperiod

576,075 for20 yearperiod

133,625 for2 yearperiod

567,630 for20 yearperiod

5. Hydraulic containment of FMC lands

worth value for annual operation, maintenance and monitoring costs calculated at a six percent discount rate.

611,245 for11 yearperiod

Total RemedialAlternative Cost

$5,648,760

1,557,735

1,719,720

367,805

5,813,575

1,151,000

The relative capital cost of Alternative

BNR 1 is estimated to be $4,644,880. Table A.I presented in

Appendix A provides a summary of work required to implement

this alternative with associated relative costs.

Operation, maintenance and monitoring costs

of Alternative BNR 1 are estimated at $15,000 for initial

capital costs and $71,840 per year as shown in Table A.I.

These operation, maintenance and monitoring costs will be

incurred for an indefinite period of time. The present worth

value over a 30 year period at a six percent net discount

rate is $988,880, giving a total relative present worth cost

of $5,648,760 for Alternative BNR 1.

ii) Alternative BNR 2a - Physical Containment Utilizinga Soil-Bentonite Contained Wall

This alternative involves construction of a

soil-bentonite containment wall approximately 1,200 feet long

and 36 feet deep and installation of one extraction well to a

depth of 35 feet, as shown on Figure 4.

The estimated pumping rate for the extraction

well would be 0.57 GPM and the estimated concentration of

TCE in the extracted groundwater would be 13,500 ppb during

the first year of pumping. Based on this concentration and

flow rate, the selected treatment and disposal alternative

76

for the extracted groundwater is direct discharge to a POTW.

Since the pumping rates are relatively low, a holding tank

with a 14 day capacity and a connection to the existing

on-site sanitary sewer are provided in the relative cost

estimate.

The relative capital cost of Alternative BNR

2a is estimated at $1,003,550. Table A.2a, Appendix A

provides a summary of work required to implement this

alternative with respective costs.

Operation, maintenance and monitoring costs

of Alternative BNR 2a are estimated at $18,000 for initial

capital cost and $54,340 to $42,340 per year as shown in

Table A.2a. These costs provide for monitoring and

maintenance of the containment wall and extraction well, and

charges from the POTW for discharging contaminated

groundwater to the sanitary sewer system. These operation

and maintenance costs will be incurred for an indefinite

period of time. The present worth value over a 20 year

period at a six percent net discount rate is $536,185, giving

a total estimated relative present worth cost of $1,557,735

for Alternative BNR 2a. Table 4 summarizes the total*

remedial alternative cost.

77

iii) Alternative BNR 2b - Physical Containment Utilizinga Soil-Bentonite Containment Wall with a LowPermeability Soil Cap_________________________

This alternative involves construction of a

soil-bentonite containment wall and one extraction well

similar to that for Alternative BNR 2a with the addition of a

low-permeability soil cap covering the 59,000 square foot

affected area of the BNR lands. The low permeability soil

cap involves pregrading the affected area of the Site to a

minimum grade of three percent, placing a 2-foot thick layer

of clay, placing a 6-inch deep sand layer over the clay,

placing a 3-foot thick layer of common fill over the sand,

placing six inches of topsoil over the entire surface, and

revegetating the area.

Due to the low-permeability soil cover, the

estimated average pumping rate for the extraction well is

reduced from 0.57 GPM for Alternative BNR 2a to 0.01 GPM at

an average estimated concentration of 13,500 ppb TCE during

the first year. Based on this concentration and flow rate,

direct discharge to a POTW is the selected treatment and

disposal alternative for the extracted groundwater. Since

the pumping rates are extremely low, a holding tank with a

90-day capacity, and a connection to the existing on-site

sanitary sewer is provided in the relative cost estimate.

78

The relative capital cost of Alternative BNR

2b is estimated at $1,125,645. Table A.2b, Appendix A,

provides a summary of work required to implement this

alternative with respective costs.

Operation, maintenance and monitoring costs

of Alternative BNR 2b are estimated at $18,000 initial

capital cost and $57,818 to $45,818 per year as shown in

Table A.2b. These provide for maintenance of the low

permeability soil cover in addition to the operation and

maintenance items identified for Alternative BNR 2a. These

operation, maintenance and monitoring costs will be incurred

for an indefinite period of time. The present worth value

over a 20 year period at a six percent net discount rate is

$576,075, giving a total relative present worth cost of

$1,719,720 for Alternative BNR 2b. Table 4 summarizes the

total remedial alternative cost.

iv) Alternative BNR 3a - Hydraulic Containment UtilizingExtraction Wells

This alternatve consists of installing two

extraction wells to an average depth of 35 feet, and

installing 360 lineal feet of collection piping, as shown on

Figure 5.

79

The estimated combined pumping rate for the

two extraction wells is 30 GPM and the estimated average

concentration of TCE is 4,000 ppb during the first pore

volume extracted. The total time of pumping required to

achieve a 20 pore volume change over is estimated at two

years. Based on the pumping rate, TCE concentration and

pumping period, direct discharge to a POTW is the selected

treatment and disposal alternative for the extracted

groundwater. The relative cost estimate, therefore, provides

for direct discharge to the on-site sanitary sewer system.

The relative capital cost of Alternative BNR

3a) is estimated at $216,180. Table A.3, Appendix A,

provides a summary of work required to implement this

alternative with relative costs.

Operation, maintenance and monitoring costs

for Alternative BNR 3a) are estimated at $18,000 for initial

capital costs and $72,900 annual costs as shown in Table A.3.

These provide for monitoring and maintenance of the

extraction wells, and charges from the POTW for effluent

discharge to the sanitary sewer system. These operation,

maintenance and monitoring costs will be incurred for an

estimated two year period only, after which time the system

is no longer required. The present worth value over a two

year period at a six percent net discount rate is $133,625,

giving a total present worth cost of $367,805 for Alternative

80

BNR 3a). Table 4 summarizes the total remedial alternative

cost.

The potential alternative of combining

reinjection with the extraction well system for the BNR lands

is not economically justified since the installation costs

alone of the injection well system far exceed the total

present worth operation, maintenance and monitoring costs for

the extraction well system. Therefore, the reinjection

alternative does not require further consideration.

v) Alternative BNR 3b - Hydraulic Containment UtilizingExtraction Wells with a Low Permeability Soil Cap

The addition of a cap would effectively

reduce the pumping rate of the extraction well system by 0.46

GPM over the estimated two-year period of operation. The

present worth cost for disposal of the volume of water not

pumped due to the installation of a clay cap is less than

?1,000. Therefore, it is apparent that the low-permeability

soil cap would not be economically justifiable when combined

with a hydraulic containment system. This alternative,

therefore, warrants no further consideration.

81

3.4.2.3 FMC Lands Assembled Potential RemedialAlternatives

i) Alternative FMC 1 - Physical Containment UtilizingA Grout Curtain

This alternative involves construction of a

grout curtain wall approximately 3,000 feet in length and 135

feet in depth and installation of one extraction well to a

depth of approximately 135 feet, as shown on Figure 4.

The estimated pumping rate for the extraction

well would be 0.15 GPM with an estimated concentration of

TCE within the extracted groundwater of 95 ppb. The

selected treatment and disposal method for this volume and

concentration is direct discharge to the POTW. Since the

volume of water extracted is low, a 90-day capacity holding

tank and a discharge outlet to the on-site sanitary sewer

system is provided in the relative cost estimate.

The relative capital cost of Alternative FMC

1 is estimated at $5,197,945. Table A.4, Appendix A,

provides a summary of work required to implement this

alternative and relative costs.

Operation, maintenance and monitoring costs

of Alternative FMC 1 are estimated at $48,000 initial capital

82

costs and $62,144 to $42,144 per year as shown in Appendix A

on Table A.4. These annual costs provide for monitoring and

maintenance of the grout curtain wall and extraction well,

and charges from the POTW for effluent discharge to the

sanitary sewer system. These operation, maintenance and

monitoring costs will be incurred for an indefinite period of

time. The present worth value over a 20-year period at six

percent net discount rate is $567,630, giving a total

relative present worth cost of $5,813,575 for Alternative FMC

1.

ii) Alternative FMC 2 - Hydraulic Containment UtilizingExtraction Wells

This alternative consists of installing six

extraction wells to an average depth of 135 feet and

installing 950 lineal feet of collection piping, as shown on

Figure 6.

The estimated combined pumping rate for the

six extraction wells would be 95 GPM with an estimated

average concentration of TCE within the extracted groundwater

of 500 ppb during the first pore volume extracted. The total

time of pumping required to achieve a 20 pore volume

extraction is estimated at 11 years. Based on this pumping

rate, estimated TCE concentration and pumping period, the

appropriate treatment and disposal method is on-site

83

treatment by air stripping designed to a 95 percent VOC

removal efficiency, with subsequent disposal of treated

waters to the on-site storm sewer system. The relative cost

estimate, therefore, provides for an air stripping treatment

system with subsequent effluent discharge to the storm

sewer.

The relative capital cost of Alternative FMC

2 is estimated at §455,025. Table A.5, Apendix A, provides a

summary of work and associated costs required to implement

this alternative.

Operation, maintenance and monitoring costs

for Alternative FMC 2 are estimated at $48,000 for initial

capital costs and $77,500 per year as shown in Table A.5.

These provide for monitoring and maintenance of the

extraction wells, and operation and maintenance of the air

stripping treatment system. These operation and maintenance

costs will be incurred for an 11 year period only, after

which the system is no longer required. The present worth

value over an 11 year period at a six percent net discount

rate is $611,245, giving a total present worth of $1,151,000

for Alternative FMC 2. Table 4 summarizes the total remedial

alternative cost.

Combining reinjection with the extraction

well system can effectively reduce the required time of

84

pumping to produce a 20 pore volume extraction by

approximately 50 percent. This would realize a net present

worth savings in the operation, maintenance and monitoring

costs of the extraction well system of $94,460. This saving

is well below the estimated cost to install, operate and

maintain an injection well system. Therefore, the reinjection

alternative does not require further consideration with

respect to cost for the FMC lands.

3.5 SELECTED REMEDIAL ALTERNATIVES

Section 3.3 assembled potential remedial

alternatives based on achieving the primary criterion of

reducing the concentration of TCE in groundwater to less 2.8

ppb at the Site boundary. Potential remedial alternatives

were generated separately for the BNR lands and the FMC

lands.

On the basis of the discussion presented in

Section 3.4.1, technical feasibility, and environmental,

public health, institutional impacts criteria and cost, the

extraction well hydraulic containment alternative is the

appropriate remedial alternative applicable to both the BNR

and FMC lands. The extraction well hydraulic containment

alternative for the combined Site is primarily selected for

the following reasons:

85

1. minimal time and Site disturbance is required to

construct the extraction well system, thereby minimizing

short-term health and environmental impacts,

2. the source of contamination is removed from the

groundwater regime, thereby eliminating future potential

impacts on public health or environment,

3. contaminants are removed within the hydraulic influence

of the extraction wells, and

4. since contaminants are removed from the groundwater

regime, the system only requires implementation for a

specific period of time, after which the Site may be

fully restored and returned to normal unrestricted

usage.

On the basis of the discussion presented in

Section 3.4.2, the extraction well hydraulic containment

alternative would again be the selected remedial alternative

for both the BNR lands and the FMC lands. The selected

treatment and disposal alternative of contaminated

groundwater from the BNR lands was identified as direct

disposal to the on-site sanitary sewer system without

pretreatment, and for the FMC lands, treatment by air

stripping and subsequent disposal to the on-site storm sewer

system. However, should remediation of the BNR and FMC lands

86

occur concurrently, it is realized that an air stripping

treatment system will be provided for treatment of extracted

contaminated groundwater on the FMC lands, and, therefore,

the initial capital cost for hydraulic containment of the BNR

lands may be reduced by utilizing a common air stripping

system. In addition, treatment/disposal costs for the BNR

extracted groundwater would be reduced by an estimated

$14,000 per year.

Based on the above discussion, the

discussion presented in Sections 3.4.1 and 3.4.2, and

considering simultaneous implementation of the remedial

alternatives for the BNR lands and the FMC lands, the

selected remedial atlernative to reduce the concentration of

TCE in the groundwater to less than the 10~6 excess

cancer risk criterion at the Site boundary is the extraction

well hydraulic containment alternative with air stripping of

extracted groundwater and subsequent treated effluent

discharge to the Mississippi River via the on-site storm

sewer.

87

4.0 DISCUSSION OF HYDRAULIC CONTAINMENT ALTERNATIVE ATEVALUATION LOCATIONS

4.1 SCOPE

A qualitative review of remedial

technologies and a further quantitative review of appropriate

remedial alternatives combining preferred technologies have

identified that hydraulic containment with some form of

treatment and/or disposal is the most appropriate alternative

to reduce the off-site migration of VOCs in Site groundwater,

specifically TCE, to the 10~6 excess cancer risk

criterion at the Site boundary. This section discusses in

detail the technology of hydraulic containment and how,

through adjustments to extraction well pumping rates,

10~6 and 10 excess risk criteria can be attained

at each of the evaluation locations stipulated by the

Agencies. These Agency stipulated evaluation locations are:

- the Site boundary,

the Anoka County property,

the Mississippi River shoreline, and

the Minneapolis Water Works.

A present worth summary for the hydraulic

containment alternative at each evaluation location, for both

the 10~" and 10 excess cancer risk criteria, is

presented in Table 5. A detailed cost breakdown for each of

these alternatives is presented in Appendix B.

88

TABLE 5

SUMMARY OP ESTIMATED COST FOR HYDRAULIC CONTAINMENT REMEDIAL ACTION ALTERNATIVESTO ACHIEVE 10~6 and 10~5 RISK LEVELS AT STIPULATED EVALUATION LOCATIONS

Risk Level Achieved at Total CapitalEvaluation Point Construction Cost

1.

2.

3.

4.

5.

6.

7.

10~6 at Site boundary $576,745

10~5 at Site boundary 576,745

10~ at County lands 576,745

10" at County lands 576,745

10~6 at river shoreline 576,745

10~5 at river shoreline 184,520

10 at Water Works intake

FMC CORPORATIONMINNEAPOLIS, MINNESOTA

Operation, Maintenance and Monitoring Cost

Annual Cost Annual Cost Total Present Total RemedialCapital Cost FMC Lands BNR Lands Worth Cost Alternative Cost

$66,000 $79,900 $24,850 $675,720 $1,318,465

66,000 79,400 24,850 671,780 1,314,525

66,000 79,400 24,850 671,780 1,314,525

66,000 73,000 24,850 621,300 1,264,045

66,000 73,000 24,850 621,300 1,264,045

66,000 34,000 41,120 465,355 715,875

66,000 53.000 607,910 673,910

8. 10~5 at Water Works intake same as 10 risk level Water Works intake

Notes;

1. Annual operation, maintenance and monitoring costs for FMC lands calculated for 11 year period.2. Annual operation, maintenance and monitoring costs for BNR lands calculated for 2 year period.3. When no remedial action is provided, groundwater monitoring program carried out for 20 year period.4. Present worth costs calculated at a net discount rate of six percent.

4.2 DESCRIPTION OF HYDRAULIC CONTAINMENT TECHNOLOGY

Hydraulic containment has been selected as

the most appropriate technology to restrict off-Site

contaminant migration to predefined limits. The following is

a discussion of the technology and the approach used to

assess the effectiveness of hydraulic containment.

To prevent effectively the off-site migration

of VOC contamination in the groundwater beneath the Site,

evaluated wells were located at contaminant "hot spots" in

the BNR and FMC lands. Where theoretically required,

additional wells were sited at intermediate distances between

the "hot spots". Therefore, for the FMC lands, an adequate

hydraulic containment system would consist of six wells with

uniform spacing of 190 feet, while for the BNR lands, two

wells spaced 170 feet apart would contain the flow system.

The approximate location of these wells is illustrated on

Figure 6. The aquifer properties for each site, as presented

in Table 6, were averaged over the area of influence of the

wells.

The area of capture for each of the wells was

defined as the distance to a point downgradient from the

proposed well where the ambient groundwater velocity was

equal, but opposite in direction to the velocity induced by

pumping. On the basis of this definition, the pumping rate

89

TABLE 6

AVERAGE AQUIFER PROPERTIES

BNR Lands FMC Lands

Transmissivity (f t2/<jay) 3450 780* (well 29)*

Aquifer Thickness (ft.) 15 70

Permeability (ft/day) 230* 11.1

Hydraulic Gradient 0.0016* 0.0065 (well 15)*

Groundwater Velocity (ft/yr) 134.3 26.43

* "Final Report - Phase I and II Investigation Programs",S.S. Papadopulos & Associates Inc., August 1984

of each well was determined. This resulted in a pumping rate

of 15.8 GPM for each of the six wells on the FMC lands, for a

total pumping rate of approximately 95 GPM. Similarly/ for

the BNR lands, a rate of 15.0 GPM for each well and a total

pumping rate of 30.0 GPM was determined to provide

containment. Solving the Jacobs (Groundwater, Freeze &

Cherry) equation for drawdown at a distance from a pumping

well gives a total of 2.14 feet of drawdown midway between

pumping wells on the FMC lands. Similarly, for the BNR

lands, a total drawdown of 0.70 feet midway between the

pumping wells was calculated.

Under the described conditions of pumping,

the flux of water passing off Site towards the river is zero

and the contaminant mass flux leaving the Site is zero.

Under these conditions, a 10~6 excess cancer risk

criterion is achieved at the Site boundary.

To achieve a groundwater contaminant

concentrations equivalent to the 10"̂ and 10"̂

excess cancer risk criteria at each of the evaluation

locations, flow rates of the extraction well systems

identified above were adjusted to provide partial hydraulic

containment. A number of assumptions were employed to

determine the pumping rates to effect partial hydraulic

containment in order to meet excess cancer risk criteria at

each evaluation location.

90

Contaminant concentrations measured at

existing wells were assumed to be representative of the total

volume of aquifer influenced by any pumping well constructed

at, or directly adjacent to the existing wells. It was

concluded in the Feasibility Study submitted to the Agencies

in January 1985 that on-site contamination is unlikely to be

distributed throughout the whole vertical thickness of the

aquifer. Similarly, the combined effects of dilution,

dispersion and retardation serve to significantly reduce

contaminant levels within a short distance from the source.

Therefore, assuming a uniform distribution of contaminants

over the volume of aquifer influenced by any one well leads

to a conservative estimate of the total contaminant mass.

If the VOCs in the groundwater were

uninfluenced by reaction with the porous media, the removal

of one pore volume of water by pumping would remove the

majority of the contaminant mass from the area of pumping

influence. However, since adsorption phenomena cause a

retardation in the rate of contaminant migration, more than a

single flushing of the aquifer would be required to reduce

VOC concentrations to desired levels. It was concluded from

field experiments conducted near Ottawa, Canada (Gloucester

Project, National Hydrology Research Institute) that flushing

of 27 pore volumes could effectively remove 90 percent of the

TCE mass within that aquifer.

91

Other studies being done at a hazardous waste

site in Ohio, lead to the conclusion that from 10 to 20 pore

volumes would be required to flush 99 percent of the VOC

contaminant mass from the aquifer. For purposes of this

report, it was assumed that 20 pore volumes would remove 99

percent of the aquifer VOC contaminant mass. An assumed

desorption decay curve has been constructed and is presented

in Figure 7. A site specific desorption decay curve should

be generated from laboratory simulations conducted on samples

of aquifer materials obtained from this site before final

design for a hydraulic containment system is undertaken.

Figure 7 shows that an estimated 16 percent

of the TCE mass is removed in the first pore volume pumped

from the aquifer. One pore volume was calculated by

determining the volume of the aquifer influenced by pumping

and then multiplying that volume by an assumed porosity of

0.30. A porosity of 0.30 is considered typical for the soil

types found at the Site. Sixteen percent of the total

contaminant mass in the volume of the aquifer influenced by

pumping was divided by the total volume pumped to arrive at

an average TCE concentration in the water pumped during

removal of the first pore volume. For the BNR lands, this

average concentration was calculated to be 4,000 ppb, and for

the FMC lands, an average concentration of 500 ppb was

calculated. These concentrations would decrease with

continued flushing as illustrated on Figure 7.

92

100

L

PERCENT TCE REMOVED

NORMALIZED TCE MASS

10

PORE VOLUMES

IS 20

CRA

figure 7ASSUMED RELATIONSHIP BETWEEN TCE REMOVAL

AND MASS vs. PORE VOLUMESFMC Northern Ordnance Plant

1918- 29/04/85

I The total contaminant mass was determined

from the average TCE concentrations in existing wells and

] extrapolated over that volume of the aquifer represented by

/ these wells. This total therefore does not consider the mass

of contaminant adsorbed onto the porous media within the

volume of the aquifer. It is expected however, that because

of the large volumes of aquifer considered as being

j represented by any one well, the resulting TCE concentration

, and mass is considered as conservative.

In order to meet the 10~5 excess cancer

risk criterion of 28 ppb for TCE, the pumping rates in the

1 extraction wells were reduced by a factor such that water

passing through the now incomplete hydraulic barrier would

have a concentration of 28 ppb. The reduced pumping rate was

I calculated by subtracting the design concentration from that

of the pumped water for each of the BNR and FMC systems.

| ^ This new value, when divided by the original concentration,

I yields the factor by which the pumping rate would be reduced

in the BNR and FMC hydraulic containment systems.

iBy this approach, the pumping rate of each

I well is similarly reduced to yield the desired contaminant

* concentrations by-passing the hydraulic containment system.

It is noted that different results would be achieved if the

total required reduction in pumping was obtained by reducing

the rate at any one well.

Ii 93

Existing research data suggest that VOC

concentrations in the groundwater decrease with travel

distance from the contaminant source. The Feasibility Study

inferred from the existing concentrations observed in wells

downgradient of the Site that the concentrations of TCE in

the groundwater are reduced by at least one to two orders of

magnitude in the County lands compared with concentrations at

the Site boundary. A further reduction of one order of

magnitude is achieved between the County lands and the

river.

This phenomenon, based on the observed

contaminant distribution downflow from Well 15, is also

applicable to the BNR lands. On the BNR lands, however, the

contaminants in the upper aquifer flow off site to the south

and then to the river by some undefined pathway. Dilution in

this aquifer is achieved through infiltration as well as by

mixing with waters from the lower aquifer where the

intervening clay layer is not present. Few data are

available to confirm concentration decreases downgradient in

this aquifer although the available data suggest that the one

to three order of magnitude reductions in contaminant levels

between the Site and the River may also be applicable to the

BNR lands.

A concentration of 280 ppb crossing the Site

boundary would, therefore, be reduced to 28 ppb (10~5

risk level) at the County lands and further reduced to

94

2.8 ppb (10~6 risk level) at the river. The pumping

rates required to achieve these concentrations are summarized

on Table 7.

4.3 EVALUATION LOCATIONS

4.3.1 Site Property Boundary

As described in Section 4.2, the hydraulic

containment system necessary to achieve the 10"̂ excess

cancer risk criterion at the Site boundary must prevent

off-site migration of groundwater contaminants from all

identified "hot spots". Obtaining the 10"̂ excess

cancer rate criterion at the Site boundary would essentially

require the same design, with only a slight reduction in

pumping rates to allow a small percentage of contaminants to

pass by the hydraulic containment system.

It was assumed in Section 4.2 that removal of

20 pore volumes of groundwater from beneath the Site will

effectively reduce existing contaminant mass within the

aquifer by 99 percent. On this basis, a total pumping rate

of 125 GPM has been determined in order to remove 20 pore

volumes from the FMC and BNR lands to maintain the 10~6

excess cancer risk criterion at the Site boundary. This

total pumping rate requires a pumping rate of 30 GPM to be

maintained at the BNR extraction wells for two years, and a

95

TABLE 7

SUMMARY OF REQUIRED PUMPING RATES FOR EXTRACTION WELLFOR HYDRAULIC CONTAINMENT SELECTED REMEDIAL ACTION ALTERNATIVE

PMC CORPORATIONMINNEAPOLIS, MINNESOTA

Pumping Ratesfor Hydraulic Containment

(GPM)Combined Hydraulic Containment for FMC Lands and BNR Lands

To achieve 20 pore

PMC LandsArea

95

90

90

45

45

0

0

BNR LandsArea

30

30

30

30

30

15

0

Pumping Rate(GPM)

125

120

120

75

75

15

0

Tr ich loroethyleneConcentration'

(ppb)

1340

1375

1375

1900

1900

4000

-

volume

Pumping Rate(GPM)

12595

12090

12090

7545

7545

15

0

flushings

Time( years )

first 2 yearsremaining 9 yearsfirst 2 years

remaining 9 years

first 2 yearsremaining 9 yearsfirst 2 years

remaining 9 years

first 2 yearsremaining 9 years

2 years-

RISK LEVEL AT RECEPTOR

10 at property boundary

10 at property boundary

10 at county lands

10 at county lands

10 at river shoreline

10 at river shoreline10~6 at river intake

1. Average concentration of trichloroethylene in first pore volume is 500 ppb. Pumping period is 11 years for 20 pore volume flushings.2. Average concentration of trIchloroethylene in first pore volume is 4000 ppb. Pumping period is 2 years for 20 pore volume flushings.3. Average concentration of trichloroethylene in combined extracted groundwater during first pore volume.

pumping rate of 95 GPM to be maintained at the FMC extraction

wells for 11 years. Pumping at these rates would result in

total extracted groundwater contaminant concentrations of

1,340 ppb TCE in the first extracted Site pore volume.

The pumping rate required to obtain the

10~5 excess cancer risk criterion at the Site boundary

would be reduced to 120 GPM from both the FMC and BNR lands.

A 20 pore volume extraction at this pumping rate would

require the BNR system to operate for two years at 30 GPM and

the FMC system to operate for 11 years at 90 GPM. Pumping at

this reduced rate would result in a total extracted

groundwater contaminant concentration of 1,375 ppb TCE in the

initial pore volume.

It is noted that the concentrations of TCE

identified above are determined on the basis of removal of

the first pore volume of groundwater. These concentrations

will reduce as subsequent pore volumes are removed. (See

Section 4.2).

On the basis of the estimated contaminant

concentrations in the extraction waters, and the proposed

extraction well pumping rates, an air stripping treatment

facility would be incorporated into the remedial system

design. The air stripping unit would be designed for either

the 125 GPM or the 120 GPM extraction well pumping rates with

a removal efficiency of 98 percent for TCE. Following

96

treatment by air stripping, effluent would ultimately be

discharged to the on-site storm sewer system. Section 4.4identifies permitting requirements for this proposedtreatment facility.

Implementation of the hydraulic containment

and treatment system necessary to obtain the 10 and

10~"5 excess cancer risk criteria at the Site boundarywould require a capital expenditure of $576,745 as shown onTable 5. This cost includes all facility construction costs,

a 25 percent contingency, and all engineering and inspectionnecessary to supervise the construction and implement the

system. In addition to the initial capital costs, annualoperation, maintenance and monitoring costs would be incurredfor an off-Site groundwater monitoring program to monitor the

efficiency of the hydraulic containment system. Annual costswould also be incurred for operation of the groundwater

treatment and discharge system. The annual costs are

estimated to be approximately $104,750 per year for the firsttwo years of system operation, falling to approximately$79,900 per year for the remaining nine years of system

operation. Thus, the present worth system costs to achieve

the 10~" and 10 risk levels assuming a netdiscount rate of six percent, are estimated to be $1,318,465and $1,314,525, respectively. The small cost differential

between these two risk level alternatives reflects the

reduced pumping rates for the 10~̂ risk level system. Asummary of estimated cost is presented in Table 5. Adetailed cost estimate breakdown for each alternative ispresented in Tables B.I and B.2 of Appendix B.

97

I 4.3.2 Anoka County Lands

J The remedial action to be implemented to

. achieve the 10~° excess cancer risk criterion at the

' Anoka County lands located between the Site and the

I Mississippi River, would be similar to that proposed to' _e

obtain the 10 excess cancer risk criterion at the Site

J boundary. All capital costs and annual operation,

maintenance and monitoring costs, are the same as estimated

' ^ in Section 4.3.1 for the 10~5 excess cancer risk

I criterion. A summary of these estimated costs is presented

in Table 5. Table B.3 presented in Appendix B provides a

| detailed cost estimate for this alternative.

The 10~5 excess cancer risk criterion at

f the Anoka County lands would be achieved by reducing the

pumping rate in the Site extraction well system, thus

j ^ allowing a larger percentage of contaminated groundwater to

. pass off site. This alternative provides for a reduction in

total pumping rates to 75 GPM. This revised pumping rate

| would include pumping from the BNR lands for 2 years at 30

GPM and pumping from the FMC lands for 11 years at 45 GPM.

( The resultant concentration of TCE in the extracted

groundwater at these pumping rates would be approximately

1,900 ppb for the first pore volume extracted.

98

This alternative would require the

construction of an air stripping facility designed for a

total flow of 75 GPM with a VOC removal efficiency of 99

percent. Following treatment by air stripping, treated

effluent would be discharged to the on-site storm sewer.

General permitting requirements for implementation of this

system are discussed in Section 4.4.

Capital construction costs to implement this

containment and treatment system are estimated to be

$576,745 as shown on Table 5. This cost includes all

construction costs to construct the system, a 25-percent

contingency, and all engineering required for design and

supervision of the construction and implementation of the

system. Additional costs associated with this alternative

include estimated annual operation, maintenance, and

monitoring costs on the order of ?97,850 for each of the

first two years of operation and $73,000 for each of the

remaining nine years. These annual costs represent costs

associated with implementing a groundwater monitoring program

to monitor the effectiveness of the containment system, and

costs for maintaining the pumping and treatment system on an

annual basis. A summary of the estimated costs is presented

in Table 5. The total present worth cost of this

alternative, assuming a six percent net discount rate is

estimated to be $1,264,045. Table B.4 presented in Appendix

B provides a detailed cost summary of this alternative.

99

4.3.3 Mississippi River Shoreline

The 10~° excess cancer risk critierion

at the Mississippi River shoreline would be achieved with a

system identical to that required to achieve the 10"̂

excess cancer risk criterion at the Anoka County lands. All

capital costs and annual operation, maintenance and

monitoring costs are the same as presented in Section 4.3.2.

A summary of these costs is presented in Table 5. Table B.5

presented in Appendix B provides a detailed cost summary for

this alternative.

The 10~5 excess cancer risk criterion at

the Mississippi River would be achieved by a hydraulic

containment system pumping at a rate of 15 GPM from the BNR

lands only, for a total of two years. On the basis of the

one and two orders of magnitude decrease in groundwater

contaminant concentrations from the Site to the County lands

and from the Site to the river, respectively, as discussed in

the "Feasibility Study", no containment at the FMC lands

would be required. Pumping from only the BNR lands would

result in an estimated TCE concentration of 4,000 ppb in the

extracted initial pore volume.

Figure 2 presented in Section 3, indicates

that at a pumping rate of 15 GPM, it is cost effective to

discharge all extraction waters directly to the on-site

sanitary sewer. Discharging extraction waters directly to

100

the sanitary sewer will require an Agreement with or permit

from the MWCC. Section 4.4 discusses permitting options for

this alternative.

Capital construction costs associated with

this alternative are estimated to be $184,520 as shown on

Table 5. This includes all construction costs, a 25 percent

contingency, and all engineering required to design and

supervise the construction and implement the program. Annual

operation, maintenance and monitoring costs would be $75,120,

providing for a groundwater monitoring program to monitor the

levels and distribution of contamination downgradient of the

FMC lands for 20 years, and all operation, maintenance and

monitoring of the BNR extraction system for two years. A

summary of these estimated costs is presented in Table 5.

The total present worth value of this alternative, assuming a

six percent net discount rate, has been estimated to be

$715,875. Table B.6 presented in Appendix B provides a

detailed cost summary for this alternative.

4.3.4 Minneapolis Water Works Intake

It was concluded in the Feasibility Study

that risk levels for TCE at the Water Works intake

attributable to the Site, meet or are less than the 10-6

101

excess cancer risk criterion and that no remedial action is

required to mitigate risk. Therefore, the costs associated

with this alternative are associated with a long-term

groundwater monitoring program to monitor the levels and

distribution of contaminants leaving the Site.

The present worth cost of this alternative,

assuming a six percent net discount rate, is estimated to be

$673,910. This cost is based on an annual estimated

monitoring cost of $53,000 for a period of 20 years.

Table B.7 presented in Appendix B provides a detailed cost

summary for the annual monitoring requirements.

4.3.5 Residuals Followng System Shutdown

The effectiveness of the hydraulic containment system is

•^. based upon the assumption that 99 percent of the contaminant

I mass is removed from the aquifer by the extraction of 20 pore

volumes. Therefore, only one percent of the contaminant mass

| remains within the aquifer after the 20 pore volumes have

been removed. Any prediction of the resultant concentration

[ of TCE in the groundwater after removal of 20 pore volumes

i would be speculative. However, the rate of desorption is

likely to be much lower with the reduced TCE mass in the

aquifer indicating that concentrations within the groundwater

would be expected to be extremely low.

102

On the basis of there being limited

information available on this subject, it is not known if

this residual mass can be removed in a cost-effective manner

or in an reasonable length of time. A study of the curves

presented on Figure 7 suggest that removal would not be

cost-effective or would not be completed in a reasonable

length of time. This is evidenced by the curve flattening

out at 99 percent removal of the TCE mass in the aquifer. An

effective assessment of this residual concentration can be

made only after system implementation and water quality

monitoring.

4.4 PERMITTING REQUIREMENTS

4.4.1 General

The remedial action alternatives discussed in

Section 4.3 include two treatment and disposal options for

extracted groundwater. These options are: treatment by air

stripping with ultimate discharge of treated effluent to the

on-site storm sewer system; and direct discharge of extracted

groundwater to the on-site MWCC sanitary sewer with no pre-

treatment. Implementation of these treatment and disposal

options would require that FMC apply for the following

permits (or agreements) with the appropriate Agencies:

i) Discharge to the Mississippi

River via the storm sewersubsequent to treatment by

air stripping

- NPDES Permit issued

by MPCA, Division ofWater Quality

ii) Direct discharge to - Permit or agreement

sanitary sewer system with arranged with MWCC,

no treatment most probably based

on VOC limits in the

discharged water

iii) Discharge to atmosphere - Air quality permit

from air stripping tower issued by MPCA,

Division of Air

Quality.

The following sections discuss these permitting requirements

for each of the treatment and disposal options.

4.4.2 Fresh Water Body Discharge

Discharge of treated effluent from the air

stripping tower to the on-site storm sewer system would

require the preparation and submission of an NPDES permit.

This permit would be issued by the MPCA. In general, NPDES

permit applications require that discharge outfalls from

treatment or manufacturing facilities meet specified

discharge levels of defined parameters, and that the owners

must monitor the discharge for compliance.

Neither the USEPA or the MPCA presently have

standards to control VOCs in discharges; however, the MPCA

104

has, in the past, suggested that the 10"̂ excess cancer

risk criterion for TCE (28 ppb) may be appropriate for

discharges in the vicinity of the Site. Therefore, for the

treated effluent at the FMC Site, it has been assumed that

discharge levels of TCE would be maintained at or below 28

ppb. Treatment facilities proposed for each of the

alternatives presented in Section 4.3 have been designed for

removal efficiencies such that a TCE concentration no greater

than 28 ppb in the effluent discharge would be maintained.

Regular periodic monitoring of the NPDES permitted discharge

for VOC's probably would be required during the period that

treated effluent is being discharged through the storm sewer

to the Mississippi River.

4.4.3 Sanitary Sewer Discharge

Recent discussions with representatives of

the MWCC, and prior discharge activities approved by the MWCC

during the CTF construction program, suggest that discharge

of extracted groundwater to the local sanitary sewer would be

allowed subject to limitations on VOC effluent concentrations

and discharge rate. On the basis of discussions with MWCC

representatives, it is believed that discharge of extracted

groundwater with a TCE concentration of 4,000 ppb (4 ppm)

would be approved following submittal of a detailed proposal

to the MWCC. Effluent concentrations in excess of 20,000 ppb

105

i

(20 ppm) may not be approved by the MWCC for discharge to the

sanitary sewer system. However, any level of TCE discharge

would require negotiation of an Agreement with the MWCC.

4.4.4 Air Stripping Tower Discharge

During recent discussions with

representatives of the MPCA, Division of Air Quality, it has

^ been noted that permitting guidelines for air discharges do

I not currently exist for VOC's. However, MPCA representatives

indicated that a discharge of less than 500 pounds per year

of the criteria pollutants may not require a permit

. application. VOC discharges greater than 500 pounds per

' year, but less than one ton per year will require submittal

I of a permit application. However, these systems and the

associated emissions may not have a permit issued. An

I example of a similar case in the Twin Cities area is the Air

Stripping system currently in use at the General Mills (GM)

remediation site. MPCA representatives have stated that the

I GM stripper has an annual VOC emission less than one ton and

was not issued an air permit.

I• Calculations to determine the total mass of

' VOC potentially discharged from the air stripping tower for

I each of the alternatives discussed in Section 4.3 show that

106

between 560 pounds per year and 160 pounds per year organics

would be discharged to the atmosphere based on influent

concentrations of TCE between 1,340 ppb and 1,900 ppb,

respectively. The relationship between TCE and total VOC

concentration was determined from data available from

groundwater sampling completed at the Site to date.

Therefore, on the basis of these calculations and the recent

discussions with the MPCA, no secondary treatment would be

required for the stripped VOC's. An air permit would

probably not be issued.

107

5.0 CONCLUSIONS

1) As directed by the Agencies, an evaluation of existing

remedial action technologies and alternatives which would

reduce the VOC contaminant discharge in the groundwater

at the Site boundary to the 10-6 excess cancer risk

criterion was carried out. It was concluded that on the

basis of technical feasibility, environmental, public

health and institutional impact and cost, that hydraulic

containment with some form of treatment and/or disposal

would be the appropriate remedial alternative.

2) The hydraulic containment alternative was evaluated in

detail at each of the Agencie's/stipulated evaluation

locations. Pumping rates oetween 30 GPM and 15 GPM at

the BNR lands and between 95 GPM and 45 GPM at the FMC

lands were determined for each location to achieve the

10-6 an<j io"5 excess cancer risk criteria

respectively. The stipulated evaluation locations were

the Site Boundary, the Anoka County lands, the

Mississippi River shoreline and the Minneapolis Water

Works intake.

3) The impact of Site contaminants at the Minneapolis Water

Works intake was less than the 10 excess cancer

risk criterion under existing conditions; the appropriate

response action was determined to be long-term monitoring

for this evaluated location.

108

L

4) On the basis of the pumping rates determined at each

evaluation location, it was concluded that treatment byair stripping and subsequent discharge to the Mississippi

River via the on-site storm sewer was the appropriate

method of handling extracted groundwater to obtain

the 10-6 ana iQ-5 excess cancer risk criteria at

all of the evaluation locations except for the 10"5

excess cancer risk criterion at the Mississippi River

shoreline. It was concluded that direct discharge to the

on-site sanitary sewer was the appropriate method of

disposal for the 10-5 excess cancer risk criterion at

the river shoreline.

5) Estimated total present worth costs for each of the

hydraulic containment alternatives evaluated ranged from

a high of $1,318,465 to achieve a 10-6 excess cancer

risk criterion at the Site Boundary to a low of $715,875

to achieve a 10-5 excess cancer risk criterion at the

Mississippi River.

6) The estimated total annual groundwater monitoring costs

were estimated to be $53,000. Initial capital costs of

$66,000 to construct new monitoring wells and implement

the program were estimated. The annual monitoring costs

would be incurred for a total of 11 years to achieve the

10-6 excess cancer risk criterion at all the

evaluation locations except the Water Works intake, and

to achieve the 10"5 excess cancer risk criterion at

the Site Boundary and the Anoka County lands. The annual

109

monitoring costs would be incurred for a minimum of 20

years for the 10~6 excess cancer risk criterion at

the Water Works intake and to achieve the 10~5 excess

cancer risk criterion at the Mississippi River shoreline

and the Water Works intake.

All of which is respectfully submitted,

CONESTOGA-ROVERS & ASSOCIATES LIMITED

Richard G. Shepherd, P. Eng,

Bruce A. Monteith, P. Eng.

110

APPENDIX A

DETAILED RELATIVE COST ESTIMATES OF

REMEDIAL ACTION TECHNOLOGIES

I

TABLE A.1

EXCAVATION OF CONTAMINATED SOILS FROM BNR LANDS WITHDISPOSAL IN CONTAINMENT FACILITY ON FMC LANDS

Estimated UnitItem Description Quantity Unit price Total Price

Capital Construction Cost Estimate

1. Mobilization and demobilization 1 L.S. $18,000.00 $ 18,000.

2. Strip 6" topsoil and stockpile(allow entire contaminated BNRlands, plus CF area, plusstockpile area) 7,700 C.Y. 2.40 18,480.

3* Excavate uncontaminatedoverburden within BNR lands to20' depth and stockpile 66,130 C.Y. 4.20 277,746.

4. Excavate overburden withinproposed CF area and stockpile 26,645 C.Y. 4.20 111,909.

5. Excavate shallow clay fronproposed CF area and stockpile 21,300 C.Y. 4.20 89,460.

6. Excavate clay from base ofproposed CF and constructclay side key walls 6,770 C.Y. 6.00 40,620.

7. Construct leak and leachatecollection system in base ofCF 780 L.F. 96.00 74,880.

8. Recompact in-situ clay onbottom and sides of CF 8,860 S.Y. 2.40 21,264.

9. Construct CF bottom and sides:a) 6" sand drainage blanket

above and below polyethyleneliner on CF bottom 2,500 C.Y. 11.40 28,500.

b) polyethylene liners 205,460 S.F. 1.20 246,552.c) filter fabric 98,430 S.F. 0.20 19,686.

10. Excavate saturated contaminatedsoils from BNR lands and placein CF (including dewatering ofexcavation and sidewallstailization 50,320 C.Y. 27.40 1,378,768.

continued....

Item

11

12.

13.

14.

15.

16.

TABLE A.1 (cont'd)

EXCAVATION OF CONTAMINATED SOILS FROM BNR LANDS WITHDISPOSAL IN CONTAINMENT FACILITY ON FMC LANDS

Description

Disposal of contaminated waterfrom excavated saturatedmaterial by direct dischargeto POTW

Construct CF cap and final covera) place 3' clay cap over CF

from on-site stockpilematerial

b) place 6" sand blanket belowliner and 16" sand blanketabove liner

c) polyethylene linerd) filter fabrice) place 18" common fill over

fabric from on-site stockpile

Fill BNR Lands excavation witha) balance of on-site stockpileb) remainder from off-site

borrow pit

Estimated UnitQuantity^ Unit Price

3,050 1,000 Gal. 1.80

•

10,720 C.Y. 4.80

6,050 C.Y. 11.40125,220 S.F. 1.20136,900 S.F. 1.00

8,235 C.Y. 3.30

103,335 C.Y. 3.00

29,430 C.Y. 8.40

Total Price

5,490.

51,456.

68,970.150,264.27,380.

27,175.

310,005.

247,212.

Spread 6" topsoil over alldisturbed areas from stockpile 7,700 C.Y. 4.15 31,955.

Seed and mulch all disturbedareas 10 Acres 1,800.00 18,000.

Health and Safety (includingpersonnel protective equipment andair monitoring) 1 L.S. 54,000.00 54,000.

continued....

I

TABLE A.1 (cont'd)

EXCAVATION OF CONTAMINATED SOILS FROM BNR LANDS WITHDISPOSAL IN CONTAINMENT FACILITY ON FMC LANDS

Estimated UnitItem Description Quantity Unit Price Total Price

SUBTOTAL $3,317,772.

Contingency(25% of SUBTOTAL) 829,443.

Engineering & Site Supervision(15% of SUBTOTAL) 497,665.

I -TOTAL ESTIMATED CAPITALCONSTRUCTION COST $4,644,880.

continued....

TABLE A.1 (cont'd)

EXCAVATION OF CONTAMINATED SOILS FROM BNR LANDS WITHDISPOSAL IN CONTAINMENT FACILITY ON FMC LANDS

Estimated unitItem Description Quantity unit price Total Price

Operation, Maintenance and Monitoring Capital Cost Estimate

1. Install new groundwatermonitoring wells at CTFfor long term monitoring(351 deep) 5 Each $ 3,000.00 $ 15,000.

SUBTOTAL CAPITAL COST ESTIMATE $ 15,000.

Operation, Maintenance and Monitoring Annual Cost Estimate

1. Groundwater monitoring program:a) 5 wells sampled 4 times per

year, 4 samples per well,including QA/QC

b) sampling eventsc) reporting and administration

9641

SamplesEachL.S.

$ 500500

5,000

.00

.00

.00

$ 4825

,000.,000.,000.

2. CF:a) cap maintenance (mowing,

retopsoiling, seeding, etc.) 1 L.S. 3,620.00 3,620.b) leachate collection and

maintenance of system (assumeddisposal to POTW) 1 L.S. 1,220.00 1,220.

c) miscellaneous maintenance,inspections and administration 12 Months 1,000.00 12,000•

SUBTOTAL ANNUAL COST ESTIMATE $ 71,840.

*PRESENT WORTH OF ANNUAL COST ESTIMATE $988,880.

* Based on a six percent net discount rate for a 30 year operation period.

I

L

TABLE A.1 (cont'd)

EXCAVATION OF CONTAMINATED SOILS FROM BNR LANDS WITHDISPOSAL IN CONTAINMENT FACILITY ON FMC LANDS

SUMMARY COST

Estimated UnitItem Description Quantity Unit Price Total price

TOTAL ESTIMATED CAPITAL CONSTRUCTION COST $4,644,880.

Estimated Operation, Maintenance and Monitoring Cost:a) Capital Cost $ 15,000.b) Present Worth of Annual Cost $988,880.

TOTAL ESTIMATED OPERATION, MAINTENANCE AND MONITORING COST $1,033,880.

TOTAL REMEDIAL ALTERNATIVE COST $5,648,760.

TABLE A.2a

PHYSICAL CONTAINMENT OF BNR LANDS

Item DescriptionEstimatedQuantity Unit

UnitPrice Total Price

Capital Construction Cost Estimate

a) Without Low Permeability Soil Cover

1. Mobilization and demobilization 1

2. Purchase BNR property 2

3. Strip 6" topsoil and stockpile(allow entire area withinslurry wall plus 20' beyond) 1,475

4. Construct soil-bentonitecontainment cutoff wall tounderlying confining clay(1,000' long, 36' averagedepth) 43,100

5. Disposal of contaminatedbentonite slurry at completionof construction operation:a) transport 600b) gate fees 600

6. Install extraction well to 35'depth 1

7. Construct pumphouse (completewith electrical supply, pumpingequipment, 12,000 gallon holdingtank, piping from extraction wellto holding tank and from holdingtank to sanitary sewer manhole,and flow meter) 1

8. Initial drawdown of water tablewithin soil-bentonite slurrywall and direct disposal toPOTW (pumping rate at 5 GPMfor 30 days)

9. Spread 6" topsoil from stockpileover all disturbed areas 1,475

L.S. $30,000.00 $ 30,000.

Acres 72,000.00 144,000.

C.Y.

S.F.

TonsTons

Each

200 1,000 Gal.

C.Y.

2.40

168.00102.00

8,160.00

L.S. 58,440.00

1.80

3,540.

6.00 258,600.

100,800.61,200.

8,160.

58,440.

360.

4.15 6,121.

continued...

TABLE A.2a (cont'd)

PHYSICAL CONTAINMENT OF BNR LANDS

Item DescriptionEstimatedQuantity Unit

UnitPrice Total Price

9. Seed and mulch all disturbedareas

10. Health and Safety (includingpersonnel protective equipmentand air monitoring)

Acres 1,800.00

L.S. 42,000.00

SUBTOTAL

Contingency(25% of SUBTOTAL)

Engineering & Site supervision(15% Of SUBTOTAL)

TOTAL ESTIMATED CAPITALCONSTRUCTION COST

3,600.

42,000.

$ 716,821.

179,205.

107,524.

$1,003,550.

continued....

TABLE A.2a (cont'd)

PHYSICAL CONTAINMENT OF BNR LANDS

Item DescriptionEstimatedQuantity Unit

unitPrice

Operation, Maintenance and Monitoring Capital Cost Estimate

1. install new groundwatermonitoring wells downgradientof site for long term

Total Price

monitoring (35 ' deep) 6 Each $ 3,000.00

SUBTOTAL CAPITAL COST ESTIMATE

Operation, Maintenance and Monitoring Annual Cost Estimate

1.

2.

Groundwater monitoring program:a) 12 wells sampled 4 times per

year, one sample per wellincluding QA/QC 58

b) sampling events 4c) reporting and administration 1

Physical containment system:a) pumping equipment and well

maintenance 1*b) physical testing of cut-off

wall 20c) disposal of collected extracted

groundwater (assumed disposalto POTW) 300 1,

d) miscellaneous maintenance andinspections 12

**SUBTOTAL ANNUAL COST ESTIMATE

***PRESENT WORTH OF ANNUAL COST ESTIMATE

Samples $ 500.00Each 500.00L.S. 3,000.00

Well 1,800.00

Samples 600.00

000 Gal. 1.80

Months 500.00

$ 18,000.

$ 18,000.

$ 29,000.2,000.3,000.

1,800.

12,000.

540.

6,000.

$ 54,340.

$536,185.

* physical testing of cut-off wall to be carried out for first five years only.** Reduces to $42,340. after five years.*** Based on a six percent net discount rate for a 20 year operation period.

L continued.

TABLE A.2a (cont'd)

PHYSICAL CONTAINMENT OF BNR LANDS

SUMMARY OF COST

Item DescriptionEstimatedQuantity Unit

UnitPrice Total Price

TOTAL ESTIMATED CAPITAL CONSTRUCTION COST

Estimated Operation, Maintenance and Monitoring Cost:a) Capital Costb) present Worth of Annual Cost

TOTAL ESTIMATED OPERATION, MAINTENANCE AND MONITORING COST

TOTAL REMEDIAL ALTERNATIVE COST

$1,003,550.

$ 18,000.$536,185.

$ 554,185.

$1,557,735.

TABLE A.2b

PHYSICAL CONTAINMENT OF BNR LANDS

Item PescriptionEstimatedQuantity Unit

UnitPrice Total Price

I

Capital Construction Cost Estimate

b) With Low Permeability Soil Cover

1. Mobilization and demobilization

Purchase BNR property2.

3.

4.

7.

9.

Strip 6" topsoil and stockpile(allow entire area withinslurry wall plus 20' beyond,plus stockpile area)

Excavate overburden within areato be capped, regrade tominimum 3% slopes, andstockpile

Construct clay working platformfor slurry wall constructionwith clay imported from off-siteborrow pit

Construct soil-bentonitecontainment cutoff wall tounderlying confining clay layer(1000* long, 32' average depth)

Disposal of contaminatedbentonite slurry at completionof construction operation:a) transportb) gate fees

Construct clay cap with clayimported from off-site borrowpit

Import sand for 6" thick sanddrainage blanket over clay cap

1

2

2,430

9,520

1,250

38,300

520520

4,930

1,230

L.S. $30,000.00 $ 30,000.

Acres 72,000.00 144,000.

C.Y.

C.Y.

C.Y.

S.F.

TonsTons

C.Y.

C.Y.

2.40

2.90

11.40

168.00102.00

5,832.

27,608.

14,250,

6.00 229,800.

87,36053,040

11.40 56,202.

11.40 14,022.

continued...

TABLE A.2b (cont'd)

PHYSICAL CONTAINMENT OF BNR LANDS

Estimated UnitItem Description Quantity unit price Total price

10. Place 3' of common fill oversand blanket from on-sitestockpile 9,040 C.Y. 3.30 29,832.

11. Install extraction well to 35'depth 1 Each 8,160.00 8,160.

12. Construct puraphouse (completewith electrical supply, pumpingequipment, 200 gallon holdingtank, piping from extractionwell to holding tank and fromholding tank to sanitary sewermanhole, and flow meter) 1 Each 44,280.00 44,280.

13. Initial drawdown of water tablewithin soil-bentonite slurrywall and direct disposal toPOTW (pumping rate at 5 GPMfor 30 days) 200 1,000 Gal. 1.80 360.

14. Spread 6" topsoil, from topsoilstockpile, over all disturbedareas 2,430 C.Y. 4.15 10,085.

15. Seed and mulch all disturbedareas 4 Acres 1,800.00 7,200.

16. Health and Safety (includingpersonnel protective equipmentand air monitoring) 1 L.S. 42,000.00 42,000.

continued....

TABLE A.2b (cont'd)

PHYSICAL CONTAINMENT OF BNR LANDS

Estimated UnitItem Description Quantity Unit Price Total Price

SUBTOTAL $ 804,031.

Contingency(25% Of SUBTOTAL) 201,009.

Engineering & Site Supervision(15% of SUBTOTAL) 120,605.

I

I

TOTAL ESTIMATED CAPITALCONSTRUCTION COST $1,125,645.

continued....

TABLE A.2b (cont'd)

PHYSICAL CONTAINMENT OF BNR LANDS

Estimated UnitItem Description Quantity Unit Price

Operation, Maintenance and Monitoring Capital Cost Estimate

1. Install new groundwatermonitoring wells downgradientof site for long termmonitoring (35' deep) 6 Each $ 3,000.00

SUBTOTAL CAPITAL COST ESTIMATE

Operation, Maintenance and Monitoring Annual Cost Estimate

1. Groundwater monitoring program:a) 12 wells sampled 4 times per

year, one sample per wellincluding QA/QC

b) sampling eventsc) reporting and administration

2. Physical containment system:a) pumping equipment and well

maintenance*b) physical testing of cut-off

wallc) disposal of collected extracted

groundwater (assumed disposalto POTW)

d) miscellaneous maintenance andinspections

e) cap maintenance and grasscutting

**SUBTOTAL ANNUAL COST ESTIMATE

***PRESENT WORTH OF ANNUAL COST ESTIMATE

Total Price

$ 18,000.

$ 18,000.

5841

1

20

10

12

1

SamplesEachL.S.

Well

Samples

1,000 Gal.

Months

L.S.

$ 500.00500.00

3,000.00

1,800.00

600.00

1.80

500.00

4,000.00

$ 29,900.2,000.3,000.

1,800.

12,000.

18.

6,000.

4,000.

$ 57,818.

$576,075.

* Physical testing of cut-off wall to be carried out for first five years only.** Reduces to $45,818. after five years.*** Based on a six percent net discount rate for a 20 year operation period.

L

TABLE A.2b (cont'd)

PHYSICAL CONTAINMENT OF BNR LANDS

SUMMARY OF COST

Estimated UnitItem Description Quantity Unit Price Total Price

TOTAL ESTIMATED CAPITAL CONSTRUCTION COST $1,125,645.

Estimated Operation, Maintenance and Monitoring Cost:a) Capital Cost $ 18,000.b) Present Worth of Annual Cost $576,075.

TOTAL ESTIMATED OPERATION, MAINTENANCE AND MONITORING COST $ 594,075.

TOTAL REMEDIAL ALTERNATIVE COST $1,719,720.

L

TABI£ A. 3

HYDRAULIC CONTAINMENT OF BNR LANDS

Item DescriptionEstimatedQuantity Unit

UnitPrice Total price

Capital Cost

1. Mobilization and demobilization

2. Secure easement on BNR property

3. Install extraction wells to 35'depth with discharge to adjacentmanhole

4. Disposal of contaminated soilfrom drilling operating cuttings

5. Construct gravity main pipingsystem to collect extractedgroundwater (including trenchexcavation, bedding, pipematerial, manholes, backfill,and electrical cable for wellpumps)

6. Construct pumphouse (includingpower supply, pumping equipment,piping to sanitary sewer manhole,and flow meter)

7. Supply and place gravel foraccess road to pumphouse

8. Site restoration

1 L.S. $12,000.00 $ 12,000.

0.4 Acres 72,000.00 28,800.

360

1

750

1

Each 10,560.00

L.S.

L.F.

L.F.

L.S.

3,000.00

72.00

L.S. 43,200.00

4.50

5,000.00

21,120.

3,000.

25,920,

43,200.

3,375.

5,000.

continued....

TABLE A.3 (cont'd)

HYDRAULIC CONTAINMENT OF BNR LANDS

Item DescriptionEstimatedQuantity Unit

UnitPrice Total Price

9. Health and Safety (includingpersonnel protective equipmentand air monitoring) L.S. 12,000.00

SUBTOTAL

Contingency(25% of SUBTOTAL)

Engineering & Site Supervision(15% of SUBTOTAL)

TOTAL ESTIMATED CAPITALCONSTRUCTION COST

12,000.

$154,415.

38,605.

23,160.

$216,180.

I

continued.

UnitPrice

TABLE A.3 (cont'd)

HYDRAULIC CONTAINMENT OF BNR LANDS

EstimatedItem Description Quantity Unit ___

Operation, Maintenance and Monitoring Capital Cost Estimate

1. Install new groundwatermonitoring wells downgradientof site for long termmonitoring (35* deep) 6 Each $ 3,000.00

SUBTOTAL CAPITAL COST ESTIMATE

Operation, Maintenance and Monitoring Annual Cost Estimate

1. Groundwater monitoring program:a) 12 wells sampled 4 times per

year, one sample per wellincluding QA/QC

b) sampling eventsc) reporting and administration

2. Hydraulic containment system:a) pumping equipment and well

maintenanceb) operation cost of system

(eg. power)c) disposal of collected

extracted groundwater(assumed disposal to POTW)

d) miscellaneous maintenanceand inspections

SUBTOTAL ANNUAL COST ESTIMATE

*PRESENT WORTH OF ANNUAL COST ESTIMATE

Total Price

$ 18,000.

$ 18,000.

5841

2

1

16,000

12

SamplesEachL.S.

Wells

L.S.

1,000 Gal.

Months

$ 500.00500.00

3,000.00

1,800.00

500.00

1.80

500.00

$ 29,000.2,000.3,000.

3,600.

500.

28,800.

6,000.

$ 72,900.

$133,625.

* Based on a six percent net discount rate for a 2 year operation period.

L

TABLE A.3 (cont'd)

HYDRAULIC CONTAINMENT OF BNR LANDS

SUMMARY OF COST

Estimated UnitItem Description Quantity Unit Price Total Price

TOTAL ESTIMATED CAPITAL CONSTRUCTION COST $216,180.

Estimated Operation, Maintenance and Monitoring Cost:a) Capital Cost $ 18,000.b) Present Worth of Annual Cost $133,625.

TOTAL ESTIMATED OPERATION, MAINTENANCE AND MONITORING COST $151,625.

TOTAL REMEDIAL ALTERNATIVE COST $367,805.

LII

TABLE A.4

PHYSICAL CONTAINMENT OF FMC LANDS

Item DescriptionEstimatedQuantity Unit

UnitPrice Total Price

L

Capital Construction Cost Estimate

1. Mobilization and demobilization

2.

3.

5.

6.

7.

8.

Strip 6" topsoil and stockpile(allow 50 foot wide strip alongcurtain wall) 2,610

Construct grout curtain cut-offwall to underlying confiningbedrock layer (2,990' long,135' average depth) 402,480

Disposal of contaminated drillcuttings from grout curtain wallconstruction:a) transport 820b) gate fees 820

Install extraction well to135' depth 1

Construct pumphouse (completewith electrical supply, pumpingequipment, 3,000 gallon holdingtank, piping from extraction wellto holding tank and from holdingtank to sanitary sewer manhole,and flow meter) 1

Initial drawdown of water tablewithin grout curtain wall anddirect disposal to POTW(pumping rate at 45 GPM for30 days)

Spread 6" topsoil fromstockpile over all disturbedareas 2,610

L.S. $36,000.00

C.Y.

S.F.

TonsTons

2.40

8.25

168.00102.00

Each 12,000.00

Each 35,160.00

1,945 1,000 Gal.

C.Y.

1.80

4.15

$ 36,000.

6,264.

3,320,460.

137,760,83,640

12,000.

35,160.

3,501.

10,832.

continued...

L

TABLE A.4 (cont'd)

PHYSICAL CONTAINMENT OF FMC LANDS

Item DescriptionEstimatedQuantity unit

UnitPrice Total price

9. Seed and mulch all disturbedareas

10. Health and Safety (includingpersonnel protective equipmentand air monitoring)

Acres 1,800.00

L.S. 60,000.00

SUBTOTAL

Contingency(25% of SUBTOTAL)

Engineering & Field Supervision(15% Of SUBTOTAL)

TOTAL ESTIMATED CAPITALCONSTRUCTION COST

7,200,

60,000.

$3,712,817.

928,205.

556,923.

$5,197,945.

continued.

UnitPrice

TABLE A.4 (cont'd)

PHYSICAL CONTAINMENT OF FMC LANDS

EstimatedItem Description Quantity Unit ____

Operation, Maintenance and Monitoring Capital Cost Estimate

1. Install new groundwatermonitoring wells downgradientof site for long termmonitoring (135* deep) 6 Each $ 8/000.00

SUBTOTAL CAPITAL COST ESTIMATE

Operation, Maintenance and Monitoring Annual Cost Estimate

1. Groundwater monitoring program:a) 12 wells sampled 4 times per

year, one sample per wellincluding QA/QC

b) sampling eventsc) reporting and administration

2. Physical containment system:a) pumping equipment and well

maintenance*b) physical testing of cut-off

wallc) disposal of collected extracted

groundwater (assumed disposalto POTW)

d) miscellaneous maintenance andinspections

**SUBTOTAL ANNUAL COST ESTIMATE

***PRESENT WORTH OF ANNUAL COST ESTIMATE

Total Price

48,000.

48,000.

5841

1

20

80

12

SamplesEachL.S.

Well

Samples

1,000 Gal.

Months

$ 500.00500.00

3,000.00

2,000.00

1,000.00

1.80

500.00

$ 29,000.2,000.3,000.

2,000.

20,000.

144.

6,000.

$ 62,144.

$567,630.

* Physical testing of cut-off wall to be carried out for first five years only.** Reduces to $42,144. after five years.*** Based on a six percent net discount rate for a 20 year operation period.

L

TABLE A.4 (cont'd)

PHYSICAL CONTAINMENT OF FMC LANDS

SUMMARY OF COST

Estimated UnitItem Description Quantity Unit Price Total Price

TOTAL ESTIMATED CAPITAL CONSTRUCTION COST $5,197,945.

Estimated Operation, Maintenance and Monitoring Cost:a) Capital Cost $ 48,000.b) Present Worth of Annual Cost $567,630.

TOTAL ESTIMATED OPERATION, MAINTENANCE AND MONITORING COST $ 615,630.

TOTAL REMEDIAL ALTERNATIVE COST $5,813,575.

LI

TABLE A.5

HYDRAULIC CONTAINMENT OF FMC LANDS

Item DescriptionEstimatedQuantity Unit

UnitPrice Total Price

Capital Construction Cost Estimate

1.- Mobilization and demobilization

2. Secure easement on BNR property

3. Install extraction wells to 135'depth with discharge to adjacentmanhole

4. Disposal of contaminated drillcuttings from extraction wellinstallation

Supply and place gravel foraccess road to treatmentfacility

0.2

1

Construct gravity main pipingsystem to collect extractedgroundwater (including trenchexcavation, bedding, pipe material,manholes, backfill, and electricalcable for well pumps) 950

Install 20,000 gallon bufferingtank 1

Construct building for collectioncenter and treatment system(including power supply, pumpingand piping from buffering tankto treatment system, piping fromtreatment system to storm sewerdischarge, and flow meter) 1

Supply and install complete airstripping treatment system 1

L.S.

Acres

Each

L.S.

L.F.

$12,000.00

72,000.00

14,400.00

10,000.00

72.00

L.S. 24,000.00

L.S. 46,800.00

L.S. 60,000.00

$ 12,000.

14,400.

86,400.

10,000.

68,400.

24,000.

500 L.F. 4.50

46,800.

60,000.

2,250.

continued..

TABLE A.5 (cont'd)

HYDRAULIC CONTAINMENT OF FMC LANDS

Item DescriptionEstimatedQuantity Unit

UnitPrice Total Price

10. Site restoration

11. Health and Safety (includingpersonnel protective equipmentand air monitoring)

L.S.

L.S.

9,000.00

18,000.00

SUBTOTAL

Contingency(25% of SUBTOTAL)

Engineering & site Supervision(15% Of SUBTOTAL)

TOTAL ESTIMATED CAPITALCONSTRUCTION COST

9,000.

18,000.

$351,250.

87,815.

52,690.

$491,755.

continued.

L

UnitPrice

TABLE A.5 (cont'd)

HYDRAULIC CONTAINMENT OF FMC LANDS

EstimatedItem Description Quantity Unit ____

Operation, Maintenance and Monitoring Capital Cost Estimate

1. Install new groundwatermonitoring wells downgradientof site for long termmonitoring (135' deep) 6 Each $ 8,000.00

SUBTOTAL CAPITAL COST ESTIMATE

Operation, Maintenance and Monitoring Annual Cost Estimate

Hydraulic containment system:a) pumping equipment and well

maintenance 6 Wellsb) operation cost of system

(eg. power) 1 L.S.c) disposal of collected

extracted groundwater(assumed on-site airstripping and disposal)to river 50,000 1,000 Gal.

d) analytical sampling oftreated effluent, 2 samplesper month 24 Samples

e) miscellaneous maintenanceand inspections 12 Months

SUBTOTAL ANNUAL COST ESTIMATE

*PRESENT WORTH OF ANNUAL COST ESTIMATE

2,000.00

1,000.00

0.25

500.00

500.00

Total Price

$ 48,000.

$ 48,000.

1 . Groundwatera)

b)c)

12 wellsyear , oneincludingsamplingreporting

monitoring program:sampled 4 times persample per wellQVQCeventsand administration

5841

SamplesEachL.S.

$ 500.500.

3,000.

000000

$ 2923

,000.,000.,000.

12,000.

1,000.

12,500.

12,000.

6,000.

$ 77.500.

$611,245.

Based on a six percent net discount rate for an 11 year operation period.

TABLE A.5 (cont'd)

HYDRAULIC CONTAINMENT OF FMC LANDS

SUMMARY OF COST

Estimated UnitItem Description Quantity Unit Price Total Price

TOTAL ESTIMATED CAPITAL CONSTRUCTION COST $ 491,755.

Estimated Operation, Maintenance and Monitoring Cost:a) Capital Cost $ 48,000.b) Present Worth of Annual Cost $611,245.

TOTAL ESTIMATED OPERATION, MAINTENANCE AND MONITORING COST $ 659,245.

TOTAL REMEDIAL ALTERNATIVE COST $1,151,000.

APPENDIX B

DETAILED RELATIVE COST ESTIMATES OF

PREFERRED REMEDIAL ACTION ALTERNATIVE

TABLE B.1

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE10~6 RISK LEVEL AT SITE BOUNDARY

Estimated UnitItem Description Quantity Unit Price Total Price

This alternative requires hydraulic containment of the FMC lands and the BNR lands,treatment by on-site air stripping, and discharge of treated effluent to the on-sitestorm sewer system.

Capital Construction Cost Estimate

1.

2.

3.

Mobilization and demobilization

Secure easement on BNR property

Install extraction wells withdischarge to proposed collectionsystem manhole:a) 35' depthb) 135' depth

1

0.4

26

L.S.

Acres

EachEach

$18,000.00

72,000.00

10,560.0014,400.00

$ 18,000.

28,800.

21,120.86,400.

4. Disposal of contaminated drillcuttings from well drillingoperation 1 L.S. 10,000.00 10,000.

5. Construct gravity main pipingsystem to collect extractedgroundwater (including trenchexcavation, bedding, pipematerials, manholes and electricalcable for well pumps) 1,120 L.F. 72.00 80,640.

6. Construct building for groundwaterpumping and treatment system(including power supply, pumpingand piping from buffering tank totreatment system, piping fromtreatment system to storm sewerdischarge, and flow meter) 1 L.S. 46,800.00 46,800.

7. Construct 20,000 gallongroundwater buffering tank 1 L.S. 25,000.00 25,000.

continued....

TABLE B.1 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE10"6 RISK LEVEL AT SITE BOUNDARY

FMC CORPORATIONMINNEAPOLIS, MINNESOTA

Item DescriptionEstimatedQuantity Unit

UnitPrice Extension

8. Supply and install complete airstripping treatment system fordesign flow rate of 125 GPMand trichloroethylene removalefficiency of 98%

9. Construct access road withgravel surface to treatmentfacility and security fencearound treatment facility

10. Site restoration

11. Health and Safety during wellinstallation (including personnelprotective equipment and airmonitoring)

L.S. 55,000.00

L.S.

L.S.

L.S.

7,500.00

8,700.00

24,000.00

SUBTOTAL

Contingency(25% of SUBTOTAL)

Engineering & Site Supervision(15% of SUBTOTAL)

TOTAL ESTIMATED CAPITALCONSTRUCTION COST

55,000,

7,500,

8,700,

24,000.

$411,960.

102,990.

i

61,795.

$576,745.

continued....

TABLE B.1 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE

10-6

RISK LEVEL AT SITE BOUNDARY

Item DescriptionEstimatedQuantity

Operation, Maintenance and Monitoring Capital Cost

1. Install new groundwatermonitoring wells downgradientof site for long term monitoringa) 135' deepb) 35' deep

SUBTOTAL

:66

UnitUnit Price

Estimate

Each $ 8,000.00Each 3,000.00

CAPITAL COST ESTIMATE

Operation, Maintenance and Monitoring Annual Cost

1.

2.

Groundwater monitoring program:a) 12 wells sampled 4 times per

year, one sample per wellincluding QA/QC

b) sampling eventsc) reporting and administration

Extraction and treatment system:a) pumping equipment and well

maintenanceb) utilities cost (eg. power)c) air stripping treatment

costsd) analytical sampling of

treated effluent, 2 samplesper month

e) miscellaneous maintenanceand inspections

SUBTOTAL ANNUAL COST ESTIMATE

*PRESENT WORTH OF ANNUAL COST

5841

61

50,000 1,

24

12

, FMC LANDS

ESTIMATE,

Estimate, FMC Lands

Samples $ 500.00Each 500.00L.S. 5,000.00

Wells 2,000.00L.S. 1,400.00

000 Gal. 0.25

Samples 500.00

Months 500.00

FMC LANDS

Total Price

$ 48,000.18,000.

$ 66,000.

$ 29,000.2,000.5,000.

12,000.1,400.

12,500.

12,000.

6,000.

$ 79,900.

$630,170.

continued....

TABLE B.1 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE

10-6

RISK LEVEL AT SITE BOUNDARY

Item DescriptionEstimatedQuantity Unit

UnitPrice Total Price

Operation, Maintenance and Monitoring Annual Cost Estimate, BNR Lands

1. Groundwater monitoring program:a) 6 wells sampled 4 times per

year, one sample per wellincluding QA/QC 30 Samples $ 500.00

b) sampling events 4 Each 500.00c) reporting and administration

included under FMC lands

$ 15,000.2,000.

2. Extraction and treatment system:a) pumping equipment and well

maintenanceb) utilities cost (eg. power)c) air stripping treatment

costs 16,000

SUBTOTAL ANNUAL COST ESTIMATE, FMC LANDS

21

0

WellsL.S.

1,000 Gal.

1,800.00250.00

0.25

3,600.250.

4,000.

$ 24,850,

**PRESENT WORTH OF ANNUAL COST ESTIMATE, BNR LANDS $ 45,550.

* Based on a six percent net discount rate for an 11 year operation period.** Based on a six percent net discount rate for a 2 year operation period.

TABLE B.1 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE

10~6 RISK LEVEL AT SITE BOUNDARY

SUMMARY OF COST

Estimated UnitItem Description Quantity Unit Price Total Price

TOTAL ESTIMATED CAPITAL CONSTRUCTION COST $ 576,745.

Estimated Operation, Maintenance and Monitoring Cost:a) Capital Cost $ 66,000.b) Present Worth of Annual Cost - FMC Lands $630,170.

- BNR Lands $ 45,550.

TOTAL ESTIMATED OPERATION, MAINTENANCE AND MONITORING COST $ 741,720.

TOTAL REMEDIAL ALTERNATIVE COST $1,318,465.

TABLE B.2

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE10~5 RISK LEVEL AT SITE BOUNDARY

Item DescriptionEstimatedQuantity Unit

UnitPrice Total Price

This alternative requires hydraulic containment of the FMC lands and the BNR lands/treatment by on-site air stripping, and discharge of treated effluent to the on-sitestorm sewer system.

Capital Construction Cost Estimate

1. Mobilization and demobilization

Secure easement on BNR property2.

3. Install extraction wells withdischarge to proposed collectionsystem manhole:a) 35' depthb) 135' depth

4. Disposal of contaminated drillcuttings from well drillingoperation

5. Construct gravity main pipingsystem to collect extractedgroundwater (including trenchexcavation, bedding, pipematerials, manholes and electricalcable for well pumps)

6. Construct building for groundwaterpumping and treatment system(including power supply, pumpingand piping from buffering tank totreatment system, piping fromtreatment system to storm sewerdischarge, and flow meter)

7. Construct 20,000 gallongroundwater buffering tank

1

0.4

26

1,120

L.S.

EachEach

L.S.

L.F.

L.S.

L.S.

$18,000.00

Acres 72,000.00

10,560.0014,400.00

10,000.00

72.00

46,800.00

25,000.00

18,000.

28,800.

21,120.86,400.

10,000.

80,640.

46,800.

25,000.

continued...

TABLE B.2 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE10"5 RISK LEVEL AT SITE BOUNDARY

Item DescriptionEstimatedQuantity Unit

UnitPrice Total Price

10.

11.

Supply and install complete airstripping treatment system fordesign flow rate of 120 GPMand trichloroethylene removalefficiency of 98%

Construct access road withgravel surface to treatmentfacility and security fencearound treatment facility

Site restoration

Health and Safety during wellinstallation (includingpersonnel protectiveequipment and air monitoring)

L.S.

L.S.

L.S.

L.S.

55,000.00

7,500.00

8,700.00

24,000.00

SUBTOTAL

Contingency(25% Of SUBTOTAL)

Engineering & Site Supervision(15% of SUBTOTAL)

TOTAL ESTIMATED CAPITALCONSTRUCTION COST

55,000.

7,500.

8,700.

24,000.

$411,960.

102,990.

61,795.

$576,745.

continued....

L

TABLE B.2 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE

10-5 RISK LEVEL AT SITE BOUNDARY

FMC CORPORATIONMINNEAPOLIS, MINNESOTA

ItemEstimated

Description Quantity

Operation, Maintenance and Monitoring Capital Cost

1. Install new groundwatermonitoring wells downgradientof site for long term monitoring:a) 135' deep 6b) 35' deep 6

UnitUnit Price

Estimate

Each $ 8,000.00Each 3,000.00

SUBTOTAL CAPITAL COST ESTIMATE

Operation, Maintenance and Monitoring Annual Cost

1.

2.

Groundwater monitoring program:a) 12 wells sampled 4 times per

year, one sample per wellincluding QA/QC 58

b) sampling events 4c) reporting and administration 1

Extraction and treatment system:a) pumping equipment and well

maintenance 6b) utilities cost (eg. power) 1c) air stripping treatment

costs 48,000 1,d) analytical sampling of

treated effluent, 2 samplesper month 24

e) miscellaneous maintenanceand inspections 12

SUBTOTAL ANNUAL COST ESTIMATE, FMC LANDS

*PRESENT WORTH OF ANNUAL COST ESTIMATE,

Estimate, FMC Lands

Samples $ 500.00Each 500.00L.S. 5,000.00

Wells 2,000.00L.S. 1,400.00

000 Gal. 0.25

Samples 500.00

Months 500.00

FMC LANDS

Total Price

$ 48,000.18,000.

$ 66,000.

$ 29,000.2,000.5,000.

12,000.1,400.

12,000.

12,000.

6,000.

$ 79,400.

$626,230.

continued....

TABLE B.2 (cont'd)

L

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE

10-5

RISK LEVEL AT SITE BOUNDARY

Item DescriptionEstimatedQuantity Unit

UnitPrice

500.00500.00

Operation, Maintenance and Monitoring Annual Cost Estimate, BNR Lands

1 . Groundwater monitoring program :a) 6 wells sampled 4 times per

year, one sample per wellincluding QA/QC 30 Samples $

b) sampling events 4 Eachc) reporting and administration

included under FMC lands

2. Extraction and treatment system:a) pumping equipment and well

maintenance 2 Wellsb) utilities cost (eg. power) 1 L.S.c) air stripping treatment

costs 16,000 1,000 Gal.

SUBTOTAL ANNUAL COST ESTIMATE, FMC LANDS

**PRESENT WORTH OF ANNUAL COST ESTIMATE, BNR LANDS

1,800.00250.00

0.25

Total Price

$ 15,000.2,000.

3,600.250.

4,000.

$ 24,850.

$ 45,550.

* Based on a six percent net discount rate for an 11 year operation period,** Based on a six percent net discount rate for a 2 year operation period.

TABLE B.2 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE

10~ RISK LEVEL AT SITE BOUNDARY

SUMMARY OF COST

Estimated UnitItem Description Quantity Unit Price Total Price

TOTAL ESTIMATED CAPITAL CONSTRUCTION COST $ 576,745.

Estimated Operation, Maintenance and Monitoring Cost:a) Capital Cost $ 66,000.b) Present Worth of Annual Cost - FMC Lands $626,230.

- BNR Lands $ 45,550.

TOTAL ESTIMATED OPERATION, MAINTENANCE AND MONITORING COST $ 737,780.

TOTAL REMEDIAL ALTERNATIVE COST $1,314,525.

1

L

TABLE B.3

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE10~6 RISK LEVEL AT COUNTY LANDS ___

Item DescriptionEstimatedQuantity Unit

UnitPrice Total Price

This alternative requires partial hydraulic containment of the FMC lands and the BNRlands, treatment by on-site air stripping, and discharge of treated effluent to theon-site storm sewer system.

Capital Construction Cost Estimate

1. Mobilization and demobilization

Secure easement on BNR property2.

3.

1

0.4

Install extraction wells withdischarge to proposed collectionsystem manhole:- 35' depth- 135' depth

4. Disposal of contaminated drillcuttings from well drillingoperation

5. Construct gravity main pipingsystem to collect extractedgroundwater {including trenchexcavation, bedding, pipematerials, manholes, and electricalcable for well pumps)

6. Construct building for groundwaterpumping and treatment system(including power supply, pumpingand piping from buffering tank totreatment system, piping fromtreatment system to storm sewerdischarge, and flow meter)

7. Construct 20,000 gallongroundwater buffering tank

26

1,120

L.S. $18,000.00

Acres 72,000.00

EachEach

L.S.

L.F.

L.S.

L.S.

10,560.0014,400.00

10,000.00

72.00

46,800.00

25,000.00

18,000.

28,800.

21,120.86,400.

10,000.

80,640.

46,800.

25,000.

continued....

TABLE B.3 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE10~6 RISK LEVEL AT COUNTY LANDS

Item DescriptionEstimatedQuantity Unit

UnitPrice Extension

8. Supply and install complete airstripping treatment system fordesign flow rate of 120 GPMand trichloroethylene removalefficiency of 98%

9. Construct access road withgravel surface to treatmentfacility and security fencearound treatment facility

10. Site restoration

11. Health and Safety during wellinstallation (including personnelprotective equipment and airmonitoring)

L.S.

L.S.

L.S.

L.S.

55,000.00

7,500.00

8,700.00

24,000.00

SUBTOTAL

Contingency(25% of SUBTOTAL)

Engineering & Site Supervision(15% of SUBTOTAL)

TOTAL ESTIMATED CAPITALCONSTRUCTION COST

55,000.

7,500.

8,700.

24,000.

$411,960.

102,990.

61,795.

$576,745.

continued...

TABLE B.3 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE

10-6 RISK LEVEL AT COUNTY LANDS

ItemEstimated

Description Quantity

Operation, Maintenance and Monitoring Capital Cost

1. Install new groundwatermonitoring wells downgradientof site for long term monitoring:a) 135' deep 6b) 35' deep 6

UnitUnit Price

Estimate

Each $ 8,000.00Each 3,000.00

SUBTOTAL CAPITAL COST ESTIMATE

Operation, Maintenance and Monitoring Annual Cost

1.

2.

Groundwater monitoring program:a) 12 wells sampled 4 times per

year, one sample per wellincluding QA/QC 58

b) sampling events 4c) reporting and administration 1

Extraction and treatment system:a) pumping equipment and well

maintenance 6b) utilities cost (eg. power) 1c) air stripping treatment

costs 48,000 1,d) analytical sampling of

treated effluent, 2 samplesper month 24

e) miscellaneous maintenanceand inspections 12

SUBTOTAL ANNUAL COST ESTIMATE, FMC LANDS

*PRESENT WORTH OF ANNUAL COST ESTIMATE,

Estimate, FMC Lands

Samples $ 500.00Each 500.00L.S. 5,000.00

Wells 2,000.00L.S. 1,400.00

000 Gal. 0.25

Samples 500.00

Months 500.00

FMC LANDS

Total Price

$ 48,000.18,000.

$ 66,000.

$ 29,000.2,000.5,000.

12,000.1,400.

12,000.

12,000.

6,000.

$ 79,400.

$626,230.

continued....

L

TABLE B.3 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE

10-6

RISK LEVEL AT COUNTY LANDS

Item DescriptionEstimatedQuantity Unit

UnitPrice Total Price

Operation, Maintenance and Monitoring Annual Cost Estimate, BNR Lands

1. Groundwater monitoring program:a) 6 wells sampled 4 times per

year, one sample per wellincluding QA/QC 30 Samples $ 500.00 $ 15,000.

b) sampling events 4 Each 500.00 2,000.c) reporting and administration

included under FMC lands

2. Extraction and treatment system:a) pumping equipment and well

maintenance 2 Wells 1,800.00 3,600.b) utilities cost (eg. power) 1 L.S. 250.00 250.c) air stripping treatment

costs 16,100 1,000 Gal. 0.25 4/000.

SUBTOTAL ANNUAL COST ESTIMATE, FMC LANDS $ 24,850.

**PRESENT WORTH OF ANNUAL COST ESTIMATE, BNR LANDS $45,550.

* Based on a six percent net discount rate for an 11 year operation period.** Based on a six percent net discount rate for a 2 year operation period.

(f[

TABLE B.3 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE

10~ RISK LEVEL AT COUNTY LANDS

SUMMARY OF COST

Estimated UnitItem Description Quantity Unit Price Total Price

TOTAL ESTIMATED CAPITAL CONSTRUCTION COST $ 576,745.

Estimated Operation, Maintenance and Monitoring Cost:a) Capital Cost $ 66,000.b) Present Worth of Annual Cost - FMC Lands $626,230.

- BNR Lands $ 45,550.

TOTAL ESTIMATED OPERATION, MAINTENANCE AND MONITORING COST $ 737,780.

TOTAL REMEDIAL ALTERNATIVE COST $1,314,525.

I

I

I

TABLE B.4

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE10-5 RISK LEVEL AT COUNTY LANDS

Item DescriptionEstimatedQuantity Unit

UnitPrice Total Price

This alternative requires partial hydraulic containment of the FMC lands and the BNRlands, treatment by on-site air stripping, and discharge of treated effluent to theon-site storm sewer system.

Capital Construction Cost Estimate

1.

2.

3.

Mobilization and demobilization

Secure easement on BNR property

Install extraction wells withdischarge to proposed collectionsystem manhole :- 35' depth- 135' depth

1

0.4

26

L.S.

Acres

EachEach

$18,000.00

72,000.00

10,560.0014,400.00

$ 18,000

28,800

21,12086,400

4. Disposal of contaminated drillcuttings from well drillingoperation

5. Construct gravity main pipingsystem to collect extractedgroundwater (including trenchexcavation, bedding, pipematerials, manholes, and electricalcable for well pumps)

6. Construct building for groundwaterpumping and treatment system(including power supply, pumpingand piping from buffering tank totreatment system, piping fromtreatment system to storm sewerdischarge, and flow meter)

7. Construct 20,000 gallongroundwater buffering tank

1,120

L.S.

L.F.

L.S.

L.S.

10,000.00

72.00

46,800.00

25,000.00

10,000.

80,640.

46,800.

25,000.

continued..

i

I

I

TABLE B.4 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE10-5 RJSK LEVEL AT COUNTY LANDS

Estimated UnitItem Description Quantity Unit Price Total Price

8. Supply and install complete airstripping treatment system fordesign flow rate of 75 GPMand trichloroethylene removalefficiency of 99% 1 L.S. 55,000.00 55,000.

9. Construct access road withgravel surface to treatmentfacility and security fencearound treatment facility 1 L.S. 7,500.00 7,500.

10. Site restoration 1 L.S. 8,700.00 8,700.

11. Health and Safety during wellinstallation (including personnelprotective equipment and airmonitoring) 1 L.S. 24,000.00 24,000.

SUBTOTAL $411,960.

Contingency(25% of SUBTOTAL) 102,990.

Engineering & Site Supervision(15% of SUBTOTAL) 61,795.

TOTAL ESTIMATED CAPITAL $576,745.CONSTRUCTION COST _______

continued....

TABLE B.4 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE

10-5

RISK LEVEL AT COUNTY LANDS

ItemEstimated

Description Quantity

Operation, Maintenance and Monitoring Capital Cost

1. Install new groundwatermonitoring wells downgradientof site for long term monitoring:a) 135' deep 6b) 35' deep 6

UnitUnit Price

Estimate

Each $ 8,000.00Each 3,000.00

SUBTOTAL CAPITAL COST ESTIMATE

Operation, Maintenance and Monitoring Annual Cost

1.

2.

Groundwater monitoring program:a) 12 wells sampled 4 times per

year, one sample per wellincluding QA/QC 58

b) sampling events 4c) reporting and administration 1

Extraction and treatment system:a) pumping equipment and well

maintenance 6b) utilities cost (eg. power) 1c) air stripping treatment

costs 24,000 1,d) analytical sampling of

treated effluent, 2 samplesper month 24

e) miscellaneous maintenanceand inspections 12

SUBTOTAL ANNUAL COST ESTIMATE, FMC LANDS

*PRESENT WORTH OF ANNUAL COST ESTIMATE,

Estimate, FMC Lands

Samples $ 500.00Each 500.00L.S. 5,000.00

Wells 2,000.00L.S. 1,000.00

000 Gal. 0.25

Samples 500.00

Months 500 . 00

FMC LANDS

Total Price

$ 48,000.18,000.

$ 66,000.

$ 29,000.2,000.5,000.

12,000.1,000.

6,000.

12,000.

6,000.

$ 73,000.

$575,750.

continued....

TABLE B.4 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE

10-5

RISK LEVEL AT COUNTY LANDS

Item DescriptionEstimatedQuantity Unit

UnitPrice Total Price

Operation, Maintenance and Monitoring Annual Cost Estimate, BNR Lands

1. Groundwater monitoring program:a) 6 wells sampled 4 times per

year, one sample per wellincluding QA/QC 30 Samples $ 500.00 $ 15,000.

b) sampling events 4 Each 500.00 2,000.c) reporting and administration

included under FMC lands

2. Extraction and treatment system:a) pumping equipment and well

maintenance 2 Wells 1,800.00 3,600.b) utilities cost (eg. power) 1 L.S. 250.00 250.c) air stripping treatment

costs 16,000 1,000 Gal. 0.25 4,000.

SUBTOTAL ANNUAL COST ESTIMATE, FMC LANDS

**PRESENT WORTH OF ANNUAL COST ESTIMATE, BNR LANDS $ 45,550.

* Based on a six percent net discount rate for an 11 year operation period.** Based on a six percent net discount rate for a 2 year operation period.

L

TABLE B.4 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE

10~ RISK LEVEL AT COUNTY LANDS

SUMMARY OF COST

Estimated UnitItem Description Quantity Unit Price Total Price

TOTAL ESTIMATED CAPITAL CONSTRUCTION COST $ 576,745.

Estimated Operation, Maintenance and Monitoring Cost:a) Capital Cost $ 66,000.b) Present Worth of Annual Cost - FMC Lands $575,750.

- BNR Lands $ 45,550.

TOTAL ESTIMATED OPERATION, MAINTENANCE AND MONITORING COST $ 687,310.

TOTAL REMEDIAL ALTERNATIVE COST $1,264,045.

I

I

I

TABLE B.5

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE10-6 RISK LEVEL AT RIVER SHORELINE

Item DescriptionEstimatedQuantity Unit

UnitPrice Total Price

This alternative requires partial hydraulic containment of the FMC lands and the BNRlands, treatment by on-site air stripping, and discharge of treated effluent to theon-site storm sewer system.

Capital Construction Cost Estimate

1. Mobilization and demobilization

Secure easement on BNR property2.

3.

1

0.4

Install extraction wells withdischarge to proposed collectionsystem manhole:- 35' depth- 135' depth

4. Disposal of contaminated drillcuttings from well drillingoperation

5. Construct gravity main pipingsystem to collect extractedgroundwater (including trenchexcavation, bedding, pipematerials, manholes, and electricalcable for well pumps)

6. Construct building for groundwaterpumping and treatment system(including power supply, pumpingand piping from buffering tank totreatment system, piping fromtreatment system to storm sewerdischarge, and flow meter)

7. Construct 20,000 gallongroundwater buffering tank

26

1,120

L.S.

Acres

EachEach

L.S.

L.F.

L.S.

L.S.

$18,000.00

72,000.00

10,560.0014,400.00

10,000.00

72.00

46,800.00

25,000.00

18,000.

28,800.

21,120.86,400.

10,000.

80,640.

46,800.

25,000.

continued....

TABLE B.5 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE10~6 RISK LEVEL AT RIVER SHORELINE

Estimated UnitItem Description Quantity Unit Price Total Price

8. Supply and install complete airstripping treatment system fordesign flow rate of 75 GPMand trichloroethylene removalefficiency of 99% 1 L.S. 55,000.00 55,000.

9. Construct access road withgravel surface to treatmentfacility and security fencearound treatment facility 1 L.S. 7,500.00 7,500.

10. Site restoration 1 L.S. 8,700.00 8,700.

11. Health and Safety during wellinstallation (including personnelprotective equipment andair monitoring) 1 L.S. 24,000.00 24,000.

SUBTOTAL $411,960.

Contingency(25% of SUBTOTAL) 102,990.

Engineering & Site Supervision(15% of SUBTOTAL) 61,795.

TOTAL ESTIMATED CAPITAL $576,745.CONSTRUCTION COST

continued....

TABLE B.5 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE

10-6

RISK LEVEL AT RIVER SHORELINE

Item DescriptionEstimatedQuantity

Operation, Maintenance and Monitoring Capital Cost

1. Install new groundwatermonitoring wells downgradientof site for long term monitoringa) 135' deepb) 35' deep

SUBTOTAL

••

66

UnitUnit Price

Estimate

Each $ 8,000.00Each 3,000.00

CAPITAL COST ESTIMATE

Operation, Maintenance and Monitoring Annual Cost

1.

2.

Groundwater monitoring program:a) 12 wells sampled 4 times per

year, one sample per wellincluding QA/QC

b) sampling eventsc) reporting and administration

Extraction and treatment system:a) pumping equipment and well

maintenanceb) utilities cost (eg. power)c) air stripping treatment

costsd) analytical sampling of

treated effluent , 2 samplesper month

e) miscellaneous maintenanceand inspections

SUBTOTAL ANNUAL COST ESTIMATE

*PRESENT WORTH OF ANNUAL COST

5841

61

24,000 1,

24

12

, FMC LANDS

ESTIMATE,

Estimate, FMC Lands

Samples $ 500.00Each 500.00L.S. 5,000.00

Wells 2,000.00L.S. 1,000.00

000 Gal. 0.25

Samples 500.00

Months 500.00

FMC LANDS

Total Price

$ 48,000.18,000.

$ 66,000.

$ 29,000.2,000.5,000.

12,000.1,000.

6,000.

12,000.

6,000.

$ 73,000.

$575,750.

continued....

TABLE B.5 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE

10-6 RISK LEVEL AT RIVER SHORELINE

Item DescriptionEstimatedQuantity Unit

UnitPrice Total Price

Operation, Maintenance and Monitoring Annual Cost Estimate, BNR Lands

1. Groundwater monitoring program:a) 6 wells sampled 4 times per

year, one sample per wellincluding QA/QC 30 Samples S 500.00 $ 15,000.

b) sampling events 4 Each 500.00 2,000.c) reporting and administration

included under FMC lands

2. Extraction and treatment system:a) pumping equipment and well

maintenance 2 Wells 1,800.00 3,600.b) utilities cost (eg. power) 1 L.S. 250.00 250.c) air stripping treatment

costs 16,000 1,000 Gal. 0.25 4,000.

SUBTOTAL ANNUAL COST ESTIMATE, FMC LANDS $ 24,850.

**PRESENT WORTH OF ANNUAL COST ESTIMATE, BNR LANDS $ 45,550.

* Based on a six percent net discount rate for an 11 year operation period.** Based on a six percent net discount rate for a 2 year operation period.

TABLE B.5 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE

10~6 RISK LEVEL AT RIVER SHORELINE

SUMMARY OF COST

Estimated UnitItem Description Quantity Unit Price Total Price

TOTAL ESTIMATED CAPITAL CONSTRUCTION COST $ 576,745.

Estimated Operation, Maintenance and Monitoring Cost:a) Capital Cost $ 66,000.b) Present Worth of Annual Cost - FMC Lands $575,750.

- BNR Lands $ 45,550.

TOTAL ESTIMATED OPERATION, MAINTENANCE AND MONITORING COST $ 687,300.

TOTAL REMEDIAL ALTERNATIVE COST $1,264,045.

TABLE B.6

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE10~5 RISK LEVEL AT RIVER SHORELINE

Item DescriptionEstimatedQuantity Unit

UnitPrice Total Price

This alternative requires partial hydraulic containment of the BNR lands only, withdirect discharge to on-site sanitary sewer system. No on-site treatment is provided.

Capital Construction Cost Estimate

1. Mobilization and demobilization

Secure easement on BNR property2.

3.

4.

Install extraction wells to 35'depth with discharge to proposedcollection system manhole

Disposal of contaminated drillcuttings from well drillingoperation

5. Construct gravity main pipingsystem to collect extractedgroundwater (including trenchexcavation, bedding, pipematerials, manholes, and electricalcable for well pumps)

6. Construct pumphouse for groundwaterpumping (including powersupply, pumping equipment, pipingfrom collection system to pumphouse,and flow meter)

7. Construct gravity main frompumphouse to on-site sanitarysewer manhole

1

0.4

170

L.S. $ 9,000.00

Acres 72,000.00

Each

L.S.

L.F.

80

L.S.

L.F.

10,560.00

3,000.00

72.00

39,600.00

70.00

9,000.

28,800.

10,560.

3,000.

12,240.

39,600.

5,600.

continued....

TABLE B.6 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE10~5 RISK LEVEL AT RIVER SHORELINE

Estimated UnitItem Description Quantity Unit Price Total Price

8. Construct access road withgravel surface to pumphouseand security fence aroundpumphouse 1 L.S. 7,500.00 7,500.

9. Site restoration 1 L.S. 3,500.00 3,500.

10. Health and Safety during wellinstallation (including personnelprotective equipment andair monitoring) 1 L.S. 12,000.00 12,000.

SUBTOTAL $131,800,

Contingency(25% of SUBTOTAL) 32,950.

Engineering & Site Supervision(15% of SUBTOTAL) 19,770.

TOTAL ESTIMATED CAPITAL $184,520,CONSTRUCTION COST

continued...

TABLE B.6 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE

10 RISK LEVEL AT RIVER SHORELINE

Estimated UnitItem Description Quantity Unit Price Total price

Operation, Maintenance and Monitoring Capital Cost Estimate

1. Install new groundwatermonitoring wells downgradientof site for long term monitoring:a) 135' deep 6 Each $ 8,000.00 $ 48,000.b) 35' deep 6 Each 3,000.00 18,000.

SUBTOTAL CAPITAL COST ESTIMATE $ 66,000.

Operation, Maintenance and Monitoring Annual Cost Estimate, FMC Lands

1. Groundwater monitoring program:a) 12 wells sampled 4 times per

year, one sample per wellincluding QA/QC 58 Samples $ 500.00 $ 29,000.

b) sampling events 4 Each 500.00 2,000.c) reporting and administration 1 L.S. 3,000.00 3,000.

SUBTOTAL ANNUAL COST ESTIMATE, FMC LANDS $ 34,000.

*PRESENT WORTH OF ANNUAL COST ESTIMATE, FMC LANDS $389,980.

continued....

TABLE B.6 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE

10~ RISK LEVEL AT RIVER SHORELINE

Item DescriptionEstimatedQuantity Unit

UnitPrice Total Price

Operation/ Maintenance and Monitoring Annual Cost Estimate, BNR Lands

Groundwater monitoring program:a) 6 wells sampled 4 times per

year, one sample per wellincluding QA/QC

b) sampling eventsc) reporting and administration

included under FMC lands

304

SamplesEach

500.00500.00

2. Extraction and disposal system:a) pumping equipment and well

maintenanceb) utilities cost (eg. power)c) disposal of collected

extracted groundwater(assumed disposal to POTW)

d) miscellaneous maintenanceand inspections

"PRESENT WORTH OP ANNUAL COST ESTIMATE, BNR LANDS

$ 15,000.2,000.

21

8,000 1,

12

BNR LANDS

WellsL.S.

000 Gal.

Months

1,800.00120.00

1.80

500.00

3,600.120.

14,400.

6,000.

$ 41,120.

$ 75,375.

* Based on a six percent net discount rate for an 20 year operation period.** Based on a six percent net discount rate for a 2 year operation period.

TABLE B.6 (cont'd)

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE

10~ RISK LEVEL AT RIVER SHORELINE

SUMMARY OF COST

Estimated UnitItem Description Quantity Unit Price Total Price

TOTAL ESTIMATED CAPITAL CONSTRUCTION COST $ 184,520.

Estimated Operation, Maintenance and Monitoring Cost:a) Capital Cost $ 66,000.b) Present Worth of Annual Cost - FMC Lands $389,980.

- BNR Lands $ 75,375.

TOTAL ESTIMATED OPERATION, MAINTENANCE AND MONITORING COST $ 531,355.

TOTAL REMEDIAL ALTERNATIVE COST $ 715,875.

TABLE B.7

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE10~6 RISK LEVEL AT RIVER INTAKE

Estimated UnitItem Description Quantity Unit Price Total Price

This alternative requires no hydraulic containment. Therefore, the initial capitalconstruction cost is zero.

Operation, Maintenance and Monitoring Capital Cost Estimate

1. Install new groundwatermonitoring wells downgradientof site for long term monitoring:a) 135' deep 6 Each $8,000.00 $ 48,000.b) 35' deep 6 Each 3,000.00 18,000.

SUB-TOTAL CAPITAL COST ESTIMATE $ 66,000.

Operation, Maintenance and Monitoring Annual Cost Estimate

1. Groundwater monitoring program:a) 18 wells sampled 4 times per

year, one sample per wellincluding QA/QC 88 Samples $ 500.00 $ 44,000.

b) sampling events 4 Each 1,000.00 4,000.c) reporting and administration 1 L.S. 5,000.00 ____5,000.

SUBTOTAL ANNUAL COST ESTIMATE

* PRESENT WORTH OF ANNUAL COST ESTIMATE $ 607,910.

* Based on a six percent net discount rate for a 20 year operation period.

L

TABLE B.7

HYDRAULIC CONTAINMENT REQUIRED TO ACHIEVE10~6 RISK LEVEL AT RIVER INTAKE

SUMMARY OF COST

TOTAL ESTIMATED CAPITAL CONSTRUCTION COST $ 0

Estimated Operation, Maintenance and Monitoring Cost:a) Capital Cost $ 66,000.b) Present Worth of Annual Cost $607,910.

TOTAL ESTIMATED OPERATION, MAINTENANCE AND MONITORING COST $ 673,910.

TOTAL REMEDIAL ALTERNATIVE COST $ 673,910.