- PROPOSED PLANCOMMODORE SEMICONDUCTOR/MOS SITE

LOWER PROVIDENCE TOWNSHIP, PENNSYLVANIA

Introduction

This Proposed Plan has been prepared by the U.S.Environmental Protection Agency (EPA), Region III to provide thepublic with the opportunity to review and comment on the remedialaction for addressing the groundwater contamination at theCommodore Site ("Site"). This document contains an evaluation ofthe remedial alternatives considered by EPA; identifies thealternative preferred by the EPA and explains the reasons forthis preference. In addition, the plan explains how the publicmay participate in the decision-making process and providesaddresses and telephone numbers for the appropriate EPA contacts.This action is the only action planned for the site.

This document is issued by the EPA, the lead agency for SiteSuperfund activities. The EPA, in consultation with thePennsylvania Department of Environmental Resources (PADER), willselect a remedy only after it has reviewed and considered thecomments received during the public comment period.

The EPA is issuing this Proposed Plan as part of its publicparticipation responsibilities under Section 117(a) of theComprehensive Environmental Response, Compensation and LiabilityAct (CERCLA). This plan highlights key information that iscontained in the Remedial Investigation and Feasibility StudyReport ("RI/FS") but does not serve as a substitute for thesedocuments. The RI determines the nature and extent ofcontamination at the Site and estimates the risks posed by theSite to human health and the environment. The FS then examinescomprehensive cleanup alternatives. The RI/FS Report iscontained in the Administrative Record File for the Site. TheAdministrative Record File consists of technical reports andreference documents used by EPA to compile the Proposed Plan.These documents are available to the public at the localinformation repositories:

Lower Providence Community Library2765 Egypt RoadAudubon, PA 19405(215) 666-6640

and

Montgomery County Planning Commision County CourthouseOne Montgomery PlazaNorristown, PA 19404(215) 278-3733

A copy of the Administrative Record File is also availafihS waQ OEelH 8

Region III Offices; for an appointment contact:

Anna ButchAdministrative Record CoordinatorU. S. Environmental Protection Agency, Region III841 Chestnut BuildingPhiladelphia, PA 19107(215) 597-3037

EPA and PADER invite the public to review the materialsavailable and to comment on the Proposed Plan which begins onJuly 21, 1992 and ends on August 20, 1992.

EPA, in consultation with PADER, may modify the preferredalternative or select another response action presented in thisplan, based on new information or public comments. Therefore,the public is encouraged to review and comment on thealternatives identified here. The final remedy for ground waterremediation and for an alternate water supply will be selected ina Record of Decision, which shall also be available for review atthe local repository. This is the only action planned for thisSite.

SITE BACKGROUND AND HISTORY

The Commodore Semiconductor Group ("CSG") Site islocated in the Valley Forge Corporate Center (VFCC) inNorristown, Lower Providence Township, Pennsylvania. TheCommodore Semiconductor Group facility is located at 950Rittenhouse Road in Norristown. The facility is approximatelyone mile north of the Schuylkill River. The facility is borderedon the northwest by Rittenhouse Road, on the northeast by VanBuren Avenue and on the southeast by Adams Avenue. The GeneralWashington Country Club golf course occupies all the propertyimmediately west of the facility on Rittenhouse Road with theremainder of the surrounding property being occupied byindustrial and commercial facilities. Private residences arelocated approximately one-half mile from the facility in alldirections. (See Figure 1, Location of CSG Site)

The facility was constructed in 1970 by Alien-BradleyCorporation and leased to MOS Technology, Inc. In 1976, CSG adivision of Commodore Business Machines purchased the stock ofMOS Technology, Inc. The facility continued to operate under thename of MOS Technology. In April 1978 Alien-Bradley sold theproperty, including the building to Commodore Business Machines.Currently CSG operates the facility.

The facility was built to manufacture semiconductor chipsused in the production of computers, calculators, and otherelectronic equipment. At the time the original building wasconstructed an underground concrete storage tank, reported to

hold 250 gallons of liquid was installed adjacent to thesoutheast side of the building. The concrete tank was used tostore a waste solution known to contain trichloroethene (TCE) andother solvents used in the manufacturing of semiconductor chips.Based on PADER field notes, the concrete tank was reported tohave leaked in 1974. MOS Technologies discontinued the use ofthis tank and installed an unlined steel tank undergroundadjacent to the concrete one in 1975.

In 1978, the Audubon Water Company (AWC), suppliers of waterto the Village of Audubon and Lower Providence Township, detectedTCE in two of its wells located at the Site. PADER identifiedthe Commodore facility as a possible TCE source. In the fall of1979 the underground tanks were excavated. Tests conductedduring the excavation revealed very high levels of TCE and PCE inthe soil directly below the underground storage tanks and in thesurrounding groundwater. In 1979 Commodore replaced these tankswith a waste solvent collection system consisting of a tankwithin a lined vault. In 1981 Commodore discontinued the use ofTCE in its manufacturing process. The company also installedgroundwater monitoring wells and began a sampling program.

At PADER's direction measures to reduce TCE concentrationsstarted in early January 1981. From 1981 to 1983 public supplywell numbered VFCC-4 (Audubon Water Company is the owner) waspumped and the ground water was spray irrigated. Sprayirrigation is a practice consisting of spraying contaminatedwater on a field and allowing volatile organics to evaporate intothe air. Commodore held a state permit for the spray irrigationsystem. In February 1984, CBM purchased and installed an airstripper on VFCC-4. Commodore also installed an additional airstripper on Commodore property to treat shallow ground water thatis collected in the french drain system underneath the portion ofthe building which was expanded in 1985. In 1984, also atPADER's direction, Commodore began a residential sampling programand installed whole-house carbon filter systems on residenceswith 1 ppb of organics detected. A total of 23 residences weresupplied with filters.

In February 1984 EPA performed a site inspection of theCommodore Facility. A Preliminary Assessment and SiteInvestigation were completed on 12/5/86 and 12/15/86respectively. The sampling results revealed the presence of TCEand showed that TCE was present in nearby residential wells. TCEand TCE related compounds were also found in the groundwater,surface water, and soil samples taken from the Site. TheCommodore Facility was proposed for inclusion on the NationalPriorities List in January 1987. The Site scored a 42.35 underEPA's hazard ranking system and in October 1989, the CommodoreSite was made final on the NPL.

Commodore Business Machines Inc., was identified as a

•s

•i

Potentially Responsible Party (PRP), and conducted a RemedialInvestigation/Feasibility Study (RI/FS) at the Site pursuant tothe terms of an Administrative Order By Consent (Docket No. III-88-09-DC) signed by the PRP and EPA in July 1988. The purpose ofthe RI/FS is to characterize the type and extent of contaminationrelated to the Site, quantify any existing or potential humanhealth risks, and evaluate potential environmental risks, and todevelop alternatives to address the contamination problems.

SCOPE AND ROLE OF THE ACTION

The goal of the selected remedy is to prevent furthermigration of the contaminants in the groundwater; to recover andtreat contaminated groundwater; to provide a permanent alternatewater supply for the affected and potentially affectedresidential well users southwest of the Site; to prevent theingestion of and dermal contact with contaminated groundwater andthe inhalation of vapors from contaminated groundwater; and torestore contaminated groundwater to its beneficial uses, ifpracticable. The remedy also provides for continued maintenanceof carbon filters currently provided by the PRP in theresidential area southeast of the Commodore site.

The remedial alternatives under consideration are summarized inthis proposed plan. The RI/FS report presents a more thoroughdescription and evaluation of these alternatives. Based on newinformation or public comments, EPA, in consultation with thePADER, may modify the preferred alternative or select anotherresponse action presented in this Proposed Plan and the FSReport. The public is encouraged to review and comment on allalternatives identified.

SUMMARY OF SITE RISKS

Data collected during the RI/FS, was used to assess andestimate the risk that the site would pose to human health andthe environment if no remedial actions were taken. This processis called a Baseline Risk Assessment (RA). The RA involvesassessing the toxicity, or degree of hazard, posed by substancesrelated to the Site, and involves describing the routes by whichhumans and the environment could come into contact with thesesubstances. Separate calculations are made for those substancesthat can cause cancer (carcinogenic) and for those that can causenon-carcinogenic health effects.

The National Oil and Hazardous Substances Contingency Plan(NCP) established acceptable levels of carcinogenic risk forSuperfund sites ranging from 1 in 10,000 to l in l million excesscancer cases. This translates to a risk range of between IxlO"4and IxlO"6. The NCP also states that sites should pose no non-carcinogenic threat, which EPA defines as a chronic dose AR302252exceeding the reference dose, as indicated by a hazard

index,(HI), greater than 1. The hazard index identifies thepotential for the most sensitive individuals to be affectedadversely by noncarcinogenic chemicals. If the hazard indexexceeds one (1.0), there may be concern of potentialnoncarcinogenic effects.

The medium of concern is groundwater. Chemicals of concernat the site are volatile organic compounds (VOCs). Chemicalsdetected in the groundwater are listed below with theirrespective maximum contaminant level (MCL) or in the absence ofan MCL, a risk-based calculation. Not all the contaminants weredetected at each of the receptor location used to evaluate risks.Attachment 1 (following page 19) summarizes the wells with majorMCL and proposed MCL exceedances.

(MCL ppb)Bromodichloromethane 100chloroform 1001,2 Dichlorobenzene 751,4 Dichlorobenzene 6001,1 Dichloroethane 810*1,1 Dichloroethene 71,2 Dichloroethene 70tetrachloroethene 51,1,1 Trichloroethane 200Trichloroethene 5vinyl chloride 2

*Non-carcinogenic health-based concentration.

Persons who utilize untreated water from the public supply wellsor from private wells are identified as the population at risk.The primary routes of exposure to contaminants in groundwateroccurs through ingestion, inhalation of volatiles, dermalabsorption and inhalation of volatiles in outdoor air due toexisting air stripper emissions.

The risk assessment was conducted assuming residents, areaworkers and country club members would use groundwater withouttreatment. The NCP requires that the risk assessment considerexposure scenarios both for current land use and for aconservative reasonable future use. The exposure scenariosdeveloped to evaluate the risk are the following:

1. Current private residential wells2. Current public residential water supply wells3. Future George Washington Country Club (GWCC) residential well

(This scenario assumes country club will undergo residentialdevelopment)

4. Current GWCC member5. Current GWCC worker6. Current Valley Forge Corporate Center (VFCC) worker

7. Future VFCC worker

Risks related to the Site are summarized in Table 1. The risknumbers represent the total risks from all the routes of exposureto contaminants in groundwater which occurs through ingestion,inhalation of volatiles, dermal absorption, and inhalation ofvolatiles in outdoor air due to the existing air stripperemissions near the site.

TABLE 1Summary of human health risk results

Scenario

PrivateResidentialWell

PublicResidentialWellGWCC FutureResidentGWCC MemberGWCC WorkerVFCC CurrentWorkerVFCC FutureWorker

Childnon-cancertotal chronicHI

0.27

:W?T'î :¥riK¥A§J

1.0

-

-

-

-

Adultnon-cancertotal chronicHI

0.082

0.37

0.31

-

0.0036

0.055

0.93

Adult & Childcancer totallifetime risk

2xlO~5

4xlO~5

•̂̂ ^̂ Ê̂ Ŵ̂ ^

IxlO"6

IXlO"7

IxlO"5

5xlO~5

Risks from one future use scenario and one current usescenario exceed the NCP range: lifetime cancer risk for a GWCC

I future resident is 1.4 x 10~4, and the chronic hazard index forI a child using public water is 1.2.i • •

I Table 2 summaries the chemicals which collectively contribute; over 90% of the risks for each of the scenarios evaluated.

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TABLE 2Summary of chemicals contributing over 90% of risk

Private ResidentialWell

Public ResidentialWellGWCC Future Res.

GWCC MemberGWCC Work

VFCC current worker

VFCC future worker

Child non-cancer

1,2 DCE,TCE,(Ch)

TCE, 1,2 DCE

TCE, 1,1 DCE

-

-

1,1,1 TCA;1,2 DCE

-

Adult non-cancer

1,2 DCE, TCE(Ch)

TCE, 1,2 DCE

TCE;1,1, 1TCA

-

(Ch)

1,1,1 TCA;1,2 DCE

TCE; PCE;1,1 DCE

Adult & childcancer

1,1 DCE, TCE,(Ch)

1, 1 DCE,

1,1DCE;VC;TCE

(Ch) ; BCM;TCE-

BCM, (Ch) TCE

1,1 DCE; TCE;PCE

TCE; 1,1 DCE;VC; TCE

BCM - BromodichloroemethaneCh - ChloroformDCE - DichloroetheneTCE - TrichloroetheneTCA - TrichloroethanePCE - Tetrachloroethene

There are several shallow monitoring wells at the Site thatare screened in the overburden. These wells have greaterconcentrations of contaminants than the deep wells screened inthe bedrock. However their yields are so low that it is notplausible that this portion of the aquifer could be used as adrinking water source in the future. Therefore exposure to thesewells was not evaluated in the risk assessment. Neverthelesscleanup of this shallow aquifer is necessary to mitigate thepotential migration of contaminants to the bedrock aquifer.

Ingestion and dermal contact with Site soils under a workerexposure scenario was evaluated. The concentrations of thecontaminants in soils did not exceed risk-based concentrationlevels.

There are air strippers on four public supply wells near theSite and the french drain system beneath the CSG building.

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Emissions from these air stripping towers were modeled toevaluate risks from inhalation of outdoor air for all theexposure scenarios. Risks were well below the 10~6 risk.

Based upon consultation with State and Federal agenciesknowledgeable about threatened or endangered species in theCommonwealth of Pennsylvania, EPA has determined that noendangered species or sensitive habitats are near the Site.

Five surface water samples were collected from theintermittent part of Lamb Run which is the only stream near theSite. Samples were analyzed for volatile organics. TCE, PCE,and 1,2 DCE were detected. The concentrations detected are wellbelow ambient water quality criteria for those contaminants.

Actual or threatened releases of hazardous substances fromthis Site, if not addressed by the preferred alternative or oneof the other remedial measure considered, present a current orpotential threat to public health, welfare, or the environment.

SUMMARY OF REMEDIAL ACTION ALTERNATIVES

The draft RI/FS dated February 1992 discusses the alternativesevaluated for the Site and provides supporting informationleading to alternative selection by EPA.

Five remedial alternatives were carried through a detailedanalysis in the Feasibility Study. These are numbered tocorrespond with the numbers in the RI/FS Report. Thealternatives for the Site are the following:

Alternative 1: No action

I Alternative 2: Institutional controls and connection to publicj water supply

Alternative 3: Commodore property deep groundwater Recovery andExisting off-property deep groundwater recoverywith treatment by air stripping (option A) orcarbon absorption (option B) and institutionalcontrols

Alternative 4: Commodore property deep and shallow groundwaterrecovery and existing off-property deepgroundwater recovery with treatment by airstripping (option A) or Carbon adsorption(option B) and institutional controls

Alternative 5: Commodore property deep and shallow groundwaterrecovery and modified off-property deep fl D ogroundwater recovery with treatment by air * ̂

10 •stripping (option A) or carbon adsorption(option B) and institutional controls.

ALTERNATIVE 1: NO ACTION

The Superfund Program requires that the "no action"alternative be evaluated at every site to establish a baselinefor comparison. Under this alternative, no action other thanonsite groundwater monitoring would be implemented. Maintenanceof the whole-house carbon filtration systems on the 23residential wells would be discontinued and no monitoring ofresidential wells. Under this alternative the seven monitoringwells will be sampled semi-annually. Because this alternativewould result in contaminated groundwater remaining on site, 5-year site reviews would be required. Zero time required forimplementation. There are no capital costs for this alternative.Costs of long-term monitoring of groundwater is estimated at$26,000 per year. The 30 year present worth cost is $277,400.

ALTERNATIVE 2: institutional Controls and connection to thePublic Water Supply

The intent of this alternative is to prevent any unacceptable ^bpresent and future risk associated with potable and nonpotable F̂use of contaminated groundwater. Residences south of the Site onRittenhouse Road and on Audubon Road between Rittenhouse Road andThrush Line would be connected to the public water supply. Forthe costing of this alternative, short-term institutionalcontrols, which would last two years, include continuedmaintenance of the existing whole-house carbon filtration systemsto the southwest plus the installation of one additional system.In addition maintenance of whole-house carbon filtration systemswill continue for the residences southeast of the Site which areidentified as Group 2 in the Feasibility Study. It is assumedthat 2 years will be sufficient to confirm the source of thecontamination in these residential wells.

Long-term institutional controls include implementation of along-term groundwater monitoring program, upgrading of securitylocks on all wells used for monitoring and assumes that theresidences in the area defined as Group three which are locatedon Rittenhouse Road south of the Site and on Audubon Road betweenRittenhouse Road and Thrush Lane would be connected to the publicwater supply. Development of groundwater management zones isincluded in institutional controls to establish areas in the sitevicinity where well installations and permit restrictions will berequired. The estimated implementation time for installation ofadditional water lines in the community near the site is 2 years.

Capital Costs: $125,500 anonooRO & M Cost/Year (Years 1-2): $232,600 flnoU

11' O&M Cost/Year (Years 3-30): $211,800| 30 Year Present Worth: $2,564,900

' ALTERNATIVE 3: Commodore property deep groundwater extraction; with treatment by air stripping (option A) or carbon absorption(option B) and off-property deep groundwater extraction withexisting treatment.

:!

i In addition to the elements described in Alternative 2 whichi provide public health protection, Alternative 3 provides for on-l and off-property extraction of contaminated groundwater. Thei objective of on-property deep groundwater extraction is toj provide migration control and recovery of onsite deepI groundwater. Off-property extraction of the public water supply; will also continue to provide interception and recovery of thei plume offsite. The Audubon Water Company water supply wells: Audj 3, Aud 5, and VFCC-2 will be utilized for the off-propertyi extraction. The off-property water supplies will continue to be| treated by their existing air strippers. Treated water from| onsite extraction may be used in the CSG plant during operation,'I discharged to the POTW or provided to the public water supply.i

I Under Option A, the existing onsite air stripper with vaporphase carbon emission control will be used to treat thecontaminated groundwater from the deep onsite recovery well and

, the French drain.

! Under Option B, the existing stripper will continue to be; used for treatment of groundwater from the French drain and ani aqueous phase carbon treatment system will be used to treat! contaminated groundwater recovered from the new onsite deep\ recovery well. Air standards for air emissions will beI attained. Monitoring and 5-year site reviews would be provided; to measure the effectiveness of the cleanup.ij For costing purposes the remediation time for this| alternative was based on 30 years (the maximum period ofI performance used by EPA for costing purposes). It is anticipated,! however, that this alternative will take more than 30 years.l| The costs figures presented in Alternatives 3 assume thati the PRPs will reach agreement with the Audubon Water Company toutilize their existing water supply wells and air stripper asdescribed above. If existing wells and air strippers can not beiused then new extraction and recovery wells with air emissionicontrols will be installed. In this event the costs for^ implementing Alternative 3A or 3B will increase.

\ Implementation time considers the time required to designand construct the alternative. Implementation time for thisalternative is estimated between two and five years.

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Option A CostsCapital: $375,100O & M/Year (Years 1-2) $281,200O & M/Year (Years 3-30) is 239,000 per year30 Year Present Worth: $3,141,000

Option B CostsCapital: $628,100O & M/Year (Years 1-2) $318,0000 & M/Year (Years 3 -30) is $274,80030 Year Present Worth: $3,800,400

ALTERNATIVE 4: Commodore property deep and shallow recovery withtreatment Option A or Option B and existing off-property deeprecovery with existing treatment

This alternative includes all the elements described inAlternative 3 as well as extraction and treatment of shallowgroundwater using three existing on-property monitoring wells.The primary objective for the Commodore property recovery is toprovide a hydraulic control that will minimize off-propertymigration of VOCs and recover groundwater near the source areas.The supplemental on-property shallow recovery wells will recoverthe higher concentration VOCs before they migrate down to thedeep aquifer. By extracting from both shallow and deepgroundwater on the Commodore property the overall volume of waterextracted over the life of remediation should be reduced as wellas the length of the remediation. Federal and State airstandards for air emissions will be attained. Groundwatermonitoring and five-year site review would be provided to measurethe effectiveness of the cleanup.

Under Option A, recovered water from a new deep groundwaterwell, (RW-1), the French Drain and wells MOS 11,14, and 15 willbe treated in the existing air stripper with vapor phase carboncontrol.

Under Option B, an aqueous phase carbon treatment systemwill be used to treat contaminated groundwater recovered from theon-property deep and shallow wells.

For costing purposes the remediation time for thisalternative was based on 30 years (the maximum period ofperformance used by EPA for costing purposes). It is anticipated,however, that this alternative will take more than 30 years.

The costs figures presented in Alternative 4A or 4B assumethat the PRPs will reach agreement with the Audubon Water Companyto utilize their existing water supply wells and air stripper asdescribed above. If existing wells and air strippers can not beused then new extraction and recovery wells with air emission

AR302259

13

controls will be installed. In this event the costs forimplementing Alternative 4A or 4B will increase.

Implementation time considers the time required to design andconstruct the alternative. Implementation time for thisalternative is estimated between two and five years.

Option A CostsCapital - $375,1000 & M/Year (1-2 years) - $292,500O & M/Year (3-30 years) - $250,30030 Year Present Worth - $3,346,400

Option B CostsCapital - $713,600

' O & M/Year (1-2 years) $348,400O & M/Year (3-30 years) $306,20030 Year Present Worth - $4,236,000

ALTERNATIVE 5 : Commodore property deep and shallow groundwaterrecovery and modified off-property deep groundwater recovery with

! treatment by air stripping (option A) or carbon adsorptioni (option B)

This alternative is similar to alternative 4 except that off-property deep groundwater recovery is modified such that off-property pumping maximizes capture within the CSG plume by

I changing the location of one of the off-property pumping wells.\Instead of utilizing VFCC-2 as in Alternatives 3 & 4 a newjrecovery well, RW-2, will be utilized to more effectively recover|the off-property plume. RW-2 would pump at the same rate thatiVFCC-2 currently pumps thereby supplying the same water supplyi capacity. This pumping scenario is expected to recover theihighest rate of VOCs while maximizing the use of the local waterI resources. For costing purposes it is assumed that the water|extracted from RW-2 will be piped to the existing air stripperjnear VFCC-2 and air emission controls will be required. Federal|and State air emission standards will be attained. Groundwateri monitoring and five-year site reviews will be required to measure|the effectiveness of the cleanup.

i Under Option A recovered water from a new on-property deepigroundwater well, (RW-1), the French Drain and wells MOS 11,14,iand 15 will be treated in the existing air stripper with vaporiphase carbon control. Existing treatment on Aud 3 and 5 would bejused. For, the additional deep well off-property, RW-2, the'existing stripper at VFCC-2 with vapor phase carbon will be used!for treatment.

I Under Option B, treatment of combined groundwater from RW-11, and shallow wells, MOS 11, 14, 15, and the French drain will

AR302260

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be treated using aqueous phase carbon control. Treatment at Aud3, 5 and RW-2 are the same as in Option A

For costing purposes the remediation time for thisalternative was based on 30 years (the maximum period ofperformance used by EPA for costing purposes). It is anticipatedthat this alternative will take 25 years.

The costs figures presented in Alternative 5A or 5B assumethat the PRPs will reach agreement with the Audubon Water Companyto utilize their existing water supply wells and air stripper asdescribed above. If existing wells and air strippers can not beused then new extraction and recovery wells with air emissioncontrols will be installed. In this event the costs forimplementing Alternative 5A or 5B will increase.

Implementation time considers the time required to designand construct the alternative. Implementation time for thisalternative is estimated between two and five years.

Option ACapital Costs: $619,000O & M (0-2 years) $448,800O & M (3-30 years) $406,60030 Year Present Worth $5,271,700

Option BCapital Costs: $876,000O & M/Year (0-2years) $513,800O & M/Year (3-30 years) $469,70030 Year Present Worth $6,243,400

EVALUATION OP ALTERNATIVES

This section includes a summary of the evaluation of thealternatives identified above. This section also contains adiscussion of why EPA has selected the "Preferred Alternative."

EPA's preferred alternative fox- addressing contamination atthe Commodore Semiconductor Site is Alternative 5A. While thegoal of this alternative is to remediate groundwater tobackground levels, the ability to achieve cleanup levels at allpoints throughout the contaminated groundwater plume cannot bedetermined until the extraction system has been implemented.This alternative would protect public health and the environmentby treating and discharging water at safe levels, which are belowthe MCLs for drinking water. This alter

Based on current information, this alternative would appearto provide the best balance of trade-offs among the alternatives

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with respect to the nine criteria the EPA uses to evaluate eachalternative. The following section summarizes the performance ofthe preferred alternative against the nine criteria, noting howit compares to the other options under consideration.

EPA uses nine criteria to evaluate remedial alternatives.These criteria include the statutory requirements of Superfund aswell as other technical, economic and practical factors used toassess the feasibility and acceptability of alternatives.

These are the nine criteria*:

1. Overall protection of human health and the environment2. Compliance with "Applicable or Relevant and Appropriate

Requirements" (ARARs)3. Long-term effectiveness and permanence4. Reduction of toxicity, mobility or volume through

treatment5. Short-term effectiveness6. Implementability7. Cost8. State Acceptance9. Community Acceptance

i

* see page 19 for Glossary of the Evaluation CriteriaiI These nine criteria are commonly divided into three groups:I threshold criteria (1 & 2), primary criteria (3 - 7) andI modifying criteria (8 & 9). Alternatives must meet the threshold! criteria before they are evaluated in any further detail. The| primary criteria are then used to weigh tradeoffs among thealternatives that pass the threshold test. The finalconsiderations include comments from the public and the| Pennsylvania Department of Environmental Resources.ii|i. overall Protection. Alternatives 3, 4, and 5 are protective!of public health and the environment. Each of these alternatives]would provide a public water supply to residences to thejsouthwest of the site; and continued carbon filter systemmaintenance for those residential wells with contaminantssoutheast of the site that are not confirmed to be site related;and will potentially remove groundwater contaminants down tobackground levels or MCLs. Alternatives 3, 4 and 5 would prevent

I exposure to groundwater contaminants, protect uncontaminatedIgroundwater, and potentially restore contaminated groundwater tojthe background cleanup levels. However the preferred alternativeshould attain cleanup levels in a shorter time period.Alternative 2 protects public health but not the environment'since Alternative 2 does not actively remediate the groundwater.Alternative 1, The "No Action" alternative would only provide

I continued monitoring and is not protective of human health and

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the environment, it is not considered further in this analysis asan option for the Site.

2. Compliance with ARARs.

Alternatives 3, 4, and 5 will comply with applicable or bothrelevant and appropriate federal and state environmentalregulations. Alternative 5 should attain compliance withgroundwater ARARs in less time than Alternatives 3 and 4.Alternative 2 does not comply with federal groundwater cleanupARARS, or the State's requirement to remediate groundwater tobackground quality. Since Alternative 2 will not comply withgroundwater cleanup ARARS, it will not be considered further inthis analysis as an option for remediation.

Major ARARs include:

1) Pennsylvania's ground water ARAR is that groundwater mustbe cleaned up to background levels. Halogenated organics do notoccur naturally in groundwater and therefore background would be"zero or nondetect. However at this site, based on theinformation available at the present time, there are believed tobe other sources of organic contamination in the site vicinitywhich are contributing to the type and concentration of organiccontaminants identified in the groundwater. Therefore backgroundmay actually be greater than MCLs for the site relatedcontaminants. In this case, cleanup of the plume shall be toMCLs.

2) The Federal and State Safe Drinking Water regulationslists the primary maximum contaminant levels as applicablerequirements for public drinking water supplies

3) Handling and disposal of the granular activated carbonunits would comply with 25 PA Code 261.6(a), Department ofTransportation (DOT) Rules for Hazardous Materials Transport, andRCRA requirements for hazardous waste handling, transportation,and disposal of hazardous waste.

4) Air Emissions from air strippers will be in compliancewith Federal and State Air Regulations.

3. Long-term Effectiveness and Permanence. Alternative 3, 4 and5 will provide long-term protection of public health fromexposure to contaminated groundwater by providing an alternativewater supply and by potentially removing the contaminants ofconcern to background levels or MCLs which ever is lower.

4. Reduction of Toxicity, Mobility, or Volume through Treatment.Alternatives 3, 4, and 5 would provide an irreversible treatmentprocess which would reduce the toxicity of the contaminatedgroundwater through essentially complete removal (99.8 percent

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plus) of the volatile chlorinated organic contaminants. Mobilityof the contaminants would be reduced through the creation ofhydraulic barriers which would prevent their migration intouncontaminated areas. Alternative 3 will not effectively controlcontaminant migration in the shallow aquifer and therefore wouldnot effectively have the same benefit as the preferredalternative. The preferred alternative would provide thegreatest degree of hydraulic control and would effect a largereduction in the volume of contaminated media by potentiallycleaning the groundwater to background or MCLs (which ever islower). Spent carbon from the vapor phase granular activatedcarbon for the air emission control on the air strippers will bedisposed of in an approved facility or regenerated on Site.

5. Short-term EffectivenessActions under all alternatives should be performed such thatthere would be minimal risk to the community and to workers.This would mean that appropriate health and safety measures wouldbe practiced during the construction and operation phases of thealternatives. Alternative 3 & 4 would require a longer duration'and greater volume of groundwater extracted to remediate thegroundwater to cleanup goals than the preferred Alternative 5A.

6. Implementability. Alternative 3, 4, and 5 will require theapproval of the state and local governments for the constructionof water lines within existing road right-of-ways. Alternatives3, 4 and 5 involve the installation of additional groundwaterrecovery well(s) a groundwater collection system/piping system, aholding tank, and activated carbon units. However, Alternative 5is more complex since cooperation of another property owner forthe RW-2 well will be required. The treatment process forAlternative 3, 4, 5 are the same, are well demonstrated and arereadily implementable.

7. Costs. The estimated 30 year present worth cost of thepreferred alternative, Alternative 5 (Option A) is $5,271,700.The highest estimated cost is Alternative 5 (Option B) at$6,243,400. Alternative 4 (Option A) is $3,346,400; Alternative4 (Option B) is $4,236,000. Alternative 3 (Option A) is$3,141,000; Alternative 3 (Option B) is $3,800,400.

8. state Acceptance. PADER has assisted EPA in the review of| reports and Site evaluations. The State has reviewed and! tentatively agrees with the proposed remedy and is awaiting pubicj comment before final concurrence.I

I 9. Community Acceptance. Community acceptance of the preferred|alternative will be evaluated after the public comment periodends and will be described in the Record of Decision.

| In summary, the preferred alternative is believed to

18

the best balance of trade-offs among the five alternativesevaluated with respect to the nine criteria above. Based on theinformation available at this time, EPA believes the preferredalternative would protect human health and the environment, wouldcomply with ARARs and be cost-effective. In addition, permanentdisposal options would be utilized to the maximum extentpracticable.

PUBLIC PARTICIPATION

EPA solicits input from the community on the cleanup methodproposed for each Superfund response action. EPA has set apublic comment period from July 21, 1992 to August 20, 1992, toencourage public participation in the response process. Thecomment period includes a public meeting at 7:00 P.M., on August6, 1992, during which EPA will present the proposed alternativeaction, answer questions, and accept oral and written comments.The meeting will be held at the following location:

Lower Providenc Township Meeting Room100 Parklane DriveEagleville, PA

Comments will be summarized and responses to significant commentsprovided in the Responsiveness Summary section of the Record OfDecision. Once the ROD is issued, EPA or potentially responsibleparties can begin Remedial Design activities at the Site.

To send written comments or obtain further information,contact:

Ruth Rzepski, Remedial Project ManagerUS EPA Region III, (3HW21)841 Chestnut BuildingPhiladelphia, PA 19107(215) 597-3216

orMervin Harris, Community Relations CoordinatorUS EPA Region III, (3EA21)841 Chestnut BuildingPhiladelphia, PA 19107(215) 597-2129

All comments must be submitted to one of the above people andpostmarked no later than August 20, 1992.

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Glossary of Evaluation Criteria

Overall Protection of Human Health and the Environment; addresseswhether the remedy provides adequate protection to human healthand the environment and describes how risks posed through eachexposure pathway are eliminated, reduced or controlled throughtreatment, engineering controls, or institutional controls.

Compliance with ARARs; addresses whether a remedy will meet allof the applicable or relevant and appropriate requirements(ARARs) of Federal and State environmental laws and/or justifiesa waiver

Long-term Effectiveness and Permanence; refers to the expectedresidual risk and the ability of a remedy to maintain reliableprotection of human health and the environment over time, onceclean-up goals have been met.

Reduction of Toxicity. Mobility, or Volume through Treatment;refers to the anticipated performance of the treatmenttechnologies a remedy may employ.

Short-term Effectiveness addresses the period of time needed toachieve protection and any adverse impacts on human health andthe environment that may be posed during the construction andimplementation period, until clean-up goals are achieved.

Implementabi1ity is the technical and administrative feasibilityj of a remedy, including the availability of materials and servicesneeded to implement a particular option.

Cost includes estimated capital, operation & maintenance (O&M),and net present worth costs.

State/Support Agency Acceptance indicates whether, based on itsreview of the site information and Proposed Plan, the Stateconcurs with, opposes, or has no comment on the preferredalternative.

Community Acceptance; will be assessed in the Record of Decision(ROD)following a review of the public comments received on theAdministrative Record and the Proposed Plan.

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