RECORD OF DECISIONREMEDIAL ALTERNATIVE SELECTION

Site: McKin, Gray, Maine

DOCUMENTS REVIEWED SDMS D°ClD 262502

I am basing my decision primarily on the following documentsdescribing the analysis of cost-effectiveness of remedialalternatives for the McKin site:

1. Remedial Investigation for McKin Company Hazardous WasteSite, Gray, Maine, January 1985, prepared for the Stateof Maine, Department of Environmental Protection, Augusta,Maine, prepared by Camp Dresser and McKee, Inc., Boston,Massachusetts.

2. Feasibility Study for McKin Company Hazardous Waste Site,Gray, Maine, March 1985, prepared for State of Maine,Department of Environmental Protection, Augusta, Maine,prepared by Camp Dresser and McKee, Inc., Boston,Massachusetts.

3. Summary of Remedial Alternative Selection (attached).

4. Community Relations Responsiveness Summary (attached).

5. The National Oil and Hazardous Substances PollutionContingency Plan, 40 C.F.R. Part 300.

6. 40 C.F.R. Part 264 - Standards for Owners and Operatorsof Hazardous Waste Treatment Storage, and DisposalFaci1ities.

7. Hydrogeologic Study, East Gray, Maine for the MaineDepartment of Environmental Protection, November 29, 1982,prepared by Robert G, Gerber, Inc.

8. Health Surveillance Program Protocol for Persons Exposedto Hazardous Wastes from the McKin Dump site, Gray, Maine,prepared by State of Maine, Department of Human Services,Bureau of Health, Division of Disease Control, August, 1983.

9. Compilation of Information Generated since May 6, 1985,Regarding Record of Decision for McKin Site, July 1, 1985.

10. Memoranda, letters, and recommendations of staff andother Federal agencies.

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DESCRIPTION OF SELECTED REMEDY

- On-site aeration of soils in site areas of identifiedhazardous substance contamination to achieve soil qualitylevels protective of public health, welfare, and theenvironment.

- Off-site disposal of approximately 16 drums found on thesite and their contents.

- Performing soil tests in petroleum contaminated areas tocharacterize further the nature of contamination.

- Constructing a groundwater extraction, treatment, andsurface water discharge system and operating this systemas a remedial treatment unit for a period of five yearswith a target groundwater performance standard of 92 ppb1,1,1-trichloroethane and 28 ppb trichloroethylene forgroundwater quality.

- Re-evaluating the groundwater performance standard, if thisstandard is not achieved at the end of the five-year periodor earlier if warranted by system performance or siteconditions.

- Initiating an off-site groundwater and surface watermonitoring program to evaluate the effectiveness of theon-site source control and off-site groundwater extractionand treatment system.

- Performing site removal and closure activities includingdisposal of on-site debris, disposal of discrete areasof significant non-volatile contamination not identifiedin the RI, disposal of metallic structures, demolitionand disposal of the site's building, draining and fillingin the lagoon, removal and disposal of known buried drumsand their contents, removal and disposal of decontaminationrinsate and other waste materials that result from remedialactivities, removal and disposal of a buried fuel tank,fencing the site with appropriate signs, learning thesite, and vegetating the site.

DECLARATIONS

Consistent with the Comprehensive Environmental ResponseCompensation, and Liability Act of 1980 (CERCLA), and the NationalContingency Plan (40 C.F.R. Part 300), I have determined that atthe McKin Company site, on-site soil aeration, extraction andtreatment of groundwater from off-site contaminated areas andthe other measures as described above are the cost-effective

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renedies for the on-site soil and off-site groundwatercontamination and provide adequate protection of publichealth, welfare, and the environment.

The State of Maine has been consulted and concurs with theselected remedy. In addition, the action will requireoperation and maintenance activities to ensure the continuedeffectiveness of the remedy. These activities will beconsidered part of the approval action and eligible for TrustFund monies for a period of one year from the completion ofremedial actions.

I have also determined that the action being taken is thecost-effective alternative when compared to other remedialoptions reviewed and is appropriate when balanced against theavailability of Trust Fund monies for use at other sites. Inaddition, the off-site transport and secure disposition of asmall quantity of contaminated drums and other material ismore cost-effective than other remedial action for this smallquantity of contaminated drums and other materials.

Date / Regional Administrator

SUMMARY OF REMEDIAL ALTERNATIVE SELECTIONMcKin Company Site - Gray, Maine

SITE LOCATION AND DESCRIPTION

The McKin Company site is located on the west side ofMayall Road between Route 115 and Pownall Road in Gray, Maine,approximately fifteen miles north of Portland, Maine and theAtlantic Ocean (see figure 1). The site is approximately7 acres with approximately 4.5 acres being cleared and partiallyexcavated. Between 1965 and 1978, the McKin Company operateda waste collection, transfer, and disposal facility at thesite.

Following removal actions, the site presently consistsof a fenced enclosure containing an incinerator, a concreteblock building, an asphalt-lined lagoon, miscellaneousdebris, and one buried fuel tank. An outer fence alongMayall Road and portions of the northern and southern siteboundaries restricts vehicle access and deters pedestrianaccess to the site.

The topography of the site area is relatively flat west ofMayall Road. The topography of the site has been modified bypast excavations, with the on-site fenced enclosure surroundedby steep upward slopes to the west, south, and north. At-gradeaccess is from Mayall Road, and beyond Mayall Road, the landslopes steeply eastward to the Royal River. Elevations rangefrom approximately 300 feet mean sea level (MSL) at the siteto less than 200 feet MSL at the river, approximately 3/4 milesdue east. The site area is located on a relatively permeableglacial outwash plain comprised of stratified sand, gravel, andboulders overlying heavily weathered granitic bedrock (seefigure 2). Cores of the underlying bedrock were moderatelyto heavily fractured and demonstrate a moderately high bulkpermeability as determined by computer simulations. Nosurface run-off from the site has been observed, and it isinferred that site surface drainage is contained on-site andincident water either evapotranspirates or percolates intothe soil. The eventual surface discharge location of thispercolating water is the Royal River system. The Royal Riveris a State Class C waterway, acceptable for recreationalboating and fishing, but not for water contact recreation oras a drinking water source without treatment. The site isnot located in a wetland or floodplain based on a site evaluationby the U.S. Army Corps of Engineers.

Neighboring lands include residential areas, wooded areas,and rural farmland. The nearest residences are immediately northand west of the site, located within 1500 feet of the site andwithin a triangle formed by pownal Road, Mayall Road, and

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Route 115. The closest hone is within approximately 200 feetof the site. The bedrock aquifer beneath homes to the northof the site served as a private water supply until privatewells were contaminated with chlorinated organic compounds.

RITE HISTORY

In 1963 Richard A. Dingwell, the owner of the McKin Company,purchased the McKin site and shortly thereafter began to usethe site to store and dispose of liquid wastes. Prior to useby the McKin Company, the land was reportly used intermittentlyas a sand and gravel pit. From 1965 to 1978 the McKin Companyoperated a tank cleaning and waste removal business using theGray site for collection, storage, disposal and transfer ofpetroleum wastes and industrial chemical wastes. Wastehandling facilities at the site used during McKin Companyoperations included 22 above-ground storage tanks, an asphalt-lined lagoon, and an incinerator (see figure 3). Liquidwastes were trucked to the site by the McKin Company andothers. On-site waste handling procedures included dischargeto the ground, storage in tanks or the lagoon, transportoff-site by truck, incineration, and on-site burial. Approxi-mately 100,000 to 200,000 gallons of waste were receivedannually by the McKin facility between 1972 and 1977.

In 1972 the McKin Company business expanded and the on-siteasphalt lagoon and the incinerator began operating to accommodatewastes generated by an ocean oil spill when a tanker owned byTexaco ran aground off the Maine coast. The McKin Company helda permit from the Maine Department of Environmental Protectionto operate the incinerator in the 1970's. Hse of the incineratorceased in or around 1973. Site operations ended in 1977 or 1978.

As early as 1973, nearby residents in East Gray reportedodors in well water and discoloration of laundry. Samplingindicated the presence of organic contaminants in residentialwells, and the Town of Gray issued an Emergency Health Ordinanceplacing a moratorium on any new construction within about twomiles of the site. In November 1977 Fred C. Hart Associates,a contractor to EPA, conducted a hydrogeologic assessment ofthe area, which indicated contaminants from the McKin sitehad reached many local private wells. In December 1977, theTown of Gray issued a Cleanup Order to the McKin Company.Also in December 1977, sixteen private water supply wells werecapped, and emergency water supplies were brought in by truckto service nearby residents. In August 1978 affected homeswere connected to a public water supply in an action funded bya $300,000 "Imminent Threat Grant" from the U.S. Departmentof Housing and Urban Development (HUD) and matching funds fromthe Town of Gray. The Maine Attorney General's office filed asuit against the McKin Company in 1978. This suit has not

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heen resolved. A separate class action initiated by a Graycitizens group was settled out of court. During the summerof 1979, Maine DEP supervised the removal of pumpable liquidwastes from the above-ground tanks and drums. This amountedto approximately 33,500 gallons of oil and chemical waste.Additional DEP actions taken in 1979 and 1980 included movingempty 55 gallon drums into the fenced area, performing amagnetometer survey, installing and sampling monitoring wellsaround the site and collecting and analyzing soil and groundwatersamples. In a November 1982 hydrogeologic study prepared byRobert G. Gerber and funded by DEP, Gerber simulated groundwatermovement in the site area and concluded that local groundwatercontamination in the surficial and bedrock aguifer resultedfrom waste disposal practices at the McKin site. Air qualityat the site was monitored by EPA in November 1982, and residualmaterials in the above-ground tanks were sampled and analyzedby DEP in March 1983. In April 1983, DEP contracted JetlineServices to rinse and crush a number of on-site barrels andcontainers and provide cost estimates to clean and dispose ofall remaining above-ground tanks.

A Remedial Action Master Plan (RAMP) for the McKin site wasprepared in April 1983 by Camp, Dresser and McKee (COM) undercontract to EPA. The RAMP recommended collecting the necessarydata, developing the required site area remedial action programand implementing certain Initial Remedial Measures (IRM's)to remedy potential hazards. DEP entered into a CooperativeAgreement with EPA in June 1983 to implement the IRM's and theRemedial Investigation and Feasibility Study (RI/FS) as recommendedin the RAMP. The IRM work conducted by Jetline Services includedthe cleaning and removal of all remaining above-ground tanks fromthe site. This work was completed in September 1983 and representsthe most recent removal action to take place on the site. InJanuary 1984, COM was awarded a contract by DEP to undertakethe RI/FS for the McKin site. The RI was completed in February1985 and the Ffi in March 1985.

CURRENT SITE STATUS

As identified in the RI, there are two remaining majorcontamination problems associated with the site. The first ison-site soil contamination in specific areas, which serves asa source for off-site groundwater contamination. The secondis groundwater contamination of the surficial and bedrockaquifers downgradient of the site. These two problems areconsidered in a series of source control alternatives and asecond series of off-site control alternatives in the FS.

On-site Soil Contamination

The nature and extent of the on-site contamination problemwas identified during the RI based on surface and sub-surface

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on-site soil sampling conducted by means of drilling (seelocations in figure 4), test pits (see locations in figure 5),hand auger borings (see locations in figure 6), and monitoringcontamination in horizontal grids around contaminated locations.Sample locations shown in figures 4, 5 and 6 were selected inpart based on detected magnetic anomalies, historical disposaldata and visual evidence of contamination. The laboratoryanalytical results of on-site soil samples are summarizedin Table 1. The samples listed in Table 1 were analyzedduring the RI and found to contain all or some of the 17hazardous substances listed in Table 1. In soil tests conductedin 1980, other priority pollutants were detected in on-sitesoils in concentrations ranging from zero to several partsper million (ppm). These pollutants Include polyaromatic compounds,phenols, and phthalates. Based on Maine DEP records thelocations of these 1980 soils tests were near soil boringsSS08 and SS01 shown in Figure 6 taken during the RI.

Each of these 17 hazardous soil contaminants detected in theRI can be classified as either a volatile organic compound ora heavy metal. Generally, the volatile organic compoundssuch as trichloroethylene and 1,1,1-trichloroethane aresoluble and susceptable to leaching and migration to thegroundwater. The detected concentrations of heavy metalsare relatively small (15 ppm soil or less) and withinranges typically found in soils. Compared with the volatileorganics, the heavy metal contaminants are generallyless susceptable to leaching and migration to groundwater.Of the contaminants detected in on-site soils only trichloro-ethylene and 1,1,1-trichloroethane were detected in ground-water during the RI.

Six areas of surface soil contamination were identifiedand staked out in the field based on surface and subsurfacetests. These areas are identified on a site map in Figure 7,as Areas 1 through 6. Area 1 is further divided in Areas 1A,IB and 1C based on physical and chemical properties. Volumeestimates of the contaminated soil in each area are providedin Table 2.

Areas 1A, 1C and 2 appear to be old oil disposal locations,where oil soaked debris and other suspected contaminants weredisposed of and covered with various thicknesses of fill. Inareas 1A, 1C, and 2, the major contaminants appear to betypical derivatives of petroleum refining, constituentsof petroleum, or Incidental petroleum contaminants based onlaboratory analyses and physical observations. It is possiblethat remedial actions in areas 1A, 1C, and 2 are not coveredby CERCLA given the discrete nature of this petroleum contami-nation on this site and the lack of groundwater contaminationby typical constituents of petroleum. Further soil tests are

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required to make this determination and will he performed duringthe remedial design. Prior to this determination areas 1A,1C, and 2 are not specifically included in the on-site CERCLAremedy described herein.

Areas 3, 4, and 5 are the most contaminated areas foundremaining on the site. Aerial photographs reveal that areas3, 4, and 5 exhibit obvious signs of discoloration and contami-nation. Among the most contaminated soils found on-site arethose in test pit TP6A, in Area 3 (1400 mg/kg trichloroethylene,49 mg/kg methylene chloride, 4.5 mg/kg 1,1 1-trichloroethane,and other contaminants), and soils found in soil boring RR02in Area 4 (1500 mg/kg trichlorethylene, 21 mg/kg xylenes,9.2 mg/kg dichlorobenzene, and other contaminants).

The depth of contamination in Areas 1, 2, 4, 5 and 6 wasidentified at six feet or less in the RI field studies. Thedepth of contamination in Area 3 is at least 12 feet, and a40 foot depth, the measured depth to groundwater in the area,has been used to estimate conservatively the volume of contami-nated soil in Area 3. In addition to soil contamination inAreas IB, 3, 4, 5 and 6, sixteen drums were located on thesite as presented in Table 3. The FS addresses source controlremedial action for Area IP, 3, 4, 5 and 6, the 16 knownburied drums, and the remaining building and structures onthe site.

Off-site Groundwater Contamination

The off-site groundwater contamination problem caused bythe McKin site was investigated in the RI by groundwatermonitoring and modeling. Groundwater at various depths wassampled in locations shown in Figure 8. Of the compoundsanalyzed for in the RT (see Table 4) the only compoundsdetected in the off-site groundwater were 1,1,1-trichloroethaneand trichloroethylene as presented in Table 5.

Previous tests identified 1,1,1-trichloroethane andtrichloroethylene as the major groundwater contaminants withseveral other contaminants also identified in the off-sitegroundwater. Rome of the previously detected compounds suchas 1,2-dichloroethane, 1,1-dichloroethane, chloroform, andtetrachloroetheylene were tested for specifically and notdetected during the RI. Others, such as dimethyl sulfide andFreon, are not considered priority pollutants.

In the surficial aguifer, the location of the highest levelof contamination is R-l, which is approximately 600 feetnorth, northwest of the site adjacent to Pownal Road (16,000ppb trichloroethylene and 170 ppb 1,1,1-trichloroethane).

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Th e location with the next highest level of contamination inthe surficial aquifer is B-3, approximately 1200 feet northnortheast of the site (1,800 trichloroethylene and 65 pph1,1,1-trichloroethane). These levels and a computer simulationof groundwater flow reveal a groundwater contamination plume.In the surficial aquifer the contamination plume is locatedfrom the site for roughly 1,000 feet, then swings to the easttowards the Royal River. The inferred surficial aquifer plume asmodeled with observed 1984 1,1,1-trichlorethane concentrationsis presented in Figure 9. A north-south bedrock ridge directlyeast of the site appears to account for the swing in thesurficial aquifer direction in the site vicinity. LocationB-3 represents the furthest lateral extension of surficialaquifer contamination detected in the RI field studies. Thewell at B-4 which is screened at the soil-bedrock interfaceapproximately half-way between the site and the Royal Riverdid not show detectable contamination. This may indicate thatthe contamination is contained entirely within the bedrockat that point.

In the bedrock aquifer, which prior to 1977 served as thedrinking water supply of nearby residences, the groundwaterappears to be conducted in fractures and cracks. The locationof the highest level of contamination is B-l approximately600 feet north, northwest of the site and adjacent to Pownal Road(29,000 ppb trichloroethylene and 500 ppb 1,1,1-trichloroethane).Downgradient concentrations of trichloroetheylene in the bedrockgroundwater at B-2, B-3, and B-5 are 56 ppb, 120 ppb and 190 ppb,respectively. Figure 10 depicts the bedrock aquifer plume,as modeled with the 1984 1,1,1-trichloroethane concentrations.The information suggests that the centerline of the bedrockcontamination plume falls more or less under the surficialaquifer contaminant plume, however the bedrock contaminationplume is more dispersed than the surficial aquifer contaminationplume. This is attributed to the fractured nature of the bedrock.

The eventual discharge location of both the surficial andbedrock aquifers is the Royal River system. This system includesa number of springs, including Boiling Springs, located on theeasterly sloping land between the site and the Royal River.Previous sampling programs found trace amounts of volatileorganic contaminants in Collyer Brook, a tributary to theRoyal River. During the 1984 RI field study, surface waterquality monitoring was performed in both of these surface watersas well as Boiling Springs and the on-site lagoon (see Figure 11).The laboratory results presented in Table 6 indicate the levelsof trichloroethylene and 1,1,1-trichloroethane in Collyer Brookand the Royal River are below a 1 ppb detection level. Concen-trations of trichloroethylene (44 and 32 ppb) and 1,1,1-trichloro-ethane (30 and 10 ppb) were detected in Boiling Springs. The

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absence of any volatile organic contaminants in the RoyalRiver or Collyer Brook indicate that these water courses arenot being adversely impacted by the McKin site. The mostprobable explanation for these absences is the volatilizationof these contaminants from the surface water.

Risk Assessment

Current potential health and environmental risks involvedwith no action alternatives are associated primarily withcontaminated groundwater. For exposures to other environmentalmedia, the risks are insignificant based on comparisons withrelevant guidelines and the risk assessment performed in theFS. The risk assessment performed in the FS, as summarized below,is based on hydrogeology, climate, toxicity data, and other factors

The concentrations of contamination in the Royal Riverpresent neither a significant health risk through directingestion of river water or dermal absorption during swimmingnor a significant environmental risk to aquatic species inthe river based on a comparison with applicable or relevantEPA criteria. On-site air monitoring detected concentrationsof contaminants below available state guidelines for ambientair levels. Ingestion of ten grams of the most contaminatedon-site soil would result in an exposure to trichloroethylenebelow known acutely toxic effects and the risk from chronicingestion of contaminated soil is not significant based onlimited exposures to the site and the degree of soil contami-nation. Acute or chronic public health affects from dermalcontact with on-site contaminated soil are not expectedbased on soil concentrations, the volatile nature of thecontaminants, and toxicological literature.

The release of contamination to the off-site aquifer is animpact to an environmental resource. It has caused theclosure of private wells. Since this aquifer also representsa potential drinking water source, the existing contaminationmay restrict future use of this resource. The public healthrisk associated with the groundwater contamination is consideredpotential because there are no known users of. the groundwaterfor a drinking water supply since extension of a municipalwater line in 1977. No RPA primary drinking water standardsexist for the two detected groundwater contaminants. For1,1,1-trichloroethane, not classified as a suspected humancarcinogen, the most relevant guideline for risk assessmentis a proposed recommended maximum contaminant level (RMCL)of 200 ppb. This level is exceeded in one of the groundwatermonitoring wells (R-l,bedrock). Trichloroethylene is asuspected human carcinogen, and the concentrations associatedwith a 10~5 lifetime risk of cancer for a 2 liter per day

water intake by a 70 kg adult is 28 pph based on CancerAssessment Group (CAG) data. This guideline level isexceeded at most of the groundwater sampling locations.Therefore, there is a public health risk associated with thelong term consumption of groundwater at its present contami-nation levels. Furthermore, groundwater is considered anintegral portion of the environment, and therefore, thepresence of groundwater contamination at levels found in theRI represents a risk to the environment.

ENFORCEMENT ANALYSIS

Potentially responsible parties (PRP's) for the McKin site includethe former owner and operators, generators, and transporters.To date, approximately ten notice letters have been sent togenerators or transporters based primarily on McKin Companyrecords, which suggest these parties contributed hazardoussubstances to the site. RPA is continuing to identify additionalresponsible parties and may send out further notice lettersas new evidence is developed. There are also over two hundredadditional parties which apparently sent petroleum wastes tothe site.

Richard Dingwell is the former owner and operator of theMcKin Company at the Gray site. ningwell was sued by the MaineAttorney General's Office in 1978 and this case has not beenresolved. In addition, a separate class action suit was filed bya Gray citizens group and was settled out of court.

Several of the potentially responsible parties have expressedwritten interest in participating in the remedial design andconstruction process. EPA is continuing negotiations with theseparties. Representatives of these companies have also participatedin the public hearing and public comment period. Given theinterest in responsible party cleanup by potentially responsibleparties there is a chance of concluding successful negotiationsfor construction.

EPA's overriding concern is ensuring that the selected remedycomplies with the National Contingency Plan. In this regard,there is no flexibility for negotiations. Technical differencesin design and construction approaches used to achieve thisremedy may be the subject of negotiations. Technical differencesbetween the selected remedy and the remedies proposed by thepotentially responsible parties are contained elsewhere in thisdocument and in the attached Responsiveness Summary.

COMMUNITY RELATIONS

Community interest in the McKin site has been strong sincethe detection of contamination in the 1970's. A public meetingto describe the RI/FS and to respond to citizen's questions was

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held at Stinson Hall in Gray, Maine on April 17, 1985. Approxi-mately 40 persons attended including citizens, elected officials,and technical and legal representatives of potentially responsibleparties. On April 24, 1985, a public hearing was held at the samelocation to record comments by the public including potentiallyresponsible parties. Comments were given by Maine DRP, theTown Council, the Gray Conservation Commission, privatecitizens, the Maine's People's Alliance, two state congressmen,and three representatives of potentially responsbileparties. Written comments from some of the same parties andadditional parties were received during the remainder of thepublic comment period. These comments and EPA's responsesare included in the attached responsiveness summary. Inaddition, the comments are summarized below. Following twotime extensions, the public comment period on the RI/FS wasextended twice to ensure that all interested parties had anopportunity to comment and was open from March 27 to May 6, 1985.On July 2, 1985, FPA representatives participated in aGray Town Council Meeting to inform the Council and the publicof EPA's proposed remedial action and to answer questionsfrom the Council and the public.

Regarding source control alternatives, oral and writtenstatements against capping have been made by Cathy Hinds ofthe Maine's People Alliance (speaking for a number of citizensat the public hearing), other citizens, State RepresentativeDonnell P. Carroll and State Representative James Mitchell.The Maine's People Alliance favored on-site incineration.The Town Council considered the proposed alternatives and wassplit with three councilors endorsing a cap and two councilorspreferring incineration. The Town Council stated a preferencefor a clay cap rather than a synthetic cap. A letter represent-ing four residents near the Gray site indicated a changedpreference from incineration to capping. Capping was endorsedas the least objectionable source control method in a separateletter from a member of the Gray Planning Board and the McKinSite Evaluation Committee. The State DEP and potentiallyresponsible party representatives presented comments in favorof on-site aeration as a source reduction method. Publichealth concerns regarding airborne emissions are themost often cited objection to both aeration and incinerationwhile public objection to capping centers on the argumentthat a cap covers but does not eliminate the waste andeventually contaminants will emerge.

A number of comments also were received regarding off-sitecontrol alternatives. Many comments centered on the inequityof possibly having the state tax-payers saddled with the burdenfor payment of operation and maintenance costs. Commentsreceived from citizens and from the Town Council endorsedextraction and treatment of groundwater from the contaminated

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aquifer. The Maine's People Alliance and citizens were infavor of Alternative 1C, specifically. Considerable oppositionto an off-site groundwater extraction system and questionsregarding the system were raised by potentially responsibleparties and by Maine DEP. Concerns primarily centered on thecost effectiveness of an off-site groundwater recovery system,the system's feasibility, and the need to accelerate activelythe restoration of the aquifer which is not presently beingused as a drinking water supply.

CONSISTENCY WITH OTHER FEDERAL ENVIRONMENTAL LAWS

One measure used by EPA in determining whether a remedialalternative at Superfund sites adequately protects publichealth, welfare, and the environment is whether the alter-native attains the substantive provisions of other federalpublic health and environmental standards. The primaryFederal Standards which are relevant to the McKin site arethe provisions and regulations of the Resource Conservationand Recovery Act (RCRA) describing site closure and groundwatermonitoring requirements for RCRA treatment, storage, anddisposal facilities. In addition, the requirements of theNational Pollutant Discharge Elimination System (NPDES)program are applicable to the discharge of waste streams tosurface waters.

The following source control alternatives have been proposedto meet RCRA requirements for hazardous waste facilities andhazardous waste handling when applied to the site, eitherindividually or combination:

On-site Aeration; The RCRA closure regulations requireeither closure by removal of waste and waste residues whichis equivalent to closure as a surface impoundment or closureas a landfill by capping and appropriate post closure care.The proposed aeration process, will meet the intent andtechnical requirements of the general RCRA closure standards(40 C.F.R. Part 264 Subpart G) and the specific closurestandards of 40 C.F.R. Part 264 Subpart K (SurfaceImpoundments). The surface impoundment standards, andspecifically 40 C.F.R. §264.228 the applicable closure standard,require the removal or decontamination of all wasteresidues and contaminated subsoils. As discussedherein, the residual soil contamination level after theaeration process that will be protective of human healthand the environment is 0.1 ppm trichloroethylene. Thislevel was determined by site specific solute fate andtransport modeling that considered the potential impactof this level on groundwater. This level was reviewedby the Centers of Disease Control and found to pose no

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hazard for direct soil ingestion, particulate ingestion ordermal contact. A groundwater monitoring program will beimplemented to monitor water quality and verify the assumptionsmade in the fate and transport modeling.

Excavation of Contaminated Soil, Debris, and Buried Drumswith Off-site Deposition: This alternative meets therelevant requirements of RCPA. Disposal of wastes will bein accordance with the appropriate RCRA regulations forthe transportation and disposal of hazardous waste.Off-site facilities used for disposal or incineration willbe RCRA approved facilities which have a permit or interimstatus and are in compliance with the RCRA regulations.Proper manifesting of wastes will be conducted. Off-sitedisposal will not reguire on-site treatment, storagebeyond staging time or disposal of hazardous wastes, andtherefore, there are no issues involving the consistencyof on-site actions with RCRA other than the need to charac-terize each load of material.

Regarding off-site controls, the relevant federal laws areRCRA hazardous waste facility regulations regarding groundwaterprotection (40 C.F.R. Subpart F) and the 1984 RCRA Amendments.The RCRA groundwater regulations reguire the setting ofgroundwater protection standards, which are levels that areprotective of human health and the environment. Correctiveaction is required if these levels are exceeded. The ground-water protection standard of RCRA requires the contaminationlevels (MCL's) or alternate concentration limits (ACL's).ACL's are site specific levels that are demonstrated to beprotective of human health and the environment. The 1984RCRA Amendments require off-site groundwater corrective actionto attain the groundwater protection standards. Generally,RCRA regulations and RCRA Amendments provide for ensuring thatgroundwater contamination levels do not cause a hazard to humanhealth or the environment. The selected off-site control alter-native, provides for groundwater extraction to the extentpractical followed by treatment and surface water discharge.This alternative is consistent with the intent of RCRA byrestoring the aquifer. A groundwater monitoring program todemonstrate the effectiveness of the extraction program will beperformed as required in the RCRA regulations. In extractinggroundwater from the surficial aquifer and in the uppermostportion of bedrock, the system reduces flow of contaminatedgroundwater to the bedrock aquifer, actively treats the surficialaquifer, and treats a substantial portion of the bedrock aquifer.

In this decision, performance standards to be achieved in thefive-year remedial treatment unit of groundwater extraction andtreatment are established as target groundwater concentrationsin the off-site aquifer. These performance standards are 28 parts

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per billion (ppb) trichloroethylene and 92 ppb 1,1,1-trichloroethaneThe analysis in the PS and this document used in setting theseperformance standards is based on environmental and health criteria.This analysis is technically equivalent to a RCRA ACL determination.

The selected groundwater extraction and treatment optionincludes a surface discharge of treated groundwater. Designspecifications for the treatment plant, effluent concentrationsand discharge structures will be consistent with the provisions ofthe relevant federal program.

ALTERNATIVE EVALUATION

Remedial Action Objectives

As identified in the National Contingency Plan, the objectiveof the evaluation of alternatives is to select the "lowest costalternative that is technologically feasible and reliable andwhich effectively mitigates and minimizes damage to and providesadeguate protection of public health, welfare or the environment."40 C.F.R. §300.68(j).

With certain exceptions that are consistent with FPA policy,the adequacy of protection of public health, welfare, and theenvironment posed by each alternative will be determined basedon the alternative's attainment of the substantive provisions ofother Federal public health and environmental standards.The following list identifies EPA's specific public health andenvironmental objectives for remedial action selection at McKin,as well as applicable or relevant standards which are used, in part,to judge attainment of these objectives:

0 To maintain adequate safe drinking water for the populationthat could be affected by groundwater contamination.Applicable federal drinking water standards are used, whenpossible, to determine the attainment of this public healthobject ive.

0 To prevent exposure of the public to inhalation of harmfulamounts of airborne contamination. Relevant ambient airlevels recommended by the Centers for Disease Controlare used, when possible, to determine the attainment ofthis public health objective.

0 To prevent the subsurface discharge of contaminatedgroundwater from the site to off-site aquifers. Relevantfederal standards for hazardous waste facilities(40 C.F.R. 264 and recent RCRA Amendments) will beused to determine the attainment of this environmentalobjective.

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To restore, within a reasonable time and practical limits,the off-site aquifer that has been contaminated by groundwatermigrating from the site to levels protective of public healthas a drinking water supply and the environment. Relevantfederal standards will be used to determine the attainment ofthis public health and environmental objective.

To protect state-designated Royal River surface water usesand aquatic life in the Royal River. Applicable state waterquality criteria will be used to determine the attainmentof these environmental objectives.

To prevent hazardous dermal contact with or hazardousingestion of contaminated soil by the public.

ALTERNATIVES CONSIDERED

The following remedial action alternatives were considered:

Source Control

0 No action

0 No action with monitoring

0 Capping the site.

0 Installing a containment wall and capping.

0 Excavation and off-site disposal.

° Excavation with on-site incineration and disposal.

0 Excavation with on-site treatment and disposal.

0 Excavation with off-site treatment and disposal.

Off-site Control

0 No action.

0 No action with monitoring.

0 Pumping, treating, and reinjection of groundwaterto aquifer or discharge to Royal River.

0 Restriction on future development.

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Site Closure Activities Common to all Alternatives

0 Disposal of all above-ground on-site debris (i.e. hoses,rags , etc. ) .

0 Removal and disposal of on-site metallic structures(i.e. incinerator, conveyor system, tubing, etc.).

0 Demolition and disposal of the masonry block building.

0 Draining and filling in the existing asphalt lagoon.

0 Removal and disposal of all known buried steel and fiber drumsand their contents.

0 Removal and disposal of decontamination rinsate and otherwaste materials that result from remedial actions.

0 Removal and disposal of the buried 3,000 gallon tank locatedsouth of masonry building.

0 Fencing entire cleared site with placement of appropriatewarning signs.

0 Learning and vegetating the site.

As described in FS , a review and initial screening processeliminated the following alternatives or portions of alternativesas not mitigating identified public health or environmentalthreats, being technically infeasible or providing no substantiallygreater public health or environmental benefits over alternativesincurring less cost:

1. No action (does not mitigate public health or environmentalthreats).

2. Capping entire cleared area of the site (no substantiallygreater benefits).

3. Installing a containment wall around the contaminated areas(no substantially greater benefits).

4. On-site soil encapsulation (no substantially greater benefits'

5. Systematically recovering contaminated groundwater fromfractured bedrock to clean the bedrock aguifer in acomprehensive manner (technically infeasible).

The screening of remedial alternatives indicates that asource control remedial action will be necessary to mitigatethe threat to public health and the environment. A source control

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action to lessen the generation of groundwater contamination andfurther prevent direct contact with the site is required. Forthis reason the "No Action" alternative does not warrant furtherconsideration as a source control remedial action alternative.

The remaining alternatives were then evaluated based onenvironmental and technical concerns, reliability, implementability,operations and maintenance (O&M) requirements, health and safetyconsiderations and detailed cost estimations, including distributionof costs over time in accordance with 40 C.F.R. 5300.68(i). Thealternatives evaluated during this detailed review and screeningincluded both on-site source controls or off-site controls:

On-Site Source Control

0 Alt. 1 - No Action with monitoring.

0 Alt. 2 - Capping of contaminated soil areas.

0 Alt. 3A - Excavation of contaminated soil with off-sitelandfill disposal.

0 Alt. 3B - Excavation of contaminated soil with off-sitei ncineration.

0 Alt. 4 - On-site incineration of contaminated soil withon-site landfilling.

0 Alt. 5A - On-site aeration and landfilling of contaminatedsoil.

0 Alt. 5R - Off-site aeration and landfilling ofcontaminated soil.

0 Alt. 5C - On-site aeration and capping of certaincontaminated soil.

O f f - S i t e Control

Alt. 6 - No Action with monitoring.o

0 Al t . 7 - Groundwa te r ext rac t ion and t rea tmentand on-site recharge.

7A - Groundwater extraction wells at one location.

7B - Groundwater extraction wells at two locations.

7C - Groundwater extraction wells at three locations.

0 Alt. 8 - Restrictions on Future Development.

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A brief description of these alternatives is given below, andTable 7 summarizes the costs, (capital, O/M, present worth),technical considerations, environmental considerations, publichealth considerations, and public comments for each alternative.

1. No Action with Monitoring. Monitoring wells wouldbe installed around the site and periodically sampled;these samples would be analyzed for hazardous substancesin order to monitor contamination of the groundwater.

2. Capping. An impermeable cap would be placed overcontaminated areas of a site. Contaminated areas IB, 3,4, and 5 (see Figure 2) would be capped under a singlecap and consistent with RCRA requirements, the contaminatedsoil in area 6 either would be removed for disposaloff-site or would be placed under the on-site cap.

3. Excavation and Off-Site Disposal. Contaminated soilfrom the site would be removed and transported off-site for disposal. Two disposal alternatives wereconsidered: (1) landfilling, which would involvedisposal of hazardous material in a licensed hazardouswaste landfill, or (2) incineration, which woulddestroy the contaminants by burning the contaminatedsoil at very high temperatures.

4. On-Site Incineration. Contaminated soil would beexcavated and incinerated in a mobile incineratorset up with appropriate auxiliary facilities on-site,and the ash residue remaining after incinerationwould be disposed of on-site.

5. Aeration. Contaminated soil would be rototilled orotherwise broken up and exposed to the air, allowingthe contaminants to volatilize. Three versions ofthis alternative were considered:

A. Aerate soil on-site

R. Transport contaminated soil off-site for aeration; and

C. Transport contaminated soil off-site for aeration,except Area 3, which would be capped.

6. No Action with Off-Site Monitoring. Off-site monitoringwells would be sampled periodically; these samples wouldbe analyzed for hazardous substances to monitor contaminationof the groundwater.

7. Groundwater Extraction and Treatment. Contaminated ground-water would be pumped from the ground by extraction wells

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then treated to remove the contaminants. Three versions ofthis alternative were considered in the FS :

A. One series of extraction wells,

R. Two series of extraction wells, or

C. Three series of extraction wells.

This alternative would remove contamination already in thegroundwater. To do this, contaminated groundwater would heintercepted as it leaves the site and further extractedfrom the off-site contaminated areas then pumped out by aseries of extraction wells. Extraction well locationsproposed in the FS are shown in Figure 12. The extractedwater would be treated to remove the contaminants. Itis estimated that groundwater extraction and treatment wouldreduce contamination of the groundwater to a level of 50 ppbof volatile organic contaminants in about five years.Based on the groundwater characterization in the RI, airstripping and carbon filtration would be used to removecontaminants from the extracted groundwater. The airstripping process causes the contaminants to evaporatefrom the water into the air, and the air would then besent through containers of activated carbon to removecontaminants from the air. In the three extraction andtreatment options considered in the FS, treated waterwould be the discharged back to the groundwater on site.

An additional groundwater extraction and treatmentalternative was proposed after the completion of thedraft FS. This alternative does not specify theexact number or locations of groundwater extractionwells but proposes to extract groundwater and restorethe offsite aquifer to the extent practical in atimely manner. To meet this objective, new wellsdeveloped for extraction most likely would be screenedin the surficial aquifer and in the uppermost portionof the bedrock. The necessary treatment operationsanticipated to remove contaminants from the extractedgroundwater are the same as presented in the FS,however these operations and the treatment designwill be assessed during a remedial design treatabilitystudy. This treatability study will evaluate groundwaterquality for all priority pollutants in the contaminatedaquifer and treatment efficiencies. Unlike thealternatives described in the FS, this alternativeproposes to discharge treated groundwater to localsurface water rather than to the groundwater. Thecosts, advantages and disadvantages of this groundwaterextraction and treatment alternative are presented

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in Table 7. The cost estimate for this alternativeis based on cost data in the PR modified by thedevelopment of 25 extraction wells with an estimatedwithdrawal rate of 5 gallons per minute and a surfacedischarge to the Royal River.

8. Restrictions on Future Development. Future developmentin areas affected by the groundwater plume would berestricted, which would preclude the need to providepublic water to new developments and would prevent thedevelopment of any contaminated water supply wells inpresently undeveloped areas.

RECOMMENDED ALTERNATIVE

Section 300.68(j) of the National Contingency Plan (NCP)states that the appropriate extent of remedy shall be determinedby the lead Agency's selection of the remedial alternative, whichthe Agency determines is cost-effective (i.e. the lowest costalternative that is technologically feasible and reliable andwhich effectively mitigates and minimizes damage to and providesadequate protection of public health, welfare or the environment).Rased upon our evaluation of the RI, the FS, the commentsreceived on these reports, and the options specified in thesereports and comments, EPA has determined and the state hasagreed that the following remedy meets the NCP criteria:

- r»n-site aeration of soils in site areas of identifiedhazardous substance contamination to achieve soil qualitylevels protective of public health and the environment.

- Off-site disposal of approximately 16 drums found on thesite and their contents.

- Performing soil tests in petroleum contaminated areas tofurther characterize the nature of contamination.

- Constructing a groundwater extraction, treatment, andsurface water discharge system and operating this systemas a remedial treatment unit for a period of five yearswith a target groundwater performance standard of 92 ppb1,1,1-trichloroethane and 28 ppb trichloroethylenefor groundwater quality.

- Re-evaluating the groundwater performance standard, if thisstandard is not achieved at the end of the five-year periodor earlier if warranted by system performance or sitecondi tions.

- Initiating an off-site groundwater and surface watermonitoring program to evaluate the effectiveness of theon-site source control and off-site groundwater extractionand treatment system.

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- Performing site removal and closure activities includingdisposal of on-site debris, disposal of discrete areas ofsignificant non-volatile contamination not identified inthe RI, disposal of metallic structures, demolition anddisposal of the site's building, draining and filling inthe lagoon, removal and disposal of known buried drumsand their contents, removal and disposal of decontami-nation rinsate and other waste materials that result fromremedial activities, removal and disposal of a buriedfuel tank, fencing the site with appropriate signs, loaningthe site, and vegetating the site.

The following discussion describes the recommended alternativeand the reason for its selection.

Source Control Remedy

Regarding the source control alternative, Alternative 1,No Action with Monitoring, was not selected because it is notresponsive to the groundwater contamination issue and does notfulfill the site objectives. The implementation of Alternative1 would result neither in the timely restoration of the off-sitecontaminated aquifer to the extent practical nor in the institu-tional controls to ensure no possible exposure to the contaminantedaquife r.

Each of the remaining source control alternatives is proposedto control further migration of pollutants from the contaminatedunsaturated zone to the groundwater. Contamination below thehigh water table is addressed with off-site controls ratherthan source controls.

Alternative 5R, off-site aeration was not considered becauseit was found to be infeasible. During the FS no local off-siteareas could be identified which would receive the contaminatedsoils for aeration and final deposition.

The remaining source control alternatives, Alternatives2,3,4, and 5A, were all judged to be technologically feasibleand reliable and to mitigate and minimize damage effectivelyand to provide adequate protection of public health, welfare,or the environment. Given the effectiveness of each of thesealternatives, consideration of cost is appropriate in selectinga source control option. The estimated total present worth ofcapping the contaminated areas using a clay cap is $430,000(5192,000 capital, $38,900 annual operation and maintenance)and is essentially the same as the estimated total presentworth of on-site aeration, which is $440,000 ($424,000 capitaland $1,600 annual operation and maintenance). The estimatedpresent worth of the remaining alternatives are significantlyhigher: $1,863,000 for excavation and off-site landfilling,

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($1,847,000 capital, $1,600 annual operation and maintenance);$5,103,000 for off-site incineration ($5,087,000 capital and$1,600 annual operation and maintenance); and $6,855,000 foron-site incineration ($6,840,000 capital, $1,600 annualoperation and maintenance). Therefore, the cost-effectivenessof two alternatives, capping and on-site aeration, are judgedto be essentially equivalent and the remaining source controlalternatives are judged to be not cost-effective. Given theessentially equivalent cost-effectiveness of capping andon-site aeration, EPA has selected on-site aeration as thesource control based on the Agency's policy to pursue responseactions that use treatment over land disposal to the greatestextent practicable, consistent with CERCLA requirements forcost-effective remedial actions. In selecting this remedyEPA also selects target performance standards to be used inassessing the remedy's effectivenss. One performance standardis an average soil concentration of 0.1 ppm trichlorethyleneaveraged over a treatment volume. For heavy metal soilcontaminants, the levels established in the ExtractionProcedure (EP) toxicity tests (40 C.F.R. Part 261.24) or theresults of solute fate and transport modeling using these testresults represent performance standards. These performancestandards are based on a health-based assessment specific forthe McKin site and are applicable to soils removed from orremaining in the contamination Areas IB, 3, 4, 5, and 6 identifiedin the RI. An on-site pilot study will be initiated to determinethe extent to which soil aeration can be utilized to removecontaminants from the site, and the specific engineeringmethodologies to be used to aerate soils in a manner protectiveof public health.

While EPA regards Alternatives 2, 3, 4, and 5A as effective,there is variation in the approach each alternative uses toachieve this effectiveness. EPA recognizes uncertaintiesassociated with each approach and has considered the advantagesand disadvantages of each approach in its decision. For eachapproach, these considerations are summarized in the followingdiscussion, beginning with the selected source control alter-native .

The selected source control alternative, on-site aeration, isa means of actively and significantly reducing the amount ofcontamination that remains on the site in a relatively simpleand expedient manner. In selecting this alternative EPA hasweighed the advantages and disadvantages of this approach aswell as the technical concerns associated with applying thisremedy to the McKin site. These concerns include (1) attainingnon-hazardous levels of contaminants in the soil; (2) confirminga determination of the depth of contamination in contaminationArea 3; and (3) maintaining ambient air quality protective ofpublic health once volatile organic compounds in the soil are

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exposed to air. While EPA recognizes these concerns anduncertainties, the Agency feels there is sufficient reason toproceed with soil aeration as the source control method with theprecautions and provisions described herein and that the benefitsof this waste reduction method offset the potential disadvantagesassociated with technical concerns.

A cap constructed and maintained in a manner consistent withRCRA is an effective means of isolating the soil contaminationfrom the primary transport mechanism of infiltration to thegroundwater. Engineering the construction of the cap is arelatively routine process, and measures are established to ensurereliable construction. The major negative factor associated withcapping is that wastes remains in-place and are not reduced oreliminated. Essentially, this closure method renders the site apermanent land disposal area. In addition, the effectiveness ofcapping is dependent in part on monitoring the cap's long-termintegrity and, if necessary, taking future maintenance or correctivemeasures. Cap inspections and groundwater monitoring during the30-year post closure period would provide substantial assurancesthat significant leakage is not occurring. Regarding flushingresulting from water table fluctuations, the cap cannot assurecontainment of those contaminants present below the high watertable. Uncertainty regarding the significance of this effectwould be minimized by monitoring the effects of this flushingin downgradient monitoring wells, particularly during the periodof the remedial treatment unit to extract groundwater immediatelydowngradient of the cap for treatment. Finally, there are a numberof advantages associated with avoiding the soil disturbancesassociated with soil removal and treatment. These includeavoidance of the following: (1) possible uncontrolled volatili-zation of organic contaminants when soils are exposed to air, (2)confirming a determination of the depth of contamination in contami-nation Area 3, (3) confirming a determination of the hazardousnature of a treatment end product and the appropriateness andrisks of redeposition of this material on-site and off-site.

The primary advantage of incineration is that the contaminantreduction associated with thermal degradation is the most effectivedestruction technology considered. Incineration of many wastestreams is a proven technology, however site specific test burnswould be necessary to demonstrate the effectiveness of incinerationfor several types of on-site contaminated soils. Of the alternativesconsidered, incineration is the most difficult engineering techniguefor source control. For on-site incineration, uncertainties,concerning effectiveness would be addressed by testing emissionsand combustion efficiency to meet air quality licensing requirementsor their technical equivalents. The use of a portable incineratoris a relatively new technology which, as of this writing, has beenfully utilized on only a small number of hazardous waste sites andonly one Superfund site in an experimental capacity. Significant

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t ime delays can he expected associated with demonstrating incinerationeffectiveness and safety, on-site scheduling of mobile incineration,or permitting. Baser) on recent test burns of dioxin contaminatedsoils in Missouri substantially more site preparation and mobilizationeffort, would be required than estimated in the F.S. This wouldprobably include the mobilization of approximately five tractortrailers on temporily foundations, contruction of two temporarybuildings and development of water supply and waste water disposalcapabilities for quench water. The comments expressed by Maine DEPwhich call for further "thorough examinations" of the technology toensure it is effective and implementable reflect a high concern forpublic health and the environment but suggest what may be a lengthyperiod before the on-site source is actually controlled. Finally,there are a number of uncertainties that must be addressed inon-site incineration as a technique proposed to treat soils on-sitein a batch process. These uncertainties center on:

(1) the possible uncontrolled volatilization of organiccontaminants when soils are excavated and exposed to air;

(2) confirming a determination of the depth ofcontamination in contamination Area 3; and

(3) confirming a determination of the hazardous natureof the ash and the appropriateness and risks ofredeposition of ash on-site or off-site.

Off-site disposal alternatives, Alternatives 3A and 3R,share the advantage of off-site incineration in that theyremove contamination from the site rather than controllingmigration of the waste. In addition, off-site disposala l t e rna t ives share wi th on-si te inc ine ra t ion s i m i l a rdisadvantages associated with soil removal. These include(1) possible uncontrolled volatilization of organic contaminantswhen soil is exposed to air during excavation; and (2) confirminga determination of the depth of contamination in contaminationArea 3. An additional disadvantage of off-site disposal isthe transfer of the contamination and safe disposal problemto another community. Whether that disposal is via incinerationor a secure landfill, there are a number of technical issuesto be addressed in that receiving community to ensure adequateprotection of human health, welfare, and the environment. Insome Superfund cases obtaining the assurance that humanhealth, welfare, and the environment is adequately protectedin the off-site facility receiving the waste has lead to timedelays in implementing source controls by off-site disposal.

The selected on-site alternative consists of aerating thesoil of Areas IB, 3, 4, 5, and 6 at a rate dictated bymaintaining off-site air quality protective of public health.This action includes continously monitoring ambient air,establishing site specific, health based performance standardsfor soil that will be left on site and establishing a verification

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monitoring program to evaluate the appropriateness and attainmentof performance standards. If, the soil aeration pilot studydemonstrates that soil aeration in specific locations isineffective in meeting these soil performance standards orinfeasible to accomplish while maintaining acceptable ambientair quality, a determination regarding selection of anotherremedy will be made by the Region Administrator. Regardlessof any future determinations, certain removal and site closureactivities will be performed including disposal of on-sitedebris, disposal of discrete areas of significant non-volatilecontamination not identified in the RI, disposal of metallicstructures, demolition and disposal of the site's building,draining and filling in the lagoon, removal and disposal ofknown buried drums and their contents, removal and disposalof a buried fuel tank, fencing the site with appropriate signs,loaming the site, and vegetating the site. Regarding thedisposal of buried drums, the 16 fiber and steel drums identifiedin the RI will be disposed of off-site.

In pursuing on-site aeration as a remedial action it isnecessary to establish health based, site specific performancestandards which represent soil contamination levels which cansafely remain on-site following aeration and provide a degreeof certainty that these levels can be attained. Health basedperformance standards must consider each route of exposureincluding potential groundwater contamination, dermal exposure,soil ingestion and inhalation.

Regarding potential off-site groundwater impacts, a maximumaverage soil concentration of 0.1 ppm of trichloroethylene,averaged over a treated volume of soil, is judged conservativelyto be protective of possible off-site ingestion of groundwatercontaminated by the migration of pollutants from residualon-site soil contamination. This value is derived usingsolute fate and transport modeling to estimate the on-sitesoil concentration associated with the off-site groundwaterconcentration protective of human health as drinking water.(This groundwater concentration is judged to be 28 ppb fortrichloroethylene based on a 10-5 lifetime cancer risk asdescribed in this document's discussion of the selectedoff-site remedial measure). Calculations, assumptions, andmethodologies used in this solute fate and transport modelingare attached to this Summary of Remedial Alternative Selectionas Attachment A. As described in this attachment, trichloroe-thylene is selected as an appropriate organic indicator forthis evaluation based on its elevated environmental concentrations,its toxicity relative to other organic chemicals detected inthe soil, and other factors. During the pilot soil aerationstudy, it is possible that the Agency's understanding of thenature and concentrations of organic soil contaminants willimprove. Should the soil performance standard of 0.1 ppm for

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trichloroethylene or the solute fate and transport modelingprovided in Attachment A prove to be inappropriate based onfurther information regarding mathematical modeling, hydro-geology, or on-site conditions, improved solute fate andtransport modeling nay be utilized to adjust the trichloroe-thylene soil performance standard or establish soil performancestandards for additional organic compounds.

For those metal contaminants detected in soils at the McKinsite, the extraction procedure (RP) toxicity standards containedin 40 C.F.R. §261.24 or the results of similar solute fateand transport modeling using these test results are judged tobe protective of public health via groundwater contaminationexposures for the McKin site. EPA recognizes that aerationwill not effectively remove heavy metal contaminants fromsoil, however, based on RI soil analysis results it is likelythat the above performance standards for metals are attainablewithout further netal removal.

Regarding the risks associated with dermal exposure withsoils, soil ingestion, and inhalation of soil particulate, theCenters for Disease Control has reviewed the soil performancestandards previously described and has found that attainmentof these performance standards will provide more than adequatepublic health protection from these exposure routes. Thisevaluation is based in part on acute and chronic dermaltoxicity data.

The extent of volatilization of susceptable compounds fromsoil during the aeration process is dependent in part onthe amount of soil surface area exposed to air arid the durationof this exposure. The selected remedy is to aerate soilsuntil the above performance standards are met or exceededbased on random soil sampling of treatment volumes. EPAEPA bases the feasibility of this remedy on theoretical andexperimental evidence which demonstrates if aeration isallowed to proceed for sufficient time essentially all volatileorganics will volatilize from the soil. Soil aeration hasbeen used to remove volatile contaminants from soil at otherlocations.

As described in the FS, the rate of aeration will be dictatedby ambient air conditions. Ambient air quality will be monitoredcontinuously during soil aeration. If air concentrations approachsite specific health based standards developed by the Centers forDisease Control then actions will be taken to abate the volatilizationof organics on the site. The practicality and effectiveness ofabatement methods will be evaluated during the pilot aeration study.Possible abatement methods to be evaluated during the pilotaeration study include ceasing excavation and soil mixing,covering exposed soil, aerating within an on-site enclosure,and subsurface aeration using a forced soil aeration technique.

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An air quality monitoring plan for volatile organics andparticulates will be developed during remedial design inorder to assure ambient air levels are protective of publichealth. This plan will rely on multiple continuous airmonitors and will stipulate contingency actions to be takenif threshold levels are exceeded. EPA has requested theCenters of Disease Control to establish the necessary thres-hold levels in consultation with the Maine Bureau of Health.These levels will serve as the basis for the air qualitymonitoring plan for volatile organics. If these level areviolated work will be discontinued and the feasibility ofthe ongoing process evaluated. The potential for dustgeneration during on-site aeration also will be evaluatedin the pilot treatment study, and dust control measures willbe addressed in the remedial design.

Regarding on-site Areas 1A, 1C, and 2, EPA feels there isinsufficient evidence to determine the applicability ofCERCLA to remedial actions in these areas. Therefore, furthersoil testing in these areas will be performed during remedialdesign and a determination of the appropriate remedial responsewill be made.

Off-site Remedy

Regarding the off-site groundwater contamination, EPA hasdecided to implement groundwater extraction and treatment asa positive, cost-effective means of restoring the off-sitecontaminated aquifer and thereby minimizing damage to publichealth, welfare and the environment. The selected remedy isto extract contaminated groundwater to the extent of technicalpracticality in order to to restore the off-site contaminatedaquifer in a timely manner. Extracted groundwater will betreated and discharged to local surface water. In makingthis decision, EPA has carefully considered several otheroff-site alternatives (1) No Action, (2) No Action withMonitoring Alternative 6, (3) Restricting off-site developmentAlternative 8, (4) Treating recovered water at Boiling Springsand/or the Royal River as proposed by several potentiallyresponsible parties, (5) Less extensive off-site groundwaterextraction systems, Alternatives 7A and 7B and (6) the ground-water extraction treatment and recharge system configurationdescribed in Alternative 7C. The basis for EPA's selectionis that the Agency sees the groundwater extraction and treat-ment system selected as the only alternative which is feasibleand effective in meeting the remedial action objectives setforth in this Summary of Remedial Alternative Selection.

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As previously stated, EPA's remedial action objective re-garding off-site groundwater is to restore the off-siteaquifer to contamination levels protective of human healthand the environment within a reasonable period of time andpractical limits. A No Action Alternative for off-sitecontrol coupled with the selected source control remedy islikely to restore the contaminated aquifer eventually throughnatural flushing and dispersion mechanisms. The FS predictsthis will occur within about ten years based on a 50 ppbtotal volatile organic chemical target concentration. Giventhe feasibility of restoring the aquifer in a shorter periodof time with an extraction and treatment system, the uncer-tainty in this ten year estimate, and the possibility ofother, less mobile constituents in the groundwater, EPA hasdetermined that a No Action Alternative, the No Action withMonitoring Alternative and No Action with both monitoringand restrictions on future development alternatives are notresponsive to correcting the present levels of contaminationthat have migrated from the site and that these alternativesare not effective in meeting the remedial action objectives.Furthermore, EPA recognizes the contaminated aquifer as anenvironmental resource and finds a No Action Alternative tobe inadequate protection of the environment.

Alternative 8, restricting future development in affectedareas, is aimed at ensuring that no one will be exposed towater from the contaminated aquifers. This alternative wasnot selected because of the difficulty and uncertainty ofguaranteeing the implementation and enforcement of suchrestrictions for the time period until safe water qualitylevels are achieved. Moreover, this alternative does notseek to mitigate or minimize the threat to the environment.Notwithstanding this decision, EPA requests the State andTown to take measures to ensure that the contaminated aquifersare not used as a water supply during the period of aquiferrestoration.

E. C. Jordan, a technical consultant to a potentially respon-sible party, has suggested an off-site alternative whichpossibly includes the treating of water as it discharges fromthe contaminated aquifers at Roiling Springs, the Royal Riveror both. Based on available information, EPA has determinedthat this off-site alternative is neither directed nor respon-sive to the objective of restoring the off-site aquifer thatis presently contaminated. The objective of this proposedalternative appears to be protection of surface water qualityand uses. EPA shares this objective with the commentors but

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has determined from the present evidence that this objectiveis being met currently without treatment at the groundwaterdischarge location in the area of the Royal River.

Alternatives 7A and 7B as described in the FS representgroundwater extraction and treatment systems less extensivethan Alternative 1C. EPA has determined that the intent of theselected Alternative is to restore the contaminated aquiferin a timely manner to the extent of practical feasibility, andAlternatives 7A and 7B were not selected because Alternative 7Cwas viewed as a more extensive treatment alternative.

Comments received from local citizens and elected officialseither endorsed a groundwater extraction system as an off-sitecontrol or were silent with respect to an endorsement. Commentsfrom potentially responsible parties were opposed to thegroundwater and the extraction system proposed in the FS.Major reasons for this opposition include the views that thesystem is unnecessary to protect adequately public healthsince an alternative drinking water supply is in use andappears to meet additional future needs and that the systemis not cost-effective compared to implementing source controlsand allowing natural mechanisms to cleanse the aquifer. EPArecognizes that the existing public water supply greatlyreduces the public health risk associated with the contaminatedaquifer, but is not confident that long-term institutionalrestrictions could be implemented and enforced on the affectedland to ensure that contaminated groundwater is not utilized.Furthermore, EPA's selection of the effective off-site remedialaction is based on the NCP standard of effectiveness whichprovides for adequate protection not only of public health andwelfare but also of the environment. The contaminated aquiferis a former and potential environmental resource. Restorationof this environmental resource which was degraded by themigration of contaminants from the McKin site is consistentwith provisions of other Federal laws (i.e. the 1984 RCRAAmendments) as well as the EPA Groundwater Protection Strategy.The National Contingency Plan requires EPA to select the theremedial alternative which the Agency determines is costeffective. In the case of this contaminated aquifer, EPA hasdetermined that expedient restoration to the extent practicalas provided by a groundwater extraction and treatment systemis the only off-site alternative which meets this standard ofeffectiveness, and therefore, this alternative is the costeffective alternative.

EPA has studied comments received from Maine DEP andpotentially responsible parties which raise technical concernsassociated with Alternative 7C as described in the FS. Thesetechnical concerns include:

- the abililty of attaining the projected well yields

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- the feasibility of discharging treated groundwater on thesite as described in the FS which may cause unacceptableadverse environmental effects.

- the appropriateness of groundwater modeling assumptions.

- the possible creation of a stagnant zone of contaminatedgroundwater between Mayall Road and Boiling Springs.

On the basis of EPA's review of these concerns the Agency hassufficient reason to question the feasibility of Alternative 7Cas proposed in the FS with its specified extraction well anddischarge locations. Therefore, the Agency does not considerAlternative 7C to be an effective off-site alternative at thistime. EPA feels, however, that the above concerns can beadequately addressed in the selected groundwater extractionand treatment alternative and finds the selected off-sitecontrol alternative to be reliable and effective.

Regarding the discharge of treated groundwater, this dischargewill be to local surface water rather than to on-site groundwateras proposed in Alternative 7C. Regarding the other concernslisted above, although EPA feels that the selected extractionand treatment system is the cost effective remedy, more precisedeterminations regarding well yields, modeling assumptions,and groundwater flow will be made during the remedial design.Available well logs presented in the RI, permeability generallyassociated with the surficial materials presented in theselogs, and recent pump test and hydraulic conductivity datacollected at the site further demonstrate that an effectivegroundwater extraction system can be constructed in thecontaminated aquifer. This recent pump test indicates asignificantly greater permeability than assumed by potentiallyresponsible parties in their comments regarding the infeasibilityof a groundwater extraction system. The remedial design willinclude field tests to characterize more accurately theoff-site contamination plume between the site and its surfacewater discharge and to determine well yields, drawdowns,saturation thickness, and the most effective placement andpumping rates of the extraction wells. A degree of flexibilityin the extraction and treatment systems is allowable based ondesign studies in order to achieve the objectives of theremedial action and the concepts of design outlined in theFS. Areas of flexibility include the number of wells, thelocation of wells, and the need for the three series ofextraction wells as proposed in Alternative 7C if significantincreased effectiveness as a result of additional wellscannot be demonstrated.

Another area of study during the remedial design is a treat-ability study using the contaminated groundwater. Thistreatability study will address all priority pollutants in

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determining an effective treatment design. A five-yearperiod of groundwater extraction and treatment is beingstipulated in this decision as a remedial treatment unit.

Relative to the off-site remedy, performance standards areestablished in this decision to be achieved by the five-yearremedial treatment unit for the two detected groundwatercontaminants. The performance standards set for the extractionand treatment system at the McKin site are 92 ppb of 1,1,1-trichloroethane and 28 ppb trichloroethylene applicablethroughout the aquifer contaminated affected by the migrationof these chemicals from the McKin site. These performancestandards are based on levels that protect human health, welfareand the environment at this site with consideration to potentialexposures and possible synergistic or additive effects.Regarding protection of the aguatic environment, the riskto surface water use of the Royal River presently does notappear to be significant and will not increase with theattainment of these performance standards.

EPA has determined that exposures at or below theseperformance standard levels at this site will be at levelswhich do not pose a substantial threat to human health andthe environment. The trichloroethylene performance standardis based on a cancer risk of 10~5 (i.e., that a personexposed to this level of contamination in drinking waterthroughout his or her lifetime (70 years) will bear anincreased risk of less than or equal to 1 in 100,000 ofcontracting cancer as a result of ingesting trichloroetheylene).EPA recognizes trichloroethylene as a suspected carcinogenand has made a determination of its performance standard forthis site through the risk management process. In general,the Agency has made decisions to reflect specific situationsto allow concentrations of suspected or known carcinogenswhere the individual risk values have been within a range of10~8 ^0 10~4. In selecting 10~5 as the appropriate lifetimestatistical cancer risk value within this range, EPA hasconsidered the following site specific factors:

0 There will be a relatively low level of uncertaintyregarding the levels of contamination in the affectedaquifers following five years of monitoring localgroundwater, surface water, and the effectivenessof the extraction and treatment system.

0 There is presently no known regular human use of thecontaminated aquifer, a situation which is expected tocontinue based on the availability of an alternativedrinking water supply. The areas of the most concentratedcontamination are developed areas least likely toutilize the aquifer for a drinking water supply bydeveloping new private wells.

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0 Based on the physical and chemical characteristics ofthe waste (mobile organic solvents), the hydrogeologicalcharacteristics of the site (fractured bedrock andrelatively permeable surficial material in areas ofgreatest contamination), and the groundwater flow rateand direction, natural attentuation mechanisms areexpected to diminish groundwater contamination furtherin areas where the extraction and treatment system issuccessful following the five-year remedial treatmentunit. Based on these factors, this further decreasein contamination levels is expected to reduce furtherthe lifetime cancer risk relatively rapidly.

0 The groundwater extraction and treatment systemis expected to be effective and reliable inattaining the performance standards.

0 The models used in calculating public health riskswere structured to be conservative in nature.

The 1,1,1-trichloroethane performance standard is based onthe recommended maximum concentration limit (RMCL) of200 ppb, as a toxic, non-carcinogenic contaminant having athreshold. The 200 ppb level is adjusted to a performancestandard of 92 ppb based on a consideration of possiblesynergistic or additive effects with trichloroethylene.This adjustment is based on the fractional approach forestimating guidance levels for multiple toxicant exposure.This approach assumes additive and similar systemic effects.The determination of the 92 ppb performance standard for1,1,1-trichloroethane is calculated from: (1) a 52 ppb adjustedacceptable daily intake (ADI) level for trichloroethylenein drinking water; (2) the 28 ppb performance standard fortrichloroethylene previously described; and (3) the 200 ppbrecommended maximum concentration limit for 1,1,1-trichloroethane

The extraction and treatment system selected in this decisionis a five-year remedial treatment unit. If at the end of thisfive-year treatment period the performance standards are notachieved, an evaluation of the system, concentration limits,and public exposures will be made. In this case, followingthis evaluation, the Regional Administrator with concurrencefrom the State of Maine will make a decision regarding appro-priate actions. This decision may mandate continued operationof the system beyond the remedial treatment period. Theremedial treatment unit will be allowed to operate less thanthe five-year period only after the performance standards areachieved or after a determination and decision regarding thetreatment system, potential exposures, or concentrationslimits is made by the Regional Administrator with concurrencefrom the State of Maine.

-31-

In association with the selected source control and off-siteremedial actions, groundwater and surface water monitoringprograms will be developed in order to evaluate the effective-ness of the actions, verify predictive modeling assumptions,and monitor concentrations in the groundwater plume andreceiving surface water. New groundwater monitoring locationsmay be developed for this program if warranted.

OPERATIONS AND MAINTENANCE (O&M)

Regarding the source control remedy, operation and maintenance(O&M) actions associated with on-site aeration of the contaminatedareas involve site maintenance activities such as mowing. ProjectedO&M costs as estimated in the FS as $1,600 per year. Operation andmaintenance costs for groundwater quality verification monitoringis included in the cost estimate for the off-site remedy.

Regarding the off-site remedy, the groundwater extractionand treatment system is selected as a remedial treatment unitto treat contaminated groundwater for a five-year period. Assuch, no operation and maintenance costs are associated with thisremedy during this five-year period. Performance standards havebeen established to be achieved in this five-year treatment. Ifthey are not achieved, the performance standards and method ofachievement at the McKin site will be evaluated at the completionof the treatment unit. That evaluation may include a commitment totake further corrective action to remedy groundwater contamination,and O&M costs may be associated with these future actions. However,with the present expectations of a successful remedial treatmentunit, there are no O&M costs associated with the remedial actiondecision for the off-site groundwater contamination, outside ofcontinuing groundwater monitoring costs. The purpose of thisprogram is to monitor the effectiveness of the source controlalternative and the extraction and treatment system. Costs forinitiating and utilizing a groundwater and surface watermonitoring program during the five-year treatment unit areassociated with the construction of the remedial actiontreatment unit and are not considered operation and maintenancecosts. Continuation of the monitoring program beyond theremedial treatment unit will result in operation and maintenancecosts estimated to be $37,300 per year.

The state has made a commitment to provide the operation andmaintenance costs to fund surface water and groundwatermonitoring and on-site maintenance after completion of thefive-year remedial treatment unit. Assuming a successfulfive-year groundwater remedial treatment unit, these costsare estimated at $38,900 per year. The state funding mechanismis the Uncontrolled Hazardous Substance Site Bond Account, andthe Maine Department of Environmental Protection is the stateagency responsible for O&M.

-32-

SCHEDULE

The following are the key milestones and dates forimplementation of the selected remedy:

Approval Remedial Action (sign ROD) July 18, 1985

Award Contract for Design July 19, 1985

Start Design July 19, 1985

Complete Aeration Pilot Study and September 6, 1985Design to a Reasonable Cost Estimate

Obligate Funds for Construction September 20, 1985

Complete Design March, 1986

Start Construction May, 1986

Begin Remedial Treatment Unit for 1986Treatment of Groundwater

End Remedial Treatment Unit 1991

-33-

FUTURE ACTIONS

A sufficient characterization of the soils and petroleumwastes in on-site contamination Areas 1A, 1C, and 2 is notavailable at this time. Soil testing in these areas will beperformed during remedial design to determine the applicabilityof CERCLA to these areas and the appropriateness of includingthese areas in the remedial response described herein.

Regarding the selected source control remedy, a pilotsoil aeration study will be performed during remedial design.If during this pilot study or during the remedial action, itis determined that soil aeration of the contaminated areasidentified in FR cannot be performed in a manner protectiveof public health and the environment, a determination regardingthe selection of another source control remedy will be madeby the Regional Administrator. This determination is apossible future action.

As additional possible future actions, a re-evaluation ofperformance standards for off-site groundwater contaminationlevels or the on-site soil contamination levels may benecessary. Regarding off-site groundwater contaminationlevels, any decision to alter these performance standards basedon such an evaluation would be made by the Regional Administrator.It is anticipated that this evaluation will be made if necessary,at the conclusion of the five-year remedial treatment unitbased in part on information gathered from the off-site ground-water and surface water monitoring program. If site conditionswarrant, a reevaluation and decision can be made by the RegionalAdministrator at an earlier date. Such site conditions includethe performance of the extraction and treatment system, off-sitegroundwater contamination levels, and exposures to and impactsof the contaminated water. This decision may include additionalremedial actions to ensure adequate protection of public health,welfare or the environment.

ATTACHMENT A TO

SUMMARY OF REMEDIAL ALTERNATIVE SELECTION

McKIN COMPANY SITE - GRAY, MAINE:

ANALYSIS OF PROPERTY BOUNDARYCONTAMINANT CONCENTRATIONS

CAMP, DRESSER AND McKEE

July 10, 1985

TABLE OF CONTENTS

Section Title Page

1.0 Introduction 1-1

2.0 Selection of Indicator Compounds 2-1

3.0 Selection of an Analytical Model 3-1for Simulation of GroundwaterContamination

4.0 Groundwater Model Application 4-1

Appendix COM, Gerber and other Referencesused to estimate model imputparameters

LIST OF TABLES

Table No. Title Page

1 Compounds Found On-Site, 2-3Preliminary Protective ConcentrationLimits, (PPCL's), and the Ratio ofthese Two Parameters

2 Frequency of Occurence of the Volatile 2-5Compounds

3 Compounds with High Concentration/PPCL 2-6Ratio

4 Physical and Biological Parameter Values 2-7

5 Input Parameter Values Used for the Model 3-4

6 Estimation of the Saturated Thickness A-2of the Overburden Aquifer

7 Data from Installation of Monitoring A-3Wells

8 Relative Levels of Organic Matter A-4

9 Laboratory Analytical Results of A-5Groundwater Quality Monitoring

10 Other Paramters Referenced A-6

11 Typical Values of Aquifer Parameters A-7

1.0 INTRODUCTION

The objective of this analysis is to present computations of chemicalmigration rates and the resultant groundwater concentrations of chemicalcompounds which may migrate from the McKin Chemical Co. site. To beconservative, the following circumstances are assumed:

1. The source of the contaminants are those which remain in theunsaturated zone soil.

2. The back calculated groundwater concentration in the saturated zone,below the site, is equal to the concentration in the unsaturated zonegroundwater. Therefore, no dilution of the unsaturated zonegroundwater, as it mixes with the saturated zone groundwater, isassumed.

3. No degradation of the contaminants, either biological or chemical isassumed.

4. Contaminant sorption in the saturated zone is neglected.

5. Dilution from recharge infiltration is neglected.

1-1

2.0 SELECTION OF INDICATOR COMPOUNDS

The chemical monitoring data for the McKin site was reviewed to select"indicator compounds", that is, those compounds which should be of greatestconcern due to their known on-site concentration, their behavior based onchemical properties, and their observed concentrations relative to,thePreliminary Protective Concentration Limits (PPCL's) (Salee, 1984) .PPCL's are suggested levels of chemical compounds that should not beexceeded on a long term exposure basis. They are not standards, but ratherguideline values on which to base consideration of remedial actions. Thefollowing procedures was used to select the indicator compounds.

o Chemical compounds found on-site were listed.

o The list was compared to the PPCL preliminary tabulations obtainedfrom EPA. The basic consideration is long-term (chronic), lowlevels of exposure through ingestion of potable water. Theingestion rate was computed based on exposure of a 70 kilogram adultconsuming two liters of water per day over a 70 year period.

o The on-site concentrations of the compounds listed in Table 1 weredivided by the PPCL's yielding a relative value in terms ofimportance of the particular chemical from a health effectstandpoint relative to its concentration on-site and resulted in theselection of the compounds in Table 3. This is an indirectcomparison, as the PPCL, a concentration in water, is being comparedwith a sludge or soil (solid) concentration on-site.

o The frequency of occurence of volatile organics was reviewed anddetailed in Table 2 to give an indication of the ubiquitousness ofthe most mobile chemicals.

Based on of the ratio of the on-site concentration to the PPCL, certaincompounds were singled out as indicator compounds. These are listed inTable 3. Further consideration was given to the physical and biologicalcharacteristics for the compounds in Table 3. These include:

1. Solubility,2. KOC (Adsorption Coefficient), and3. Biodegradation Susceptability

The relevant values for those parameters are listed in Table 4.

Memorandum from Mark A. Salee, Land Disposal Branch USEPA to Kenneth A.Shuster, Chief of Land Disposal Branch USEPA, October 24, 1984.

2-1

Based on a review of the data in Table 4, the polynuclear aromatichydrocarbons (PAH's) found on-site can be realistically eliminated fromfurther consideration as indicator compounds since it becomes apparent thatthese materials typically are not mobile in the subsurface environment.Support is given to this statement by examination of the physical and'biological properties of these compounds. The four polynuclear aromatichydrocarbons listed in Table 3 have low solubility, in one case almost onemillion times less than that for trichloroethylene (TCE), higher adsorptioncoefficients, approximately ten thousand times more than that for (TCE) andhave significant biodegradation susceptability. As a result of a review ofthe physical properties of these compounds and this site investigation, PAHcompounds are not considered good indicator compounds. Therefore, the twoindicator compounds remaining are TCE and 1-2 dichloroethylene. Most ofthe physical parameters considered for these two compounds are quitesimilar, with the exception of solubility (see Table 4). Trichloroethyleneis an order of magnitude larger in terms of solubility thandichloroethylene and as such trichloroethylene is selected as the indicatorcompound and is used to evaluate remedial action options. In addition, tobe conservative and consistent with a worst case approach, soil retardationin the saturated zone and biodegradation effects have been neglected.

2-2

TABLE 1

Compounds Found On-Site, Preliminary Protective ConcentrationLimits (PPCL's), and the Ratio, of These Two Parameters

Highest MeasuredCompound Cone. (Soil) (ppb)

Volatiles

Trichloroethylene

Ethyl benzene

Xylenes

Dichlorobenzene

Tetrachloroethylene

1,1,1-Trichloroethane

1-2 Dichloroethylene

Tol uene

Acid Extractable Compounds

Pentachlorophenol

Phenol

2-Chl orophenol

2, 4-Di methyl phenol

Base/NeutralExtractable Compounds

Acenapthene

2-Chloronapthalene*

Fluoranthene

1,500,000

250,000

580,000

49,000

16,000

4,500

87,000

> 30, 000

220

370

57

170

770

44

110

PPCL (ppb)

1.84

4,750

none listed

470

1.0

21.9

0.238

15,000

1,050

3,500

none listed

385

none listed

0.00303**

210

Cone

815,217

52.6

104

16,000

205

365,546

>2

0.210

0.106

0.442

14,521

0.524

2-3

TABLE 1 (Cont'd)

Highest MeasuredCompound Cone. (Soil) (ppb)

Base/NeutralExtractable Compounds Cont.

Naphthalene*

Nitrobenzene

N-nitrosodiphenylamine

Bis(2-ethylhexyl ) phthalate

Di-n-butyl phthalate

Di-n-octyl phthalate

Dimethyl phthalate

Benzo (a) anthracene*

Benzo (a) pyrene

3,4 - Benzo-fluoranthene*

Chrysene

Acenaphthylene

Anthracene/phenanthrene*

Benzo (ghi) perylene

Fluorene

Dibenzo (a,h) anthracene*

Indeno (1,2,3-cd) pyrene

Pyrene*

240

81

3,200

1,500

88

67

87

350

120

54

260

180

2,400

41

440

12

33

380

PPCL (ppb)

0.00303**

none listed

7.14

21,000

none listed

none listed

350,000

0.00303**

0.00304

0.00303**

0.00303

none listed

0.00303**

none listed

none listed

0.00303**

none listed

0.00303**

Conewin:

79,208

448

0.071

0.0025

115,511

39,604

17,822

85,809

792,079

3960

125,413

* Polynuclear Aromatic Hydrocarbon (PAH)** PPCL = 0.00303 for all PAHs

2-4

TABLE 2

Frequency of Occurence of the Volatile Compounds

Compound

Trichloroethylene

Ethyl benzene

Xyl enes

Di chlorobenzene

Tetrachl oroethyl ene

1,1,1 - Trichloroethane

Toluene

1-2 Dichl oroethyl ene

Number of TimesDetected

8

11

11

8

5

6

4

2

Number of Ti mesAnalyzed

33

34

34

27

22

33

8

18

PercentOccurence

24.2

32.4

32.4

29.6

22.7

18.2

50.0

11.1

2-5

TABLE 3

Compounds with High Concentration/PPCL Ratio

Compound CUss Concentration/PPCL

Trichloroethylene Volatile 815,217

1,2 Dichloroethylene Volatile 365,546

Benzo (a) anthracene PAH 115,511

Anthracene/phenanthrene PAH 792,079

Pyrene PAH 125,413

NOTE: PAH = Polynuclear Aromatic Hydrocarbon

2-6

TABLE 4

Physical and Biological Parameter Values

Compound

Trichloroethylene

1-2 Dichloroethylene

Benzo (a) anthracene

Anthracene/phenanthrene

Pyrene

Solubility,(ppb) l

1.1 x 106

4.0 x 105

5.7

50/1000

130

KOC9(ml/9)

38

38

2.2 x 105

1.6 x 10

4.4 x 104

BiodegradationSusceptability

Slow, if any3

Slow3

Significant^

Significant.

Significant.

References:

1 & 2 - Report to Wald, Harkrader 4 Ross, Washington D.C. by A.D.L. Inc.,Cambridge MA "Reference Constants for Priority Pollutants andSelected Chemicals", March 1981.

3 Wilson, J.T. et al, "Potential for Biodegradation of Organo -Chlorine Compounds in Groundwater", USEPA - 600/D-84-138, May, 1984Page 6.

4 Tabak, H.H. et al, "Biodegradability Studies with Organic PriorityPollutant Compounds"

2-7

3.0 SELECTION OF AN ANALYTICAL MODEL FORSIMULATION OF GROUNDWATER CONTAMINATION

A groundwater model was applied to compute contaminant concentrations atthe boundary of the McKin site and at the location of the nearest potentialreceptor under no action and source treatment conditions. Several analy-tical solution models were considered; each was conservative, continuous,and suitable for environmental conditions observed at the McKin site.

The first model considered is the ROCEM (Revised Off-the-Wall ContaminationEvaluation Methodology) model. This model is taken directly from Freezeand Cherry's text, Groundwater, but was not deemed useable for the McKinapplication, as it does not simulate a continuous source.

The first of the continuous source models was proposed by D.C. Kent,et al . in an article published in the Spring 1985 edition of GroundwaterFTohTTorinq Review entitled "Analytical Methods for the Prediction ofLeachate Plume Migration". This model was eliminated because the inputparameters yielded an undefined mathematical term, a negative square root.The second model was obtained from the EPA's office of Solid Waste Studiesand Methods Branch. It is the solution of a two-dimensional solutetransport equation utilizing dimensionless numbers. It was rejectedbecause the input parameters yielded downstream contaminant concentrationsthat were unrealistically small. In addition, the infiltration term, I,has the units of I/time. It is not clearly defined in the report howinfiltration, with typical units of inches/year, can be expressed in theseunits. As such, this model was rejected for application to the McKin site.

The next model considered was a modified version of the two-dimensionalanalytical solution provided by Wilson and Miller. The model applied wastaken from a paper presented by John Wilson at the 1980 BSCE HydrologyLecture Series at M.I.T. This model originally was presented by Wilson andMiller, entitled "Two-Dimensional Plume in Uniform Groundwater Flow",Journal of the Hydraulics Division, ASCE, April 1978,p. 503. The equation is :

C «C.Q .

(u._ ,.&,. 0}

Where: C the downgradient concentration

C = concentration of "injected" waste3

0 = volumetric injection rate [L /T]

B = uniform saturated thickness [L]

W = (u,r/B) is the Hantush - Jacob Leaky Well Function

B = 2 D /V = 2. [L]xx L J

3-1

r = (1 + 2p X Rd/V)

u = (r2

r = C(x2

The function r is a weighted distance or radius from the source, dependingon relative dispersion DXX/

DVV

= <* i/^-j- and radioactive decay, "X • « L and

ex T are the lateral and transverse aispersivity, respectively.

As time goes on the plume grows larger, until there is a balance betweenthe rate at which pollution disperses and the rate of injection. For asteady state, reached as t-»«»and u-»0, the well function and contaminantconcentration are:

where K (r/B) = modified Bessel function of the second kind,approximated for r/p > 1 by:

* ( Ir

which is

Therefore, under steady state conditions, Eq. (2) can be written as:

Q.C. .

^ ^For worst case situations, at the centerline of the plume, y=o, thereforefrom the definition of r in Eq. (1) r=x, Eq. (4) can be written as:

QC.

BIT

Substituting 2"f. for B and simplifying yields:

air E> ne

Equation 6 can be rearranged to solve for the initial concentration as

QTable 5 is a listing of parameter values for the McKin site. They weretaken from the COM Remdial Investigation and the Robert Gerber groundwaterstudy. When the parameters listed in Table 5 are substitued into Eq. (7)

3-2

the result is an initial concentration is 7,200,000 ppm, far above themaximum sol utility of TCE in water, 1100 ppm. The modified Wilson-Millermodel was therefore rejected for application to the McKin site as ityielded results that were not reasonable for field conditions.

The other model considered in this task is entitled SOCEM (Soil EvaluationContaminant Evaluation Model). This model, taken from an article publishedin the May-June 1982 edition of Groundwater, is the solution to a partialdifferential equation which describes dispersion and convection for acontamianted parcel emanating from a continuous source moving in a steadyone-dimensional flow field. By applying the boundary condition that theonly real point of concern is at the center line of the plume the equationcan be simplified to that presented in SOCEM. This equation is alsopresented in the Federal Register, Vol. 50, No. 38, Tuesday, February 26,1985. The model is described as:

C,E,. C8)

where: CQ is the initial source concentration

C is the downgradient concentration = 16 ppm (Table 5)

Z is the satuarated thickness = 15 ft. (Table 5)

X is the distance from the site boundary to the Well B-l = 800 ft.(Table 5)

Y is the lateral extent of the plume at the solid waste boundary =200 ft. (Appendix)

erf is an error function (Appendix)

is the transverse dispersivity = 3.3 ft. (Table 5)

The model yields a source concentration of 117 ppm at the water tablebeneath the source. This concentration is one-tenth of the maximumsolubility of TCE in water, 1100 ppm, which is reasonable. Support isgiven to this argument from a recent article published in EnvironmentalScience and Technology, (Vol. 19, No. 5, 1985) p. 387 which indicates thatorganic compounds are only rarely found in groundwter at concentrationsapproching their solubility limits. The author states that the observedconcentrations are usually found to be about a factor of 10 lower than

3-3

TABLE 5

Input Parameters Values Used for the Model

Input Parameter Value Reference

Q = Contaminant Flow Rate

8 = Saturated Thickness

ne = Effective Porosity

K = Hydraulic Conductivity

i = Hydraulic Gradientbetween the siteand well B-l

V = GroundwaterVelocity = Ki_

ne

C*, = LongitudinalDispersivity

<X.T = TranverseDispersivity

C = Downgradient PlumeConcentration at B-l

X = Distance from theSite to Well B-l

125 gal = 16.7 ft_°yr yr

15 ft

0.25

7xl(T4 cm = 724.3 ft.sec yr

250'-224' = 0.03258W

(723.4)(0.0325) = 94.0 ft = 0.26 ft0.25 yr day

10m (32.8 ft)

1m (3.3 ft)

16 ppm

800 ft

Page 3 of the letterof transmittal of theGerber HydrogeologicalStudy

Table G-2 p. 6-6 ofRemedial Investigtionand boring logs inAppendix

Estimated from Yeh,G.T. in Appendix

Well boring logs fromRemedial Investigation

Figure 6-4Remedial Investigation

Eq. (7)

Estimated from Yeh,G.T.

Esimated from Yeh,G.T.

Table 7-9, RemedialInvestigation

Figure 6-1 RemedialInvestigation

3-4

their solubility limit, which puts the expected concentration at about 110ppm. Further, Table 1 of the 1982 hydrogeologic report presented by Gerberindicates that TCE was measured at 130 ppm in DEP well #7, considered byGerber to be on-site.

On the basis of this information it seems the model of choice is the SOCEMmodel, as it predicted a source concentration near what would typically beexpected and what was actually measured at the site.

3-5

McKINGRAY, MAINE

10 Mild

SCALE

McKIN SITE , GRAY MAINE

REGIONAL MAP

N CAMP DRESSER & KcKEE INC.

On* Ctntv Plu*Boston, MMMChuMttt 021 Off

FIGURE

y -?ow - **n

SITE AREA - GEOLOGIC MAP

•:: ro»-*r' a*:,-e e**.ii

ftH£ tnG»tvtlff 3;*r *. ":i

, -" KO*CX>iC f3»UrTS

^ s*»mss

<ZZ fOHOtO <**rt»

I Wit Dl'lt.*:'g **r*+< n &VM*

0- »OO- 1OOO' 2 OCX)'

•evr—»r» n i»a?

^ /

I / 2* A

/7 •• x=

McKIN SITE. GRAY MAINE

McKIN SITE AREA GEOLOGIC MAP(1962 GERBER HYDROGEOLOGIC STUDY)

NCAMP DftEtSCT t McKEE IHC.

On* Center PlazaBoston. MasMchuMtts 02108

FIGURE 2

5-2

MONITORINGWELL (TYP)

HORIZONTALTANK ( TYP )FUEL TANK FILL PIPEUNIDENTIFIED PIPE

DEBRIS ( HOSING)

55 GAL. DRUMS

ASPHALT }—GATERAMP

APPROXIMATE £D3EOF CLEARED AREA

VERTICAL TANK (TYP)

CHAIN LINKFENCE

BOTTOM OF SLOPE

• TOP OF SLOPE

APPROXIMATE SCALE: l"s 100*

Me KIN SITE GRAY, MAINE

SITE PLAN

TRUE

3-2

CAMP DRCSSDl & UcKEE INC

•oucn. kU 02 1 M

FIGURE

i i ill i i i i i a i i i i iNOUS

KEY

BORING LOCATIONS

McKIN SITE. GRAY MAINE

McKIN ON-SITE SOIL BORING LOCATIONS(MARCH 1984)

NTRUE CAMP DRESSER * McKEE INC.

On* Ont«r Plat*Boston, MMMChuselt*

F I G U R E 4

4.0 GROUNDWATER MODEL APPLICATION

Since the model chosen yields concentration estimates consideredreasonable, the next step is to apply the model to predict what the sourceconcentration would have to be if the concentration at the site boundarywere to be at the water quality criteria level, 28 ppb. This level _wiasestablished by the EPA and corresponds to a carcinogenic risk of 10" . Thecalculation is essentially the same as for the previous section with theexception of C, now 28 ppb, and X, now 200 ft, where X is the distance fromthe location of the most contaminated soils to the site boundary. Theresult of this is a predicted on-site groundwater concentration of 96 ppb,see Appendix for calculation.

Since 0.096 ppm is the maximum allowable groundwater contaminantconcentration at the source, it is necessary to convert this concentrationto an allowable soil contaminant concentration to determine the requiredlevel of soil treatment. This is done by using a partition coefficient K,,the distribution coefficient, which is defined as the ratio of theconcentration in the soil to the concentration in the water. The problemis to estimate K^. Expressed as an equation, K^ is:

K. .

The typical method used to estimate K,, without performing column studiesor batch equilibrium tests, is to obtain K from listed K values. K isanalogous to K. , that is, the ratio of solute concentration on the solid tothat of the sorute concentration in the liquid, except that in this casethe adsorbing material is organic carbon.

The assumption is that the most significant parameter affecting adsorptionis organic carbon. Undoubtedly, other factors such as clay content, CationExchange Capacity and the surface area of a particular inorganicconstituent will increase the ability of the soil mixture to adsorb anadditional mass of chemical contaminants.

According to Lyman, Reehl and Rosenblatt in a text entitled Handbook ofChemical Property Estimation Methods; Environmental Behavior of Organic'Compounds, the values for K are relatively constant and reasonablyIndependent of the soil or sediment used. The spread of values obtainedresults in a range of uncertainty, coefficent of variation, of 10 to 140%.As a result, K. are usually obtained from listed K values. To furthercomplicate the situation in soil, organic carbon is intermixed with othernon-adsorbing organic matter. Although most of the organic matter doescontribute to adsorption, a correction is made to account for the fact thatnot all the soil organic matter is involved in the adsorption process. Theratio of organic matter to organic carbon varies somewhat from soil to soilbut Lyman et_ al_. (1982) indicate that the typical value is:

4-1

In a report prepared by Arthur D. Little Corporation for Wald, Harkraderand Ross of Washington D.C. entitled "Reference Constants for PriorityPollutants and Selected Chemicals", March 1981, page 28, the value of Klisted for trichloroethylene is 38 ml/g. Using eq. (10) yields: oc

An EPA publication entitled "Evaluating Cover Systems for Solid andHazardous Waste" EPA SW-867 Sept. 1982 has a table estimating organicmatter typically found in soils. From that source (Table 10 page 47) itwill be assumed that the soil organic matter is approximately 5% (0.05).To estimate K. it is necessary to multiply the K by the fraction oforganic

.matter, om Expressed as an equation: om

ET 03}

ev 03}£<v

Finally, the on-site soil concentration can be estimated by multiplying theallowable groundwater concentration by the distribution coefficient, shownas :

w»U . o. ii . EVOOTherefore, it would appear from calculations using the SOCEM model that inorder to generate off-site (at site boundary) TCE groundwaterconcentrations £ 28 ppb the on-site soil contamination must be decreased to0.1 ppm.

It should be noted that some uncertainty exists as to the accuracy of anyanalytical model. This uncertainty is largely a result of the anisotropicnature of the porous medium. Gerber in his hydrogeologic study indicatesthat the types of soils at McKin vary with depth and distance and as suchmake predictive modeling difficult. This modeling effort is based upon thedata available to describe site conditions at McKin and the application ofacceptable engineering analysis. The analysis represents an initialattempt to evaluate permissible levels of contamination for a remedialaction. Prior to proceeding with additional work, it is necessary toestablish that the methodology used in this analysis is conceptuallycorrect (reflects the real world situation); have been properly formulated(mathematically); have utilized the most appropriate input data; have beenproperly computed (no arithmetic errors); and have been tempered to reflectmany of the assumptions inherent in their development.

4-2

APPENDIX

References for Model Parameter Values

Calculation of On-Site Groundwater Concentrationusing SOCEM

c.C -

0.026

Y

r I I 5" ft \ / 300 t

er4

- HO

A-l

TABLE 6

Estimation of the Saturated Thickness of the Overburden Aquifer

Wei 1 (Feet to Rock)^ Depth to Groundwaterg Saturated Thickness

B-l (300.2-209.0) = 91.2 (300.2 - 224.6) = 75.6 91.2 - 75.6 = 15.6

B-3 (301.1-166.1) = 135.0 (301. - 176.5) = 124.6 135.0 - 124.6 = 10.4

1 Obtain from Table 6-2 of COM R.I.

2 Obtain from Appendix III of COM R.I.

A-2

TABLE 7

DATA FROM INSTALLATION OF MONITORING UELLS1

Groundwater ElevationElevation of Zone of Permeability (ft MSL)

Well

B-l (soil)

B-l (rock)B-2A

B-2BB-2C

B-3 (soil)B-3 (rock)

B-4

B-5 (soil)B-5 (rock)

Installation (ft MSL)

209.0 -

188.6 -131.5 -

153.9 -187.5 -

171.2 -145.6 -

28.6 -

150.5 -

132.6 -

224.8

204.9148.5

160.8

193.9

185.1161.6

65.1

158.4

147.6

(cm/sec)*

7 x lO'4

4.5 x 10"6

8.3 x 10'6

» 10"2

1.7 x 10'3

1.4 x 10'4

2.6 x 10~6

9.3 x 10"5

2.8 x 10"5

1.2 x 10"5

4/9/84

224.6

218.8193.4

203.0 £203.1

- 176.5

168.9

97.0171.0

170.9

* Based on variable head permeability tests performed by Gerber, 1982

Camp, Dresser & McKee, Remedial Investigation 1985

A-3

TABLE 8

RELATIVE LEVELS OF ORGANIC MATTER AND MAJOR NUTRIENTS IN SOILS,

RelativeLevel*Very lowLow

Medium

HighVery

High

Sand,LoamySand<0.6

0.6-1.5

1.6-2.5

2.6-3.5

<3.5

Sandy Loam,Loam,

Silt Loam<1.61.6-3.0

3.1-4.5

4.6-5.5

>5.5

Clay Loam,Sandy Clay,

Clay<2.6

2.6-4.5

4.6-6.5

6.6-7.5

>7.5

* Medium level is typical of agricultural loam soil.

"Evaluating Cover Systems for Solid and Hazardous Waste," EPA SW-867Office of Solid Waste and Emergency Response, Washington, D.C. 20460Sept. 1982.

A-4

TABLE 9

LABORATORY ANALYTICAL RESULTS OF GROUNDWATER QUALITY MONITORING1

Location

B-l (shallow soil )

B-l (bedrock)B-2 (shallow soil )

B-2 (deep soil )B-2 (bedrock)

B-3 (shallow soil)B-3 (bedrock)

B-4 (deep soil )B-5 (deep soil)

B-5 (bedrock)

Date(1984)

3/21

3/213/22

3/223/22

3/20

3/20

3/213/20

3/16

1 , 1 , 1-Tri chl oroethane(ppb)

170** (230)

470** (500)

' 9

16

5

65

3

ND

NO (NO)*

7 (8)*

Trichloroethylene (TCE)(ppb)

16,000

29,00091

16056

1,800120

NDND (ND)*

190 (177)*

* duplicateND = not detected

** These samples were diluted for the analysis of trichloroethylene. Thecompanion results in parentheses for 1,1,1-trichloroethane are for theundiluted samples.

1 Camp Dresser & McKee, Remedial Investigation (1985)

A-5

TABLE 10OTHER PARAMETERS REFERENCED

Parameter Description Reference

oc! organic carbonadsorptioncoefficient

om' organic matteradsorptioncoefficient

ug adsorbed/g organic carbonug/mL solution

KocTT774

Lyman, W.J., Reehl, W.F,and Rosenblatt, D.H.Handbook of ChemicalProperty EstimationMethods, McGraw-HiTlBook Co. New York,1982, page 4-1.

(same as above page4-3)

di stributioncoefficient

K x fom om

or n , "effectiveporosity

Volume of VoidsAvailable forGroundwater TransportVolume Total

Jury, W.A. , Spencer,W.F. and Former, W.J.,"Behavior AssessmentModel for TraceOrganics in Soil: I.Model Description", J.Environ. Qual., Vol.12, No. 4, 1983 p. 559

Yen, 6.T., "AnalyticalTransient One-, Two-,Three-DimensionalSimulation of WasteTransport in theAquifer System", OakRidge NationalLaboratory, Environ-mental SciencesDivision, PublicationNo. 1439, Contract No.W-7405-eng-26, March,1981.

K, hydraulicconductivity

<X I » longitudinaldispersivity

O< T, transversedispersivity

Groundwater Velocity nHydraulic Gradient

Longitudinal DispersionCoefficient

Sroundwater Velocity

Transverse DispersionCoefficient

Groundwater Velocity

Bear, Jacob, Hydraulicsof Groundwater,McGraw-Hill Book Co.,New York, New York,1979, page 63.

Freeze, R.A., Cherry,J.A., Groundwater,Prentice-Hall, Inc.,Englewood Cl i f fs, NJ,1979, p 389.

(same as above)

A-6

TABLE 11

Typical Values of Aquifer Parameters1

Effective Porosity, n

Hydraulic Conduct! viy, K (cm/sec)

Longitudinal dispersi vity» (m)

Transverse dispersivity, cx.j (m)

Sand

0.1-0.3

10-10'2

10-100

1~10

Si l t

0.05-0.1

10"~10"4

1-10

0.1-1.0

Clay

0.03~0.05

io-5~io~6

0.1-1.0

0.01-0.1

Source: Yeh, G.t. "Analtyical Transient One-,Two-, andThree-Dimensional Simulation of Waste Transport in the AquiferSystem", Oak Ridge National Laboratory, Environmental SciencesDivision, Publication No. 1439, Contract No. W-7405-eng-26, March,1981.

A-7

81 VMONITORINQ WELL BI• \1984 OBSERVED WATER224 / TABLE ELEVATION

(224 feet)

or SPOT TOT I^—-•—^IB^^M v

McKIN SITE. GRAY MAINE

INFERRED SURFICIAL WATER TABLE ELEVATION FROM GERBER

(1982) WITH 1984 DATA SUPERIMPOSED

N CAMP DRESSER A McKOE INC.

On* C«nl«r PlataBoalon. Ma9»acttus«lls 02 1 08

FIGURE 6-4

COMPOSITE BORING LOG BORING NO. B~1

PROJECT NO. 265 PROJECT NAME focKin Site PAGE 1 OP 2

GROUND ELEVATION 300.2 CASING ELEVATION 303.3 COORDINATES Table 1 N. E

DATE BORING COMPLETED 20 Feb. 1984 WELLS B-1A (Rock) B-1B (Soill

cu

COMPILED BY C. White DATE 10 Apr. 84 CHECKED BY Fisher DATE 12 Apr 84

181iJniform>andF: finen : med i urn

$$<C

Jrayelly>and ! » • • • • > X

:: coarse?tf?rsW $&

\

Bedrockf "

WELL BORING PERMEABILITY - CM / SEC.

300. <

190

.280

270

260

Z50

260

n

in

?f)

•

30

4D

SO

fin]

Ml

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mn»uv«t

a 4-9-a/

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—

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MMIMC

Wrf* *•«-«'

WILL

to" ID* «• »- «•

-

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w* «•• »• ,6* ID'

NOTES

Roiurt 6. Gtrtor. Inc.

COMPOSITE BORING LOG

PROJECT NO. 265 PROJECT NAME McKin Site

BORING NO. DJStbl_

PAGE 2 or 2GROUND ELEVATION 300.2 CASINO ELEVATION 303.3 COORDINATES- Tablel N. E

DATE BO*»NG COMPLETED 20 Feb. 1984 WELLS B-1A (Rock) B-1B (Soil)

COMPILED BY c. White DATE 10 Apr. 84 CHECKED av Fisher . DATE 12 Apr 84

pfesl uniform

I It: tine .| j m: medium

K&tiS gravelly :...:.! uniformKm^a 'and ...... 1 siity sand£.'•>- )\ 7TJI

Iv-l bedrock u 11

|c: co,rse , , || , ,

WELL BOftINO PERMEABILITY - CM,/SEC.

111

VCLL

NOTE§ !• Bedrock Lithology: rusty brown medium- grained biotite-muscovite granite.Heavily weathered and disaggregated throughout

*»b«rt G. Gtrbtr. Inc.

COMPOSITE BORING LOG BORING NO. 9^3

PROJECT NO. 265 PROJECT NAME McKinSi te PAGE] OF 3

GROUND ELEVATION 301,1 CASING ELEVATION 3Q3 5 COORDINATES TABLE 1 M* E

DATE BORING COMPLETED^ ppb. iqfl4 . WELLS B.3A (Rock) B.3B (Soi1

COMPILED BY w.R. Holland 0*TliO Aor. 1984CMECKEO 8Y Fisher DATE 12 Apr. 84•

SS£j£c| uniform':'V:'--:!".:::-\ 5 and

I T: fineffl^mediuffl

^^•yj gravelly

1 c: coarse

WELLn t* OIPIM

301.J

290

280

270,

260

•250

240

0

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en

60

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|4-9-84

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l££.

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BC

—

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1 1L'v/'M bedrock

1 1r•« -

MING PERMEABILITY - CM. / SEC.

w i•«• 8

•

•

% MW1TUM

» nee*™*

MMN»

^*4*rf*»-W-(

•

•CLL

w*4*w*tf*»*

»

LAB

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.

NOTES

Robtrt G. G«rb«r. Inc.

I.

r

rr1..

rr..

r-t

'J

\t

*

I

I»r

J

I

r-

i.

rt

t

ri

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111111

111111]JJJ1

1

COMPOSITE BORING LOG BORING NO. R-3

HKXICCT Wl 265 PROJECT KAMI M(-K1n S1te "OE 2 OT ,

OIWUNO ELEVATION 301. ] CASINO ELEVATION 3Q3. 5 COOW>IHATeSTABLE j N. E

OATE BOmNO COMPLCTCO J3 Feb. 1984

COMPILED BY^ — —

tl;?0S

WELLS D_^A ^Do/ k ^^ R ^D ^Cn^ l \D-JH l«DCKJ B-JB l iOIIJ

W.R. Holland OATElO Aor. igs^*1601*60 8Y Fisher ' OATE12 Apr. 84

uniform ||a c 9ravel ly

F If: fine |c: coarse

• • ' - ' lurTi form==^siUv sand

1 1L ""f ~\rvL^:

1bedrock 1"1

•

WCLl •OffINO PERMEABILITY - CM / SEC.

U* KPW

240*

230

220

•

210

5nncuu

190

180

60

1

7f

on

on

nn

IK

12f

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|4-9-84

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• ^5rfc/^•c.HMM."Tf**t

U-££-mf-z

n^U,-•/.-

HH-4*.f(Jmmt\

ttmn&Mu.

r"u,»y <-AO

nfeaIT"U, ,W^:-1 I MAI.

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-

-

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ass* £^

J0^* S. 0«rb«r. Inc.

% MOirruMt

% Mcovtav» • t* «

•

MHINC

«•* rf* 4* 4* •'

•

.

•fUL

W* ••*«••-!•'

'

LAB

»• »• •• I.4 l«»

NOlfS

SCALE

McKIN SITE, GRAY MAINE

TEST PIT LOCATIONS FOR EXPLORATORYPYCAVATION PROCJRAM

N TRUE CAMP DRESSER A McKEE INC.

One Center Pl«jaBoston. Massachusetts

It—•o

MOHS

McKIN SITE. GRAY MAINE

LOCATIONS OF HAND AUGER BORINGS (APRIL 1984)

M TRUE

>rCAMP DRESSER A McKEE INC.

On* Cantor PlataBoston, Massachusetts '

FIGURE 6

TABLE

LABORATORY ANALYTICAL RESULTS OF OH-SITE SOIL QUALITY MONITORING (mg/kg)

(See Figures 1-8,1-9, and 1-10 For Locations)

1

SaraoieLocation

SS01Si'JiSSJ1S5U1SSulSSUZSSujSSU*SSUbSiUi5S05&:SS0502SS'JbOZSSOsOZSS%SS06SSU7SSOBSSOBsyjiSS08

SS09ssuySS09SSC9 •SB015BD1

SB02SB03SD01SOOZ

TP1A

TP4ATP4STPbATP9BIPliATP138TP15

SampleNumoer

1Z34

b11i12j4-5fciZ11'i34

12

41Z

51

1A .

4A '

48fiA98

ISA13815*"

Deptn(Feet)

0-13

11-126-7

11-IZ0-20-1L>- 1

0-2!)-Z

10-1114-1514-1514-15

0-14-52-33-43-43-4

3

b3-43-4

35-6

10-11

25-265-6

D1C

HLO

RO

E!H

YLEN

E

NDNDNDND

7.0ND

WND

NDND

<.l<. 1<.l49<.l< . 1<.]

MET

HYL

ENE

CH

LOR

IDE

NDNDNDND

--NONU----NDNi)

NDNDNDKONDND

NDNDND

NDN3

UJZt*t_*^X

io

Ga.

NOND

NDND

1503NOTiD240

17.522.9

NDNDNONO0.05ND

NDNDND

NDNDNDNDNDHI)

560*< .1<.l

1400*<.l< . 1<.l

111-

TRIC

HLO

RO

ETH

AN

E

NDNDNDND

2.;NDNDNDNDNDNO

NDNDNDNONDNT

NDNOND

NDND

NDNO

0.01ND

0.3*<.l<.l4.5*

O0.4W

"6.9*

TETR

ACH

LOR

OET

HYL

EME

NONDNDND

5.0NDND169.9.27

.12

NDNDNDHONDND

NUNOND

NDND

UJzUJ

ZUJCO

Mj

NDNDNDND

.24NDTO250ZOO>33.Ob

NDNDWNDNDND

NDNO

0.04

NDD.UZ

«CNDNDND

220«<.l<.l1.0*<.lU.fl*0.3*>10

XY

LEN

ES

NONDNDNT

?1NDNO580570

>6.7.10'

NDNDNONO0.03ND

NDND0.22

NDND

m0.02NOND

150*<. 1<.l

a<.l1.7*0.5->30

OIC

HLO

RO

BEN

ZEN

E

NDNT

NDND

9.2NDND308713T . 7

NDNDNONDNDND

NDNOND

NO0.17

TO1.2NDND

>10

TOLU

ENE

0.9*<.l<.l0.6*

<.l<•!1.0*>_30

AR

SE

NIC

9.0

1510

10

3.0

BA

RIU

M

<Z5

<25<Zi>

<25

<25

§

<_>

<Z.b

<2.5<Z.b

<2.5

<2.5

CH

RO

MIU

M

7.b

7.511

7.5

3.0

oUJ

Z.O

1.01.0

2.2

<1.0M

ERCU

RY

<0. 1

<0.1<0.1

<0.1

z

zUJ

UJ

Z.6

3.7Z.5

<7.5

<2.5

eeUJ

-

<z.o

2.0<z.o

<7.0

<2.0

• Approximately•• Simple taken July 10, 19M. analyzed September 4, 1984

due to delay specific concentrations are unknowna « Xylerte not analyzed for in this sanple.NO • B«)o* Detection UaHs.b • Field Blank

1 Volatiles were analyzed on a wet weight basisMetals were analyzed on a dry weight basis.

I•—•cn

AREA 16

MOTIS

SCALE

McKIN SITE. GRAY MAINE

PRIMARY AREAS OF SHALLOW SOIL CONTAMINATION

NTRUE CAMP DRESSER A McKEE INC.

On* C«nl«r PlazaBoston. MasMchuMlls 02108

FIGURE;

TABLE 2

SUWARY OF SIGNIFICANT CONTAMINATED SOIL AREAS

Estimated Dimensions

Description of SurfaceArea Contamination** Area (s. f . ) Depth(ft.) Volume (c.y.)

Area IB Grey and black sludge 400 5 74(see TP13A & TP13B Lab Tests)

TP# 1A Soil Around Buried Drum(Area 6) (See Figure 6-1) 9 3 1

Area 3 See TP6A Lab Tests 1,500 40* 2222

Area 4 See SS01 * SS02 Lab Tests 3,200 3 356

TP# 15 See TP15 Lab Tests 100 2 8(Area 5)

TOTAL 5,209 2661

ESTIMATE 5,200's.f. ESTIMATE 2,700 c.y.

NOTES:

1. Areas 1A, 1C, and 2 were not determined to be significantly contaminatedbased on laboratory analysis and physical observations. The major con-taminants in these areas appear to be typical derivatives of petroleumrefining and not covered under CERCLA.

2. The estimated depth for Area IB is estimated as debris would not allowauger penetration. The remaining depths are estimated based on physical/visual field observations.

* Due to limitations of sampling device exact depth of contamination cannotbe determined, therefore the depth to groundwater was used as a conserva-tive figure.

** See Table 1-2 for lab test results.

TABLE

LOCATION AND TYPE OF BURIED DRUMS TO BE REMOVED

1Location

TP-1

TP-4

TP-6

TP-8

TP-9

TOTAL

Number of ,,Known Drums Type of Drum

1 Deteriorated Fiber w/LID

8(4) Metal

3(2 ) Fiber

1 Metal

3 (2 ) 2 Metal-1 Deteriorated

16(8) Fiber

see Figure 6-1

"Numbers in parentheses denote contingency quantity for possible unknown

drums.

ANALYSIS OF CONTAMINATED SOILASSOCIATED WITH DRUMS (ppm)

Dichloroethylene

1,1,1-Tricholorethane

Trichloroethylene

Ethyl benzene

Xy 1 eneTo!uene

LOCATION

TP-1

<0.1

00'. 3

0560

0220

0150

00.9

TP-4 TP-6 TP-8 TP-9

<0.1 49 * <0.1

<0.1 04.5 * <0.1

<0.1 01400 * <0.1

<0.1 01.0 * <0.1<0.1 * <0.1

<0.1 00.6 * <0.1

*No sample taken

0 - Approximately

6-9

LEGEND

rMONITORING WELL B11984 OBSERVED WATERTABLE ELEVATION

(224 feet)

SCALE

McKIN SITE, GRAY MAINE

INFERRED .SURFICIAL WATER TABLE ELEVATION FROM GERBER

,/»,ITU 1QAA DATA SUPERIMPOSED

N CAMP DRESSER A McKEE INC.

On* Cvnler PlazaBotlon. Massachusetts

F I G U R E 8

TABLE 4

COMPOUNDS ANALYZED IN GROUNDWATER SAMPLES*

ACROLEINACRYLONITRILEBENZENECARBON TETRACHLORIDECHLOROBENZENE1,2-DICHLOROETHANE1,1,1-TRICHLOROETHANE1,1-OICHLOROETHANE1,1,2-TRICHLOROETHANE1,1,2,2-TETRACHLOROETHANECHLOROETHANE2-CHLOROETHYL VINYL ETHERCHLOROFORM1.1-DICHLC30ETHYLENETRANS-1.2-DICHLOROETHYLENE1,2-DICHLOROPROPANETRANS-1.3-DICHLOROPROPYLENECIS-1.3-DICHL030PROPYLENEETHYLBENZENEMETHYLENE CHLORIDECHLOROMETHANEBROMOMETHANE'BROMOFORMDICHLOROBROMOMETHANETRICHLOROFLOUROMETHANEOICHLORODIFLOUROMETHANECHLORODIBROMOMETHANETETRACHLOROETHYLENETOLUENETRICHLOROETHYLENEVINYL CHLORIDE

* Of all the compounds analyzed for only 1,1,1-trichloroethane andtrichloroethylene were detected.

7-31

TABLE 5

LABORATORY ANALYTICAL RESULTSOF GROUNDWATER QUALITY MONITORING

Location

B-l (shallow soil)

B-l (bedrock)

B-2 (shallow soil)

B-2 (deep soil )

B-2 (bedrock)

B-3 (shallow soil )

B-3 (bedrock)

8-4 (deep soil )

B-5 (deep soil)

B-5 (bedrock)

Date(1984)

3/21

3/21 .

3/22

3/22

3/22

3/20

3/20

3/21

3/20

3/16

1,1,1 Trichloroethane(ppb)

170** (230)

470** (500)

9

16

5

65

3

ND

NO (ND)*

7 (8)*

Trichloroethylene (ICE)(ppb)

16,000

29,000

' 91

160

56

1,800

120

ND

ND (ND)*

190 (177)*

* duplicateND = not detected

** These samples were diluted for the analysis of trichloroethylene. Thecompanion results in parentheses for 1,1,1-trichloroethane are for theundiluted sample.

7-33

rvj

o- soo- 1000-

// I -200— Itocon

HcKIN SITE, GRAY MAINE

3TEADY STATE SURFICIAL AQUIFER (1984)1,1,1-TRICHLOROETHANE CONTAMINANT PLUME

N CAMP DRESSER A McKEE IMC.

On* C«nt«r PlazaBoston. M«s»«chui«H» 02 i 06

FIGURE 9

McKIN SITE, GRAY MAINESTEADY STATE BEDROCK AQUIFER (1984)1,1,1-TRICHLOROETHANE CONTAMINANT PLUME

N CAMP DRESSER A McKEE INC.

On« C«nl«r PlataBtMlon. Ma»Mchus«lls 02108

FIGURE 10

APPROXII TE SCALE 1" EQUALS 1600'

KEY

O SAMPLING LOCATION

FIGURE 11

McKIN SITE. GRAY MAINE Camp Drttter & McKea Ir

TABLE 6

LABORATORY ANALYTICAL RESULTS OFSURFACE WATER QUALITY MONITORING

Location

SW-1

SW-2

SW-3

On-site lagoon

Boiling Springs

Date(1984)

3/16

3/16

3/16

4/11

4/11

4/11

Trichloroethylene (TCE)and 1,1,1 Trichloroethane (ppb)

ND (ND)*

ND

ND

flD

44 (TCE) and 30

32 (TCE) and 10 **

* duplicate** second Boiling Springs sampleND = not detected (detection limit = 1 ppb)

7-4

TABLE 7A

McKIN CCMPANY SITE. MAINE

SOURCE CONTROL REMEDIAL ALTERNATIVES

1.

2.

Alternative

No Action with/Monitoring

Capping Con- jtaminated Areas

PROJECT COST (H.OOO)Present

Capital CUM WorthPublic HealthConsiderations

EnvironmentalConsiderations Technical Considerate."";

Public and ElectedOfficials Comments

20 37.3 24? Continued contamination No Source Control. Con- Adjustments in Remedial Unacceptable. Not re-

192 38.9 130

3A. Limited Excavationw/Off-Site Land-filling

1,847 1.6 I,fl63

38. Limited Excavationw/Off-Site Incin-erators

5.0R7 1.6 5,103

nf groundwater by con-taminated soils remain-ing on-site.

droundwater remainscontaminated althoughadditional contaminationis eliminated. No ex-cavation required there-fore no emissions.

tinned contamination ofgroundwater. Relativelyrapid leaching with sourcecontinuing for at least 25years.

Effective source control.Inhibits migration. Nowaste reduction, firound-water 20-40 ft. belowsurface. Low watertable eliminates impactof fluctuating watertable elevation.

Eliminates future gen-eration of contaminatedgroundwater. Ground-water still contaminated.Potential risk due toemissions during ex-cavation. Transfershazard to off-sitelocation.

Same as Alt. 3A, exceptthat EPA and Statepermitted incineratormust be used.

Effective source controlvia source removal. Siteregradlng required. Po-tential for contaminationduring transport or asresult of off-site land-filling.

Same as Alt. 3A, exceptno off-site potentialcontamination at land-fill.

Action may be requirHbased on response tomonitoring. Inconsistentw/RCRA. OHM required forgroundwater monitoring.

High reliability w/properinstallation and long-termmaintenance. Low level oftechnology required. MeetsRCRA requirements. Long-term OftM required to en-sure long-term effective-ness. Estimated construc-tion period-90 days.

Reliability dependent oncontamination boundary de-finition and availabilityof off-site landfill. Lowlevel technology requiredon-site. RCRA Complianceassuming Licensed Trans-porter and Landfill. Eachload of soil must becharacterized. Air Moni-toring required. Min-mum long-term fJRM. Esti-mated excavation period-90 days.

Reliability dependent oncontamination boundarydefinition and permitstatus of Incinerator.RCRA Compliance assumingLicensed Transporter andIncinerator and non-hazardous ash. High levelof mechanical technologyrequired. Air monitoringrequired. Minimal long-

sponsive to problem.

Acceptable to some. Somevery opposed due to lackof source reduction.Clay cap preferred tosynthetic.

No Comment.Acceptable.

Assumed

No Comment.Acceptable.

Assumed

TABLE 7A

HcKIN CCK>A*Y SITE. HMK

SOURCE COHTRfl ROCDIAL ALTtKMATlVFS

(CtWT'O)

PROJECT COST

Alternative •PresentWorth

Public HMlthConsiderations

I imited Fxr.avatfonw/On-SHe Incin-eration and Disposal'

6,840 1.6 6.856 El Iminates future gen-eration of contaminatedgroundwater. Ground-water still contamlna-ed. Potential risk dueto missions duriny ex-cavation and incinera-tion.

M. Limited Excavat1onJ

w/On-Slte Aerationand Di sposa1 *

EnvironmentalConsiderations

Effective source con-trol via source removal.Environmental assurancesof stack emissions, in-cineration efficiency andproduction of a non-hazardous ash required.Obtaining permits may betime consuming. Treat-ability (Test Burn) in-formation required. Siteregradlng required.

4?4 l.fi 440 Eliminates future gen-eration of contaminatedgroundwater. Grounrtwaterstill contaminated. Airemissions during aera-tion are potential ha-zard.

Effective source controlvia source removal. En-vironmental assurancesof treatment efficiencyand non-hazardous residualsoil required. Signifi-cant odors producedtemporarily duringaeration.

ConsiderationsPublic and Elected JOfficials Comments

tnd favoredby sane. Opposed by saneb«s«d on potentialair emissions.

tent (HM required. Eachlo*1 of soil requirescKirjcterizttlon. Est<-•Mted excavation perlod-V) days.

Reliability dependent oncontamination boundary de-fi niton and permittingissues. RCRA Compl ianceassuming either permitobtained or technicalequivalency shown and non-hazardous ash. Each load ofsoil requires characteri-zation. Air monitoringrequired. Minimal .long-term OW required. Highlevel of mechanicaltechnology required.Estimated Incinerationperiod-] 80 days.

Reliability dependent on Little or no publiccontamination boundary de- acceptance.finiton. Design pilot studyrequired to determine treat-ment effectiveness. RCRACompliance assuming ef-fective treatment obtai'ned.Soil requires testing jftertreatment. Action limitsiwrf testing pcocedw^s needto be established. Lowlevel of pechanlcal tech-nology required duringaeration. Exteirslv* airmonitoring required. Mini-mal flW. Estimated aerationperiod-*0 weeks spreadover a ? year period.

TWLE 7A

CnhPAKV SITE, MAINE

SOURCE CONTROL RCWEOIAI

(COKT'D)

PR<UECT COST ($l.(Wl) JPresent Public Health Environmental Public and Elected

Alternative Capital CUM* Worth Considerations Considerat ions Technical Considerations Officials Comments

bR. Limited Excavation ?«fi 1.6 ?6? Same as Alt. bA, except Same as Alt. 5A, except Same as Alt. 5A. Estimated Ho public comment ob-w/Of f -S i te Aeration h«z»rd is transferred off-site location Is aeration period-10 weeks. tained.and Disposal to off-site location. Impacted.

SC. (Yi-Site Aeration ' 177 38.P 415 Combination of Alt. ? Combination of Alt. ? aori Combination of Alt. ? and Combination of Alt. ? andand Cap and 5A. 5A. 5A. 5A comments.

* Selected Hpmedial Action

1. Use of clay cap instead of synthetic liner reflectedin revised F.S. cost.

2. Revised F.S. cost estimate based on the followingassumptions:

. Use of EPA Portable Incinerator

. 1 cubic yard capacity/hour

. SOX down time

. $23,000/day operational cost

3. Revised F.S. cost estimate due to more conservativeestimate as to duration of aeration than waspresented in the F.S.

TAW.E 7B

HcKIN CrK-AHY SITt, MAINE

OFF-SITt COKTRU ROCDIAL ALTTKHATIVES

Alternative

6. No Actionw/Monitoring

PROJECT COST (Jl.OOO)Present

Capital OSM Worth

3.5 37.3 ??*

Public HealthConsiderations

stillrontaminatert with de-creases due to sourcecontrol and naturalmechanisms only. Alter-nate water supply re-duces potential forexposure. ND guaranteeof use restriction.

EnvironmentalConsiderations

Nn action to restoreaquifer. Time to re-duce Total VolatileOrganic* to 50 ppbestimated at 10 years,assuming source control.

Withdrawal Wel ls,Treatment andDischarge ofTreated Ground-water*3

3,495 37.3 3,128 Groundwater contawl nation Active restoration to

8. Restrictions onfuture Development

115 37.3

reduction accelerated,particularly 1n sur-ficlal aquifer, becauseof extraction and treat-ment. Alternate watersupply further reducespotential for exposure.

Same as Alt. 6 exceptuse restrictionseliminate exposures.

restore aquifer. Timeto restore Total Vol-atile Organics to 50ppb estimated at 5years, assuming sourcecontrol. Treatmentstandards for groundwaterdischarge»nd airemissions from treatmentsystem needed.

fc> action to restoreaquifer. Time to re-duce Total Volatile Or-ganics to 50 ppb esti-mated at 10 years,assuming source control.

Technical ConsiderationsPublic and ElectedOfficials ferments

Reliability haseci on com- Unacceptable to most.puter modelling of aquifer.Adjustments In response toHcnltorirxj may be necessary.low level technology required.Inconsistent with RCRA. (W*required for groundwatermonitoring.

Reliability based onaccurate location, depthand pumping rate of ex-tracton wells and ground-water discharge and, 1npart, on uncertain sub-surface conditions. Accessto installation and moni-toring of wells on privateproperty is needed. Nooperation and maintenance,other than monitoring costs,if performance standardsare met.

host are in favor ofthis action withreservations regardingstate costs.

Reliability based on un-certain ability to im-plement and enforce re-strictions. Aerial extentof restrictions needs to bedefined in legal restrictions.

Nn public comment ob-tained.

T Selected Remedial Action

1. Each off-site control assumes th* Implementation of a source control location other than Alternate 1.

?. Assumes 5-year remedial treatment unit achieving performance standards, see text of Remedial Alternative Selection.

3. Revised F.S. costs reflect revised, selected groundwater extraction and treatment option based on:

. 25 wells P 5 gpm/wcll

- discharge of treated groundwater to surface water.

INJ

AREA OF INFLUENCE OFWITHDRAWAL WELL

O1 5CXJ1 ICXXJ I /

*&*«rK-200- l9t>con.

McKIN SITE. GRAY MAINE

GROUNDWATER WITHDRAWAL WELL LOCATIONS SUPERIMPOSEDON INFERRED 1.1,1-TRICHLOROETHANE SURFICIAL AQUIFER PLUME

NOn* C«nl«r PlataBo.(oo.M.«.chu..M.O*