feasibility study (fs) addendumtreatment alternatives presented in chapter 2 of the main feasibility...

SAVAGE MUNICIPAL WATER SUPPLYSUPERFUND SITEFEASIBILITY STUDY ADDENDUM

ox

By

Haley & Aldrich, Inc.Bedford, New Hampshire

For

Savage Well PRP GroupManchester, New Hampshire

June 1991

TABLE OF CONTENTS

Section

Introduction 1

Screening of Alternatives 3

Detailed Analysis of Alternatives 4

Alternative MM-7A 4-3Alternative MM-9A 4-22Alternative MM-11A 4-41

INTRODUCTION

This document serves as an amendment to the SavageMunicipal Water Supply Superfund Site (Savage Well Site)Feasibility Study for the purpose of evaluating UV/OxidationTechnologies for the treatment of recovered groundwater at thesite.

UV/oxidation is a process alternative to air stripping andvapor phase carbon adsorption that effectively destroyscontaminants of the nature contained in the predominant plume atthe Savage Well Site.

The Savage Well PRP Group retained HMM Associates, Inc. toperform an RI/FS of the Savage Municipal Water Supply SuperfundSite (Savage Well Site) for submission to the USEPA.Subsequently, the PRP Group retained Haley & Aldrich, Inc. toevaluate oxidation technologies to treat site groundwater and toprepare this addendum to the HMM Feasibility Study Report.

This document serves as supplemental information ontreatment alternatives presented in Chapter 2 of the MainFeasibility Study and carries forward UV/oxidation as apotentially applicable treatment technology. This documentincludes Chapters 3 and 4 as related to UV/oxidation. Asprepared and presented, this document will refer to informationcontained within the main Feasibility Study and focuses on sitespecific application of UV/oxidation as an innovative andeffective treatment alternative.

The Savage Well Site is located in the western portion ofthe Town of Milford, New Hampshire, a community of approximately12,000 residents located in Hillsborough County, in the southcentral portion of the state. The site location is depicted onFigure 1.

The Savage well was a municipal W.S.W. at the time andcurrently is a private water well that has not been used as awater supply since February 1983 when the New Hampshire WaterSupply and Pollution Control Commission (WSPCC) detectedvolatile organic compounds in the well during routine waterquality monitoring (see Figure 1-2). The five volatile organiccompounds (VOC's) detected were Tetrachloroethylene (PCE),Trichloroethylene (TCE), 1,2-Dichloroethylene (DCE), 1,1,1Trichloroethane (TCA), and 1,1 Dichloroethane (DCA). Theconcentrations of several of these compounds exceeded Federaland State public health limits (MCLs).

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Four of the five compounds, with the exception being DCA,also were detected in a nearby mobile home water well. Amunicipal water line serving the trailer park has been installedas a completed remedial action at this site. The Town ofMilford has completed the interconnection with Pennichuck WaterWorks in order to replace water that might have been drawn fromthe Savage Well Site area. Alternate municipal sources of watersupply now serve the entire site area, with the exception of theMilford Drive-in Theater. Private production wells at theHitchiner and Hendrix manufacturing facilities continue toutilize local groundwater for industrial process and coolingwater. Private production wells are also used at the GeorgeBrox, Inc./Granite State Concrete property, at the Milford FishHatchery, and at Souhegan Valley Aquaculture, a private fishhatchery.

For purposes of providing continuity between the documents,information related to pumping scenarios has been included inthe amendment which reflects the alternatives developed forsource control and mitigation of contaminant migration presentedin the Feasibility Study. Haley and Aldrich has not endeavoredto evaluate the anticipated performance of the pumping scenarioscontained in the Feasibility Study, but is in agreement that thetechnology as conventionally applied is an effective method ofcontrolling migration of contaminants in groundwater.

The amendment reflects capital and operating costs for theselective application of UV/oxidation technology for treatmentof recovered groundwater as an alternative for use at the SavageSite. UV/oxidation is an innovative technology that has proveneffective at destroying contaminants of the nature containedwithin the predominant plume at Savage. Capital and operatingcosts for the treatment systems have been developedindependently of the Feasibility Study and used to replacetreatment system costs contained in alternatives presented inthe study.

The alternatives brought forward for analysis do notinclude technologies which may be specific to the recovery andtreatment of free phase DNAPL. Free phase DNAPL has not beenfound, however the data suggests that the concentrated plumearea may contain free phase DNAPL. As a result of thispotential, all alternatives will have as a component theperiodic evaluation of technologies and state of the artremediation techniques which would address the concentratedplume/free phase DNAPLs and the implementation of thosetechniques which may be successful.

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In addition the location and expected yield of extractionwells will be determined by location specific analysis duringdesign. Each alternative will have provision for groundwaterrecharge or withdrawal of portions of the aquifer that will beexamined during design and remediation for the purpose ofdecreasing the time of remediation and for environmental/agricultural protective measures.

Capital and operating costs for we11s/recovery systems,metals pretreatment, monitoring, disposal and buildingconstruction have been consolidated and carried forward from theoriginal Feasibility Study to help gain a consistent evaluationof the treatment alternatives relative to each other.

The amendment consists of the application of UV/oxidationwhere appropriate to the following Alternatives contained in theoriginal Feasibility Study:

Alternative MM-7: Treatment of the Concentrated Plume/Treatment of Extended Plume: Four Recovery Wells at 1225gpm total flow/Groundwater Treatment/Discharge.

Alternative MM-9: Treatment of the Concentrated Plume/Treatment of Extended Plume: Six Recovery Wells at 1150gpm total flow/Groundwater Treatment/Discharge.

Alternative MM-11: Treatment of the Concentrated Plume/Treatment of Extended Plume: Six Recovery Wells at 1100gpm total flow/Groundwater Treatment/Discharge.

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DEVELOPMENT AND SCREENING OFREMEDIAL ALTERNATIVES

In this section of the Feasibility Study Addendum, remedialalternatives are developed that meet the remedial actionobjectives outlined in Section 2.0, but were not carried forwardto Sections 3 & 4 of the Feasibility Study.

Table 3-1A presents the representative technologies andprocess options which make up each of the remedial alternativesaddressed in the addendum. The process options referencenumbers are presented on Figure 2-5 of the Feasibility Study.

TABLE 3-1A

Remedial Technologies and Process OptionsApplicable to Each Alternative

Process OptionsAlternative Reference Options*

MM-7A Treatment of Concentrated 2,3,4,5,10,11,13,15,16,17,Plume @ 400 GPM/Treatment of 18, 20, 27, 28, 30extended plume @ 825 gpm

MM-9A Treatment of Concentrated 2,3,4,5,10,11,13,15,16,17,Plume §400 GPM/Treatment of 18, 20, 27, 28, 30extended plume §750 GPM

MM-11A Treatment of Concentrated 2,3,4,5,10,11,13,15,16,17,Plume § 400 GPM/Treatment of 18, 20, 27, 28, 30extended plume §700 GPM

* Refer to Table 2-5 for listing of Process Options byReference number in the F.S.

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SCREENING OF ALTERNATIVES

Method

Alternatives were evaluated for three broad criteria asdefined by the NCP; effectiveness, implementability, and cost.These criteria are defined below. Alternatives with the mostfavorable composite evaluation of all factors were retained forfurther consideration during detailed analysis.

Effectiveness: "This criterion focuses on the degree towhich an alternative reduces toxicity, mobility, or volumethrough treatment, minimizes residual risks and affordslong-term protection, complies with ARARs, minimizes short-termimpacts, and how quickly it achieves protection. Alternativesproviding significantly less effectiveness than other, morepromising alternatives may be eliminated. Alternatives that donot provide adequate protection of human health and theenvironment shall be eliminated from further consideration." 40CFR 300.430(6)(7)

Implementability: "This criterion focuses on the technicalfeasibility and availability of the technologies eachalternative would employ and the administrative feasibility ofimplementing the alternative. Alternatives that are technicallyor administratively infeasible or that would require equipment,specialists, or facilities that are not available within areasonable period of time may be eliminated from furtherconsideration." 40 CFR 300.430(e)(7)

Cost; "The costs of construction and any long-term coststo operate and maintain the alternatives shall be considered.Costs that are grossly excessive compared to the overalleffectiveness of alternatives may be considered as one ofseveral factors used to eliminate alternatives. Alternativesproviding effectiveness and implementability similar to that ofanother alternative by employing a similar method of treatmentor engineering control, but at greater cost, may beeliminated." 40 CFR 300.430(e)(7)

The cost analysis for each alternative is based on theestimated cost of construction (the capital cost) and the annualoperation and maintenance (O&M) cost. For the monitoringrequirement, 40 CFR 264 (Subpart G) specifies that a 30-yearprogram is necessary. Therefore, the present worth calculationsare based on 30-years at a discount rate of 10% as outlined inthe NCP. It is possible to have a monitoring program whichlasts less than 30 years. For example, if complete removal ofwaste is performed, the monitoring period may last for fiveyears. Under this scenario, the SARA 5-year review may find nofurther action required, and the site could be delisted.

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These "study estimate" costs presented in the FS areexpected to provide an accuracy of +50 percent to -30 percent.They do not represent construction cost estimates or cost atcompletion.

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MANAGEMENT OF MIGRATION ALTERNATIVES DEVELOPMENT

Management of Migration Objectives

The remedial action objectives for management of migrationwere previously identified in Section 2.2, according tocontaminants, media of concern, potential pathways andremediation goals.

The following remedial action objectives apply togroundwater:

1. Prevent ingestion of water having carcinogens inexcess of target clean-up levels (MCLs) and a totalexcess cancer risk (for all contaminants) of greaterthan the 1.0 x 10~4 to 1.0 x 10~6 target range.

2. Prevent ingestion of water having non-carcinogens inexcess of target clean-up levels or reference doses,or MCLG's.

3. Restore groundwater aquifer to concentrations thatcomply with Federal and State ARARs. See Table 2-1which presents chemical-specific ARARs includingSafe Drinking Water Act MCLs.

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Screening of Alternatives;

Alternative MM-7A: Treatment of Concentrated Plume § 400GPM /Treatment of Extended Plume at 825 gpm Recovery

Description

This alternative provides for treatment of the 22.1 mg/1PCE concentrated plume at O.K. Tool using the UV/oxidationprocess, treatment of the 1300 ug/1 TCA concentrated plume atHitchiner using air stripping and vapor phase carbon treatment,and recovery of a portion of the extended plume downgradient ata flow of 825 gpm and treatment using the UV/oxidation process.This alternative provides for recovery of the concentrated plumeas outlined in alternative MM-3 and the extended plume asoutlined in alternative MM-7.

Recovery wells in the extended plume would pump at acombined rate of 825 gpm to capture contaminants along the 1,000ug/1 PCE plume. The objective of this pumping is theminimization of further migration of contaminated groundwater tothe Souhegan River, adjacent wells and downgradient portions ofthe aquifer.

Effectiveness: This alternative would further reducemigration of contaminants to the Souhegan River, adjacent wellsand downgradient portions of the aquifer.

Contaminated groundwater within the proposed zones ofcapture would be treated until target levels are reached. Thisalternative would provide treatment of the concentrated plume(s)and would also treat some portion of the extended plume.

The results of human health risk assessments do notindicate health threats to workers would exist duringconstruction and operation. The potential for risk to workersduring construction and operation would be minimized through useof adequate preventive measures, monitoring and personalprotective equipment, all of which have applicable OSHAguidelines for the anticipated conditions. All on site workerswould require OSHA training.

Implementability: The collection and process systemsassociated with this alternative have been demonstratedsuccessfully on hazardous wastewaters. Design and constructionof groundwater extraction wells is a proven technology.UV/oxidation is an innovative technology that has been shown

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effective on the contaminants of concern. The proposedtreatment systems outlined in this alternative (UV/oxidation atOK Tool and downgradient sites and air stripping with vaporphase carbon adsorption at Hitchiner) are expected to attain theMCLs, once system operations are optimized.

Direct discharge to the process stream or Souhegan Riverwould be considered as part of this alternative. The dischargewould be completed in accordance with the requirements of theNPDES permit program.

All components for groundwater extraction and treatment arereadily available from more than one vendor. Necessaryspecialists are available for design, construction and operationof the systems involved in this alternative.

Cost: The costs associated with Alternative MM-7Aincorporate all of the component costs associated with recoveryand treatment of the concentrated plume and extended plume asoutlined above. Estimated costs have been prepared to +50% -30%accuracy. The total capital, annual O&M and total present worthcost for 30 years at a 10% discount rate are:

Capital Operating Present Worth 30 yr §10%

$2,532,150 $1,472,004 $16,408,736

Summary: This alternative has been retained as it furtherscontainment of the concentrated plume and reduces migration ofthe extended plume while permanently treating contaminantsremoved from the aquifer.

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Alternative MM-9A: Treatment of Concentrated Plume @ 400GPM /Treatment of Extended Plume at 750 gpm Recovery

Description

This alternative provides for treatment of the 22.1 mg/1PCE concentrated plume at O.K. Tool using the UV/oxidationprocess, treatment of the 1300 ug/1 TCA concentrated plume atHitchiner using air stripping and vapor phase carbon treatment,and recovery of a portion of the 1,000 ug/1 PCE extended plumedowngradient at a flow of 750 gpm and treatment using theUV/oxidation process. This alternative provides for recovery ofthe concentrated plume as outlined in alternative MM-3 and theextended plume as outlined in alternative MM-9A.

Recovery wells in the extended plume would pump at acombined rate of 750 gpm to capture contaminants along the 1,000ug/1 plume. The objective of this pumping is the minimizationof further migration of contaminated groundwater to the SouheganRiver, adjacent wells and downgradient portions of the aquifer.




Implementability: The collection and process systemsassociated with this alternative have been demonstratedsuccessfully on hazardous wastewaters. Design and constructionof groundwater extraction wells is a proven technology.UV/oxidation is an innovative technology that has been showneffective on the contaminants of concern. The proposedtreatment systems outlined in this alternative (UV/oxidation atOK Tool and downgradient sites and air stripping with vaporphase carbon adsorption at Hitchiner) are expected to attain theMCLs, once system operations are optimized.

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$2,586,505 $1,449,580 $16,251,695


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Alternative MM-11A: Treatment of Concentrated Plume @ 400GPM /Treatment of Extended Plume at 700 gpm Recovery

Description

This alternative provides for treatment of the 22.1 mg/1PCE concentrated plume at O.K. Tool using the UV/oxidationprocess, treatment of the 1300 ug/1 TCA concentrated plume atHitchiner using air stripping and vapor phase carbon treatment,and recovery of a portion of the 1,000 ug/1 PCE extended plumedowngradient at a flow of 700 gpm and treatment using theUV/oxidation process. This alternative provides for recovery ofthe concentrated plume as outlined in alternative MM-3 and theextended plume as outlined in alternative MM-11.

Recovery wells in the extended plume would pump at acombined rate of 700 gpm to capture contaminants along the 1,000ug/1 plume. The objective of this pumping is the minimizationof further migration of contaminated groundwater to the SouheganRiver, adjacent wells and downgradient portions of the aquifer.




Implementability: The collection and process systemsassociated with this alternative have been demonstratedsuccessfully on hazardous wastewaters. Design and constructionof groundwater extraction wells is a proven technology.UV/oxidation is an innovative technology that has been showneffective on the contaminants of concern. The proposedtreatment systems outlined in this alternative (UV/oxidation atOK Tool and downgradient sites and air stripping with vaporphase carbon adsorption at Hitchiner) are expected to attain theMCLs, once system operations are optimized.

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$2,359,985 $1,396,871 $15,528,285


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DETAILED ANALYSIS OF ALTERNATIVES

INTRODUCTION

Site Specific Context of the Analysis

This section provides a detailed analysis of the remedialalternatives brought forward from Section 3.0. Thesealternatives are analyzed in the context of site-specificconditions as well as the nine criteria that are required by theNCP, which are discussed in the subsection on "EvaluationCriteria".

The detailed analysis recognizes that the contaminatedportion of the aquifer may include a concentrated plume and anextended plume. The concentrated plume being the area which maycontain dense non-aqueous phase liquids (free phase DNAPL).Existence of free phase DNAPL has not been observed; however,the circumstantial information of site history andconcentrations in the groundwater lead to this possibleconclusion. The extended plume is considered to be the areacontaining only dissolved contamination.

General Structure of the Detailed Analysis of Alternatives

The detailed analysis of alternatives presents relevantinformation necessary to further define and evaluate thosealternatives that have been identified and carried forward fromSection 3.0. Site wide remediation plans address theconcentrated plume and the extraction and treatment ofincremental portions of the balance of the contaminated aquifer,i.e., the extended plume. The addendum presents UV/oxidation asa treatment alternative to air stripping/carbon adsorption forthe O.K. Tool and downgradient sites. As such the costsdeveloped for Alternatives 7,9 & 11 in the Feasibility Study areadjusted to reflect the change in treatment. The alternativeswill be evaluated in terms of comparative cost, comparativeimpacts on the time frame for remediation of the aquifer, andcomparative benefits in terms of protection of human health andthe environment.

Based on the development and screening of alternatives inSection 3.0 of the addendum, one source control and threemanagement of migration alternatives were retained for detailedevaluation with alternate treatment technologies. Eachalternative has been defined with respect to the volume andareas to be addressed, the specific technologies and otherassumptions to be used for costing, and the performancerequirements of each alternative.

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DETAILED EVALUATION

Evaluation Criteria

The EPA requires that nine evaluation criteria be used tostandardize the detailed evaluations. These criteria serve asthe basis for the feasibility study (FS) and for subsequentselection of the EPA's preferred alternative. These evaluationcriteria area:

o Overall protection of human health and theenvironment;

o Compliance with ARARs;o Long-term effectiveness and permanence;o Reduction of toxicity, mobility, or volume through

treatment;o Short-term effectiveness;o Implementability;o Cost;o State acceptance; ando Community acceptance.

Each of the preceeding nine criteria are described fully in theFS.

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Alternative MM-7A Treatment of Concentrated Plume: RecoveryWell at O.K. Tool/Treatment with UV/oxidation at 250 GPM:,recovery well at Hitchiner/Treatment with Air Stripping andVapor Phase Carbon at 150 GPM. Recovery of extended plume at825 gpm/Treatment with UV/oxidation.

This alternative combines the recovery of the concentrated plumeas outlined in MM-3 with additional recovery and treatment atthe downgradient edges of the extended plume. This alternativereflects the selective application of UV/oxidation treatmenttechnologies in lieu of air stripping at the O.K. Tool anddowngradient sites.

Alternative MM-7A includes the following key components:

* Groundwater recovery from well(s) pumping atapproximately 250 gallons per minute (gpm) atO.K. Tool. These wells have a predominantcontaminant of PCE in concentrations ofapproximately 22,100 ug/1.

* Treatment of recovered groundwater (metalspretreatment and UV/oxidation) at O.K. Tool

* Groundwater recovery from well(s) pumping atapproximately 150 gpm at Hitchiner. These wellshave a predominant contaminant of TCA inconcentrations of approximately 1,300 ug/1.

* Treatment of recovered groundwater (metalspretreatment, air stripping and vapor phasecarbon treatment) at Hitchiner.

* Scheduled evaluations of state-of-the-artremediation techniques for the concentratedplume/free phase DNAPLs and implementation of thosetechniques which may be successful.

* Groundwater recovery from a series of wellslocated at the downgradient edge of the extendedplume at approximately 825 gpm. These wells have apredominant contaminant of PCE in concentrations ofapproximately 645 ug/1.

* Treatment of recovered groundwater (metalspretreatment and UV/oxidation) from the extendedplume

* Discharge of treated water from the concentratedplume to the Souhegan River or Hitchiner Hendrixdischarge stream. Discharge of treated water fromthe extended plume to the Souhegan River.

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* Natural attenuation of portions of the extendedplume not extracted by the pumping scheme withinstitutional controls.

DESCRIPTION

Alternative MM-7A will consist of treatment of groundwaterextracted from the most highly concentrated areas of the plumeat O.K. Tool and Hitchiner as well as recovery at thedowngradient edge of the extended plume. Recovery wells sitedat Hitchiner and O.K. Tool yielding 150 and 250 gallons perminute respectively will be designed to capture contaminantsmigrating from areas of concentrated contamination in theaquifer in these areas. (This portion of option MM-7A isidentical to the recovery system outlined in FS option MM-3).

A secondary recovery system, designed to yield 825 gallonsper minute will be located adjacent to the leading downgradientedge of the extended plume to help arrest further migration ofthe plume.

This alternative would provide for groundwater recovery atfour locations. Two wells would be located near the edge of the1000 ug/L plume and would pump at rates of approximately 200 gpmand 160 gpm. Additionally, the Savage Well would be used torecover groundwater at 240 gpm and a fourth well would belocated northwest of the Savage Well with a yield of 225 gpm(see Figure 4-5A) for a combined pumpage of 825 gpm, whichcombined with a recovery of the concentrated plume, results in atotal pumpage of 1225 gpm. For the purposes of this analysis,separate treatment systems are assumed due to the nature of thecontaminants. Separate treatment systems may allow phasedimplementation of this alternative.

Figure 4-6A illustrates the portions of the concentratedplume which are recovered and treated, the portion of theextended plume which is recovered and treated, and the portionof the extended plume which is not recovered but is allowed toundergo natural attenuation.

The actual location of the groundwater withdrawal wells forany alternative would be finalized during design. The actualpumping rates and resultant treatment rate would also bedependent on location specific investigations of the aquifernormally done during remediation design.

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Each pump and treat alternative will also include theunderstanding that periodic evaluations of the state of the artremediation techniques for concentrated plumes/free phase DNAPLsand implementation of those techniques which may be successful.

Groundwater Treatment

Three treatment trains are assumed necessary for thisalternative due to the relative locations of the recovery wellsand the nature of the contaminants identified at each site. Ofthe 1225 gallons per minute forecast to be recovered, 1075 willreceive metals pretreatment and UV/oxidation for contaminantdestruction with separate systems located at the O.K. Tool anddowngradient sites. The remainder of the recovered groundwater(at Hitchiner) will also be pretreated for metals removal.Since UV/oxidation is not as effective on saturated organicssuch as TCA as identified at Hitchiner, air stripping and vaporphase carbon adsorption for contaminant removal will beutilized. The other treatment systems will be designed to treatthe recovered groundwater to the MCL, eliminating the need forcarbon polishing.

Tables 4-7A, B & C reflect anticipated influent andeffluent conditions for this alternative.

Metals Pretreatment

This alternative is assumed to require the metalspretreatment process outlined in the original feasibility studyunder option MM-7.

Site conditions suggest extensive metals pretreatment maynot be necessary. Metals pretreatment alternatives will befurther evaluated during the detailed design phase.

Table 4-7A

Treatment Design Parameters at O.K. Tool

UV/Oxidation

ContaminantInfluent ConcentrationWater Loading RateWater TemperatureEffluent Concentration

Tetrachloroethy1ene22.1 mg/1250 gpm10°c<5 ug/1

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Table 4-7B

Treatment Design Parameters at Hitchiner

Air Stripping

ContaminantInfluent ConcentrationWater Loading RateTower HeightTower DiameterPacking DepthPacking MaterialWater TemperaturePressureAir: Water RatioAir Flow RateEffluent Concentration

1,1,1-Trichloroethane1300 ug/1150 gpm13 feet3 feet7.5 feet2-inch plastic10°C1 atm1002410 cfm196.2 ug/1

Vapor Phase Carbon Adsorption

ContaminantInfluent ConcentrationAir Flow RateAmount of CarbonPacking DepthEmpty Bed Contact TimeTemperaturesFreundlich KFreundlich 1/nCarbon Usage Rate

Trichloroethane475 ug/12410 cfm7540 Ibs.5.0 feet6.3 sec.25°C2746.50.2989816 days

Table 4-7C

Alternative MM-7A Treatment Design Parameters@ Downqradient Wells

UV/Oxidation


Tetrachloroethylene645 ug/1825 gpm10°C<5 ug/1

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UV/Oxidation

UV/oxidation is a process that is particularly effective onchlorinated solvent contaminated streams. Volatile organiccontaminants dissolved in groundwater are contacted with aproportional amount of hydrogen peroxide solution in thepresence of ultraviolet radiation. The ultraviolet radiationbreaks the hydrogen peroxide solution into hydroxyl radicalswhile simultaneously exciting the bond structure of the organicsmaking them susceptible to oxidation. The end products of thereaction are carbon dioxide, water and chloride ions.

Air Stripping/Vapor Phase Carbon Treatment

Air stripping coupled with vapor phase carbon treatment hasbeen selected as a recommended treatment option for thecontamination at Hitchiner due to the presence of 1,1,1-TCA.UV/oxidation is less effective at destroying saturatedchlorinated organics and therefore is generally less costeffective than air stripping and carbon adsorption for thiscompound. In this process, contaminated groundwater is passedthrough a packed column countercurrent to an air flow whichvolatilizes the compounds from the liquid stream. Thecontaminant laden air stream is then treated using carbon forremoval of the contaminants.

Discharge Options

This alternative will include construction of a dischargepipe or structure at the Souhegan River or process dischargestream which will have a short-term impact on a minimum amountof wetland vegetation. Erosion control techniques andrestoration of the river or stream bank will minimize long-termimpacts. The pumping of the extended plume may impact wetlandareas due to lowering of the groundwater table. Since finalwell locations and withdrawal rates are to be determined indesign, each alternative has provision for evaluation of thispossibility with protective measures such as recharge included.Should the necessity for structure relocation within thefloodplain occur during design the structures would beconstructed to meet the requirements of Executive Order 11988and 40 CFR Part 264.18 subpart B.

EVALUATION

The evaluation of the MM-3 portion of this alternative isnot repeated here but is incorporated by reference.

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Overall Protection of Human Health and the Environment

This treatment of the concentrated plume and a portion ofthe extended plume in combination with institutional controlswould provide protection to human health and the environment.Institutional control would be implemented in those areas,however, to prevent withdrawal of the contaminated groundwaterfor consumption.

This alternative would remove contaminants from theconcentrated plume, thereby minimizing further contributions ofcontaminants to downgradient portions of the aquifer, remove amass of contaminants from a portion of the extended contaminantplume, and reduce the time frame for natural flushing to reclaimthe aquifer. Further the application of UV/oxidation as atreatment method results in destruction of recoveredcontaminants.

Treatment of groundwater from the concentrated plume andextended plume areas would lessen over time the risks to humanhealth and the environment as the stabilized mass ofcontaminants in the extended plume is allowed to reduce throughflushing.

This alternative provides for capture of all contaminantsabove 1000 ug/1 but does not capture and treat all contaminantsabove 500 ug/1 and does not capture and treat contaminants northof the Souhegan River.

Compliance with ARARs

ARARs must be met unless they are waived under CERCLA.

Alternative MM-7A provides for pumping and treating theconcentrated plume to reduce contaminant concentrations asdiscussed for Alternative MM-3 in the FS. Further extractionand treatment of the plume within the 100-ppb contour will beprovided in the extended (dissolved) plume to enhance managementof contaminant migration and mass reduction of contaminants inthe aquifer. Natural attenuation is relied upon to reducecontaminant concentrations in the remainder of the plume. Thisalternative also provides for an alternative water supply andinstitutional controls to prevent further use of sitegroundwater for potable supply.

Action-specific ARARs that will be met by Alternative MM-7Ainclude elements of state and federal waste handling regulationsfor process residuals, coordination of discharge pipe

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installation with the Corps of Engineers, performance ofperiodic groundwater monitoring, preparation of a publicnotification plan, and personnel training in conformance withOSHA and SARA. Treated effluent would conform to NPDESrequirements, although a permit would not need to be secured.

Applicable location-specific ARARs for Alternative MM-7Ainclude conformance with floodplain and/or wetlands requirementsrelative to construction of discharge structures. Additionally,interagency communications will be maintained throughout theimplementation of this alternative as mandated by the Fish andWildlife Coordination Act.

In terms of chemical-specific ARARs, Alternative MM-7A willresult in contaminant reduction in the concentrated plume aswell as the extended plume through long-term extraction andtreatment. In addition, contaminants extracted and treated byUV/oxidation will be destroyed, leaving no residual fordisposal, further treatment, or future handling. It isanticipated that MCLs will be attained in the concentratedplume, if free phase DNAPLs do not exist. The time frame iscurrently not known but is expected to be less than thatrequired for natural attentuation or for treatment to meet MCLsin the dilute plume. However, if free phase DNAPL is foundduring the design and/or remediation, the pumping period may beindefinite and eventually ARARs may have to be waived. Thisalternative will limit further contaminant contributions todowngradient portions of the extended plume and reduce the timerequired for attainment of target clean up levels (MCLs) in theextended plume over time. MCLs will be attained in thegroundwater treatment system effluent prior to discharge.Treatment system air emissions, in the case of Hitchiner, willbe controlled to meet state air quality regulations.

The compliance of Alternative MM-7A with action-,location-, and chemical-specific ARARs is presented in AppendixVII of the FS.

Long-Term Effectiveness and Permanence

Contamination in the extended groundwater plume would meetMCLs as a result of groundwater extraction/treatment and naturalattentuation.

The result of recovering and treating contaminatedgroundwater from the concentrated plume will reduce themigration of contaminants from the concentrated plume into theextended plume. Treatment of this contaminated groundwaterwould be to MCLs. The risks associated with groundwatercontamination in the area of the concentrated plume would be

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greatly lessened. The risks associated with groundwater in theextended plume would be reduced as contaminants greater than1000 ug/1 are recovered and treated and the remainder of thecontamination is allowed to flush and be naturally attenuated.Provided continuous treatment of the concentrated groundwaterplumes and institutional controls on the aquifer usage, thereare no remaining sources of risk due to untreated residual ortreatment residual. A five-year review would be required toevaluate the effectiveness of the implemented treatmentalternative.

This alternative utilizes proven treatment technologiesapplied on a site specific basis to reach required treatmentefficiencies and performance specifications. It is expectedthat, due to the likely existence of dense nonaqueous phaseliquids (DNAPLs) at depth in the aquifer in the concentratedplume areas, the treatment facilities may have to operateindefinitely in order to treat the area of the concentratedplume to MCLs. In addition, contaminants extracted and treatedby UV/oxidation will be destroyed, leaving no residual fordisposal, further treatment or future handling.

Long-term management includes institutional controls toprevent future use of untreated groundwater during remediationfor drinking water purposes. Long-term monitoring would entailgroundwater sampling and analysis of sampling results.Five-year reviews would be required to reevaluate the siteconditions. Continuous operation and maintenance would berequired for the treatment system. A treatment plant operatorwould be required to perform operation and maintenance functionswhich would include: groundwater and air effluent sampling andanalyses; treatment system adjustments based on effluentmonitoring; removing and dewatering sludge generated by themetals removal system; changing the carbon in the vapor phasecarbon system (actual procedure would vary depending on the typeof vapor phase carbon unit); replacing or cleaning air stripperpacking; replacing lamps on UV/oxidation systems andservicing/replacing chemical feed pumps. No difficulties oruncertainties are associated with operation and maintenancefunctions at this time. The technical components would requirereplacement approximately every 15 years for pump and motors andevery 30 years for the treatment units. At the time oftreatment unit replacement, appropriate modifications orupgrades could be implemented. Provided the contaminatedgroundwater is not a drinking water source, the risk due to thereplacement of the treatment technology would be minimal. Thereis a high degree of confidence that the treatment system process

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controls and the treatment plant operator would be able tohandle any potential problems. At Hitchiner the contaminantsare removed from the groundwater and collected in the vaporphase carbon units. The spent carbon is sent to a carbonreactivitation plant where the contaminants are destroyedthrough the high temperatures during the reactivation process.No land disposal would be required for the activated carbon. AtO.K. Tool and downgradient sites contaminants are destroyedthrough the UV/oxidation process directly. No secondarytreatment or land disposal would be required.

Reduction of Toxicity. Mobility, or Volume ThroughTreatment

The treatment process employed in this alternative wouldaddress the principal threats (carcinogens and non-carcinogens)through removal of contaminants from the concentrated plume.There are no special requirements for the treatment process.

The extraction and treatment of contaminated groundwaterwould reduce the mass of contaminants in groundwater, therebyreducing the toxicity, mobility, and volume of contaminants ingroundwater.

The toxicity of concentrated plume would decrease asconcentration of contaminants are reduced. The mobility andvolume of the contaminants in the concentrated plume would bereduced. However, due to the potential DNAPLs, the volume ofcontaminants would decrease slowly over time. Recovery andtreatment of contaminants in the extended plume would alsoreduce the toxicity, mobility, and volume of contaminants withinthe extended plume. The mobility of the portions of theextended plume which are not captured would not lessen and itsvolume increase at more dilute concentrations as it is allowedto naturally flush. Treatment of the contaminated groundwaterwould be irreversible. Contaminants treated by UV/oxidation aredestroyed directly by the process. Contaminants removed fromthe groundwater during air stripping and are ultimatelydestroyed during reactivation of the vapor phase carbon units.

Treatment residuals include a metal hydroxide sludgeproduced in the metals removal unit. The sludge would requireland disposal in a RCRA TSD facility if the sludge does not passthe TCLP test. Proper disposal of the sludge does not pose anyrisk to human health or the environment.

This alternative addresses the management of migrationresponse objectives. Treatment is used to meet the responseobjectives, satisfying the statutory preference for treatment.

4-13

Based on the combined pumping rate of 825 gpm and anassumed estimated average influent concentration of 500 ug/1,this alternative would result in contaminant mass removal fromthe extended plume corresponding to approximately 370 Ibs/yearin addition to the estimated 1920 Ibs/year removed from theconcentrated plume.

The total mass of dissolved VOCs in the groundwatercontaminant plume has been estimated to be approximately 9.8 x106 grams or 22,000 pounds (see Section 2.2.4). Therefore,this alternative would result an annual removal of approximately10.4% of the total mass of contaminants in the first year. Itshould be noted that these are rough approximations and that theestimate of the total mass of VOCs corresponds to the mass ofdissolved VOCs in the concentrated and extended plume. Becausecontamination may exist as separate phase (DNAPL) in theconcentrated plume, the estimate represents a minimum totalmass.

Short-Term Effectiveness

The human health risk assessment does not indicate thathealth threats to workers would exist during construction andoperations. The potential for risk to workers would beminimized by the use of adequate preventive measures, monitoringand personal protection equipment. OSHA training would berequired for on-site workers.

Through treatment of the concentrated plume, the extendedplume, and natural attenuation contaminant levels and healthrisks will be reduced. It is estimated that the contaminants inthe plume will be reduced to MCLs in 15 to 65 years.

The construction of the treatment plant(s) and thetreatment of contaminated groundwater is not anticipated to havethe potential to adversely impact the local community or theenvironment. Environmental disturbance during the constructionshould be minimal and any adverse impacts on wetlands would beminimized by adjusting the location of the discharge. Sincewell locations will be finalized during design, any impact ofgroundwater withdrawal upon the environmental/agriculturalresources will be evaluated and have remedial measures such asrecharge to the aquifer part of the design. Protection shouldbe maintained by compliance with the ARARs. Once operationalthere should be no further impacts on wetlands or thefloodplain.

4-14

Implementability

Technical Feasibility: All the unit processes andcollection systems associated with this alternative have beenused to treat industrial and hazardous wastewaters and have beeninstalled at other NPL sites. The design and construction ofgroundwater extraction wells is a proven technology. Metalspretreatment and UV/oxidation have been demonstrated effectivelyon contaminants of the nature and concern at the OK Tool andDowngradient Sites. Air stripping coupled with metalspretreatment can remove the contaminants of concern atHitchiner. The proposed treatment scheme for this alternativeshould attain discharge requirements, once system operations areoptimized. Monitoring of migration pathways would be performedby long-term monitoring.

Administrative Feasibility; All remedial action activitieswould be coordinated and approved by the US EPA and NewHampshire DBS. Direct discharge to the process stream orSouhegan River would be considered as part of this alternative.Obtaining a discharge permit for these waterways would not benecessary because the Savage Well site is a NPL site. However,the discharge levels would be expected to meet the substantiverequirements of the NPDES program. The implementation ofinstitutional controls would be based on negotiation betweenlandowners, PRPs, and agencies.

Availability of Services and Materials: All components forgroundwater extraction and treatment are readily available frommore than one vendor. Necessary specialists are available fordesign, construction and operation of these extraction,treatment, and discharge systems.

All groundwater collection, treatment and dischargefacility systems proposed for MM-7A would include sufficientdesign margin to handle additional flow and be of standarddesigns employing no special equipment or materials.

Several vendors and suppliers of water treatment equipmentwould be available to procure the units necessary to implementMM-7A. Therefore, competitive bids could be received fromcontractors and vendors for the implementation of MM-7A.

The capital cost for this Alternative MM-7A estimated at$2,532,150.

4-15

Alternative MM-7A contains the following cost data developed byHMM Associates.

DESCRIPTION CAPITAL O&HM

OK Tool GroundwaterRecovery Costs $21,749

Treatment UnitBuilding Costs $17/sq. ft.

Metals PretreatmentSystem $220,000 $100,300

Hitchiner


HitchinerOperating Air StripperSystem $30,000

Vapor Phase Carbon $36,850 $8,740

Discharge System $23,400

Disposal of TreatmentResiduals 890 drums @$297.73 per drum $264,982

Discharge ComplianceSampling 12 months at$1200 per month $14,400

Long-term monitoring $119,560

Dovnaradient Wells

Groundwater RecoverySystem $237,456

4-17

A__-=3f


Disposal of TreatmentResidues 611 drums§297.73 per drum $181,687


Discharge ComplianceSampling 12 months@$600 per month $7,200

4-18

COMPONENT/SYSTEM DESCRIPTION

O.K. TOOLGROUNDWATER RECOVERY SYSTEM

POWER OPERATING COST

GROUNDWATER TREATMENT SYSTEM

TREATMENT BUILDING(12X18)

INC HECH/ELECT ETC

HETALS PRETREATHENT SYSTEM

DISPOSAL OF TREATMENT RESIDUALS

UV/OXIDATION SYSTEM(LSB-90)

SITE WORK

POWER CAPITAL COST


TREATMENT PLANT OPERATOR

HITCHINER

GROUNDWATER RECOVERY SYSTEM


GRODNDWATER TREATMENT SYSTEM


INC HECH/ELECT ETC

METALS PRETREATMENT SYSTEM


AIR STRIPPER SYSTEM

VAPOR PHASE CARBON

CASE MM-7A

QTY COST/UNIT COST/CAPITAL COST/O&H

1 EA.

1 EA.

216 SF

21749

9795

17

$21,749

$3,672

432 SF 17 $7,344

1 EA. 190000 $190,000

334 DRUMS $297.71/DRUM

1 EA. 30000 $30,000

1 EA. 36850 $36,850

$9,795

1 EA. 220000 $220,000 $100,300

556 DRUMS $297.71/DRUM $165,527

1 EA. 135000 $135,000 $24,000

1 EA.

1 EA.

1 EA.

520 HR

1 EA.

1 EA.

20000

30000

76667

$30/HR

21149

4897

$20,000

$30,000

$21,149

$76,667

$15,600

$4,897

$103,000

$99,435

$8,740

A A rr NEW YORK

SITE WORK

POWER CAPITAL COST



DISCHARGE SYSTEM

DISCHARGE COMPLIANCE SAMPLING

DOHNGRADIENT WELLSGROUNDWATER RECOVERY SYSTEM




INC HECH/ELECT ETC



DV/OXIDATION SYSTEM

SITE WORK

POWER CAPITAL COST



DISCHARGE SYSTEM


LONG TERM MONITORING

1 EA.

1 EA.

1 EA.

520 HR

1 EA.

12 MO

1 EA.

1 EA.

600 SF

25000

35000

16978

$30/HR

23400

$1200/HO

*$16

$25,000

$35,000

$23,400

$9,600

370000 $370,000

20000 $20,000

50000 $50,000

1 EA. 520000 $520,000

611 DRUMS 297.36/DRDM

1 EA.

1 EA.

1 EA.

1 EA. 155000

1040 HR $30/HR

1 EA. 19500 $19,500

12 MO 600

1 EA.

$16,978

$15,600

$14,400

237456 $237,456

39180 $39,180

$102,600

$181,707

$46,800

$155,000

$31,200

$7,200

$119,560

SOB TOTALS

EQUIP REPLACEMENTi 10*

ENGINEERING 101

$2,025,720 $1,338,186

$133,819

$202,572

O~z.LJ

H & A OF NEW YORKV C.-tL " r P ' J C u « v , ,

CONTINGENCY 101 $202,572

ADMINISTRATION 51 $101,286

SUB TOTALS $2,532,150 $1,472,004

PRESENT WORTH (i=10l, n=30 yr) W/0 INFLATION

$16,408,736

PRESENT WORTH (1=103, n=30 yr) W/51 INFLATION

$25,159,803

FUTDRE WORTH (i=10S, n=4 yr) W/51 INFLATION

$30,581,741

oLU

I

^ H & A OF NEW YORK












4-22

Natural attenuation of portions of the extendedplume not extracted by the pumping scheme withinstitutional controls.

DESCRIPTION


A secondary recovery system, designed to yield 750 gallonsper minute will be located adjacent to the leading downgradientedge of the extended plume to help arrest further migration ofthe plume. The six additional wells of this system are intendedto capture the entire width of the contaminated plume on thesouth side of the river so that all contaminated groundwater tothe south of the river is treated to 5 ug/1.

The recovery well(s) in the extended plume location wouldpump at a total of approximately 750 gpm, which in combinationwith the MM-3 wells results in a total pumpage of 1150 gpm. Theproposed location of recovery wells and treatment facilities forAlternative MM-9A is shown on Figure 4-8A.

Figure 4-9A illustrates the capture zones superimposed on amap of the contaminant plume. The figure also illustratesstreamlines used in the analysis of treatment times and flushingtimes (see main FS Alternative MM-9 for this analysis).

The figure also illustrates the portions of theconcentrated plume which are recovered and treated, and theportion of the extended plume which is not recovered but isallowed to undergo natural attenuation.


4-23



Three treatment trains are assumed necessary for thisalternative due to the relative locations of the recovery wellsand the nature of the contaminants identified at each site. Ofthe 1150 gallons per minute forecast to be recovered, 1000 willreceive metals pretreatment and UV/oxidation for contaminantdestruction with separate systems located at the O.K. Tool anddowngradient sites. The remainder of the recovered groundwater(at Hitchiner) will also be pretreated for metals removal.Since UV/oxidation is not as effective on saturated organicssuch as TCA as identified at Hitchiner, air stripping and vaporphase carbon adsorption for contaminant removal will beutilized. The treatment systems will be designed to treat therecovered groundwater to the MCL, eliminating the need forcarbon polishing.


Metals Pretreatment



Table 4-10A


UV/Oxidation

Contaminant TetrachloroethyleneInfluent Concentration 22.1 mg/1Water Loading Rate 250 gpmWater Temperature 10°cEffluent Concentration <5 ug/1

4-26

Table 4-10B


Air Stripping






Table 4-10C

Alternative MM-10A Treatment Design Parameters@ Downqradient Wells

UV/Oxidation


Tetrachloroethylene115 ug/1750 gpm10°C<5 ug/1

4-27

UV/Oxidation

UV/oxidation is a process that is particularly effective onchlorinated solvent contaminated streams. Volatile organiccontaminants dissolved in groundwater are contacted with aproportional amount of hydrogen peroxide solution in thepresence of ultraviolet radiation. The ultraviolet radiationbreaks the hydrogen peroxide solution into hydroxyl radicalswhile simultaneously exciting the bond structure of the organicsmaking them susceptible to oxidation. The end products of thereaction are carbon dioxide, water and a chloride ion.


Air stripping coupled with vapor phase carbon treatment hasbeen selected as a recommended treatment option for thecontamination at Hitchiner due to the presence of 1,1,1-TCA.UV/oxidation is less effective at destroying saturatedchlorinated organics and therefore is generally less costeffective than air stripping and carbon for this compound. Inthis process, contaminated groundwater is passed through apacked column countercurrent to an air flow which volatilizesthe compounds from the liquid stream. The contaminant laden airstream is then treated using carbon for removal of thecontaminants.

Discharge Options

This alternative will include construction of a dischargepipe or structure at the Souhegan River or process dischargestream which will have a short-term impact on a minimum amountof wetland vegetation. Erosion control techniques andrestoration of the river or stream bank will minimize long-termimpacts. The pumping of the extended plume may impact wetlandareas due to lowering of the groundwater table. Since finalwell locations and withdrawal rates are to be determined indesign, each alternative has provision for evaluation of thispossibility with protective measures such as recharge included.Should the necessity for structure relocation within thefloodplain occur during design the structures would beconstructed to meet the requirements of Executive Order 11988and 40 CFR Part 264.18 subpart B.

EVALUATION


4-28







Alternative MM-9A provides for pumping and treating theconcentrated plume to reduce contaminant concentrations asdiscussed for Alternative MM-3 in the FS. Further extractionwill be provided at the downgradient end of the extended plumeto capture all contaminants above 5 ug/1 on the south side ofthe river. The 5 ug/1 level corresponds to MCLs. Naturalattenuation is relied upon to reduce contaminant concentrationsin the remainder of the plume. This alternative also providesfor an alternative water supply and institutional controls toprevent further use of site groundwater for potable supply.

Action-specific ARARs that will be met by Alternative MM-7Ainclude elements of state and federal waste handling regulationsfor process residuals, coordination of discharge pipe

4-29

installation with the Corps of Engineers, performance ofperiodic groundwater monitoring, preparation of a publicnotification plan, and personnel training in conformance withOSHA and SARA. Treated effluent would conform to NPDESrequirements, although a permit would not need to be secured.


»

In terms of chemical-specific ARARs, Alternative MM-7A willresult in contaminant reduction in the concentrated plume aswell as the extended plume through long-term extraction andtreatment. In addition, contaminants extracted and treated byUV/oxidation will be destroyed, leaving no residual fordisposal, further treatment, or future handling. It isanticipated that MCLs will be attained in the concentratedplume, if free phase DNAPLs do not exist. The time frame iscurrently not known but is expected to be less than thatrequired for natural attentuation or for treatment to meet MCLsin the dilute plume. However, if free phase DNAPL is foundduring the design and/or remediation, the pumping period may beindefinite and eventually ARARs may have to be waived. Thisalternative will limit further contaminant contributions todowngradient portions of the extended plume and reduce the timerequired for attainment of target clean up levels (MCLs) in theextended plume over time. MCLs will be attained in thegroundwater treatment system effluent prior to discharge.Treatment system air emissions, in the case of Hitchiner, willbe controlled to meet state air quality regulations.




The result of recovering and treating contaminatedgroundwater from the concentrated plume will reduce themigration of contaminants from the concentrated plume into theextended plume. Treatment of this contaminated groundwaterwould be to MCLs. The risks associated with groundwatercontamination in the area of the concentrated plume would be

4-30

greatly lessened. The alternative would also capture allcontaminants above MCLs on the south side of the river. Thenorth side of the river would be allowed to naturallyattenuate. Provided continuous treatment of the concentratedgroundwater plumes and institutional controls on the aquiferusage, there are no remaining sources of risk due to untreatedresidual or treatment residual. A five-year review would berequired to evaluate the effectiveness of the implementedtreatment alternative.


Long-term management includes institutional controls toprevent future use of untreated groundwater during remediationfor drinking water purposes. Long-term monitoring would entailgroundwater sampling and analysis of sampling results.Five-year reviews would be required to reevaluate the siteconditions. Continuous operation and maintenance would berequired for the treatment system. A treatment plant operatorwould be required to perform operation and maintenance functionswhich would include: groundwater and air effluent sampling andanalyses; treatment system adjustments based on effluentmonitoring; removing and dewatering sludge generated by themetals removal system; changing the carbon in the vapor phasecarbon system (actual procedure would vary depending on the typeof vapor phase carbon unit); replacing or cleaning air stripperpacking; replacing lamps on UV/oxidation systems andservicing/replacing chemical feed pumps. No difficulties oruncertainties are associated with operation and maintenancefunctions at this time. The technical components would requirereplacement approximately every 15 years for pump and motors andevery 30 years for the treatment units. At the time oftreatment unit replacement, appropriate modifications orupgrades could be implemented. Provided the contaminatedgroundwater is not a drinking water source, the risk due to thereplacement of the treatment technology would be minimal. Thereis a high degree of confidence that the treatment system process

4-31

controls and the treatment plant operator would be able tohandle any potential problems. At Hitchiner the contaminantsare removed from the groundwater and collected in the vaporphase carbon units. The spent carbon is sent to a carbonreactivitation plant where the contaminants are destroyedthrough the high temperatures during the reactivation process.No land disposal would be required for the activated carbon. AtO.K. Tool and downgradient sites contaminants are destroyedthrough the UV/oxidation process directly. No secondarytreatment or land disposal would be required.

Reduction of Toxicitv. Mobility, or Volume ThroughTreatment



The toxicity of concentrated plume would decrease asconcentration of contaminants are reduced. The mobility andvolume of the contaminants in the concentrated plume would bereduced. However, due to the potential DNAPLs, the volume ofcontaminants would decrease slowly over time. Capture of theentire extended plume to the south of the river would reduce themobility of the plume. The mobility of the extended plume tothe north of the river would not lessen and its volume wouldincrease at more dilute concentrations as it is allowed tonaturally flush. Treatment of the contaminated groundwaterwould be irreversible. Contaminants treated by UV/oxidation aredestroyed directly by the process. Contaminants removed fromthe groundwater during air stripping and ultimately destroyedduring reactivation of the vapor phase carbon units.



4-32

The additional wells in the extended plume provided byAlternative MM-9A are located along the outer perimeter of theplume where concentrations are dilute, and therefore, wouldresult in very little additional mass reduction.

Based on the combined pumping rate of 750 gpm and anassumed average influent concentration of 115 ug/1, thisalternative would result in a contaminant mass removalcorresponding to approximately 80 Ibs/year in addition to the1920 Ibs/year provided by recovery of the concentrated plume fora total removal of 2000 Ibs/year.






4-33

Implementability

Technical Feasibility; All the unit processes andcollection systems associated with this alternative have beenused to treat industrial and hazardous wastewaters and have beeninstalled at other NPL sites. The design and construction ofgroundwater extraction wells is a proven technology. Metalspretreatment and UV/oxidation have been demonstrated effectivelyon contaminants of the nature and concern at Hitchiner. Theproposed treatment scheme for this alternative should attaindischarge requirements, once system operations are optimized.Monitoring of migration pathways would be performed by long-termmonitoring.

Administrative Feasibility; All remedial action activitieswould be coordinated and approved by the US EPA and NewHampshire DES. Direct discharge to the process stream orSouhegan River would be considered as part of this alternative.Obtaining a discharge permit for these waterways would not benecessary because the Savage Well site is a NPL site. However,the discharge levels would be expected to meet the substantiverequirements of the NPDES program. The implementation ofinstitutional controls would be based on negotiation betweenlandowners, PRPs, and agencies.

Availability of Services and Materials; All components forgroundwater extraction and treatment are readily available frommore than one vendor. Necessary specialists are available fordesign, construction and operation of these extraction,treatment, and discharge systems.



Cost


4-34

The operation and maintenance costs include the O&Minvolved with each of the treatment systems, as well as thelong-term monitoring costs carried through from MM-2. The totalannual O&M cost is $1,449,580. The most substantial O&M costsinclude O&M for the metals removal system; and electricityrequired to operate the extraction and treatment systems.

«

The total present worth cost for Alternative MM-9A @ 10% is$16,251,695 based on 30 years and is summarized in the attachedtable.

PMT15

4-35


DESCRIPTION CAPITAL O&M

OK Tool

GroundwaterRecovery System $21,749

Treatment UnitBuilding Costs $17/sq. ft.


Hitchiner


HitchinerOperating Air StripperSystem $30,000

Vapor Phase Carbon $36,850 $8,740

Discharge System • $23,400

Disposal of TreatmentResiduals 1340 drums@$297.73 per drum $264,982

Discharge ComplianceSampling 12 months at$1200 per month $14,400

Long-term monitoring $119,560

Dovngradient Wells


4-36


Disposal of TreatmentResiduals 560 drums@$297.73 per drum $166.522



4-37

OZLU




GROONDWATER TREATMENT SYSTEM


INC MECH/ELECT ETC



UV/OXIDATION SYSTEM(LSB-90)

SITE WORK

POWER CAPITAL COST


TREATMENT PLAOT OPERATOR

HITCHINER





INC MECH/ELECT ETC



AIR STRIPPER SYSTEM

VAPOR PHASE CARBON

CASE MM-9A

QTY COST/UNIT COST/CAPITAL COST/OSM

1 EA.

1 EA.

216 SF

21749 $21,749

9795 $9,795

17 $3,672

1 EA. 220000 $220,000 $100,300

556 DRUMS $297.71/DRUM $165,527

1 EA. 135000 $135,000 $24,000

1 EA.

1 EA.

1 EA.

520 HR

1 EA.

1 EA.

20000

30000

76667

$30/HR

21149

4897

$20,000

$30,000

$21,149

$76,667

$15,600

$4,897

432 SF 17 $7,344

1 EA. 190000 $190,000

334 DRUMS $297.71/DRUM

1 EA. 30000 $30,000

1 EA. 36850 $36,850

$103,000

$99,435

$8,740

H & A OF NEW YORK

SITE WORK

POWER CAPITAL COSTS

POWER OPERATING COSTS

TREATMENT PLANT OPERATOR(S)

DISCHARGE SYSTEM


DOWNGRADIENT WELLS





INC HECH/ELECT ETC



UV/OXIDATION SYSTEM

SITE WORK

POWER CAPITAL COST


TREATMENT PLANT OPERATOR(S)

DISCHARGE SYSTEM



1 EA.

1 EA.

1 EA.

520 HK

1 EA.

12 HO

1 EA.

1 EA.

25000

35000

16978

$30/HR

23400

$1200

330340

39180

$25,000

$35,000

$23,400

$330,340

$16,978

$15,600

$14,400

$39,180

600 SF 17 $10,200

1 EA. 470000 $470,000 $102,200

560 DRUMS $297.71/DRUH $166,521

1 EA. 370000 $370,000 $42,000

20000 $20,000

50000 $50,000

1 EA.

1 EA,

1 EA.

1040 HR

1 EA.

12 HO

1 EA.

SUB TOTALS

155000 $155,000

$30/HR $31,200

19500 $19,500

600 $7,200

$119,560

EQUIP REPLACEMENT§ 101

ENGINEERING 10?

$2,069,204 $1,317,800

$131,780

$206,920

OzLU_JLL H & A OF NEW YORK

ozai_j"- H & A OF NEW YORK

ROCHESTER, NEW YORK

CONTINGENCY 10* $206,920

ADMINISTRATION 51 $103,460

SUB TOTALS $2,586,505 $1,449,580

PRESENT WORTH (1=10%, n=30 yr) W/0 INFLATION

$16,251,695

PRESENT WORTH (1=10$, n=30 yr) W/51 INFLATION

$24,869,447

FUTURE WORTH (i=10l, n=4 yr) W/5* INFLATION

$30,228,813












4-41

Natural attenuation of portions of the extendedplume not extracted by the pumping scheme withinstitutional controls.

DESCRIPTION


A secondary recovery system, designed to yield 700 gallonsper minute will be located adjacent to the leading downgradientedge of the extended plume to help arrest further migration ofthe plume.

This alternative would include recovery and treatment ofthe extended plume through: 1) two recovery wells pumping at300 gpm each in the central portion of the extended plume torecover the entire width of the plume at this point (one ofthese wells is located at the location of the Savage Well); and2) two recovery wells located on the north side of the SouheganRiver pumping at approximately 50 gpm each to recover andprevent further migration of the end of the plume (see Figure4-12A).

The recovery well(s) in the extended plume location wouldpump at a total of approximately 700 gpm, which in combinationwith the MM-3 wells results in a total pumpage of 1100 gpm.

Figure 4-13A illustrates the capture zones superimposed ona map of the contaminant plume. The figure also illustratesstreamlines used in the analysis of treatment times and flushingtimes (see FS Alternative MM-11 for analysis).

The figure also illustrates the portions of theconcentrated plume which are recovered and treated, the portionof the extended plume which is recovered and treated, and theportion of the extended plume which is not recovered but isallowed to undergo natural attentuation.

4-42

This alternative also retains the possibility of adding avertical barrier, which could consist of sheet piling, a slurrywall, or recovery/injection wells. The barrier would be locatedalong Elm Street to the east of the Hendrix facility (see Figure4-13A). The intent of the barrier is to minimize the capture ofcleaner water to the south of Elm Street by the recovery welllocated at the Savage Well. The vertical barrier is notincluded in the cost estimate but is retained as a potentialfuture option.




Three treatment trains are assumed necessary for thisalternative due to the relative locations of the recovery wellsand the nature of the contaminants identified at each site. Ofthe 1100 gallons per minute forecast to be recovered, 950 willreceive metals pretreatment and UV/oxidation for contaminantdestruction with separate systems located at the O.K. Tool anddowngradient sites. The remainder of the recovered groundwater(at Hitchiner) will also be pretreated for metals removal.Since UV/oxidation is not as effective on saturated organicssuch as TCA as identified at Hitchiner, air stripping and vaporphase carbon adsorption for contaminant removal will beutilized. The treatment systems will be designed to treat therecovered groundwater to the MCL, eliminating the need forcarbon polishing.


Metals Pretreatment



4-45

Table 4-11A


UV/Oxidation


Tetrachloroethylene22.1 mg/1250 gpm10°c<5 ug/1

Table 4-11B


Air Stripping






4-46

Table 4-11C

Alternative MM-11A Treatment Design Parameters@ Downaradient Wells

UV/Oxidation

Contaminant TetrachloroethyleneInfluent Concentration 475 ug/1Water Loading Rate 700 gpmWater Temperature 10°CEffluent Concentration <5 ug/1

UV/Oxidation

UV/oxidation is a process that is particularly effective onchlorinated solvent contaminated streams. Volatile organiccontaminants dissolved in groundwater are contacted with aproportional amount of hydrogen peroxide solution in thepresence of ultraviolet radiation. The ultraviolet radiationbreaks the hydrogen peroxide solution into hydroxyl radicalswhile simultaneously exciting the bond structure of the organicsmaking them susceptible to oxidation. The end products of thereaction are carbon dioxide, water and a chloride ion.


Air stripping coupled with vapor phase carbon treatment hasbeen selected as a recommended treatment option for thecontamination at Hitchiner due to the presence of 1,1,1-TCA.UV/oxidation is less effective at destroying saturatedchlorinated organics and therefore is generally less costeffective than air stripping and carbon for this compound. Inthis process, contaminated groundwater is passed through apacked column countercurrent to an air flow which volatilizesthe compounds from the liquid stream. The contaminant laden airstream is then treated using carbon for removal of thecontaminants.

Discharge Options

This alternative will include construction of a dischargepipe or structure at the Souhegan River or process dischargestream which will have a short-term impact on a minimum amountof wetland vegetation. Erosion control techniques andrestoration of the river or stream bank will minimize long-termimpacts. The pumping of the extended plume may impact wetlandareas due to lowering of the groundwater table. Since finalwell locations and withdrawal rates are to be determined in

4-47

design, each alternative has provision for evaluation of thispossibility with protective measures such as recharge included.Should the necessity for structure relocation within thefloodplain occur during design the structures would beconstructed to meet the requirements of Executive Order 11988and 40 CFR Part 264.18 subpart B.

EVALUATION






The alternative provides protection by recovering anddestroying contaminants on the north side of the river, whichhave been detected at levels greater than 500 ug/1, however thealternative does not provide for capture of all contaminantsgreater than 1000 ug/1 to the south of the river.

Institional controls would be implemented in those areas,however, to prevent withdrawal of the contaminated groundwaterfor consumption.



4-48

Alternative MM-11A provides for pumping and treating theconcentrated plume to reduce contaminant concentrations asdiscussed for Alternative MM-3 in the FS. Further extractionwill be provided in the central portion of the extendeddissolved plume to capture the width of the plume (above 5 ug/1)to enhance management of contaminant migration and massreduction of contaminants in the aquifer. The alternative alsoprovides for recovery and treatment north of the river. Naturalattenuation is relied upon to reduce contaminant concentrationsin the remainder of the plume. This alternative also providesfor an alternative water supply and institutional controls toprevent further use of site groundwater for potable supply.

Action-specific ARARs that will be met by AlternativeMM-11A include elements of state and federal waste handlingregulations for process residuals, coordination of dischargepipe installation with the Corps of Engineers, performance ofperiodic groundwater monitoring, preparation of a publicnotification plan, and personnel training in conformance withOSHA and SARA. Treated effluent would conform to NPDESrequirements, although a permit would not need to be secured.


In terms of chemical-specific ARARs, Alternative MM-11Awill result in contaminant reduction in the concentrated plumeas well as the extended plume through long-term extraction andtreatment. In addition, contaminants extracted and treated byUV/oxidation will be destroyed, leaving no residual fordisposal, further treatment, or future handling. It isanticipated that MCLs will be attained in the concentratedplume, if free phase DNAPLs do not exist. The time frame iscurrently not known but is expected to be less than thatrequired for natural attentuation or for treatment to meet MCLsin the dilute plume. However, if free phase DNAPL is foundduring the design and/or remediation, the pumping period may beindefinite and eventually ARARs may have to be waived. Thisalternative will limit further contaminant contributions todowngradient portions of the extended plume and reduce the timerequired for attainment of target clean up levels (MCLs) in theextended plume over time. MCLs will be attained in thegroundwater treatment system effluent prior to discharge.Treatment system air emissions, in the case of Hitchiner, willbe controlled to meet state air quality regulations.

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The result of recovering and treating contaminatedgroundwater from the concentrated plume will reduce themigration of contaminants from the concentrated plume into theextended plume. Treatment of this contaminated groundwaterwould be to MCLs. The risks associated with groundwatercontamination in the area of the concentrated plume would begreatly lessened. The risks associated with groundwater in theextended plume would be reduced as a portion of the plume isrecovered and treated and the remainder of the contamination isallowed to flush and be naturally attenuated. Providedcontinuous treatment of the concentrated groundwater plumes andinstitutional controls on the aquifer usage, there are noremaining sources of risk due to untreated residual or treatmentresidual. A five-year review would be required to evaluate theeffectiveness of the implemented treatment alternative.


Long-term management includes institutional controls toprevent future use of untreated groundwater during remediationfor drinking water purposes. Long-term monitoring would entailgroundwater sampling and analysis of sampling results.Five-year reviews would be required to reevaluate the siteconditions. Continuous operation and maintenance would berequired for the treatment system. A treatment plant operatorwould be required to perform operation and maintenance functionswhich would include: groundwater and air effluent sampling andanalyses; treatment system adjustments based on effluent

4-50

monitoring; removing and dewatering sludge generated by themetals removal system; changing the carbon in the vapor phasecarbon system (actual procedure would vary depending on the typeof vapor phase carbon unit); replacing or cleaning air stripperpacking; replacing lamps on UV/oxidation systems andservicing/replacing chemical feed pumps. No difficulties oruncertainties are associated with operation and maintenancefunctions at this time. The technical components would requirereplacement approximately every 15 years for pump and motors andevery 30 years for the treatment units. At the time oftreatment unit replacement, appropriate modifications orupgrades could be implemented. Provided the contaminatedgroundwater is not a drinking water source, the risk due to thereplacement of the treatment technology would be minimal. Thereis a high degree of confidence that the treatment system processcontrols and the treatment plant operator would be able tohandle any potential problems. At Hitchiner the contaminantsare removed from the groundwater and collected in the vaporphase carbon units. The spent carbon is sent to a carbonreactivitation plant where the contaminants are destroyedthrough the high temperatures during the reactivation process'.No land disposal would be required for the activated carbon. AtO.K. Tool and downgradient sites contaminants are destroyedthrough the UV/oxidation process directly. No secondarytreatment or land disposal would be required.

Reduction of Toxicity. Mobility, or Volume ThroughTreatment



The toxicity of concentrated plume would decrease asconcentration of contaminants are reduced. The mobility andvolume of the contaminants in the concentrated plume would bereduced. However, due to the potential DNAPLs, the volume ofcontaminants would decrease slowly over time. Recovery andtreatment of contaminants in the extended plume would alsoreduce the toxicity, mobility, and volume of contaminants withinthe extended plume. The mobility of the portion of the extendedplume which are not captured would not lessen and its volume

4-51

would increase at more dilute concentrations as it is allowed tonaturally flush. Treatment of the contaminated groundwaterwould be irreversible. Contaminants treated by UV/oxidation aredestroyed directly by the process. Contaminants removed fromthe groundwater during air stripping and ultimately destroyedduring reactivation of the vapor phase carbon units.



Based on the combined pumping rate of 700 gpm and anassumed estimated average influent concentration of 475 ug/1,this alternative would result in contaminant mass removal fromthe extended plume corresponding to approximately 300 Ibs/yearin addition to the estimated 1920 Ibs/year removed from theconcentrated plume.





4-52


Implementability

Technical Feasibility; All the unit processes andcollection systems associated with this alternative have beenused to treat industrial and hazardous wastewaters and have beeninstalled at other NPL sites. The design and construction ofgroundwater extraction wells is a proven technology. Metalspretreatment and UV/oxidation have been demonstrated effectivelyon contaminants of the nature and concern at the OK Tool andDowngradient Sites. Air stripping coupled with metalspretreatment can remove the contaminants of concern atHitchiner. The proposed treatment scheme for this alternativeshould attin discharge requirements, once system operations areoptimized. Monitoring of migration pathways would be performedby long-term monitoring.

Administrative Feasibility: All remedial action activitieswould be coordinated and approved by the US EPA and NewHampshire DBS. Direct discharge to the process stream orSouhegan River would be considered as part of this alternative.Obtaining a discharge permit for these waterways would not benecessary because the Savage Well site is a NPL site. However,the discharge levels would be expected to meet the substantiverequirements of the NPDES program. The implementation ofinstitutional controls would be based on negotiation betweenlandowners, PRPs, and agencies.

Availability of Services and Materials: All components forgroundwater extraction and treatment are readily available frommore than one vendor. Necessary specialists are available fordesign, construction and operation of these extraction,treatment, and discharge systems.

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Cost


The operation and maintenance costs include the O&Minvolved with each of the treatment systems, as well as thelong-term monitoring costs carried through from MM-2. The totalannual O&M cost is $1,396,811. The most substantial O&M costsinclude O&M for the metals removal system; and electricityrequired to operate the extraction and treatment systems.

The total present worth cost for Alternative MM-11A @ 10%is $15,528,285 based on 30 years and is summarized in theattached table.

PMT16

4-54


DESCRIPTION CAPITAL

OK Tool

GroundwaterRecovery System

Treatment UnitBuilding Costs

Metals PretreatmentSystem

Hitchiner

Metals PretreatmentSystem

HitchinerOperating Air StripperSystem

Vapor Phase Carbon

Discharge System

Disposal of TreatmentResiduals 1340 drums@$297.73 per drum

Discharge ComplianceSampling 12 months at$1200 per month

Long-term monitoring

Dovngradient Wells


$21,749

$17/sq. ft.

$220,000

$190,000

$30,000

$36,850

$23,400

O&M

$100,300

$103,000

$8,740

$398,931

$14,400

$119,560

4-55




4-56






INC MECH/ELECT ETC

METALS REMOVAL SYSTEM


PEROXIDATION SYSTEM(LSB-90)

SITE WORK

POWER CAPITAL COST



BITCHINER





INC MECH/ELECT ETC



AIR STRIPPER SYSTEM

VAPOR PHASE CARBON

SITE WORK

CASE MH-11A

QTY COST/UNIT COST/CAPITAL COST/O&M

1 EA.

1 EA.

216 SF

21749 $21,749

9795

17 $3,672

432 SF 17 $7,344

$9,795

1 EA. 220000 $220,000 $100,300

556 DRUMS $297.71/DRUM $165,527

1 EA. 135000 $135,000 $24,000

1 EA.

1 EA.

1 EA.

520 HR

1 EA.

1 EA.

20000

30000

76667

$30/HR

Lj

21149

4897

$20,000

$30,000

$76,667

$15,600

'9oW -}?',*>$21,149

$4,897

1 EA. 190000 $190,000 $103,000

334 DRUMS $297.71/DRUM $99,435

1 EA. 30000 $30,000

1 EA. 36850 $36,850 $8,740

1 EA. 25000 $25,000

OzLLJ_J

u_ H & A OF NEW YORKROCHESTFP, NEW V

POWER CAPITAL COSTS

POWER OPEEATING COSTS


DOWNGRADIENT SITES

RIVERGROUNDWATER RECOVERY SYSTEM



TREATMENT BUILDING(18x24)

INC MECH/ELECT ETC



UV/OXIDATION SYSTEM

SITE WORK

POWER CAPITAL COSTS



DISCHARGE SYSTEM



1 EA.

1 EA

520 H

1 EA.

1 EA.

35000 $35,000

16978 $16,978

$30/HR ^ $15,600

155880 $155,880

37874 $37,874

432 17 $7,344

1 EA. 470000 $470,000

450 DRUMS $297.71/DRUH

1 EA.

1 EA.

1 EA.

1 EA.

1040 HR

1 EA.

12 MO

1 EA.

SUB TOTALS

EQUIP REPLACEMENTi 101

ENGINEERING 101

CONTINGENCY 101

ADMINISTRATION 52

GRAND TOTALS

370000 $370,000

20000 $20,000

50000 $50,000

155000

$30/HR

39000 $39,000

600

$102,600

$133,970

$42,000

$1,887,988

$188,799

$188,799

$94,399

$2,359,985

$155,000

$31,200

$7,200

; $119,500

$1,269,882

$126,988

X

$1,396,871

O2THI

H & A OF NEW YORKROCHESTfP NEW YORK

feasibility study (fs) addendumtreatment alternatives presented in chapter 2 of the main feasibility...

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