NEVILLE LAND COMPANY1900 Grant Building

Pittsburgh, Pennsylvania 15219(412)281-2620

June 30, 1995

Mr. Romuald A RomanRemedial Project ManagerU.S. Environmental Protection Agency841 Chestnut BuildingPhiladelphia, Pennsylvania 19107

Dear Mr. Roman:

Enclosed are five copies of the final version of the Feasibility Study for the Ohio RiverPark Site (ORS), Neville Township, Pennsylvania, which are hereby submitted in accordance withAOC Docket N6.UI-91-74-DC. Accompanying this transmittal is a 3 1/2" diskette containingone copy of the text and tables of the main section of the Feasibility Study in WordPerfect 6.0(Windows) format. ^ /

Neville Land Company (NLC) hereby also submits for the record two attachments to thisletter. Attachment 1 responds to the comments of EPA on the Draft Feasibility Study, which yousent May 15, 1995. Attachment 2 is NLC's response to your letter of June 13, 1995 and tosubsequent discussions between NLC and EPA during meetings on June 19 and June 22,1995.

Very truly yours,

. W)MMariakF. DietrichVice President

MFD:dlk - '

Enclosures

cc: Annette T.PaluhThomas C. ReedMark StellaAnthony J. Burlando , .

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n. Attachment 1 to 'Neville Land Company Letter of June 30. 1995

RESPONSE TO U.S. EPA AND Pa DER COMMENTSDRAFT FEASIBILITY STUDY ,OHIO RIVER SITE, NEVILLE TOWNSHIP, PENNSYLVANIA

Comments on the Draft FS are recorded below in sequence for each document noted.Direct quotations of comments and questions posed in each of the documents are provided, withthe response following in italics.

Source Document; US EPA letter of May IS. 199S fR. Roman to H. Vaughan Blaster.NLO • • ; :.V •••.; '. ..'-•-•-. . . •

' ' • ' • / * " ' . '

1. Section 6.0 must screen alternatives to present the best choices for the detailed evaluation.Unfortunately, none of the evaluated alternatives meets the "threshold criteria" (OverallProtection of Human Health and Environment, and Compliance with ARARS). None ofthe selected alternatives includes provisions for containment, removal or treatment of thesource material in the waste trenches. These alternatives do not represent a long termsolution since pumping of the groundwater is planned for only 15 years. If one of thesealternatives were selected, the waste material would still exist on She, and this materialwouldn't be appropriately contained, since the erosion cap does not guarantee sufficientprotection. Consequently, there would be a long term potential for generatingcontaminated groundwater.

Therefore, present more than one alternative meeting the "threshold criteria" and add a, new alternative (based on the alternative 4A) to Sections 6.0, and 7.0. This alternativeshould include: -

s \

• Institutional Controls

• . Surface Runoff Control, including monitoring at the "pointsofcompliance", at the property borders, before the groundwater enters theriver

(By letter of May 18, 1995 EPA clarified to reworks concerning the impliedrequirement of the second bulleted item above for surface water monitoringonthe site perimeter. This particular comment is understood to refer to thepreferred location of groundwater monitoring points rather to require surfacerunoff monitoring as part of the overall Site monitoring program).

- . • k ; • \ ' .

• Plugging the abandoned, old oil well at the north-east part of the Site

• Groundwater remediation by pumping system, which will operate untilMCLs or l.OE-6 total risk level is achieved at the "points of compliance".

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Response, to Comments /"">•Draft Feasibility Study .•[ tOhio River Site .V_~j/Page2 .' - ' ' '• . .-.-. . ; • ' . . . ' ' ;

, For the purpose of cost analysis, assume 200 gpm flow rate and pumpingfor 30 years. The exact figures will be developed during the RD.

• PADER's approved, multi layer cap over the trench area (The exactborders of the capped area(s).will be specified during the RD)

4 • ' -. •

• • Groundwater, surface water, and sediment monitoring program developedin such a way to detect and warn against "hot spots" (if there are any "hot

. . • . spots" identified on the Site during the RD and/or RA.) In this case "hot •'.-.-'spots" must be localized and covered with the PADER's approved, multilayer cap(s). :

Response: Alternative 4C has been developed by NLC to respond to this comment, althoughNLC disagrees with the EPA conclusion that none of the alternatives evaluated inthe draft FS meet the threshold criteria. It is included in the final version of theFeasibility Study and a description was submitted to EPA by Dames & Mooreearlier by letter. ''

' ' •• '• ' - • ' - ^ jTwo sets of groundwater remedial action objectives (RAOs) have been supplied in ^Section 3.4 of the Feasibility Study. One set is based on reducing risk ofon-sitedirect exposure to groundwater by attaining MCLs or to risk-basedconcentrations for each contaminant at the perimeter of the waste trench areas.This set of RAOs was developed at EPA's direction. The implementation ofAlternative 4C satisfies this set of RAOs.

Alternative 4Ct while incorporating virtually all ofEPA's suggested elements,does not include the plugging of the abandoned oil well on the Site as a remedialelement As discussedwith EPA on June 19, Neville Land Company previouslyapplied to the Pa DER Bureau of Oil and Gas Management for orphan wellstatus under Act 78 (1992) for the abandoned oil well on the Site. The •application is now under review. When state action on the application iscompleted, the well will be scheduled for abandonment.

' ' - . ' . . • • . . . . . . ' \2. Revise "Alternative'!" as a true"No ^ Action Alterative." The monitoring program,

including extra costs should be excluded.•' •• -

Response: Alternative 1 has been revised as requested to represent a true "no action"remedy for the Site. Refer to Section 6.2J of the final Feasibility Study.

' . . ' • • - ' " ' • ' ' ''/' ' \3. For the "recreational" land usage define Remedial Action Objectives ("RAOs") for the \

groundwater and surface water. For ecological purposes define RAOs for the soil. RAOsA:\ATtACHMT.OKS

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Response to Comments . 'Draft Feasibility Study ..,>.'.Ohio River Site

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must require that the total cancer risk and hazard index is within the EP A acceptable riskrange (Cancer Risk IE-06 to IE-4, and HI less than 1). Monitoring should be performedat the points of compliance including groundwater monitoring wells at the perimeter of theORS, and BarCad weUs for the surface water.

, - . ' • . . • • , . - . ' • '

Response: RAOs protective of 'ecological receptors have been defined 'for Site soil (seeSection 3.2.2). RAOs controlling risks associated 'with the on-site recreationalscenario are described in Section 3.6. Points of compliance for both sets ofgroundwater RAOs have been defined in Sections 3.4. J and 3.4. '2. For thegroundwater RAO defined to limit the risk associated with direct on-site use of

, groundwater, the specified points of compliance are at the perimeter of the site;for the off-site exposure RAG the points of compliance are any point "within the ,ORS water-bearing zone.

4. Specify RAOs for the groundwater and surface water utilizing MCLs for contaminantswith established MCLS, and IE-06 cancer risk levels for those that don't have MCLs.

• • / . ' , . , • ' ' ' . . ' ' ' •

!L \ Response: Two distinct sets of groundwater FiAOs have been proposed in the Feasibility~ . Study. One set is based on achievement of MCLs and/or other risk-based levels

(IE-6 or HI=1) at att points beyond the outer perimeter of the -waste trench area,and is protective against future on-site direct tuse of 'groundwater. The second setof groundwater RAOs is based on protecting against risk associated with off-siteuses of groundwater or surface water contaminated by groundwater dischargesfrom the ORS. On-site groundwater risk is eliminated through the imposition ofenforceable groundwater use restrictions in each of the remedial alternativesproposed (except the No Action alternative). Remedial alternatives are evaluatedagainst both sets of groundwater RAOs. •

5. Specify the Ecologicd Rbk Assessment (ERA), mchidmg EPA's Addendum as a reference, document in Section 1.2, Section 3.0, and Section 10.0.

Response: The Ecological Risk Assessment and the EPA Addendum have been referencedexplicitly in the specified sections of the Feasibility Study.

6. Modify the sentence on page 6-7 of the FS:"Neville Land Company's ownership of the site guarantees ..." to "Neville Land Company

.'....• will provide ... "

" Response: This phrase has been modified as requested by EPA.'

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7. Describe the way VOCs generated during the stabilization process, page 6-20, Alternative7, will be treated. .

Response: Section 5.4.3.1 describes the general means by which volatiles generated duringwaste material stabilization will be controlled. Section 6.2.7, page 6-22 of theFeasibility Study provides additional information on collection and treatment of

. volatiles generated during stabilization.

3. Correct the statement on page 6-23, second paragraph, by explaining that whileimplementing Alternative 8, the waste volume will be moved off site (but not reduced!)

Response: Section 6.2.8 (pp. 6-22 and 6-23) reflects the fact that excavated waste materialswill be transported off the ORSfor disposal without otherwise reducing theirvolume during implementation of Alternatives.

9. Present the analytical data in such a way to avoid the discrepancy between the FS, theHuman Health Risk Assessment (BHRA), and the Feasibility Study Report on the number.of samples taken from the various exposed media.

Response: The HRA and the Remedial Investigation Report have been reviewed and anydiscrepancies between the numbers reported in these documents and in theFeasibility Study have been eliminated by clarifications to the text of Section L 0.

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Source Document: Internal EPA Memo of April 20. 199S CN. Rios Jafolla to R. Romant/ ' . . ' .

I. Remedial Action Objectives (RAOs)

1 . RAOs for soil are not presented in the document for review. RAOs for surface soil areassumed to be met by capping the contaminated area (either the waste trenches and/orsurface soil hot spots). RAOs for soil need to be developed for those land uses where risk

. levels are in exceedance.- , ' ' i •

Response: Surface soil RAOs are defined in Sections 3.2.1 and 3.2.2 of the Feasibility Stucfy.

Note that capping of contaminated surface soil areas with excess cumulative risk needs tobe defined further. Total site risk for surface soil should not exceed the risk levelsacceptable to the EPA based on the assumed land use. In some cases, the risk levels forsome areas may need to be lower than the proposed risk level of IE-06 in order to achievean acceptable site risk level for surface soil.

. ' '• : - -• ,- ' ;- '• • ' ' • ' •' " 'Furthermore, soil cumulative risk contours (Figure 6-10) needs to be done using krigingtechniques, assuming the data are appropriate. Given that the sampling and analyticalconcerns with the surface soil data, especially for PAHs (major contaminants of concern insurface soil), resampling of the soil is recommended before any kriging is applied. Thealternative would be to sample after the remedial action is completed in those areas whereno action will occur to determine if those areas meet acceptable risk levels. In any event, 'RAOs need to be developed for soil as a point of reference since action levels for soil maydiffer from RAOs.

Response: The Site monitoring program includes soil and sediment sampling to determine ifany areas of excessive contaminant concentration remain outside the waste trenchareas. Capping of surface soil areas outside the waste trench areas -whereconcentrations of contaminants are excessive when considered in light of thelikely Site we scenarios has been proposed for Alternatives 4 and higher.

i2. RAOs for ground water need to be developed so that the total cancer risk and hazard

index is within the acceptable risk range acceptable to the EPA (e.g., Cancer Risk -IE-06 and HI = 1). This should be meant at the point of compliance (e.g., in surfacewater and in BarCad Wells) and should be independent of dilution effects that are

, assumed to have taken place using the ground water model. The ground water model thatassumes mixing zone dilution should be reviewed by the hydrogeologist after RAOs areestablished.

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Response to Comments - ~Draft Feasibility Study • !\ /Ohio River Site -.--x"Page 6 . '

Response: Two different sets of groundwater RAOs have been proposed: one to protectagainstriskfromhypotheticaldirecton-siteuseofgroundwater,andoneto>protect against risk resulting from exposure to surface water or to contaminatedgroundwater taken from the Coraopolis municipal well field. Direct on-siteexposures to groundwater will be precluded by imposition of enforceable waterusage restrictions as part of all proposed remedial alternatives (except the NoAction alternative). The HRA indicates that the risk of exposure to surface wateror to contaminated groundwater taken from the Coraopolis well is presentlynegligible (Table 1-4) and remediation to even the least restrictive of the twoproposed RAOs will further reduce the risk (or increase the margin to theminimum values of limiting health risk).

3. Although most of the alternatives prevent further contamination to surfacewater/sediment, none considers mitigation of the current contamination in these media.No RAOs have been established for fish consumption.

Response: Neither surface water nor river sediment was identified as a medium of concernfor the Feasibility Study. RAOs to protect against further contamination of river \ /sediments or surface water by release of soil or groundwater contaminants fromthe ORS have been proposed in the Feasibility Study. ' .'

The risks associated with fish consumption reported in the HRA are based onbioconcentration modeling and not on actual measurements of contaminantconcentrations in fish flesh. Contaminants associated with the hypothetical riskare ubiquitous in the Ohio* River and its surrounding land areas, andcontamination of fish in the Dashields pool and downstream cannot be attributedexplicitly to the ORS.

4. Tables 7-1—7-3 (Reduction in Residual Risk Levels) are based on a non-scientific,arbitrary, qualitative assessment only. No quantitative explanation is given in the

1 document.

Response: Tables 7-1, 7-2, arid 7-3 of the Draft Feasibility Study used quantitative estimatesof risk related to specific scenarios, as reported in the EPA-prepared HRA, tocharacterize the order of magnitude of risk reduction associated with theimplementation of various alternatives. The basis for risk reduction estimates.was described in various Table footnotes and inthe text of Section 7.0 of thedocument. These tables have been eliminated from the final Feasibility Study.

H. Short-term Risk - -

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~\ Response to Comments( A i\ Draft Feasibility Study•*? Ohio River Site

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1. Short term risk from the air stripping process needs to be quantitated.

Response: Vapor-phase carbon adsorption ofvolatiles released during the air strippingprocess will be used to ensure that emissions from groundwater remediationsystems will meet all applicable requirements. The system will be evaluated anddesigned to meet these requirements during the Remedial Design phase of theproject.

2. Air monitoring methods for construction need to be defined.

Response: Details of construction air monitoring will be defined during the Remedial Designphase.

ffl. Hydrogeological Concerns

1. The use of only 5 wells in the capture zone appears to be inadequate. See hydrogeolbgistfor further input.

Response: A nominal system design using 5 extraction wells has been proposed for the ORSgroundwater remediation system on the basis of preliminary evaluationsperformed with the ENSR groundwater system model described in the Rl.Specie configurations and parameters for the groundwater extraction systemwill be developed during remedial design.

2. It is not clear if the RI modeling indicates that contaminants from ORS will not bereached by the nearby Coraopolis Well #2 for several centuries, (see page 3-5)

Response: The ENSR groundwater system modeling described in Section 9 of the RIindicates that essentially no groundwater flows from the ORS to the capture zoneof the Coraopolis well field. The 500 gpm estimate used in the HRA for flow toCoraopolis well. #2 is the value of the mass balance computation closure errorand represents onfy a possible maximum value for such flow. It is not a definitiveindication that such flow does occur. ••

3. RAOs for ground water protection are based on ground water modeling that takes intoconsideration dilution effects in surface water. RAOs for ground water need to berisk-based, not based on model prediction. Hydrogeological input is recommended.

Response: RAOs for eroundwater are risk-based. RAOs for protection azainst risk fromdirect on-site use are based on MCLs and risk-based concentrations. RAOs for

. protection against off-site uses of contaminated surface water or groundwater are

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also based on MCLs and/or risk-based values. See Section 3.4 of the FeasibilityStudy.

IV. Contaminants of Concern (COCs)

1. Downstream surface water quality,/ particularly the levels of gamma-chlordane, are notsimilar to upstream surface water quality. The levels of gamma-chlordane in surfacewater downstream are greater than the levels upstream. In addition, several metals (Sb,As, Be, Cr, Co, Mn and Hg) were detected in surface water that are of concern, (seepage

Response: The RI (page 6-5) indicates that Sb, As, Be, and Co were not detected in surfacewater surrounding the ORS. Chromium was detected at levels well below both itsMCL and its risk-based concentration. Onfy one instance of a positive gamma-chlordane result (for the 11 samples collected) was noted. Manganese wasdetected at normal river background levels. Mercury was detected in two samplesbut both were at tess than the minimum detection limit for the analysis methodused. .

2. PCBs and Dioxins were detected at low levels in surface soil, (see page 1-6).

Response: The HRA indicates that the risks associated with exposures to these contaminantsin surface soil are well below the limiting action values.

V. Technical Comments

1. Physical soil vapor extraction processes are not likely to remove PAHs and metals. Airstripping is not likely to remove metals in the process waste stream (see pages 5-3 and

' 7-13).

Response: Metals will generally not be removed by soil vapor extraction. PAHconcentrations can be reduced by biological activity stimulated by subsurfaceairflow. Air stripping does not remove metals (alternatives using ex-situgroundwater remediation will also utilize a precipitation unit to remove highlevels of metals from groundwater).

2. Note capping will reduce infiltration of contaminants into ground water but will notreduce the current ground water concentrations.

Response: Capping of waste trench areas may reduce the source term for recontamination ofORS groundwater. Physical degradation and biological activity in the water-

Response to CommentsDraft Feasibility StudyOhio River ShePage9 • • ' . . . . ' •

-. „ • . .. . . . .bearing zone can further reduce the concentration ofgroundwater contaminantswithout groundwater extraction. See Appendix D of the Feasiblity Study.

3. Too much emphasis is placed on institutional control and capping. Even alternatives thatconsider pump and treat appear inadequate since pump and treat will be terminated after10 years (not the usual 30 year /period). The erosion control cap appears to be inadequatefor areas where waste will be left in place. It seems a RCRA cap is more appropriate.Either excavation or solidification/stabilization or any other physical process should beconsidered for stabilization of the waste in the trenches, especially if pump/treat will beterminated after 10 years. Note the figures in Appendix D indicate that contamination

, concentrations of benzene are much lower when an impervious cap (e.g., RCRA Cap) isused than when an erosion control cap is used.

Response: Groundwater RAOs based on protection against off-site exposures can beachieved by use of an erosion cap over •waste trenches coupled with a high-capacity groundwater extraction system within approximately 10 to 15 years afterinitiation of system operations. If the waste materials are still active sources ofgroundwater contamination then average concentrations of COCs may indeedincrease again after termination ofgroundwater extracti on system operation. Ifthe waste materials are piot active sources then no rebound of 'groundwater COCconcentrations will occur. An impermeable cap will eliminate Jvrther release of

'. '•' waste materials COCs to groundwater even if the -waste is still an active source.

Institutional control "will eliminate the potential for direct on-site exposures to. groundwater, which comprise the largest portion of 'overall risk by far as reported

intheHRA. All remedial alternatives proposed will include enforceablegroundwater use restrictions to eliminate direct exposure risks from groundwater.

Source Document; Internal EPA Memo of April 27.1995 (B. Pasquini to R. Roman)

General Comment

It appears that risk analysis and remedial action objectives were developed to only addresspotential human health risks and totally disregards the potential risks to the ecological systemassociated with the site. The remedial action objectives need, to be developed keeping in mind theecological receptors.

" • . • , . " ' '

Response: Ecological risk was considered in the development of remedial action objectivesfortheORS.

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Response to CommentsDraft Feasibility StudyOhio River SitePage 10

Section 3.2.3.1, Groundwater Discharge - Ohio River

This report only evaluates the potential discharge of contaminated ground water to the Ohio Riverand the Coraopolis Well #2 and totally disregards even in a qualitative fashion the likely scenarioof ground water contaminants impacting Ohio River sediment. Impact to this media andRemedial Action Objectives should be developed in this report.

Response: The possibility thai'groundwater discharge*imoy contaminate riverbed sedimentshas been considered (see Section 3.5 of the Feasibility Study). Currently, there islittle evidence to support the conclusion that Site groundwater discharges are asource of contaminants detected in sediment samples taken from the river nearthe Site. Furthermore, the level of ecological risk associated with the observedsediment contamination is evaluated in the ERA to be law to moderately low.However, groundwater remediation as proposed for many of the remedialalternatives described in the Feasibility Study -will reduce the concentrations ofgroundwater COCs substantially, causing an equivalent reduction in themagnitude of any ecological risk attributable to sediment contamination.

First paragraph, third sentence: This sentence as written implies that the Remedial: ActionObjective will not be protective since it is suggested that ground water discharge after mixingwith the river water will meet or exceed ambient water quality criteria. Please have Dames andMoore correct the narrative.

Response: The statement has been corrected.\ " •

I do not agree with this Mass-balance approach and have the following concerns with 3-3 through3-5: ' • _ .' ' ' •• • . ' ' .' - ' . ' ' • • ; . .

1) The first assumption that levels of contaminants will-remain constant may notnecessarily be representative of the site and may not be conservative. Since thesources are present at the site (trenches and highly contaminated ground water),

. the natural physical/chemical properties (dispersion, degradation, adsorption) maynot have a large effect on the contaminant fate and transport where ground watercontamination is the highest (above and approaching of a contaminant's solubilityin water).

Response: One of the uncertainties associated 'with the site contaminant transient modelingdescribed in Appendix D of the Feasibility Study is whether the waste materials inthe trenches are still active sources of groundwater contamination. It has been

. . conservatively assumed that they are still active Appendix D describes the

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assumptions used to estimate the effect of 'implementing groundwater remediationand capping remedies on the concentrations of key groundwater COCs.

2) Given the uncertainties associated with modeling, it is inanpropriate to estimateground water clean-up levels using this mass-balance approach. Tm not aware ofthis technique being employed to develop clean-up standards for the contaminatedground water at any other Region IE Superfund Sites.

3) The flow rates cited from the Ohio River Valley Water Sanitary Commission(ORANSCO) were most likely developed by that Commission for limitingdischarge of contaminants and aiding hi estimating maximum discharge limits forprograms such as the National Pollutant Discharge Elimination System (NPDES).Consequently, use of these flow rates would be inappropriate in estimatingclean-up levels.

Response: ACL-based RAOsfor off-site exposures to surface 'water groundwatercontaminated by groundwater discharges have been developed applying the mass-balance approach described in Section 3.4.2 of the Feasibility Study at otherCERCLA Sites and approved by the EPA. MCLs or risk-based limits at the pointof possible closure (i.e., in surface water downstream of the site) have been usedas the basis for RAO development. Precedents exist for the use of mean harmonicflow and 7Q10 flow to develop RAOs to protect against off-site exposures tocontaminated groundwater.

Source Document; Internal EPA Memo of April 21. 1995 (R. Davis to R. Roman)

The Draft FS has been given a preliminary review and the following comments areoffered to you prior to formal BTAG review.

From my cursory review, I do not believe that any of the alternatives will fully protectecological receptors. But, from the generic viewpoint, our objectives would be met bycontrolling the main pathway of contamination from the site to the river, where it islikely that the greatest impacts will be felt More specifically, the bottom sediments are of

; most concern, as the contamination found there both impacts benthic organisms andrepresents a continuing secondary source to the river's ecosystem over the long term.

The impervious RCRA cap covering the main hot spots of contamination would serve asa method for controlling percolation of precipitation into the under ground repositories.This alternative coupled with pump and treat to control the site-to-river contaminant

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pathway would likely satisfy concerns regarding continuing potential for risk to aquaticreceptors in the river.

Capping should be concentrated on the trench area as well as any other hot spotsidentified on site through the remedial investigation and remedial design processes. Itwould be desirable to precisely define the boundaries of the contamination hot spotsoutside the-main trench area (if any exist)during the remedial design phase.

Response: Remedied alternatives proposed 'for the ORS include erosion and sedimentationcontrol systems, site monitoring programs designed to detect whether areas ofespecially high contaminant concentration are present outside the waste trenches,pumping and treatment of groundwdter to significantly reduce the concentrationof contaminants in groundwater discharging to the river, and the capping ofwaste trench areas and other areas with elevated concentrations of soilcontaminants.

Source Document: Tntemal EPA Memo of Mav 4.1995 fD. Donor to R. Romairt

Generally the RCRA Program does not review a CERCLA project until the Feasibility Study,when the discussion of remedial alternatives and possible selection of an alternative wouldindicate potential RCRA regulatory applicability. For this site I had attended a meeting with thePRPs and their consultants on December 14,1994. At that tirae I had only conducted a cursoryreview of the information available in this Remedial investigation (RI) for this she. Even at thatpoint it appeared clear that many of the waste constituents at this site will be subject to RCRA,dependent on how managed in die eventual selected remedy. I informed the attendees at theDecember 14,1994 meeting that special attention should be directed toward the recently listedRCRA "Coke By-Product Production Wastes" (EPA Waste Codes K141-145, and 147 and 148)as well as the existing Listed K087 waste and the Land Disposal Restriction (LDR) treatmentstandards applicable to those wastes. •

The current review conducted on this RI, confirms that a majority of the constituents will have tomeet the LDR treatment standards if regenerated or "placed" as part of the selected remedy. Thetables 1-1 to 1-8 indicate that both groundwater and soil appear to have constituents levels thatwill exceed the LDR treatment standards. The position of the retroactive application of RCRAlistings has been consistently upheld by the Courts, so the issue that these materials were disposedprior to RCRA will not impact the application of RCRA requirements. Additionally it appearsthat some soil levels of 2,4-D and 2,4,5 TP (Silvex) will exceed the RCRA TCLP level for the )D016 and D017 Toxicity Characteristic (TC) Pesticide wastes. These wastes are also subject to >LDR treatment standards if regenerated or placed. ^ J

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ThereforeAthe LDRs must be carefully considered in the remedy selection process. All the LDRsstandards for these wastes are in the September 19, 1994 Federal Register (FR) (59 FR 47982). 1believe a cppy was provided at the December 1994 meeting, however if additional copies areneeded they will be provided. ' •

Having said the above, it is also importantto note that there are many regulatory mechanisms thatwill relieve the application of LDRs to these wastes. Without going into detail, such mechanismsas the application of the EPA "contained-in" policy, the use of the "Corrective ActionManagement Unit" (CAMU) regulations, the use of allowable consolidation of wastes under theNCP's "Area of Contamination11 (AOC), LDR treatability variances, and the exit from RCRAforwastewaters treated in Clean Water Act (CWA) permitted tank based wastewater treatment units(WWTU) all may potentially be considered dependent on the remedy. Dependent on thealternatives selected for either, or both the soils and groundwater, these various mechanismsshould be evaluated. One important note is that although, for example, groundwater that istreated in a WWTU would exit RCRA regulations, any sludges generated and eventually removedfrom the WWTU tanks would be subject to RCRA. The WWTU could not have any land basedsurface impoundment as part of the unit, as this would also subject the wastes to RCRA. Also itis possible that by June of 1 996, EPA may issue LDR rules that would affect treatment in aWWTU, Since these will be proposed in August 1 995, it is difficult to predict what the eventualrules will require or if they will impact CWA WWTU at all.

In summary it will be very important for the Feasibility Study to address the potential applicabilityof RCRA. If there are issues the PRPs or their contractor are unsure of regarding RCRA, I wouldsuggest they work through the RPM to obtain RCRA Program input where necessary.

Response: The applicability of RCRA and especially any disposal restriction (LDR) concernsmil be considered and addressed in detail during remedial design. .

Source Document: Commonwealth of Pennsylvania Department of EnvironmentalResources Letter of May' 11.1995 f A. Paluh. Pa PER to R. Roman. EPA1

1. Erosion Control Cover

The "erosion control cap" proposed and discussed in Sections 6 and 7 and depicted onFigure 6-2 does not meet the Pa. Code Title 25, Chapter 264. Ill (2),(3) ClosureRequirements and Chapter 264.302(a)(6) Cap Requirements, referenced as part of theTable 2-5 "Potential Action - Specific Applicable or Relevant and AppropriateRequirements" (ARARs). The Department considers the proposed "erosion control cap"to consist of intermediate and final cover, which should not be characterized or presentedas a cap. To rectify this misrepresentation, all references to the "erosion control cap"

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should be corrected to "erosion control cover." In accordance with 1264.302(a)(6) andChapter 264 Appendix E, Table 3, a cap is required which is capable of preventing theinfiltration of liquid into closed portions of the landfill that meets the <1 .0 x 10"*permeability requirements. For example, the low permeability containment cap shown onFigure 6-1 of the FS would potentially meet the above cap requirements.

/ • • • , . • '

Response: The erosion control cap proposed for covering the -waste trench areas -would beengineered to provide a specific degree of refaction in infiltration by use ofsloping and Contouring, in addition to providing the requisite thickness of cover ,materials and a vegetative top cover. Refer to Section 6.2. 3 in the FeasibilityStudy for a discussion of the proposed design for this type of cap. Alternatives4C and 6 propose the use of an impermeable cap design that meets the .performance requirements of the Pennsylvania code sections cited.

2. Groundwater

A. According to the May 1994 Remedial Investigation Report (RI) prepared byENSR on behalf of NLC, during the RI, ENSR developed a two-dimensional "groundwater flow model using Flow Path. The model was developed in part toestimate the potential impact to the Coraopolis public water supply wells locateddownstream of the site. It is reported that these wells provide an average yield of1,370,000 gpd. The RI reports that groundwater modeling results indicate thatcontaminants from the Ohio River site are not anticipated to impact theCoraopolis water supply wells. The results of the ENSR flow model are highlyidealized and should not be relied upon to project groundwater discharge rates orto define the fate and transport of contaminants in the groundwater. The ENSRmodel is lacking information on calibration, boundary conditions and site specificinput parameters. ENSR developed the model as a "screening tool". Given thecharacteristics of this site and the uncertainty associated with generalizedtwo-dimensional flow modeling, and if modeling were deemed necessary, theDepartment recommends developing a three-dimensional flow model together witha contaminant transport model Both models should be developed from sitespecific data and calibrated to actual site conditions.

The area of influence created by the Coraopolis well field may be enhancing theflow of contaminated groundwater from the ORS towards the Coraopolis publicwater supply well field. To monitor this area of influence, the Coraopolis publicwater supply wells should be included in the groundwater monitoring program.

Response: Additional flaw and transport mo&liRffiiiy iL$rptyedaspartofpre-design ; jactivities or during the remedial design. A monitoring-well has been installed as

A.AAJTACHMT.ONI

Response to Comments ' : -^ •>-Draft Feasibility StudyOhio River Site : ' . ' - . 'Page'15 ; .. , • •.:••', ':. . . - ,

partof the Allegheny County Wellhead Protection project between the Coraopolismunicipal-well field and the ORS on the southern bank of the river justdownstream of the Site.

B. Data necessary to design and locate groundwater pumping wells capable ofeffectively and efficiently removing the identified groundwater plume have notbeen presented in either the RI or FS. The FS does identify additional data needsin Section 9 of this report, including predesign characterization to identify optimallocations for pumping wells. Long-term pumping tests which have not beenconducted at the site are fundamental in defining radius of influence, optimalpumping rate(s), and hydraulic properties necessary for design of an effectivegroundwater pumping system. Additionally, other data needs are listed in Section9 which the Department agrees will provide necessary data.

Response: The groundwater extraction system designs proposed in the Feasibility Study arenominal configurations selected on the basis of preliminary scoping analysesusing the ENSR groundwater model and have been used to estimate potentialperformance and cost of the remedial alternatives in which they have been .included. Additional testing and data collection will be required during theremedial design to provide information needed to develop a final design for such

. • systems.

- , C. In order to design a groundwater pump and treat system, pumping tests should beconducted for the water table aquifer. At least one long-term pumping test should

, be conducted until steady state or near steady state conditions are achieved.Additional pumping tests may be necessary depending upon variability instratigraphy across the impacted aquifer. Pumping tests should define values for

- hydraulic conductivity, transmissivity, specific yield, and radius of influence. Ingeneral, pumping test procedures should be consistent with ASTM D 4050. Datagenerated from the pumping tests should be used to design a groundwaterpumping system capable of capturing the contaminant plume.

Response: Additional testingrequiredto'design and implement the selectedremedyfor thesite is described in Section 9.0 of the Feasibility Study.

: ' • . ' » ' - ' ' ' ' . " ' ' • !

D. As defined in the FS, Alternative 5 proposes an erosion control cap over the waste: trench areas. The erosion control cap incorporates 6" of top soil over 12" of selectr" fill to be constructed over the waste trench areas. This measure will only isolate

- the trench areas from exposure and will not act as an impermeable barrier to\ ' - \ J • .' surface water infiltration. \Wthout some form of impermeable liner over the

trenches or complete source removal, the contamination in the trenches and the

AR302895

Response to CommentsDraft Feasibility StudyOhio River SitePage 16 .

unsaturated zone will continue to leach into the groundwater. The FS states thatcurrent loading from the trenches to the subsurface occurs at 2.1 kg/day. Thisongoing impact will compromise the effectiveness of the groundwater pumpingsystem.

Response: The actual water-bearing zone contaminant source loading rate from surfacewater infiltration through the trenches is unknown The waste materials may nownot be active sources of further contamination, and additional 'groundwatersampling is required to determine their status as sources. If they remain activesources for 'groundwater contamination, an impermeable barrier wouldessentially eliminate future, transport of contaminants to the water-bearing zone.See Appendix D in tta Feasibility Study for a discussion of the conceptual site.model, assumed source loading rates, and other factors that affect estimates ofthe effectiveness of groundwater remediation and capping of waste trenches inreducing groundwater contaminant concentrations.

E. To assist in development of an adequate groundwater pump and treat system, ..-•-contedata.contaminant mass loading to the Ohio River should be estimated from site specific . .- ;

Response: Current information on contaminant concentrations and distributions within theOI& water-bearing zone and their variation with time is required to producemeaningful estimates of mass loading to the river.

F. Section 3.2.3 - Page 3-2: It appears that it is proposed to use the Ohio River(following mixing/dilution of contaminated ORS groundwater with the river) asthe point of compliance, rather than the actual groundwater discharge or

~ groundwater monitoring wells. This section proposes that a contaminatedgroundwater remedial action objective (RAO)"... should, therefore provide forgroundwater discharge to the Ohio River that meets or exceeds ambient waterquality criteria after mixing with the river water...", which would violate thePennsylvania Clean Streams Law (an ARAR in Table 2-1 of the FS) as adischarge of contamination to Waters of the Commonwealth. Also, Pa. Code 25Chapter 264.111(2) (on Tables 2-5 and 2-1 of the ARARS) requires that closuresand post-closures control, minimize or eliminate threats to human health and the .environment, including post-closure escape of hazardous waste, hazardous waste /constituents, leachate, contaminated runoff or waste decomposition products togroundwater or surface water. Potential threats to human health and theenvironment from ORS contaminated groundwater should be controlled, /minimized or, eliminated in accordance with §264.111(2). Contaminated . ; }'groundwater should be addressed on-site before it mixes with the Ohio River.

AAATTACHMT.ONH

AR302896

Response to Comments . ; ; ;Draft Feasibility Study :Ohio River SitePage 17 /

Groundwater monitoring wells should be utilized for compliance points, while theOhio River should be monitored as part of the surface water monitoring program.

Response: The proposed point of"compliance for monitoring the attainment ofgroundwater• RAOs based on protection of off-site receptors is within the ORS water-bearing

zone. Attainment of this RAO (or the more restrictive groundwater RAO based onMCLs and risk-based levels) would result in groundwater discharges to the riverthat would not cause detectable increases in the concentrations of 'groundwater

. contaminants, as discussed in Section 3.5 of the Feasibility Study.

G. The FS groundwater remediation proposals in the RAOs propose 10 to 15 years ofgroundwater pumping and treating. Regardless of the timeframe for groundwaterremediation, groundwater monitoring should be conducted for a mininmim of 30years in accordance with 25 Pa. Code §264,117(a), listed as an ARAR on Tables2-1 and 2-5, since the waste will remain on-site. In addition, the Coraopolis publicwater supply wells should be included in the groundwater monitoring program.

i J Response: Monitoring programs proposed for each of the alternatives will be continued '^ throughout the entire 30-year nominal period of performance.

H. The FS does not propose levels at which groundwater pumping and treatmentwould be considered acceptable or be terminated. While MCLs (MaximumContaminant Limits) may be useful levels for constituents of concern withestablished MCLS, such as benzene, how will constituents such as phenols (i.e.,2,4,6-trichlorophenol) that do not have an MCL be evaluated?

Response: Both sets of groundwater RAOs proposed define concentrations for groundwatercontaminants at which active remediation operations can be terminated. Pointsof compliance for measurement of these concentrations are also defined. Themost limiting of either the carcinogenic or non-carcinogenic risk-basedconcentration has been used to define RAOs for those contaminants for which anMCL has not been published.

I. With regard to evaluating groundwater remediation, since much of the ORSconsists of various waste areas, the utilization of wells in an "Area of Attainment"(i.e., an area between the source and a clean area) may prove difficult. However,the utilization of wells surrounding the ORS perimeter does seem feasible for

• ., j , • "point of compliance" evaluation of groundwater remediation and groundwatermonitoring compliance.

AAATTACHMT.ONE

ftR302897

Response to Comments , ;-*Draft Feasibility StudyOhio River Site ^Page 13

Response: Points of compliance are defined for both sets of groundwater RAOs. Perimeterwells can be used for monitoring either RAO.

3. Figure 6-3 and Section 6.2.3. Page 6-8. Paragraph 4

Figure 6-3 and Paragraph 4 of Page 6-8 propose the use of 10 foot wide grass drainageswales constructed along the perimeter of the site near the mainland back channelshoreline. The proposed 10 foot wide drainage swales may possibly be wider channelwidths than necessary. How was the 10 foot swale width estimated? In accordance withPa.Code 25, Chapter 264.301(8) and (9) (aa ARAR on Table 2-5), surface water run-onand runoff management proposals should be supported by calculations. The calculationsfor proposed erosion and sedimentation controls such as drainage swaies should beprovided:

Response: The detailed design of the erosion and sedimentation control systems for the ORSwill be performed during the remedial design and supporting calculations will be ^prepared at that time.

- • • • • • •"'• • ' ••''. . ' • ' . - ' • • ' • V . ^4. Section 7.2.2.3. Page 7-12

. • ' ' • " • • >

. This section states, "Federal and State Drinking Water Standards will be met byprohibiting public water use on-site." This statement potentially could be misunderstoodto allude to restriction of a public water source on site, when the probable intent of thestatement is to prohibit the use of ORS contaminated groundwater by the public. Theintent of the above sentence should be clarified so that it is not misinterpreted.

• ' -• ••' ~ i .Response: This change has been made in the final version of the Feasibility Study.

5. Ecological Risk Assessment

The Ecological Risk Assessment (ERA) for the Ohio River Site, dated July 1994,prepared by ENSR Consulting and Engineering on behalf of WLC indicates that ORSsurface soil poses a low potential ecological risk to terrestrial receptors, while main OhioRiver channel sediments pose a low ecological risk and Ohio River back channel sedimentspose a low to moderate ecological risk. The FS does not appear to address the identified .ecological risks in any of the proposed remedial action objectives. The sedimentecological risks should be addressed in the FS remedial action objectives and be includedin the ORS monitoring program. In addition, the ORS monitoring program should alsoinclude Ohio River surface water monitoring for sediment data correlation. \

MATTACHMT.OXJ AR302898

Response to CommentsDraft Feasibility StudyOhio River SitePage 19

Response: Ecological risks have been considered in developing RAOs for the ORS. Seeespecially Sections 3.2.2 and 3.5 of the Feasibility Study. The proposed sitemonitoring program includes surface water monitoring.

' . . - ' " . ' - • i

6. Future ORS Land Use

Many of the discussed remedial alternatives mention controls on the future use of ORSland and groundwater (i.e., deed restrictions). Specifically, the deed description should beamended to reflect the nature of contamination remaining on-site, and prohibit activitiesthat would disturb contamination or interfere with completed/ongoing remediation. In theevent that the ORS property is sold, it should be made clear as to which party isresponsible for completed/ongoing remediation, monitoring and maintenance.

~ _ . " - • . . ' . ' . . ' \ •

Has the intended final use of the ORS been considered? Will the ORS be made availablefor recreational use as long as the integrity of the remediation is not compromised? Tobetter evaluate the FS remedial alternatives, possible future land use should be taken intoconsideration.

With regard to future use of the ORS, it should be noted that there are areas of subsidencein the trench areas and in existing parking lots placed over trenches. The RI identified 54waste disposal trenches. However, only three waste material samples were analyzed fromthe trench area. Chemical analysis of three waste samples from 54 disposal trenches does ,not provide enough data to characterize the nature, volume, and physical properties ofcontaminants in order to estimate continued settlement. If NLC intends a future use otherthan recreational, the continued settlement of wastes in the trenches should be considered.The integrity of the ORS remediation (i.e., cap, monitoring wells, etc.) should bemaintained. If a future land use of ORS proposes to build structures of any nature overwaste areas, the stability and continued settlement of wastes should be addressed.

Response: Future uses of the ORS hove been considered in the development of proposedremedial alternatives. Design and construction of cops, wells, remediationsystems, and other elements of the selected remedy will be integrated withproposed development plans to assure long-term .stability and the maintenance ofthe required performance ofeach component ofthe remedy.

7. Abandoned Oil Well '

Since scrubber wastes and trenches 29 and 9 are located in close proximity to theabandoned oil well (based on FS Figures 1-4 and 1-3), it may be prudent to includeplugging of this well during or prior to implementing remedial alternatives. The wellshould be plugged in accordance with Sections 210 and 211 of the Oil and Gas Act, PA

' moiTO. AR302899

Response to Comments . /*~*Draft Feasibility StudyOhio River Site " . . , ' ' . ; -——Page20 - •... ' '• .' '••'.-.- ' ' V • , .- . . '• •' '' '.

Act 223, and §578.73 and 78.91 of 25 Pa. Code Title 25, Chapter 78, listed as Table 2-3ARARs i n t h e F S . . • ' • ' - /

Response; Neville Land Company previously applied to the Pa DER Bureau of Oil and Gas• Management for orphan well status under Act 78 (1992) for the abandoned oilwell on the Site. The application is now under review. When state action on the .application is completed, the well will be scheduled for abandonment.Abandonment has not been included as an element of the remedial alternativesdescribed in the Feasibility Study.

8., Remedial Alternatives

The Department has reviewed the FS remedial alternatives with reference to feasibility,implementabiHty and ARARS. The Department recommends that Alternative 5 whichincludes institutional controls; land and groundwater use restrictions; erosion controlcover and erosion and sedimentation controls; with groundwater pumping and treatmentbe modified. The modification should address Soil Vapor Extraction (SVE), air sparging,and capping the trench areas. By using SVE and air sparging, the sources ofcontamination in the subsurface could be reduced, assisting hi groundwater pumping andtreatment As the greatest risk seems to be associated with the trenches and groundwater,an impermeable cap should be proposed for the contaminated 15 acre trench area inaccordance with 25 Pa. Code 6264.302(a)(6) and Appendix E. Table 3 of 25 Pa. Code .Chapter 264 (an ARAR on Table 2-5) to address prevention of infiltration of precipitationthrough the contaminated trenches, potentially decrease groundwater recharge, and meetthe <1.0 x 10*7 permeability requirement for landfill caps. The designed cap shouldconsist of two feet of final soil cover, single-sided drainage composite (Le. non-wovengeotextile bonded to HOPE geonet), 50 mil geomembrane, 6 to 3 oz/sy nbn wovengeotextile and 1 foot of select fill Refer to Chapter 264, Appendix E, Table 3 for furtherinformation. To prevent direct contact with the remaining 17 acres of contaminated soil,erosion cover that would meet 25 Pa. Code 1264.310(i),(4),(S) and Pa. Code Title 25,Chapter 102 Erosion Control Regulation (Table.2-5 ARARs) requirements should beaddressed.

Response: A new remedial alternative using an impermeable cap design engineered toprovide equivalent'performance to that specified for the Pa DER impermeablecap has been proposed (Alternative 4C). This type of cap has also beenincorporated into the proposed design for Alternative 6.

• ,

AR302900

Response to CommentsDraft Feasibility StudyOhio River Site .Page 21 . . • , " ,'

Source Document: Internal EPA Memo of May 17. 1995 flB. Pasquini to R. Roman)

General Comments

The projected pumping rates of 200 gpm and 100 gpm should be identified as preliminaryproposed pumping rates that are used as a'basis in the Feasibility Study to estimate costs. Theactual pumping rates could change during the Remedial Design or Remedial Action (RD/RA).Also, it was unclear how these preliminary extraction rates were estimated and it appears thatthe lower extraction rate was arbitrarily chosen based on use of a RCRA-type cap. Please haveDames & Moore clarify and address the preceding in the report narrative.

Response: The 100/200 gpm capacities for the groimdwater extraction system were selectedas representative pumping rates primarily for performance and cost estimatingpurposes. The final selection of system configurations and parameters forgroundwater remediation "Will be performed during remedial design if the selectedalternative includes this element.

. . ' - • j . ' . . . ' ' •

Section 3.3.1, Residential andCommercial/Industria! Groundwater Consumers .

Page 3-8, first full paragraph: This narrative indicates that the existing ground waterremediation technologies would most likely not be able to return the contaminated aquifer todrinking water quality and suggests that institutional controls be implemented to prevent the useof the aquifer for drinking water instead of restoring the aquifer. This is in direct opposition toEPA policy as outlined in the code of federal regulations 40, Part 300, Section 300.420: .

(D) ... "The use of institutional controls shall not substitute for active responsemeasures (e.g., treatment and/or contaminant of source material, restoration of groundwaters to their beneficial uses) as the sole remedy unless such active measures aredetermined not to be practicable, based on the balancing of trade-offs among alternativesthat is conducted during the selection of remedy. " and;

(F) "EPA expects to return usable ground waters to their beneficial uses wherever -practicable, within a time-frame that is reasonable given the particular circumstances ofthe site. When restoration of ground water to beneficial uses is not practicable, EPAexpects to prevent further migration of the plume, prevent exposure to the contaminatedground water, and evaluate further risk reduction."

At this time, we do not have the data which support that it is not practicable to restore the groundwaters to their beneficial uses. Also, there is no data which supports that active responsemeasures are determined not to be practicable. Consequently, the clean-up standards for a pumpand treat system at this site should be to restore to beneficial use. EPA therefore, does not agree

AR30290IAAATTACHWT.ONE

Response to Comments x*«*Draft Feasibility Study >Ohio River Site '"'-Page22(

with the Dames & Moore recommended development of preliminary clean-up standards in 3.2 tobe protective of off-site receptors. Please have Dames & Moore revise the report to reflect EP Aregulations.

• \ - ' ' . • * . "

Response: All remedial alternatives proposed include the imposition of enforceable 'groundwater use restrictions, which effectively eliminate any risk of 'direct on-siteuse of groundwater without the need to attain MCL-based levels in groundwaterand-which are consistent with the planned future development of the Site. Off-siteexposure scenarios are the remaining source of 'groundwater-relatedhealth risk,as described in the EPA Health Risk Assessment, The RAOs proposed in Section3.4.2 of the Feasibility Study are based on maintainingMCLs or risk-based levelsat the point of consumption, (either downstream surface water or off-sitegroundwater). A second set of RAOs based on attainment of MCLs or risk-basedlevels for groundwater contaminants has been included in the final version of theFeasibility Study at EPA's direction. • . • t. '

Section 5.6.3.2, Injection Wells k \. - • ' - . . ' , . - ' ' " • - ' ' '"*•**'

It would be prudent not to eliminate injection wells as a partial disposal method. Injection wellsmay be used in combination with disposal of treated ground water to the surface water. At leastthe potential benefits of injecting a portion of the treated ground water should be evaluated withinthe report narrative.

• • ' ; • " ' " • . ' /

Response: Injection-wells have not been considered in the Feasibility Study.

Section 6.2.3, Alternative 3

Page 6-9, first full paragraph and Appendix D: Some of the assumptions (especially assumption2) and the order (it appears to be a first order decay model) of the decay modeling may be toosimplistic to represent site conditions. Consequently, the narrative should indicate that theconclusions reached may not represent the site conditions.

, ' - • • ' , ' t - • ' * . ' • '

Section 6.2.6, Alternative 6 •

Page 6-18, paragraphs 3 and 4: See my comment above on alternative 3 and my comment onappendix D. Also, the last paragraph of this page discusses the potential for contaminantrebound effects when the extraction system is shut-off. All alternatives which evaluate groundwater extraction should list pump and treat technologies or strategies commonly employed (e.g.,pulsed pumping) to enhance contaminant recovery. .

• • ' . ' - . . ' • " . ' " • • ' . ' • • • • • ' , • ' -* -AppendfcD AR3Q2902

r

Response to CommentsDraft Feasibility StudyOhio River Site 'Page 13

Among other things, the mathematical modeling used to evaluate the effects of the differentremedial technologies which could be used at the she may not represent the potential condition ofthe source of contamination within the aquifer itself. Given the concentrations of contaminants inground water, there is a possibility that a contaminant source is within the aquifer. This wouldsignificantly impact the representiveness of the results of this analysis to the site. Also, theassumptions inherent to these mathematical'equations should be outlined and compared to the siteconceptual model. Please have Dames & Moore indicate this in the report.

Response: Appendix D has been modified to address the comments above.

AR302903A.AA.TTACBMT.ONS

Attachment 2 to • ;Neville Land Company Letter of June 30..1995 \ /

RESPONSE TO U.S. EPA COMMENTS ONAPPLICABILITY OF ACLS FOR GROUNDWATER RAO DEVELOPMENTOfflO RIVER SITE, NEVILLE TOWNSHIP, PENNSYLVANIA

1.0 Background ,

In the Draft Feasibility Study (FS) For the Ohio River Site (ORS), Neville LandCompany (NLC) proposed the application of alternate concentration limits (ACLs) as the basisfor development of remedial action objectives (RAOs) fpr groundwater. Following review of theDraft FS, EPA issued formal comments to NLC directing the use of MCLs and other risk-basedconcentration limits as the basis for development of ground-water RAOs for the ORS. As a resultof further discussions relating to this subject on May 13,199S, EPA agreed to give furtherconsideration to NLC's proposal to apply ACLs for ground-water RAO development, andrequested that NLC submit a paper supporting the request for use of ACLs. After reviewing thisdocument (D&M letter of May 31, 1995) EPA issued a formal letter of response (R. Roman to H.Vaughan Blaxter, NLC; June 13,1995) that summarized the statutory, regulatory, and policyissues pertaining to the use of ACLs as CERCLA project RAOs, and concluded that ACLs shouldnot be used as a ground-water cleanup standard for ORS because:

o the three criteria for the application of ACLs as cleanup standards (provided in Section > J121 (d) (2) (B) (ii) of CERCLA) could not be demonstrated with sufficient confidence due ^to uncertainties in the present site groundwater dataset, and .

o even if available data were sufficient to remove EPA's uncertainty regarding theattainment of the three CERCLA criteria, Agency policy mandated the application of morerestrictive, deterministic standards (i.e., MCLs and/or other risk-based concentrationlimits) unless it could be shown that cleanup of the ORS groundwater to these standardswas impracticable.

NLC requested furtter discussion on the subject of the applicability of ACLs as agroundwater cleanup standard, with the intent of obtaining a better understanding of the technicalconstraints to a finding that ACLs were applicable to the Site. Two more meetings on this subjectwere held between EPA and NLC, on June 19 and June 22, 1995.

During the June 19 meeting, EPA acknowledged that NLC could include an ACL-based groundwater RAO in the final submittal of the FS as long as the EPA-required MCL-basedRAO was also included. It was also established that the principal constraints to a finding underCERCLA that ACLs could be used as a groundwater protection standard for ORS was thepresent uncertainty regarding the possibility of transport of groundwater beneath the back channelto the capture zone of the Coraopolis well field, and the locations of groundwater discharge fromthe site to the Ohio River. EPA's position is that the existing ORS dataset is insufficient tosupport a positive conclusion that groundwater does not flow beneath the back channel to the \ _J

AR3'Q290l»

Response to U. S. EPA Comments on ,Applicability of ACLs for Groundwater RAO Development ' .Ohio River Site, Neville Township, Pennsylvania

• .Page2 '-. • • ,\ v .'• ' . ' . • • .• ~ ' - " • '- ' • . ' -

' ' . • " ' - ' r ' .

capture zone of the Coraopolis municipal well field, nor is the data sufficient to conclude thatthere has been no statistically significant deterioration of surface water and river sediment qualityas a result of the discharge of contaminated groundwater from ORS to the river. Hence, EPA hastaken the conservative position that at least two of the three qualifying criteria cited in CERCLAhave not been met and thus that ACLs cannot be used as the basis for a groundwater protectionstandard for ORS '

In the June 22 meeting, NLC proposed two different approaches to addressing thedata uncertainty issue. The first approach was a suggestion that the submittai of the FS bedelayed for approximately 2-3 months to allow for the collection of data and for completion ofgroundwater system modeling necessary to reach a firm conclusion on both points describedabove. The conclusion would indicate which type of RAO basis (either ACL or MCL) would beapplicable and most appropriate for the site. A second approach proposed was the separation ofwaste and soil media from groundwater (i.e., to define two new operable units at ORS).Remedial actions and cleanup objectives applicable to the waste/soil unit would be described inthe FS and would be submitted as scheduled. Actions necessary to eliminate EPA's presentdegree of uncertainty concerning satisfaction of the ACL-qualifying criteria for groundwaterwould be pursued in parallel with the implementation of remedial action for waste and soil at

, ORS. Data to resolve the uncertainties relating to the selection of the most appropriategroundwater cleanup standards, once obtained, would be used to generate a proposed set ofgroundwater remedies for EPA review. At the meeting, EPA indicated that a delay in submittai ofthe FS was undesirable, as would be the creation of two distinct operable units for soil and wasteand groundwater, respectively. EPA identified a third approach that might also be considered: the

. definition of remedial alternatives and groundwater cleanup criteria in the FS and ROD in a: ' manner that would assure the attainment of a specific risk-based standard of protectiveness;.. without pre-specification.of any particular approach or set of deterministic groundwater cleanup '

. . criteria. ;' • .- , - ' ' ' ' • ' . ' - ; ' ' - . . ' ; • ' - " . ' . ' • ' • ' .

At the close of the June 22 meeting EPA committed to consider NLC's proposalsfurther and granted a one-week extension of the FS submittai date, to July 1, 1995. On June 26EPA advised NLC that no further action regarding the choice of groundwater protection standard

. would be forthcoming, and that the FS should be submitted as currently scheduled.• ~ f •' ' , * " . • • " - l

2.0 NLG Comments on Development of Groundwater Protection Standard for ORS' ' - . . . . ' • ' • • • . • '

. • • " * ' • ' • ' ' . . " ' • . •

NLC appreciates EPA's efforts to clarify the technical and regulatory issuesassociated with the selection of the most appropriate groundwater cleanup standards for ORS.NLC also acknowledges that EPA has given serious consideration to the proposal to use ACLs as

I j the basis for ORS groundwater protection standards, but at present is constrained both by policy

AR302905

Response to U. S. EPA Comments on v *Applicability of ACLs for Groundwater RAO Development -'\ _JOhio River Site, Neville Township, PennsylvaniaPage'3 . • ' . . -.• ' '

and by the need to take a conservative view of the attainment of the three CERCLA criteria thatmust be met before ACLs can be used as the basis for cleanup standards. The evaluation of theORS with respect to how well it satisfies these criteria is complex. In the EPA's view, such anevaluation may require data not currently available within the site groundwater dataset. However,NLC believes that EPA's concerns regarding the present insufficiency of data with which to makea determination should alone not preclude Consideration of ACL-based RAOs for groundwater,especially since ACL-based groundwater protection standards are more directly risk-based andare clearly applicable in light of the site-specific cleanup standards allowed by State law(Pennsylvania Senate Bill SB-1,1995).

In NLC's view, EPA's selected remedy for ORS should recognize the relationshipbetween expenditure and risk reduction achieved. The cost penalties that NLC will incur byapplying an MCL-based groundwater protection standard, rather than a risk-based standard, maybe significant and will certainly.not be commensurate with the marginal reductions in riskattainable. Almost all of the groundwater-related risk at ORS is associated with direct, on-siteuse of groundwater. the possibility of future direct on-site exposure will be eliminated byimposition of enforceable groundwater use restrictions. Thus, an MCL-based groundwater RAO >provides only marginal benefits in overall risk reduction compared to the proposed ACL-based V—sRAO when explicit consideration is given to the future planned uses of the Site.

EPA has made clear to NLC that uncertainties associated with these two issuesmust be resolved before EPA can conclude that the qualifying criteria for use of ACL-basedgroundwater protection standards have been met for ORS. These issues are the effect ofgroundwater discharges on the quality of the surrounding surface water, and the potential .connection between the deep water-bearing zone of the Site and the nearby Coraopolis municipal •well field. Both issues appear amenable to early resolution with limited additional study, testing,and data collection at the Site. The perceived uncertainties could be addressed and potentiallyeliminated by implementation of a program to obtain the necessary data and to perform theevaluations required to resolve the uncertainties. Such activities could be implemented prior tothe initiation of the remedial design process or could proceed in parallel with the remedial designof other elements of the remedy selected for the site. Elimination of key uncertainties wouldallow for the development of an appropriate risk-based groundwater remediation standard for the'Site. - .;•.••• . . ' . . ' • . ' ' ,;

3.0 Site-Specific Groundwater Remediation Standard Development

For the ORS, NLC believes that EPA's selected remedy should incorporate agroundwater protection standard based on a conservative, but site specific evaluation of futurerisks associated with any residual contamination that remains at the site upon completion of the ,

AR3029Q6

Response to U. S. EPA Comments onI j. Applicability of ACLs for Groundwater RAO Development

Ohio River Site, Neville Township, PennsylvaniaPage 4 . - _ ' - ' . ' ' , • ' . : ' . ' " . • ' . ' : . . - . '

remediation. The imposition of a standard based upon overly conservative deterministic criteriadoes not encourage the efficient and effective use of resources; neither is h called for byenvironmental conditions at and near the site.

For a remedial alternative that included active groundwater remediation, forexample, such a performance-based standard could be defined in general terms as follows:

. • Groundwater at the site will be remediated through a program of pumping andtreatment to a standard that will not limit the beneficial use of surface water orwater in aquifers beyond the site boundary, Numerical standards will beestablished so that risks to potential receptors are maintained at or below thethreshold value of 10"*, and monitoring at appropriate points of compliance shall beconducted for the required period of time. The pumping and treatment system willbe designed to achieve the established groundwater remediation standardthroughout the aquifer beneath the site.

• Additional testing, data collection, and evaluation to be performed as part of thepre-design activities will expediently resolve uncertainties with the mechanisms forgroundwater discharge to surface water, and the potential for transport ofgroundwater under the back channel towards the Coraopolis well field.

In conclusion, NLC believes that such a definition of the proposed remedy is fullyprotective of human health and the environment, and that it preserves the opportunity for thedesign of the most resource-efficient permanent remedy for the ORS.

ftR302907