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GEI Consultants, Inc. TECHNICAL COMMENTS ON FEASIBILITY STUDY AND PROPOSED PLAN FOR MIDDLE MARSH SULLIVAN'S LEDGE SITE SECOND OPERABLE UNIT Submitted to: United States Environmental Protection Agency Attention: Jane Downing, RPM Region I J.F. Kennedy Federal Building Boston, Massachusetts 02003 On behalf of: Acushnet Company Amtel, Inc. and United Dominion Industries AVX Corporation Berkshire Hathaway, Inc. Bridgestone/Firestone, Inc. Chamberlain Manufacturing Corporation Commonwealth Electric Company and Commonwealth Gas Company Emhart Industries, Inc. The Goodyear Tire and Rubber Company Paramount Communications, Inc. and Universal American Corporation Teledyne Rodney Metals Prepared by: GEI Consultants, Inc. 53 Regional Drive Concord, New Hampshire 03301 AUGUSTS, 1991

GEI Consultants, Inc. · 2020. 11. 12. · Concord, New Hampshire 03301 AUGUSTS, 1991. EXECUTIVE SUMMARY These Comments address the Supplemental Remedial Investigation (SRI), Feasibility

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  • GEI Consultants, Inc.TECHNICAL COMMENTS

    ON

    FEASIBILITY STUDY AND PROPOSED PLAN FOR MIDDLE MARSH

    SULLIVAN'S LEDGE SITE SECOND OPERABLE UNIT

    Submitted to:

    United States Environmental Protection AgencyAttention: Jane Downing, RPM

    Region IJ.F. Kennedy Federal BuildingBoston, Massachusetts 02003

    On behalf of:

    Acushnet CompanyAmtel, Inc. and United Dominion Industries

    AVX CorporationBerkshire Hathaway, Inc.

    Bridgestone/Firestone, Inc.Chamberlain Manufacturing Corporation

    Commonwealth Electric Company and Commonwealth Gas CompanyEmhart Industries, Inc.

    The Goodyear Tire and Rubber CompanyParamount Communications, Inc. and Universal American Corporation

    Teledyne Rodney Metals

    Prepared by:

    GEI Consultants, Inc.53 Regional Drive

    Concord, New Hampshire 03301

    AUGUSTS, 1991

  • EXECUTIVE SUMMARY

    These Comments address the Supplemental Remedial Investigation (SRI), Feasibility Study (FS)and Proposed Cleanup Plan (Plan) for the Middle Marsh Study Area (Middle Marsh OperableUnit) at the Sullivan's Ledge Superfund Site. The SRI, FS and Plan were issued in April 1991,May 1991 and May 1991, respectively, by the US Environmental Protection Agency (EPA). Thebasic conclusions expressed in these Comments are that the proposed remedy was notappropriately selected, that the proposed remedy will cause more harm to the Marsh than isjustifiable, and that EPA should return to its original "no action" decision. Specific technicalanalyses demonstrate flaws in the supporting data, assumptions and studies.

    The Comments consist of seven volumes. The first volume contains the Technical Commentsand associated tables, figures and calculations. Appendix B consists of two volumes andcontains all references cited in the Technical Comments and the resumes of all technicalpersonnel who contributed to the development of the Technical Comments or whose work isrelied upon. Appendix C consists of four volumes and contains the associated documentationand references that support the analysis in the Technical Comments.

    In the SRI and FS, EPA itself has determined that the Marsh poses no significant risk to humanhealth. EPA has also determined that no contaminants, other than PCBs, pose unacceptablerisks to the environment in the Marsh. In 1989, EPA concluded that remedial action was notrequired at the Middle Marsh. Nothing in the SRI or FS justifies a departure from EPA's previous"no action" determination.

    EPA rests its change in position solely on the contention that the "preferred alternative" isnecessary to reduce the risk to wildlife (specifically mink) from exposure to PCBs in the Marsh.This reasoning is flawed. The concentrations of PCBs have decreased significantly since EPAfirst determined that no action should be taken in the Marsh. The purported risk to wildlife inreality is nothing more than one chance in 10,000 that one female mink could sustainreproductive impairment. In fact, it is unlikely that even one mink lives in the Marsh. None havebeen observed. The proposal to spend as much as $8 million, or more, to prevent a non-existent risk is irrational.

    There are also a number of serious technical problems with the data reported and methodologiesapplied in the SRI and the FS. Those include the improper use of the sediment quality criterion,a failure to investigate other sources of contamination of the Marsh, problems with computermodeling, and discrepancies in analytical data.

    While the technical basis for the SRI and FS is flawed and the benefits of the preferred alternativeare negligible, the dangers to the Marsh and its wildlife from implementation of the preferredalternative are substantial. There is a strong likelihood that the proposed remedy could not beperformed without irreversible harm to the Marsh, including destruction of the habitat of thespotted turtle, a species of special concern in Massachusetts. The preferred remedy alsocontains unnecessary components, and the FS is unrealistic about both the implementationschedule and the expected results of the remedial work.

    EPA's original 'no action" decision remains the appropriate alternative by which to preserve theenvironment of the Middle Marsh.

  • TABLE OF CONTENTS

    TABLE OF CONTENTSEXECUTIVE SUMMARYTABLESFIGURESAPPENDIX A

    PageNo.

    I. THERE IS NO UNACCEPTABLE RISK TO HUMAN HEALTH DUE TOEXPOSURE TO CONTAMINANTS IN MIDDLE MARSH 1

    A. EPA's May 1991 Proposed Plan correctly concluded that there are nosignificant excess risks to humans at Middle Marsh 1

    B. The risk assessment used in calculating human exposure to PCBs isbased upon several unrealistic assumptions• Maximum exposure estimates are inappropriate and are inconsistent

    with Superfund guidance 1• The health risk assessment inappropriately relies on PCB data from

    both the 1989 and 1991 Remedial Investigations for Middle Marsh,and therefore, overestimates the maximum risks 2

    • Use of arithmetic averages of sampling data for several substancesare unreliable; these averages likely do not reflect actual conditions 2

    • Exposure frequencies for contaminants in the Middle Marsh areoverestimated, and future land-use assumptions are inconsistent withthe ecological risk assessment 3

    • The assumed levels of exposure to contaminated soils and surfacewaters overestimate realistic human exposures 4

    C. The human health risk assessment for PAHs in the SRI is based onunrealistic and inaccurate factors 4

    SUMMARY 5

    II. THERE IS NO UNACCEPTABLE RISK TO THE ENVIRONMENT FROM PCBOR OTHER CONTAMINATION IN MIDDLE MARSH 6

    A. The concentrations of PCBs measured in Middle Marsh are not highand have significantly decreased since the measurements reported inthe 1989 Remedial Investigation report for Sullivan's Ledge site 6

    B. Not all elevated concentrations of contaminants appear to be originatingfrom the Sullivan's Ledge site 8

    C. EPA's withdrawal of the original "no action" remedy appears to havebeen based on an erroneous comment, the contents of which were noteven addressed in the SRI 8• The Carr memo incorrectly infers that statistical probabilities relating

    to the Sediment Quality Criterion (SQC) correspond to probabilitiesof harm to benthic organisms 9

    • The SQC for PCBs is designed to protect mink, not benthicorganisms 9

    D. The SRI and FS studies for Middle Marsh assume that the PCBconcentrations pose an unacceptable risk to female mink in theMarsh. However, there is no evidence that any mink, female ormale, inhabit the Marsh 10

  • TABLE OF CONTENTS(Continued)

    PageNo.

    E. Ranges and territorial habits of the mink would indicate that, at most,only one mink would feed in the Marsh 10

    F. The habitat ranges for mink and other animals which EPA considers tobe potentially present are applied inappropriately and inconsistentlyacross the Marsh in the computation of the ecological risk. Therefore,the exposure predictions are excessive and biased 11

    G. The mink's average dietary concentration of PCBs, if obtained solelyfrom food sources in Middle Marsh, will be lower than the dietaryconcentration used in the derivation of the sediment qualitycriterion 12

    H. The food chain presented in the SRI risk assessment is based upon theerroneous presumption that mink eat contaminated trout in the Marsh.The SRI does not provide any evidence of trout (and any other fish)being present in Middle Marsh 13

    I. The SQC methodology is applicable only if contaminated sediments aresubmerged for sufficient periods of time to establish an equilibriumbetween the sediments and the overlying water column. This conditionis not true for most of Middle Marsh where there is NO truly aquaticenvironment 14

    J. The sediment quality criteria methodology, a highly controversial andcomplex method for evaluating risk, produces extremely unpredictableand inaccurate results 16

    K. The SQC methodology improperly assumes that aquatic organismssuch as trout will be exposed to pore water concentrations ofcontaminants 17

    L The SRI correctly concludes that volatile and semi-volatile organics,heavy metals, and pesticides in the Middle Marsh sediments, porewaters, and surface waters pose no threat to the environment 18

    SUMMARY 19

    THE FEASIBILITY STUDY CONTAINS UNREALISTIC ASSUMPTIONSABOUT THE LIKELIHOOD OF SUCCESS OF THE PREFERRED REMEDY,INCLUDES UNNECESSARY STEPS IN THE PREFERRED REMEDY, ANDDEMONSTRATES NO REASONABLE JUSTIFICATION FOR THECONTINGENCY REMEDIAL ALTERNATIVE 20

    A. The remedial schedule proposed in the FS is unrealistic. Remediationof the Marsh will be seriously jeopardized by the remediation of theUnnamed Stream (during the remedial action for the First OperableUnit) if the actions are not performed simultaneously 20

    B. There is no reasonable justification for EPA's proposed contingencyalternative 20

    C. Backfilling the disturbed wetlands, as required in the preferred remedy,is not absolutely necessary and requires destruction of wetlandselsewhere in order to obtain the most suitable materials 21

  • TABLE OF CONTENTS(Continued)

    PageNo.

    D. There is no justifiable reason to manage the cleared vegetation as ahazardous waste 22

    E. Production rates and treatment technologies stated in the FS areunrealistic and likely unattainable 22

    SUMMARY 23

    IV. THE PREFERRED ALTERNATIVE WILL SIGNIFICANTLY HARM THEWETLAN DS, WITHOUT ANY ASSURANCE THAT TH E WETLANDS CAN BEADEQUATELY RESTORED 24

    A. The proposed plan would require excavation of more wetland acreagethan necessary, even accepting the SQC in the SRI 24• Areas 2, 3 and 4 24• Area 1 24

    B. The proposed plan will disturb and/or destroy the wildlife it is supposedto protect 25

    C. The proposed plan poses a substantial and unreasonable danger ofdestroying the habitat of the spotted turtle, a species of special concernin Massachusetts 26

    D. The proposed wetlands restoration plan is inadequate and notconsistent with existing wetland species 26

    SUMMARY 27

    V. THE FEASIBILITY STUDY, BASED UPON QUESTIONABLE DATA ANDMODELING STUDIES, FAILED TO ADEQUATELY INVESTIGATE ALLPOTENTIALLY APPROPRIATE REMEDIAL ALTERNATIVES, AND FAILED TOINCLUDE SIGNIFICANT FACTORS IN EVALUATING THE PREFERRED ANDCONTINGENCY ALTERNATIVES 28

    A. The data which is relied upon in the FS regarding PCB concentrationsin surface water and pore water samples contain severaldiscrepancies 28

    B. The TOC Analytical Method produces inconsistent, unreliable resultswhich are not reproducible to even an order of magnitude in thelaboratory 29

    C. The basic assumptions of the hydrologic computer models are notincluded in the SRI or available for review, either by EPA or the public.The limited information on the hydrologic computer modeling which isavailable indicates that the models may not have been calibratedcorrectly 29

    D. The Feasibility Study for Middle Marsh did not adequately evaluatepotentially appropriate remedial alternatives for Middle Marsh and failedto address critical aspects of the preferred and contingencyremedies 30

    SUMMARY 32

  • TABLE OF CONTENTS(Continued)

    PageNo.

    REFERENCES

    TABLES

    FIGURES

    APPENDIX A - Area Averages of PCB Concentrations

    APPENDIX B - Volume I of IIAPPENDIX B - Volume II of II

    APPENDIX C - Volume I of IVAPPENDIX C - Volume II of IVAPPENDIX C - Volume III of IVAPPENDIX C - Volume IV of IV

  • UST OF TABLES

    TABLE 1 - Carcinogenic Potencies of Various PAHs Relative to that ofBenzo(A)pyrene

    TABLE 2 - Comparison of Estimated Excess Carcinogenic Risks in the SRIwith Estimates of Adjusted Values That Incorporate RelativePotency Factors for PAHs

    TABLE 3 - Comparison of 1988 and 1990 PCB ConcentrationsTABLE 4 - Summary of Sediment/Soil Criteria Developed Within the SRITABLE 5 - Comparison of 1988 and 1990 PCB ConcentrationsTABLE 6 - Estimate of the Average Concentration of PCBs in the Mink's

    Diet Assuming All of Its Food is Obtained in Middle Marsh

    LIST OF FIGURES

    FIGURE 1 - Analysis of Equilibrium Partitioning

  • August 5, 1991Page 1

    MAJOR TECHNICAL ISSUES

    I. THERE IS NO UNACCEPTABLE RISK TO HUMAN HEALTH DUE TOEXPOSURE TO CONTAMINANTS IN MIDDLE MARSH

    A. EPA's May 1991 Proposed Plan correctly concluded that there are nosignificant excess risks to humans at Middle Marsh

    The Summary of Study Risks in the May 1991 Proposed Plan states, "EPA hasdetermined that, based upon the exposure assumptions, human exposure to sitecontaminants through the current and future pathways... would not result insignificant increases in carcinogenic risk". The Proposed Plan goes on to say,"EPA has further determined that there are no significant risks to public healthposed by exposure to noncarcinogenic contaminants in Middle Marsh and theadjacent wetland area." EPA properly concluded that Middle Marsh posesinsignificant excess risks to human health. Indeed, application of reasonableand realistic risk assessment assumptions (as discussed elsewhere in theseComments) re-affirms that risks at the site to human health are negligible.

    B. The risk assessment used In calculating human exposure to PCBs isbased upon several unrealistic assumptions

    A number of assumptions embodied in the health risk assessment appear to beunrealistic given the nature of the Marsh. Despite all these unrealisticassumptions, the estimated human health risks are still within an acceptablerange. This underscores that the no action alternative is fully protective ofhuman health at the Marsh. Specific examples of the unrealistic assumptionsare discussed below.

    • Maximum exposure estimates are inappropriate and areinconsistent with Superfund guidance

    The risk assessment in the SRI calculates both average and maximum exposurescenarios. These are distinguished by the manner in which exposure pointconcentrations are estimated. Average exposures utilize arithmetic averageconcentrations, an approach which implicitly assumes that (1) eachmeasurement is weighted equally and (2) people will randomly contact soils andsurface water throughout the contaminated area (either Middle Marsh or the golfcourse/wetland). EPA, in its use of the maximum exposure approach, utilizesthe maximum detected concentration for each pollutant. This assumptionignores the exposure averaging effect which in fact results when people movearound through areas of varying degrees of contamination.

  • Augusts, 1991Page 2

    There are three problems with the maximum exposure approach. Rrst, itincorrectly assumes that the individual is exposed to the highest pollutantconcentrations for the duration of the exposure period, a highly improbablescenario. Individuals do not, in fact, remain stationary, and thus would beexposed to varying levels of contamination, and to no contamination, during anexposure period. More importantly, the maximum concentrations of allpollutants were not detected at the same sample locations. Since the maximumexposure scenario assumes constant contact with the highest concentration ofeach pollutant, the individual must also be assumed to be exposedsimultaneously at numerous locations; which is, of course, physically impossible.

    The second problem with using the highest detected concentrations for theexposure point concentrations in the maximum exposure case is that thisapproach is inconsistent with Superfund guidance. Volume I of EPA's RiskAssessment Guidance for Superfund (EPA, 1989a) specifies the use of the 95thpercentile upper confidence limit of the arithmetic mean (UCL). Concerning thetwo cases in the SRI data for which computation of the UCL is performed, theUCL is lower than the maximum detected concentration. If, as the 1989Guidance provides, UCLs had been used as the basis for exposureconcentrations in estimating the reasonable maximum exposure, the overallestimates of risk would have been substantially lower.

    Finally, it is unreasonable to assume that humans will be in contaminated areasof Middle Marsh during the entire maximum or average exposure period. Theseapproaches do not consider that a person's actual movements would generallybe limited to non-contaminated areas such as most of the golf tees and fairways.

    The health risk assessment inappropriately relies on PCB data fromboth the 1989 and 1991 Remedial Investigations for Middle Marsh andtherefore overestimates the maximum risks

    Unlike the ecological risk assessment, which uses only data collected in the1991 SRI, the health risk assessment also includes the PCB data collected inMiddle Marsh during the 1989 Rl of the Sullivan's Ledge site. Since PCBs weredetected at higher concentrations in the 1989 study, the maximum exposureapproach, using both sets of data, are seriously overstated.

    Use of arithmetic averages of sampling data for several substancesare unreliable; these averages likely do not reflect actual conditions

    The summary statistics of Tables 5-2 and 5-3 of the SRI indicate that, incalculating the arithmetic averages of several substances, EPA excluded asignificant proportion of the samples, because the detection limits of nondetectswere too high relative to the maximum detected concentration. This was donefor polycyclic aromatic hydrocarbons such as acenaphthylene, for which 23 of24 potential samples were excluded from the average (following Guidance in USEPA, 1989a). (This problem apparently results from interferences in the

  • Augusts, 1991Page3

    laboratory analyses). There are at least two important deficiencies in thisapproach.

    Rrst, this approach demonstrates that there is considerable uncertaintyregarding the actual concentrations of polycyclic aromatic hydrocarbons andother compounds that are difficult to distinguish in the laboratory. Page 5-13 ofthe SRI describes difficulties in distinguishing benzo(b)fluoranthene andbenzo(k)fluoranthene; it is likely that similar difficulties were encountered inidentifying other compounds. If this is the case, then the data uncertaintiesshould have been evaluated and excluded from the risk assessment if theunderlying analytical data were suspect. EPA, however, does not appear to haveundertaken such a review.

    Second, by reason of the systematic exclusion of low concentration data, thereis an automatic bias toward indications of higher than actual averageconcentrations. This adds still another layer of bias to the analyses.

    Exposure frequencies for contaminants in the Middle Marsh areoverestimated, and future land-use assumptions are inconsistent withthe ecological risk assessment

    Current land-use scenarios 0"ables 5-9, 5-12, and 5-14 in the SRI) assume thatexposures to contaminants in Middle Marsh occur 28 days per year. The futureland-use assumptions arbitrarily double this estimate to 56 days per year. Thesefrequencies are highly unrealistic.

    Middle Marsh is a thickly vegetated area with limited access; there is noevidence of pathways transecting the Marsh upon which humans might walk.The muddy character of the Marsh is likely to dissuade potential hikers, andnature enthusiasts are likely to find nearby Apponagansett Swamp moreinteresting. The presence of golfers will inhibit trespassers during the daytimehours, and the absence of light will discourage the presence of people duringthe nighttime. Realistically, the presence of people (particularly the samepeople) likely would be limited to, at most, a very few occasions of limitedduration per year.

    The assumed frequency of exposure under the future land-use scenario in theMiddle Marsh is double that of the current land-use scenario, to account for thepossibility that Middle Marsh may be dry. However, State and Federal lawsrelative to the protection of wetlands and City zoning land use ordinances wouldgenerally prohibit the erection of any structures in the Marsh. This premise,however, is fundamentally inconsistent with the ecological risk assessment,which assumes the continued presence of a wetland.

  • August 5, 1991Page 4

    • The assumed levels of exposure to contaminated soils and surfacewaters overestimate realistic human exposures

    SOIL: The risk assessment assumes a soil ingestion rate of 100 mg per day foradults. This rate is considerably greater than the values typically found in theliterature. A review contained in EPA's Exposure Factors Handbook (EPA,1989c) lists adult ingestion estimates of 50 mg/day and 61 mg/day. In thathandbook, values are derived for categories of adults who could be expected toingest significant amounts of soil; consequently, even those ingestion ratesreflect higher-than-average consumption rates for adults. Further, any humanswho may be present in Middle Marsh would not engage in activities expected toresult in significant soil ingestion. Thus, the ingestion rate of 100 mg/dayassumed in the risk assessment is much greater than would be reasonablyexpected and adds yet another layer of excessive bias to the assessment.

    SURFACE WATER: The risk assessment's surface water exposure factorassumes that individuals would be exposed to the waters of the Middle Marshcontinuously for 8 hours in each of the hypothetical 28 exposure events per year.Further, it assumes direct body contact (e.g., submersion of an arm) for theentire period. To satisfy these assumptions, all golfers would have to beretrieving golf balls all day, instead of playing golf. This is ridiculous since nogolfer would put more than an occasional hand or arm into the water (or mud)for only a moment to recover a golf ball. Given the inaccessibility of the Marsh,its limited recreational value, and the unlikelihood that golfers would be exposedover more than a small part of their body for more than a moment, this exposureassumption adds yet another layer of bias to an unrealistic assessment.

    C. The human health risk assessment for PAHs in the SRI is based onunrealistic and inaccurate factors.

    The SRI adopts a carcinogenic potency of 11.5 (mg/kg-d)"1 for numerouspolycyclic aromatic hydrocarbons (PAHs). This value is derived specifically forbenzo(a)pyrene, but is applied to other PAHs for which the SRI apparentlyassumes potency estimates to be unavailable. Cancer potency factors appliedin the SRI do not reflect the current available data and yield a higher excesscarcinogenic risk than is accurate.

    ICF-Clement Associates (1987), under contract to EPA, has estimated thecarcinogenic potencies of several pertinent PAHs relative to the potency ofbenzo(a)pyrene. These relative potencies are listed in Table 1. The relativepotencies are generally much less than one for all chemicals exceptdibenz(a,h)anthracene.

    If these relative potencies had been applied in the SRI, the excess carcinogenicrisks estimated in Chapter 5 of the SRI would decline. Table 2 compares theestimated risks in the SRI with calculations using the cited relative potencies.Refining only this one detail - i.e., assigning each PAH its specific potency -

  • August 5, 1991Page 5

    reduces the estimated excess cancer risks by at least 20% for the maximum riskestimate for the current Middle Marsh scenarios, and by at least 60% for theaverage risk estimate for the future Middle Marsh scenario.

    These recomputed lower risks to human health once again demonstrate thatunacceptable risks to human health simply do not exist at the Middle Marsh andare a further indication that no remedial action should be implemented in theMiddle Marsh.

    SUMMARY EPA has concluded correctly that there are no unacceptable risks to humanhealth due to exposures to contamination in Middle Marsh. EPA has made this findingdespite the fact that the human health risk assessments are based upon unrealisticexposure scenarios and assumptions, and out-of-date cancer potencies. If the health riskassessment had been done correctly with realistic assumptions, it would havedemonstrated even more decisively that no unacceptable risks to human health are posedby the Middle Marsh.

  • August 5, 1991Page 6

    II. THERE IS NO UNACCEPTABLE RISK TO THE ENVIRONMENT FROM PCB OROTHER CONTAMINATION IN MIDDLE MARSH

    A. The concentrations of PCBs measured in Middle Marsh are not highand have significantly decreased since the measurements reportedin the 1989 Remedial Investigation report for Sullivan's Ledge site

    In 1989, EPA initially decided that no remedial action was appropriate for MiddleMarsh. The Proposed Plan for the Sullivan's Ledge site released by EPA inJanuary 1989, specifically explains why EPA selected the "no action" alternativefor Middle Marsh: "After assessing the advantages and disadvantages of theremediation options for Middle Marsh, EPA has determined that the benefits tobe obtained by excavating sediments would be exceeded by the adverseenvironmental impacts. Therefore, EPA is proposing no action (Option A) forMiddle Marsh." (See Page 21). This determination was based on the fact thatany remedial action would destroy habitat and potentially resuspend andredistribute contaminants throughout the marsh, resulting in adverseenvironmental impacts that would outweigh any benefit of remedial action.

    The decrease in the concentrations of PCBs in the sediments (discussedhereafter) which has occurred since EPA's initial "no action" decision, providesfurther justification for EPA's no action decision. EPA, however, has unjustifiablychanged its mind and decided that an intrusive remedial action should beimplemented, even though PCB concentrations have decreased considerably inthe Middle Marsh. EPA's reversal of its initial no-action decision is inconsistentwith the observed decrease in PCB concentrations.

    In 1989, the highest concentration of PCBs detected in the sediments was 60mg/kg. In the SRI, the highest concentration was reported to be 28 mg/kg. Atthe sampling station where PCBs were originally detected at 60 mg/kg, theconcentrations were reported in the SRI to have decreased to 20 mg/kg.Similarly, at stations where the PCB concentrations were reported to be 28 and10 mg/kg in the 1989 study, the concentrations were reported in the SRI to havedecreased to 12 and 2.2 mg/kg, respectively.

    Table 2-9 of the SRI describes the locations of stations sampled during the 1988Remedial Investigation for the Sullivan's Ledge site as compared with samplingstations reported in the SRI. Stations labeled with an ME were sampled byMetcalf and Eddy in 1990 as part of the SRI and stations labeled with MM weresampled by Ebasco in 1988. According to Table 2-9 in the SRI, there are sevensampling stations which are located near each other and can be considered"paired": ME-1 and MM-5; ME-11 and MM-20; ME-12 and MM-10; ME-15 andMM-12; ME-16 and MM-15; ME-17 and MM-12; and ME-27 and MM-25.

    The PCB concentrations in samples taken from these pairs of sampling stationsare presented in Table 3. As shown in Table 3, the concentrations of PCBs insix of the seven sampling stations have decreased an average of 54% during

  • August 5, 1991Page?

    the last three years. Only one station pair showed a slight (4%) increase inRGBs. This marginal difference between the measured values at MM-12 andME-17 is within the acceptable criteria of duplicate analysis and analyticallyrepresents essentially the same PCB concentrations (USEPA Data ReviewWorkgroup, 1988). Thus, NO statistically significant increases in PCBcontamination were observed at the Middle Marsh site between 1988 and 1990.Instead, a significant decrease was observed.

    The reduction of observed PCB concentrations is especially significant when oneconsiders that the sampling program in the SRI was specifically designed todetermine the distribution of PCBs in what EPA defined as the "hot spots." Page2-62 of the SRI specifically identifies, as its objectives, "defining the partitioningof contaminants among media and vertical distribution in previously identified'hot spots'" and "determining the persistence and extent of previously identified'hot spots." The sampling plan, biased towards finding the highestconcentrations of PCBs, instead showed a substantial decrease. The biasednature of the sampling plan makes the observed PCB decrease even moresignificant.

    There are several physical, biological and chemical mechanisms occurring onthe site that work to degrade the PCBs originally deposited there. EPAacknowledges only transport as a possible reason for lower PCB values. In fact,there are many reasons. One mechanism of natural attenuation isbiodegradation, anaerobic and aerobic. Dissolution and volatilization are alsoprocesses that may have had, and may continue to have, a significant role indecreasing PCB levels. Research in the New Bedford Harbor, for instance,concluded that a substantial amount of PCB that entered the water columnsubsequently volatilized to the atmosphere. Models developed by Thibodeauxand ASA found that as much as 50 percent would volatilize from the watercolumn. The New Bedford Harbor Estuary and Lower Harbor/Bay FeasibilityStudy (Ebasco, 1990) concluded that: "Volatilization appears to be the mostsignificant process occurring .... Approximately 86 percent of the original 283 kgwhich migrates from the sediment into the overlying water column is removedfrom the system in the 95-day simulation through volatilization."

    Volatilization would also be expected to occur more readily in the shallow watersor periodically inundated areas within Middle Marsh. The presence ofbioturbation in the aquatic and wetland sediments would substantially enhancethe rate of volatilization over what would be predicted by simple diffusiveprocesses alone.

    In addition to ignoring the reductions in overall PCB levels seen at Middle Marsh,EPA failed to consider that bacterial degradation would cause preferentialdechlorination of the co-planar, and thus potentially more toxic, PCB congeners(MacFarland and Clarke, 1989). Reductive dechlorination - and resultingdetoxification -- is a concept well recognized by EPA, yet Region I failed toexamine whether this natural process is occurring in Middle Marsh and thereby

  • Augusts, 1991Pages

    substantially reducing the potential for toxic effects to endemic organics. Dr.Anna Yoakum (Yoakum, 1989 & 1990) has documented that dechlorination isoccurring in both New Bedford Harbor and Silver Lake samples. EPA (Lake etal., 1989) has corroborated the occurrence of anaerobic biodegradation in NewBedford Harbor samples. The failure of EPA to examine whether this naturalprocess is occurring in Middle Marsh is a fundamental flaw in EPA's ecologicalrisk assessment in the SRI.

    B. Not all elevated concentrations of contaminants appear to beoriginating from the Sullivan's Ledge site

    The SRI acknowledges on Page 3-5 that "...at some locations, low levels ofcontamination in the Sullivan's Ledge area may be due to influences other thanflooding such as atmospheric deposition or runoff from nearby highways".

    Nevertheless, the SRI assumes that all contamination in Middle Marsh originatesfrom the Sullivan's Ledge site through flooding of the Unnamed Stream. Thispremise is undermined by the fact that the locations of elevated concentrationsof contaminants are not always within the flooded areas predicted by the model.As an example, the PCB concentration in sample SL-51 was 10.0 mg/kg. Thatsample location is a golf tee which is above the area predicted to be inundatedby the 100-year flood. In addition, as indicated by Figures 3 and 4 in the SRI,the highest concentrations of lead were detected in the Middle Marsh atlocations approximately 250 to 300 feet to the east and west of the UnnamedStream. The topographic map included in the SRI indicates that these locationsare within drainage swales through which the Marsh receives runoff from areas(roadways) other than the Sullivan's Ledge Site.

    These observations suggest that there may be other sources of contaminationof the Middle Marsh besides the Unnamed Stream, such as airbornecontamination and road runoff. This assumption is supported by a studyperformed by Environmental Science and Engineering in 1978 entitled"Environmental Assessment of Polychlorinated Biphenyls (PCBs) Near NewBedford, Ma. Municipal Landfill" which describes measurements of PCBs in airto be in excess of 1.0 microgram/cubic meter in ambient air over the landfill.

    C. EPA's withdrawal of the original "no action" remedy appears to havebeen based on an erroneous comment, the contents of which werenot even addressed In the SRI

    The agency originally justified withdrawal of the no action alternative in part uponconcerns raised by Kenneth Carr, U.S. Fish and Wildlife Service (seeAdministrative Record, Memorandum from Kenneth Carr to Jane Downing, datedDecember 8,1988). Mr. Carr's memo raises questions about the protectivenessof a no action remedy to benthic organisms, stating that the no action

  • August 5, 1991Page 9

    determination "has a probability of 0.975 that it will result in long-term impactsto benthic fauna." The Carr memorandum fails to support the Agency's proposalto withdraw the no action remedy for the following reasons:

    The Carr memo incorrectly infers that statistical probabilities relatingto the Sediment Quality Criterion (SQC) correspond to probabilitiesof harm to benthic organisms

    The documentation of the SQC (EPA 1989d) lists three values for PCBs in freshwater: 19.5, 3.87, and 99.9 jig PCBs/g carbon. These criteria are based upondifferent values of the partition coefficient that relates pore water concentrationsto sediment concentrations. The value of the 19.6 ng PCB/g carbon is basedon the best estimate of the partition coefficient, while the values of 3.87 and 99.9jig PCB/g carbon are based on the lower and upper limits, respectively, of the95th percentile confidence interval of the partition coefficient. In actuality, the0.975, 0.5, and 0.025 probabilities cited by Carr reflect the likelihood that theSQC will underpredict or overpredict pore water concentrations. For example,the use of the mean value of the SQC (19.5 jig PCB/g carbon) implies that theSQC will underpredict pore water concentrations half of the time and overpredictpore water concentrations the other half of the time. These probabilities thus donot express a likelihood of harm to benthic organisms or, for that matter, to anyorganisms. Estimation of probabilities of harm would require a significantly moredetailed analysis that uses additional data on the variability of organismresponse to pore water concentrations. Thus, Carr's memo misinterprets themeaning of the probabilities that pertain to the SQC.

    The SQC for PCBs is designed to protect mink, not benthicorganisms

    The Carr memorandum discusses what Carr believes is the probability of harmto benthic organisms. The memo incorrectly assumes that the SQC for PCBswas designed to protect benthic organisms. The SQC for PCBs, however, isintended to protect mink, not benthic organisms. If protection of benthicorganisms were the goal, an entirely different criterion would have to bedeveloped that is based on toxicity data specific to benthos. The toxicity valueslisted in the Ambient Water Quality Criteria Document for PCBs (EPA, 1980)demonstrate that benthic organisms can tolerate PCB concentrationsconsiderably higher than the 0.014 jig/l value on which the mink-based SQC isbased. Consequently, an SQC designed to protect benthos would be lessstringent than the 19.5 jig PCB/g carbon criterion that is used in the SRI. As aresult, the Carr memorandum provides absolutely no justification for EPA'sreversal of the "no action" decision.

    In summary, EPA's withdrawal of the original "no action remedy appears to havebeen based on a total misinterpretation of the SQC for PCBs and the underlyinginformation on which it is based. EPA's reliance on the Carr memorandum asa basis to abandon the no action alternative in Middle Marsh cannot be justified.

  • August 5, 1991Page 10

    D. The SRI and FS studies tor Middle Marsh assume that the PCBconcentrations pose an unacceptable risk to female mink In theMarsh. However, there Is no evidence that any mink, female or male,inhabit the Marsh

    The SRI, page 2-53, acknowledges that the Middle Marsh is only "...moderatelysuited to semi-aquatic carnivores as represented by the mink (Mustela vison),"and that the developed area (that is, the golf course) would "...somewhat limitoptimal habitat (for the mink)..." During the SRI's field studies, no mink wereever observed in the Middle Marsh, and the SRI did not provide any evidenceof mink habitation. Nevertheless, EPA has designed a cleanup criterion basedentirely on protecting mink. EPA has failed to explain why it placed so muchemphasis on mink, when the presence of mink has not been established.

    E. Ranges and territorial habits of the mink would indicate that, at most,only one mink would feed In the Marsh

    Even if suitable habitat for mink were present at Middle Marsh, a mink is notlikely to inhabit the Marsh. Nowak and Paradiso (1983) demonstrate thatpopulation densities for mink range from one to eight individuals per square kmand that females generally have smaller home ranges (approximately 20 to 50acres for females versus up to 2000 acres for males). These ranges are also inagreement with data derived by the USDA (1987). Mink, by nature, areextremely territorial; this means that their territories seldom overlap. The extremeterritorial nature of mink suggests that, in such a small area as Middle Marsh, itis highly unlikely that more than one mink (if any) would be present.

    The SRI uses 20 acres as the typical residence range of a mink; yet, accordingto Nowak and Paradiso (1983), this is the lowest range and applies only tofemale mink; the ranges of male mink are much larger. Female mink require acontiguous habitat for nesting purposes, and the 13 acres of the Middle Marshare not sufficient. The 65% residence time assumed in the SRI applies only ifthe female mink is willing to cross the golf course to forage in theApponagansett Swamp. This is a very unlikely scenario, given the reportedshyness of the mink (Grzimek, 1972).

    In addition, according to Grzimek, mink have highly developed day vision. Thissuggests that mink are probably more active by day than is usually thought andnot entirely nocturnal. Thus, in light of their shyness, female mink are even lesslikely to inhabit the Marsh given the activity on the golf course during the daylighthours.

  • August 5, 1991Page 11

    In sum, Middle Marsh is not a likely habitat for mink because of its small size;its proximity to the active golf course; and, the availability of more suitablehabitat elsewhere (e.g.. Apponagansett Swamp which is much larger and lessaffected by development). More realistic, verified ecological assumptions woulddemonstrate that unacceptable risks to the environment do not exist in MiddleMarsh.

    F. The habitat ranges for mink and other animals which EPA considersto be potentially present are applied inappropriately andinconsistently across the Marsh in the computation of the ecologicalrisk. Therefore, the exposure predictions are excessive and biased

    Even if the Middle Marsh were a suitable habitat for mink, there is a serious errorin the method by which the cleanup criterion is applied in the SRI. The cleanupcriterion is based on an estimate of the PCB concentration in sediment that mayinduce toxicity in mink. However, the SRI errs in applying this criterion on apoint-by-point basis to determine potential exposure.

    Mink and other animals are likely to obtain their food supply from a variety ofpoints in a habitat. Consequently, a contaminant concentration averaged overthe entire feeding range (including uncontaminated areas) should be used toestimate exposure, rather than merely assuming a maximum concentration atall locations. The SRI erroneously assumes that the mink will only feed at the"hot spots" within their residence ranges. Mink, however, are opportunists,feeding wherever there is suitable food. Hence, mink food chain exposuresmust be averaged over the entire residence range, and not just related to hotspot areas of the greatest contamination.

    Another example of a failure adequately to consider habitat range is illustratedin the selection of the bioaccumulation factor (BAF) for earthworms, which serveas a food source for carnivorous birds. Pages 4-19 of the SRI list BAF valuesof 0.16 and 0.29 for the east and west banks of the Unnamed Stream. The SRIproceeds to select the more conservative value of 0.29 for use in the exposureassessment. However, because birds can be expected to obtain food from bothsides of the stream, an average value should have been used.

    This area-averaged approach should have been used by EPA in applying theterrestrial food chain criteria to the species listed in Table 4. Because the rangeof each of the predatory species were not considered in constructing realisticexposure scenarios within the Middle Marsh, the exposure predictions are notreliable.

  • August 5, 1991Page 12

    G. The mink's average dietary concentration of PCBs. If obtained solelyfrom food sources In Middle Marsh, will be lower than the dietaryconcentration used In the derivation of the sediment quality criterion

    An average dietary concentration of PCBs can be estimated for animals inMiddle Marsh using information on the animal's diet, bioaccumulation factorsmeasured in Middle Marsh, and the area-averaged concentrations as estimatedin Appendix A. The following illustrates how the dietary concentration of PCBscan be calculated for mink assuming it were present in the Marsh. Thecalculation assumes a realistic varied diet for the mink, taken from the entireMarsh area (i.e., averaged).

    The composition of the mink's diet, taken from Grzimek, is based upon thestomach content of North American mink. Bioaccumulation factors (BAFs)measured in Middle Marsh are taken from Table 4-4 of the SRI for the speciesfor which they are available. BAFs for animal species for which measured valuesare available are conservatively extrapolated from the BAFs for other species.For example, BAFs for rabbits, moles and the "other" category are assumed tobe 0.09, the highest value measured for a terrestrial animal (Deer mouse) inMiddle Marsh. The BAF for fish and crustaceans (0.038) is assumed to be theratio of the factors used to construct the sediment quality criteria, 0.64 ppmdivided by 19.5 jig PCB/g carbon. The plant BAF of 0.017 is obtained fromTravis and Arms (1988).

    Terrestrial and aquatic PCB concentrations are assumed to be 5.3 ppm and 31.9jig PCB/g carbon, respectively, which are the area-averaged PCB concentrationsestimated in Appendix A. The dietary contributions in the right-most column ofTable 5 are the product of the dietary fraction (normalized by 100%), the BAF,and the soil/sediment concentration. Summed together over all the foodsources, the total of 0.50 ppm represents an estimate of the dietary PCBconcentration that the mink would experience if it obtained aH of its food fromthe Marsh, an unlikely scenario. This value is smaller than the dietaryconcentration of 0.64 ppm that is used in the derivation of the SQC for PCBs.If one assumes, as the SRI suggests, that mink obtains only 65% of its foodfrom the Marsh, and that the remaining 35% is from non-contaminated sourcesof the habitat, then the average dietary concentration of the mink would be 0.50ppm times 0.65, or 0.33 ppm, which is about one-half of the SQC basis of 0.64ppm. In either case, a Middle Marsh diet would provide a mink with a muchlower "body burden" of PCBs than assumed by the EPA.

  • August 5, 1991Page 13

    H. The food chain presented In the SRI risk assessment Is based uponthe erroneous assumption that mink eat contaminated trout in theMarsh. The SRI does not provide any evidence of trout (and anyother fish) being present In Middle Marsh.

    The food chain route driving the exposure assessment assumes direct ingestionof contaminated fish by mink. The aquatic food criterion is applied for a floodedarea, designated as Area 1 in the SRI (which is predicted to be sporadic inMiddle Marsh) when mink can obtain fish from the aquatic habitat. Theterrestrial food criterion presumably applies year-round and is based oningestion of small mammals. Each of these criteria assume that, in a givenseason, the mink's diet consists only of a single type of food (all terrestrialmammals or all trout).

    In actuality, the mink has a varied diet, as documented by Grzimek, who reportsthe mink's diet as rodents (voles, muskrats) (47%), lagomorphs (rabbits andhares) (4%), moles (2.5%), frogs (2.5%), fish (19%), crustaceans (16.5%), insects(7%), and plants (1%). It is, therefore, highly unlikely that the mink will derive100% of its diet in any one season from a single food source such ascontaminated fish.

    In addition, EPA's consultants have observed that large areas of water which arecapable of supporting a fish population do not exist at the site. The onlypermanent water bodies on-site are the golf course water hazards and theUnnamed Stream. Observations of conditions in the stream and water hazardsillustrate that trout are not likely to live in those conditions because of 1) lowstream velocity, 2) mucky bottom sediments and, 3) low dissolved oxygen(Raleigh, 1982).

    Volume II of EPA's 1989 Risk Assessment Guidance indicates that it isappropriate to eliminate exposure pathways which have not been found to exist.Section 4.2 of this Guidance provides:

    "Following collection of existing data, the technicalassistance group should be in a position todetermine the nature and extent of ecologicalassessment that will be necessary of the site. If noecological exposure pathways have been revealed inthis initial review, little or no additional work may beneeded. Alternatively, certain exposure pathwaysmight be eliminated from further study while othersmight require more data. For instance, if there is nosurface water on the site and no opportunity forcontaminants to reach surface waters off the site,further data on aquatic effects would very likely bepointless, even though concern about exposure toterrestrial organisms might warrant extensivesampling and testing."

  • August 5, 1991Page 14

    The site-specific reconnaissance of the Middle Marsh area and observations ofthe Unnamed Stream as it traverses the subject property found that in-streamconditions are not expected to be suitable for the maintenance of a sustainablefish, and in particular trout, population. Most notably, stream temperatures areexpected to be too high and dissolved oxygen levels too low to maintain a viabletrout population. Moreover, the bottom conditions are the antithesis of preferredtrout habitat. Rather than sand and gravel, the Unnamed Stream exhibitsextensive silt deposits unsuitable for feeding and/or spawning. In addition,areas of deep water are lacking, as are requisite pool and riffle areas. Stableaverage annual water flows in the Unnamed Stream are also insufficient. Withoutany actual demonstration that trout do, in fact, exist on-site, the observed in-stream conditions in conjunction with the scientific literature regarding fishhabitat (Raleigh, 1982; Raleigh et al, 1984 and Raleigh et al, 1986) stronglysuggest that the Unnamed Stream does not contain conditions suitable for thegrowth and survival of trout. In addition, the water hazards are also unlikelyhabitat for trout because they are too warm, have muddy bottoms and no swiftcurrents to sustain a trout population. EPA's consultants did not recordobservations of trout in the golf course water hazards in the SRI.

    The emphasis in the Guidance is on construction of plausible exposurepathways through reasonable justification. That process has simply not beenfollowed by EPA in the evaluation of the aquatic food chain pathway for the minkin the Middle Marsh.

    Hence, even if female mink were present at the site, and even if they wanted toeat trout 19% of the time, they could not do so because trout do not likely existin Middle Marsh due to lack of adequate habitat. Table 2-2 of the SRI indicatesthat no fish inhabit the Middle Marsh, and thus the appropriateness of the foodchain assumptions that are used to derive the sediment quality criterion arerefuted by EPA's own data. More realistic, verified food chain assumptionswould further demonstrate that unacceptable risks to the environment do notexist in Middle Marsh.

    I. The SQC methodology Is applicable only if contaminated sedimentsare submerged for sufficient periods of time to establish anequilibrium between the sediments and the overlying water column.This condition Is not true for most of Middle Marsh where there Is NOtruly aquatic environment.

    The Sediment Quality Criteria (SQC) approach is used by EPA for assessing thedangers of hydrophobic chemicals that can bioaccumulate in the food chain.The SQC methodology, which assumes a pollutant equilibrium between waterand solids, allows the water concentration to be implied from a measurement ofthe pollutant in the sediment solids. Pg. 4-21 of the SRI points out that"sediment quality criteria apply to permanently flooded or truly aquaticenvironments with obligate aquatic species." As discussed below, no part ofMiddle Marsh meets this criterion, and thus application of the SQC in MiddleMarsh is inappropriate.

  • August 5, 1991Page 15

    Cowardin et al. (1979) found that Area 1 in Middle Marsh is not a "truly aquatichabitat," as classified by EPA, because the surface waters are not usually greaterthan 2-m (about 6.6 feet). Nor is Area 1 a riverine system, which is defined as:

    "all wetlands and deepwater habitats contained withina channel, with two exceptions: (1) wetlandsdominated by trees, shrubs, persistent emergents,emergent mosses, or lichens, and (2) habitats withwater containing ocean-derived salts in excess of0.5°/00. A channel is 'an open conduit eithernaturally or artificially created which periodically orcontinuously contains moving water, or which formsconnecting link between two bodies of standingwater'."

    The aquatic areas in the Middle Marsh appear to be the Unnamed Stream andassociated water hazards, not any of the areas targeted by EPA for remediation,including Area 1.

    Wetlands are defined for regulatory purposes by the U.S. Army Corps ofEngineers and U.S. Environmental Protection Agency as:

    "Those areas that are inundated or saturated bysurface or ground water at a frequency and durationsufficient to support, and that under normalcircumstances do support, a prevalence of vegetationtypically adapted for life in saturated soil conditions.Wetlands generally include swamps, marshes, bogs,and similarly areas." (EPA, 40 CFR §230.3 and ACOE33 CFR §328.3)

    Based on this definition, EPA's classification of Area 1 as a wetland appears tobe appropriate, while the classification of this area as "truly aquatic," at least onthe basis of recognized and accepted definitions, is unwarranted and unjustifiedbecause of the lack of flooding frequency and sufficient depths of water.

    Numerous site visits by personnel from NUS Corporation, E.G. Jordan, andEbasco Services resulted in no observations of trout (or any other fish) in theUnnamed Stream, Middle Marsh or the Apponagansett Swamp. Site visits byconsultants for EPA and participating party representatives did not identify thepresence of any open water or flowing streams that could support fish presentthrough most of the wetland areas. It is highly unlikely that the areas designatedfor remediation are inundated sufficiently, or for long enough duration, to allowfor the establishment of a balanced population of aquatic organisms includingfish (particularly trout), or of equilibrium conditions between contaminatedsediment and the water.

  • August 5, 1991Page 16

    Aquatic conditions also would not be generated by floods. The duration of thefloods described in the SRI would inundate the Marsh for, at most, several hoursor a few days. Even a 100-year flood would not last for more than a few days,which is much less than the several months' duration needed to establishchronic toxicity conditions for fish. Therefore, the SQC methodology is notappropriate to apply to Middle Marsh.

    J. The sediment quality criteria methodology, a highly controversial andcomplex method for evaluating risk, produces extremelyunpredictable and Inaccurate results

    Sediment quality criteria ("SQC") methodology is unproven and unreliable. Themethodology must account for many complex mechanisms yet it contains manysimplifying assumptions in order to be applied. There are great uncertaintiesassociated with the assumptions, particularly those involving application of theequilibrium partitioning method ("EqP"), discussed further below. The EPA'sScience Advisory Board (EPA, 1990) has expressed significant reservationsabout the application of SQCs, observing that there are many uncertaintiesabout the assumptions of the approach and the water quality criteria upon whichmany of the SQCs are based, particularly as related to PCB uptake and releasefrom sediments. The Science Advisory Board also cautioned against theinappropriate use of water quality criteria as the basis for SQCs. The Boardwarns that water quality criteria based on residue concentrations, as is the PCBcriterion, have limited applicability.

    In the Middle Marsh SRI, EPA has used the SQC methodology in exactly theway that the EPA Science Advisory Board rejects. The Middle Marsh SRIconsiders the PCB water quality criterion which is based upon residue levels andnot effects levels. The Science Advisory Board's concern that the "leaps of faith"in the assumptions needed to link sediment quality to effects levels by usingresidue values are unsupportable makes the SRI methodology untenable.

    There is a limited amount of data available in the Middle Marsh SRI that can beused to test the partitioning assumptions of the SQC, but even this limited dataindicates that the SQC methodology cannot be relied upon. The SQC used inthe SRI predicts that a sediment concentration of 19.5 ng per g organic carbonwill correspond to a pore water concentration of 0.014 jig/« (the value of theAWQC). Larger or smaller values should scale linearly. A test of thisassumption requires simultaneous measurements of (1) the concentrations inpore water and sediments, and (2) the organic carbon content of the sediment.Such measurements are available for 11 samples from Middle Marsh.

    In Figure 1, PCB measurements in pore water samples from Middle Marsh areplotted against the expected dissolved concentrations, as predicted by theequilibrium partitioning (EqP) method for a given sediment concentration andorganic carbon measurement. The solid line indicates equal measured andexpected concentrations.

  • August 5, 1991Page 17

    Clearly, the measured concentrations are very different from those predicted. Sixof the 11 samples have dissolved concentrations below the detection limit of0.05 ng/f, and they are plotted using square symbols on Figure 1. Three ofthese nondetects (ME24, ME29, and ME02) are not inconsistent with the EqPmethod; the expected concentration (from EqP) is below the analytical detectionlimit — Le^, these samples are and should be nondetects. Laboratory results forME11, ME01, and ME17, however, are not consistent with the EqP method; themethod predicts dissolved concentrations in excess of the detection limit, yet thelaboratory reported nondetect. Note that for ME17, the expected concentrationis >0.3 |ig/( — six times the detection limit.

    For samples with measured concentrations in excess of the detection limit(ME03, ME04, ME14, ME15, and ME36-indicated by crosses), the EqP methodunderestimates some sample concentrations (ME03, ME04, and ME15) andoverestimates others (ME14 and ME36).

    Thus, the EqP method for the SQC produces results that differ significantly frommeasured data from actual Middle Marsh samples. Expected and measuredconcentrations differ by more than a factor of ten in several samples. Thisvariance indicates that the method does not accurately predict dissolution ofPCBs into the water column at Middle Marsh and thus is extremely unreliable.

    K. The SQC methodology Improperly assumes that aquatic organismssuch as trout will be exposed to pore water concentrations ofcontaminants

    As noted above, the application of the equilibrium partitioning method ("EqP")to food chain exposures requires that a series of simplifying assumptions bemade which may not be applicable to conditions in Middle Marsh. Essentially,EqP assumes a partitioning of the contaminant between solid sediment particlesand the pore water that fills the interstitial spaces. These pore waterconcentrations are then assumed to be available to aquatic organisms, a falseassumption with the possible exception of its application to some of the mostminute benthic organisms.

    The Sediment Quality Criterion for PCBs is based on the Ambient Water QualityCriterion of 0.014 ^g/l, which, again, is based on the assumption that a minkingests contaminated trout. The PCB concentrations in water accessed by trout,however, are likely to be much lower than pore water concentrations. PCBs inthe pore water of a marsh or stream must diffuse from and mix with the watercolumn. Once in the water column, PCBs volatilize rapidly, with a half-life ofabout 10 hours, and are also subject to photolytic degradation (EPA, 1979).Since these rates of removal are typically faster than the rate at which sedimentscan supply PCBs, concentrations in the water column are usually substantiallylower than those in pore water. The data collected in Middle Marsh is consistentwith this phenomenon where the highest pore water concentration observed is4.4 fjg/\, while the only detected surface water concentration in filtered samplesis reported at 0.01 /^g/l (Appendix E.4, SRI). This limited data set suggests that

  • August 5, 1991Page 18

    the PCS sediment quality criterion, which is based upon pore waterconcentrations, is overstated with respect to estimating exposures to mink.

    The SRI correctly concludes that volatile and semi-volatile organlcs,heavy metals, and pesticides In the Middle Marsh sediments, porewaters, and surface waters pose no threat to the environment

    According to the SRI, 13 soil and sediment samples were analyzed for volatileorganic compounds and 48 soil and sediment samples were analyzed for semi-volatile compounds. In addition, 10 core samples, 8 pore water samples and 6surface water samples were analyzed for both volatile and semi-volatilecompounds. The data from this sampling indicate that the concentrations ofvolatile and semi-volatile organic compounds in soils and sediments aregenerally within the range of background concentrations. In the pore water andsurface water samples, volatiles and semi-volatiles were found at levels belowor near detection limits.

    To determine the presence of heavy metals, 34 soil samples, 10 core samples,8 pore water samples and 6 surface water samples were collected and analyzed.While the data from the soil sampling indicated some elevated concentrationsof lead and zinc, the data from pore and surface water sampling shows thatmany of the heavy metals were near detection limits and were below ambientwater quality criteria.

    Based on this data, the SRI correctly concludes that no excess ecologicalhazards are present in the Marsh as a result of measured non-PCBcontaminants. As Pg 4-1 of the SRI points out, "volatile organic compoundswere detected infrequently and at concentrations below detection limits in allmedia.." and therefore "...volatile organics are not considered a threat to wildlifein the study area". Additionally, the SRI on page 4-2 goes on to state (regardingsemi-volatiles); "...semi-volatiles in both wetland areas appear to be within therange of background concentrations from the literature that are typically foundin soils near highways". For these reasons and the fact that the semi-volatilesare at or near the detection limit in pore water and surface water, the SRI onpage 4-2, concludes that "...semi-volatiles are not considered a hazard to wildlifein the study area".

    Several heavy metals were detected somewhat above background levels insediment/soil samples in the Marsh, but surface water and pore water metalsdata, when compared with the Ambient Water Quality Criteria (AWQC), revealthat the dissolved metals concentrations were near or below the AWQC for lead,zinc and other metals. The SRI, pg 4-3, concludes that "due to the low waterconcentrations, heavy metals have not been evaluated as a hazard to site biota."

    For the reasons discussed in the SRI, EPA properly concluded that volatile andsemi-volatile organics, heavy metals and pesticides pose threat to theenvironment in Middle Marsh.

  • Augusts, 1991Page 19

    SUMMARY The ecological risk in Middle Marsh is based upon highly inappropriate food chainexposures to mink, a species not even found in the Marsh. The ecological risk assessment isdriven by the Sediment Quality Criteria, a methodology inappropriately applied to Middle Marshconditions. A realistic ecological risk assessment, completed for species known to inhabit theMarsh, would show that no unacceptable risks to wildlife are present due to PCB contaminationand, therefore, that the "no action" alternative is the appropriate remedy. The EPA correctlyconcludes that there are no unacceptable risks to the environment from other contaminants.

  • August 5, 1991Page 20

    III. THE FEASIBILITY STUDY CONTAINS UNREALISTIC ASSUMPTIONS ABOUTTHE LIKELIHOOD OF SUCCESS OF THE PREFERRED REMEDY, INCLUDESUNNECESSARY STEPS IN THE PREFERRED REMEDY, AND DEMONSTRATESNO REASONABLE JUSTIFICATION FOR THE CONTINGENCY REMEDIALALTERNATIVE.

    A. The remedial schedule proposed in the FS is unrealistic. Remediationof the Marsh will be seriously Jeopardized by the remediation of theUnnamed Stream (during the remedial action for the first operableunit) if the actions are not performed simultaneously

    Even assuming that all pertinent permits can be obtained, the three-month timeframe estimated for completion of remediation efforts under the proposed Planis unrealistic. As indicated in Figure 9-2 of the FS, wetland restoration activitiesare scheduled to commence within one to two weeks of the initiation ofsoil/sediment excavation and to be completed within approximately two weeksfollowing excavation. Given the extent of site preparation, excavation, watertreatment, and wetland and site restoration, this is totally unrealistic due to theinherent constraints associated with excavation in a confirmed wetlandenvironment. The assumed excavation rate of 64 cubic yards per hour appearsunattainable due to the small working areas, and the presence of large rootsystems from the existing trees.

    In addition, the timing of excavation of the Unnamed Stream (from Operable UnitOne) will greatly affect the schedule for Middle Marsh. Problems with equipmentaccess, resuspension of sediments, and contractor interactions (Sullivan's Ledgesite vs. Middle Marsh contractors) will adversely affect the already overlyoptimistic schedule in the FS for Middle Marsh. For example, work in theUnnamed Stream for Operable Unit One, optimally, should be performedsimultaneously with excavation in Middle Marsh so that disturbance of thewetland, and road building, only occur once. Restoration efforts for eitherOperable Unit will be hampered or nearly impossible if not performedsimultaneously.

    B. There is no reasonable justification for EPA's proposed contingencyalternative.

    EPA's Proposed Plan states that implementation of the Preferred Alternative isdependent on the Middle Marsh excavation being performed prior to capping ofthe Disposal Area (Operable Unit 1 - Sullivan's Ledge Site). However, thisstatement has no engineering or risk assessment basis. Cap design andconstruction for Operable Unit 1 can readily be coordinated with Operable Unit2 activities, so that a portion of the cap (about 1 of 12 acres) is not completeduntil the excavated sediments can be placed in the disposal area.

    Delay in completing a small portion of the cap will result in no significant impactto human health or the environment because appropriate storm water controlsand diversion ditches will be in place and functional, and overburden ground

  • Augusts, 1991Page 21

    water will be intercepted by the perimeter trench. Soil under the portion of theSullivans' Ledge disposal area which may not be capped, awaiting the Marshsediments, will already have been excavated, solidified and stabilized, thusposing no unacceptable exposure risks.

    Any increase in cap construction costs attributable to delay is insignificant whencompared to the $5M cost differential between the preferred and contingencyalternatives.

    In the unlikely event that the disposal area is not ready to receive the excavatedMarsh sediments due to a delay in the remedy at the Sullivan's Ledge disposalarea, there is no significant risk to human health or the environment fromtemporary storage of the excavated Marsh sediments, until the disposal area canaccommodate the same. Sediments can be placed on a lined and bermedreceiving pad, and covered, to prevent drying and blowing of particulates.Rainwater could be diverted and the storage site protected from animal orhuman damage with construction of a proper fence.

    C. Backfilling the disturbed wetlands, as required in the preferredremedy, is not absolutely necessary and requires destruction ofwetlands elsewhere in order to obtain the most suitable materials.

    The FS would require replacement of the entire volume of sediments removedfrom the wetlands area. In question is the source of the replacement fill materialfor each of the wetland areas which would be excavated. Although the FSalludes to a variety of potential sources, the actual source(s) of suitable materialshould be identified well in advance. Ideally, soils obtained from other wetlandswould increase the likelihood for restoration success. If not available locally, thefeasibility of finding a source of suitable replacement fill and obtaining permitsfor its excavation, is very questionable.

    Placement of fill in the remediation areas will also result in problems withturbidity and will cause an increase in sedimentation in downstream areas. Itmay well be environmentally preferable to revegetate the excavated wetlandswithout replacing the excavated sediments. This would result in less disturbanceof the wetland and portions of the remediated area may develop standing water,due to the lowering of the ground surface by 18 inches, allowing for greaterdiversification of the Middle Marsh environment.

    Wetland restoration will also cause harm to other wetlands. As described in theFS, the soils excavated from the wetlands may be replaced with wetland soilmade from soil mixed with organic material and sediments dredged from a lakeor pond. Ideally, the replacement soils should be obtained from a similarwetland that is to be excavated for by development. It, thus, appears that onewetland has to be destroyed in an attempt to restore another. But this remedynot only destroys the Middle Marsh wetland, it will cause far reaching damageto another.

  • August 5, 1991Page 22

    D. There Is no Justifiable reason to manage the cleared vegetation as ahazardous waste

    The feasibility study (FS) suggests that "Contaminated stumps and loosevegetation should be contained with other contaminated materials for treatmentand/or disposal" (FS, p. 7-20). If handled properly (e.g., not dropped intocontaminated mud), these materials should not contain significant concentrationsof PCBs and could be managed as solid waste under 310 CMR 19.100-143 ofthe Massachusetts Landfill Design and Operational Standards.

    The translocation of PCBs from soils/sediments to plants is small. An uptakefactor can be used to relate the concentration of PCBs in soil/sediment to theconcentration in plant tissue.

    [^vegetation = UP13*6 factor * [^soil/sediments

    Travis and Arms (1988) report an empirical value of 0.017 (non-dimensional) forthe PCB uptake factor. This relationship can be applied to data from the MiddleMarsh. For the current highest point-value of PCBs measured in sediment/soilsamples (28 mg/kg, sample ME22), a concentration of 0.5 mg/kg would becalculated in plants using the above relationship. This value is lower than anyof the terrestrial cleanup criteria derived in the SRI. This worst-case value is alsoconsistent with non-detected results for measurements of PCBs made in rosehips and grass seed heads (at a detection limit of 0.1 mg/kg) (p 2-24 of theSRI).

    Therefore, the theoretical predicted maximum concentrations of PCBs invegetation are consistent with the observed levels for vegetation, demonstratingthat the cleared vegetation should not be managed as a hazardous waste.

    E. Production rates and treatment technologies stated in the FS areunrealistic and likely unattainable

    The FS assumes the use of a 100 ton per day treatment unit for treating PCBcontaminated excavated sediment. A more realistic treatment rate for a site withthis volume of sediments is 25 to 40 tons/day due to the size of equipmentspecified by EPA to be mobilized. This would increase the estimated timenecessary to treat the estimated 5,200 yd3 of contaminated sediments fromthree to six months, and possibly longer. This increased treatment time greatlyimpacts the overall remedial schedule and increases the cost of the remedysubstantially.

    Since the PCB treatment could take longer than the 3 months estimated in theFS, the estimate of 6 months (Section 9.3.6) for total remediation could be closerto 9 months, possibly interfering with the mating season of the Spotted Turtle,a species of special concern.

  • Augusts, 1991Page 23

    In addition, the treatment technology to be implemented under the contingencyremedy may not be capable of achieving the required reduction in PCB levels.The contingency remedy calls for sediments to be treated on-site with solventextraction and then be replaced back into the excavated areas.

    Although the FS evaluates (Section 9.3.2) the overall protection of theenvironment using solvent extraction in regard to reduction of PCBs, it does notappear to have addressed the issue of residual toxicity associated withbyproducts from the BEST preferred solvent extraction treatment method, thedesignated EPA-selected treatment.

    It should be noted that the BEST process removes oils, not specifically PCBs.The BEST process may not yield significant PCB reduction in a soil sample withPCBs but low oil and grease. Therefore, if the contingency alternative isretained, the KPEG process should have been included by EPA as an alternativetreatment technology for treatability testing given the difficulties noted above withrespect to the BEST process.

    It is entirely possible that no known treatment technology may be successful atthe site. Remediation of Area 1 (based upon the normalized PCB exceedancesat ME5 and ME19) would require that actual PCB concentrations not exceed 0.4ppm and 1.6 ppm. These are levels which may not be attainable with ANYknown treatment technology.

    SUMMARY The timetable for implementation of the preferred remedy is likely to be at leastsix months, not the three months erroneously estimated in the FS. The FS does notdemonstrate an unreasonable exposure, or engineering requirement, which justifies theimplementation of the proposed contingency alternative. Instead, the need for the contingencyalternative is unsubstantiated, and that alternative will fail because there are currently no. knowntreatment technologies which can attain the PCB levels required by the cleanup criteria in MiddleMarsh.

  • August 5, 1991Page 24

    IV. THE PREFERRED ALTERNATIVE WILL SIGNIFICANTLY HARM THEWETLANDS, WITHOUT ANY ASSURANCE THAT THE WETLANDS CAN BEADEQUATELY RESTORED.

    A. The proposed plan would require excavation of more wetlandacreage than necessary, even accepting the SQC In the SRI.

    Figure 6-1 of the FS identifies four areas to be remediated. The extent of theareas to be remediated is considerably larger than necessary dictated by theecological remediation criteria proposed in the SRI. However, the criteria, whenappropriately applied to the entire Marsh on an average basis, define smallerareas to be remediated. Additionally, following the same area averaging logic,there is no need for remediation at all in Areas 2, 3 and 4 to meet the mink-based criteria.

    Table 6-2 of the FS summarizes the various ecological cleanup criteria that arederived in the SRI. As described in the SRI, the proposed target concentrationof 15 mg/kg total PCBs is used to establish the extent of Areas 2, 3, and 4,while a target concentration of 19.5 jig PCB/g carbon is used to determine theextent of the remediation required in Area 1. These cases are discussed, in turn,below.

    • Areas 2, 3, and 4

    In these areas, the proposed target concentration of 15 mg/kg appears to bebased on the terrestrial feeding habits of mink, for which a contamination levelof 14 mg/kg may be harmful according to the SRI. Assuming female mink maylive in the Middle Marsh, it would not be exposed, on average, to contaminationin excess of the 15 mg/kg criterion. On average is emphasized because, as theSRI points out, the female mink requires a range of at least 20 acres for feeding.Since the mink will obtain food from all points of the site, the average PCBconcentration over the entire feeding area should be used to compare to thecriterion. This site-average PCB concentration is calculated to be 5.3 mg/kg, thederivation of which is presented in Appendix 1.

    Since the site average concentration of 5.3 mg/kg is smaller than theremediation criterion of 15 mg/kg, remediation is not required to meet thiscriterion. As the average PCB concentrations across the site area in Areas 2, 3and 4 are below this cleanup criterion, no remediation should be required inthese areas.

    • Area 1

    The cleanup criterion used in the SRI to estimate the extent of remediationrequired in Area 1 is the interim sediment quality criterion of 19.5 ng PCB/gcarbon. As mentioned above, this criterion should be applied on an areaaverage basis, since a female mink, if present, could obtain food throughout thearea and fish, if present, would be expected to swim throughout the aquatic

  • August 5, 1991Page 25

    environment, if present. An area-average calculation is presented in AppendixA. The area to be remediated in Area 1, would be 300 m2, or about 0.06 acres,which is considerably smaller than the area of 0.36 acres suggested in the FS.Cleanup of this smaller area (which is heavily weighted by one sample ME5)would result in an average concentration in Area 1 of 16.5 jig PCB/g carbon,which is below the criterion.

    However, the overriding point with respect to Area 1 is that EPA has determinedthe need for remediation based upon only one sample. Even if one could relyon the accuracy of the analysis for PCBs or TOG, which is doubtful, it isunreasonable, and scientifically unacceptable, to base a remedy decision on asingle extreme sample. In most instances, compliance with a certain criterionis achieved where the mean or the median is lower than the criterion. The above-described area-averaged analysis described above demonstrates that anextreme value (in this case a low value for TOC at ME5) is driving the remedyof Area 1. This indicates that the EPA's decision to remediate Area 1 is basedupon an unreasonable reliance on an outlying data point, which is not goodscience.

    B. The proposed plan will disturb and/or destroy the wildlife It Issupposed to protect

    The proposed remedy is an extremely destructive approach for remediating thelow levels of contamination in Middle Marsh. The remedy requires excavationof approximately 18 inches of sediment in the designated areas. The upperlayers of this sediment are teeming with small organisms that will be destroyedby the excavation. All vegetation, nesting areas, food sources - in short, theentire habitat - will be completely destroyed in the remediation areas. The shymink, even if present in the Marsh, would be driven out of the Marsh during themonths of road building, excavation and restoration activities, and would remainout of the Marsh afterward, because the post-remediation habitat would remainunsuitable for mink to survive. Stream dredging, stream diversion anddewatering would dry up and destroy all aquatic life. The restoration measureswould need considerable time - many years at least - to become reestablished(trees to grow, grasses and bushes to become reestablished), during which timethe Marsh will take on a vastly different character.

    Middle Marsh likely will never become reestablished to the same extent and typeof biological diversity as existed prior to remediation. Because forested wetlandswill, in part, be altered by the proposed plan, and will not be replaced in kind fora period many of years following initial restoration activities, the functions andvalues of Middle Marsh relative to wildlife may well experience a permanent netdecline. This is particularly true with respect to the Spotted Turtle, a State-listedspecies of special concern, known to inhabit Middle Marsh, which could beextremely difficult to reestablish.

    The proposed plan describes impacts to approximately 1.9 acres of wetlands.In fact, this acreage only relates to the areas to be excavated and not other

  • August 5, 1991Page 26

    areas that will be disturbed due to associated activities required by the proposedremedy. For example, additional acreage would be adversely impacted byconstruction of roadways and sediment basins. These activities, no matter howcarefully performed, will damage a considerable area of the Marsh andpotentially mobilize contaminated sediments into non-contaminated areas.

    C. The proposed plan poses a substantial and unreasonable danger ofdestroying the habitat of the spotted turtle, a species of specialconcern in Massachusetts

    Unlike mink, spotted turtles, a species of special concern in Massachusetts, areknown to inhabit at least a portion of Middle Marsh. The FS (pages 9-35) statesthat, in the event spotted turtles are discovered in the proposed remediationareas (it is doubtful that heavy equipment operators will look for them), they areto be caught and translocated to uncontaminated areas of the wetland. Thisproposed mitigation measure raises serious concerns.

    The availability and extent of suitable habitat for spotted turtles elsewhere on-sitehas not been documented. Whether or not other suitable habitats exist toaccommodate the spotted turtles, in addition to other spotted turtles that mayalready use the receiving area, is also unknown. The effects of translocation onindividual turtles and the effects of proposed activities on turtle movement bothwithin and outside Middle Marsh, are also unknown. If suitable sites areunavailable, the breeding success of translocated spotted turtles will beadversely affected. In the long term, the spotted turtle habitat conditions wouldsuffer prolonged and likely permanent change, particularly given the extendedlength of time required for disturbed forested wetlands to become reestablished.

    D. The proposed wetlands restoration plan is inadequate and notconsistent with existing wetland species

    The proposed remedy would ostensibly alter 1.9 acres of wetlands, all of whichare associated with areas of soil/sediment excavation. All of this impacted areawould have to be restored. The actual wetland impact acreage would be muchhigher. Other areas which would be disturbed under the proposed remedy, e.g.,the proposed staging area and access roadways, were not included in therestoration acreage estimate but should be included for purpose of the remedialalternatives evaluation. While all such areas may not be wetlands, they areadjacent to wetlands. Measures to minimize impacts to adjacent wetlands wouldneed to be implemented, such as in the forested wetland adjacent to theproposed staging/treatment area.

    The proposed planting plan in the restoration plan lacks biological diversity. Theexisting diversity of plant species in each of the proposed excavation/restorationareas are considerably higher than proposed in the restoration plan. Increasingthe diversity of proposed plantings with species characteristic of theexcavation/restoration areas would, therefore, be more consistent with existingconditions.

  • August 5, 1991Page 27

    Furthermore, the planting plan proposes to introduce species which may beunsuitable for the location. For example, the overall revegetation plan fordisturbed wetland areas calls for the introduction of red oak (Ouercus rubra) andarrowhead (Sagittaria spp.). According to Reed (1988), red oak is an uplandspecies. This species exists in the vicinity of Middle Marsh, but generally not inthe low-lying areas like those to be remediated. Its potential for survival in wetenvironments with high ground water tables is far reduced relative to the nativered maple (Acer rubrum). In contrast, arrowhead is characteristic of pond edgesand shallow waters. As such, it may not be suitable for revegetative purposesunless suitable water conditions, including ponded waters, are established.Arrowhead is not listed in the inventory of existing plant species on sitecontained in Table 2-2 of the SRI. Thus, its use in Areas 2 and 4 appearscontrary to the stated objective of providing similar vegetation to that which isremoved during remediation activities.

    SUMMARY The preferred alternative will cause more harm than good to the environment inthe Marsh because of long-term wetlands damage, potential destruction of the spotted turtlehabitat, and potential mobilization of contamination as a result of site activities.

  • August 5, 1991Page 28

    V. THE FEASIBILITY STUDY, BASED UPON QUESTIONABLE DATA ANDMODELLING STUDIES, FAILED TO ADEQUATELY INVESTIGATE ALLPOTENTIALLY APPROPRIATE REMEDIAL ALTERNATIVES, AND FAILED TOINCLUDE SIGNIFICANT FACTORS IN EVALUATING THE PREFERRED ANDCONTINGENCY ALTERNATIVES.

    A. The data which Is relied upon In the FS regarding PCB concentrationsin surface water and pore water samples contain severaldiscrepancies.

    The purported need for remedial action is based on reported exceedances ofAmbient Water Quality Criteria (AWQC) for PCBs in the surface water and porewater samples. The SRI reports that, in pore water samples, the dissolved PCBconcentrations ranged from undetected to 4.4 \ig/t, and the total PCBconcentrations ranged from undetected to 29 \ig/t. In the surface watersamples, the dissolved PCB concentrations ranged from undetected to 0.19

    t, and the total PCB concentrations ranged from 0.98 to 4.9 \ig/t.

    The highest concentration of dissolved PCBs in the pore water samples wasreported to be 4.4 \ig/l. However, PCBs were not detected in the unfilteredsample from the same location. It is impossible for PCBs to be present in adissolved or filtered sample when they are not present in a total or unfilteredsample from the same location. In addition, the highest concentration of totalPCBs in the pore water was reported to be 29 \ig/t, but this result was notfound in the analytical tables included in Appendix E. For surface watersamples, pg 3-31 states that PCBs were detected in filtered surface samples -values of 0.19 /^g/« and 0.077 fjg/t are listed. Appendix E-4, however, showsnondetects for all samples except SL15, for which the PCB concentration isestimated to be 0.01 vg/l. It should be noted that the detection limit forsamples SL01, SL04, SL15 and SL17 appears to be 0.01 ttg/t, a value that isbelow the AWQC of 0.014

    In another example, for the unfiltered sample ME04, Aroclor 1254 was notdetected (detection limit: 0.05 ng/J) and Aroclor 1260 was found at aconcentration of 1 .7 jig/t. However in the filtered sample, Aroclor 1260 was notdetected (detection limit: 0.05 jig/«) while Aroclor 1254 was found at 1.1 \ig/t.Since Aroclor 1254 was not detected in the unfiltered sample, one would notexpect to find it in the filtered sample. Similarly, for sample ME29, Aroclor 1254is detected in the unfiltered sample, and Aroclor 1260 is found (at a lowerconcentration) in the filtered sample.

    The discrepancies in the data call into question the reliability of the data and, inturn, the need for remedial action based on exceedances of the ambient waterquality criteria (AWQC).

    In addition, review of the analytical data for water samples in the appendices ofthe SRI indicates that ail of the PCB concentrations reported by the analyticallaboratory are labeled with the suffix "J": this indicates that the reported

  • August 5, 1991Page 29

    concentration is an estimated value that the laboratory has tentatively identified.Page 5-15, of the 1989 Volume I Interim Final Manual for Risk AssessmentGuidance, states that if the "J" qualified data contribute significantly todetermination of the estimation of potential risk, then the report should notepotential uncertainties associated with the data and proper caveats should beattached. This was not done for the critical PCB data in Middle Marsh.

    B. The TOG Analytical Method produces inconsistent, unreliable resultswhich are not reproducible to even an order of magnitude In thelaboratory

    EPA's reliance on the total organic carbon (TOC) measurements (orassumptions of average values for the Marsh) is suspect. The areas to beremediated are defined by a "normalized" PCB value, which is derived bydividing the PCB concentration by the TOC value. If the TOC value is unreliable,then the normalized PCB value is unreliable and should not be used.

    EPA analytical test methods have not been properly developed for TOC, andaccording to laboratories performing TOC analyses for EPA, the analysesproduce extremely variable results with "duplicate" samples varying an order ofmagnitude and up to three standard deviations (personal communication, R.Foster, RAI, July, 1991; M. Perkins, RAI, July 1991).

    Table 2-12 in the SRI indicates TOC analyses were performed by CLP-SAS testprocedures. This test method uses very small sample sizes (10-100 mg) andtends to yield results of low precision (Analytical Resources, Inc., 1991).Analytical variability of duplicates of samples with relatively high TOC (greaterthan a few percent) is generally high, possibly up to a full order of magnitude.This likely accounts for some of the variability in TOC values observed insamples from Middle Marsh. TOC data from the Middle Marsh range from 7,700PPM (SRI Table 3-1) to 480,000 PPM. Specifically, remediation in Area 1 isdriven by the abnormally low TOC value for ME5 (22,000 PPM).

    PCB concentrations in Area 1 range from 0.325 to 11 mg/kg. When normalizedby organic carbon, however, values range from 0.68 to 218 VQ PCB/g carbon.This increase in range could well be the result of uncertainties in themeasurement of organic carbon.

    C. The basic assumptions of the hydroloaic computer models are notIncluded In the SRI or available for review, either by EPA or thepublic. The limited Information on the hydroloqlc computer modelingwhich is available Indicates that the models may not have beencalibrated correctly

    The computer models used to predict the flood flows and the spatial extent offlooding are critical components of the SRI. EPA assumes, based on thismodeling, that the source of contamination to Middle Marsh is from theSullivan's Ledge disposal area. In addition, the models are used to predict the

  • August 5, 1991Page 30

    extent of flooding so that the sampling program can be designed to investigatethe most likely areas of high contamination. The analytical results of thesampling plan then determine the areas to be remediated. Hence, the modelsplay an integral part in the Middle Marsh remedy.

    The referenced models are very sensitive to assumptions regarding inputs suchas basin characteristics, stream routing coefficients, and stream roughnessfactors (US Army Corps of Engineers Users Manuals for HEC-1 and HEC-2,January 1985 and September 1982a). Yet, information concerning data inputsto the models is not included in the SRI. This information is critical for anindependent reviewer to determine if the Unnamed Stream was modeledproperly in the SRI. EPA should have required this information in order to verifythe EPA consultant's work i