LETTER REGARDING DISAPPROVAL WITH MODIFICATION … · The Johnson Company . 100 State Street ....

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f^^^ ^ UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

^ rr JOHN F KENNEDY FEDERAL BUILDING ^t pwjtt^ BOSTON MASSACHUSETTS 02203-0001

SDMS DocID 462334 October 15 1996

U^SVi^yirn^

Mr Christopher Crandall mdash ^ b c -gt T The Johnson Company 100 State Street Montpelier VT 05602

Re Pine Street Canal Superfund Site Disapproval with Modification Required of Additional Remedial Investigation Report dated August 1996

Dear Mr Crandall

EPA has reviewed the draft Additional Remedial Investigation Report (ARI) prepared by the Johnson Company dated August 1996 This deliverable is disapproved with modifications required pursuant to paragraph 28 of the Administrative Order by Consent for Additional Remedial InvestigationAdditional Feasibility Study USEPA Docket No 1-95-1048

EPA has significant concerns about the revised draft ARI report Our specific concerns are set out in the attached comments Generally the draft ARI reads like an advocacy piece that puts forward the perspective of the potentially responsible parties rather than an objective characterization of technical issues relating to the site As noted in our comments many of the conclusions in the draft ARI Report are overstated and simplified Often the reader is provided with inadequate context to understand what conclusions are supported by the data and what conclusions represent the opinions of the PRPs In addition the executive summary should be written to be comprehensible to the lay reader

EPAs objectives for the ARI are to have all conclusions fully supported by the data to ensure that the context for the conclusions is accurately and clearly explained to reach consensus among the Coordinating Council regarding all conclusions especially those in the executive summary and closing comments to make sure the document is clear and easily understood by the public and to make sure the document is clear and complete for the administrative record We suggest that the Executive Summary and conclusions sections be rewritten and reviewed by the Coordinating Council before revision of the entire document

( ^ RecyclttdRscyclabl ^^ Printed wKh SoyCanola Ink on paper that

contains at least 75 recycled f b t t

shyAlthough EPA has concerns with some of the conclusions reached in the report we do think that the data collected as part of the Additional Remedial Investigation are sufficient to respond to the data gaps identified by the Pine Street Barge Canal Coordinating Council and its workgroups

There are two enclosures with this letter The first attachment sets out EPAs general and specific comments on the ARI Also enclosed is a disk which contains additional corrections and clarifications marked in red-linestrike-out format

If you have any questions regarding the comments please contact Sheila Eckman at (617)573-5784

Sincerely

Mary Jane ODonnell Chief CTMEVT Superfund Section

Enclosures

cc Sheila Eckman EPA Ross Gilleland EPA Margery Adams EPA Susan Svirsky EPA Martha Zirbel MampE Pine Street Coordinating Council

3 EPA Comments on Pine Street Draft ARX Report - October 15 1996

Pine Street Canal Superfund Site EPA Comments on the Draft Additional Remedial Investigation

Major Technical Issues

The following is a summary of ARI conclusions and EPA responses Specific explanations of the EPA responses are included in the specific comments section below

GENERAL ARI It is not clear if zero or one-half the detection limit was

used for non-detects for various data sets

EPA One-half the detection limit should be used for all data sets especially at this site where high detection limits may mask some contaminants

ECOLOGICAL ARI Areas 1 and 2 in the Canal and the Turning Basin (Area 8)

exhibit biologically significant levels of toxicity Areas 3 4 and 6 do not The results from Area 7 are not clear

EPA In addition to Areas 1 2 and 8 Areas 3 and 6 exhibited significant toxicity to one or more organisms for one or more samples Area 7 remains unclear

ARI PAHs ammonia and sulfides are the likely causes of toxicity

EPA There is no data allowing distinction between toxicity due to sulfides ammonia or PAHs

ARI Cadmium copper lead nickel and zinc do not cause toxicity in the canal sediments

EPA Although it is fair to speculate that the toxicity of the metals may be somewhat mitigated by the presence of sulfides and organic material data are not sufficient to conclude that metals do not contribute to toxicity particularly for those metals that are not divalent Mercury roust be removed from this analysis since SEMAVS has not been definitely identified as a predictive mechanism for mercury toxicity

ARI Low levels of dissolved oxygen in canal are not contaminant related and have an effect on the ecosystem

4shyEPA Comments on Pine Street Draft ARI Report - October IS 1996

EPA Periodic low DO levels were documented and probably has an effect on the canal ecosystem A primary source of DO depletion is biodegradation of coal tar wastes Since no COD or BOD was measured it is impossible to determine the cause of depletion of DO

ARI High sulfides and ammonia in site sediments are not contaminant related and create toxicity

EPA Sulfides and ammonia are byproducts of the coal gassification process There is not enough information to determine what proportion of these substances are contaminant related Both have potential effects on toxicity but there is not enough info to distinguish between effects from PAHs metals and sulfides ammonia

ARI The report presents an avian model

EPA EPA had given verbal instructions to the Johnson Co not to include an avian model which is a tool used for the ecological risk assessment to demonstrate effects from food chain exposure to receptor species This is being done as part of the Supplemental Baseline Ecological Risk Assessment where all parties have had an opportunity for input into the risk assessment model The avian model should be taken out of the ARI Only the RI component of collecting the insects and performing the analyses should be included in the ARI EPA is not providing detailed comments on the model however it should be noted that the conclusion stated in the text that adverse effects were not expected from contaminants is not supported by the Red-winged Blackbird Energy Assimilation-based model presented in the ARI report

CONTAMINANT FATE AND TRANSPORT ARI Groundwater contamination is in an equilibrium condition and

is not migrating to the lake

EPA Contamination is probably in equilibrium but may still be migrating to the lake Uncertainties in the model must be clearly stated However EPA agrees that contaminant migration to the lake is probably not significant

ARI Biodegradation is a significant mechanism in groundwater

EPA No data exists to support this conclusion

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EPA Comments on Pine street Draft ARI Report - October 15 1996

ARI LNAPL has largely dissipated from the site

EPA LNAPL is ephemeral and localized but still present

ARI The canal has a beneficial effect on stormwater entering the canal

EPA There is probably some benefit that the canal serves regarding stormwater input to Lake Champlain The canal itself is not benefitted by the stormwater constituents This has not been evaluated or c[uantified through studies

ARI Sedimentation is significant in the canal and contamination is becoming less accessible to animals as a result

EPA There is are no empirical data to support an analysis of sedimentation over time in order to determine the significance The rate of sedimentation in the decades since disposal has not eliminated exposure of organisms to the sediments in much of the canal as can be seen from the sediment chemistry and toxicity results

AIR Contaminant migration via sediment transport from the Canal to the Lake is not a significant process

EPA EPA agrees that the sediment transport to the Lake does not appear to be significant under current conditions However this conclusion should be qualified in light of the ephemeral nature of the beaver dam

ARI The potential for significant migration of nonaqueous liquids is very low

EPA EPA agrees with the general conclusion but not with the certainty presented in the ARI report Assumptions and uncertainties should be clearly presented

ARI The report presents a model for fluvial processes in the canal system

EPA This model was not part of the Statement of Work agreed to by the Coordinating Council No site-specific calculations are included which support the conclusions of the model

(p

EPA Comments on Pine Street Draft ARI Report - October 15 1996

HUMAN HEALTH ARI The original findings of no unacceptable human health

risks (except for ingestion of groundwater) stand

EPA EPA agrees with the general conclusion but the new data must be explicitly compared with previous data and the questions raised in the position papers must be clearly addressed

ARI The Site does not have an adverse effect on the local ambient air

EPA EPA agrees with this general conclusion but the text should be modified to acknowledge anomalous benzene and toluene results

General Comments

1 Additional comments are provided in the electronic format as redlinestrikeout to the actual text of the Draft ARI report

2 The ARI Report is not marked draft on every page as required by the Administrative Order (paragraph 27) and agreed to by the PRPs In fact the footer on every page indicates that this is the Final Additional Remedial Investigation creating the situation in which the current reader and readers in the future will conclude that the August 1996 ARI Report is the final approved ARI Report To correct this error the Johnson Company should send a letter to all recipients of the draft report clearly indicating that it is a draft which has not been approved In addition the Johnson Company should mark each page of the draft ARI report in a public repository (Fletcher Free Public Library and UVM library) with a conspicuous stamp indicating that the draft report is a draft and has not been approved

3 The purpose of the ARI report is to provide a stand-alone report which provides a complete assessment of the site conditions characterizing the nature and extent of contamination Given the purpose all sections of the ARI report aside from Section 22 should be written with that purpose in mind Many sections are however the report sometimes tends to focus only on the ARI results Specific examples are provided in the Specific Comments

4 The executive summary is densely written and not particularly comprehensible to the public It must be

7 EPA Comments on Pine street Draft ARI Report - October 15 1996

rewritten keeping in mind that the purpose of this section is to summarize the data and conclusions in a way that both the public and the technical reader can understand

5 It is recommended that the discussions of site history (Sections 11 14 and 30) be combined

6 The site history is inadequate both in the executive summary and the introduction These sections present a picture of the site as a routinely disturbed urban area and obscures the fact that significant amounts of PAH-contaminated wastes were disposed of at the site for many decades during the operation of the manufactured gas plant contaminating hundreds of thousands of cubic yards of soil and sediment The report is misleading in that it minimizes the relative contribution of the manufactured gas plant and overstates the significance of other contaminant sources The site history needs to be rewritten in a more objective manner

7 The introduction states (p 8) that if the site presents unacceptable risks related to MGP related contamination then a remedial response will be required This is not accurate and must be changed A remedial response does not depend on the presence of MGP wastes If the site presents an unacceptable risk from any source a remedial response will be evaluated and undertaken The PRPs may choose to contest that response if they believe they are not legally responsible for the wastes addressed

8 As spelled out in more detail below many conclusions are not fully supported by data

9 The draft Report is biased toward the PRP view The draft report minimizes conclusions related to ecological effects and contaminant distribution while attempting to make conclusions regarding sedimentation and alternate contaminant sources that are not fully supported by the studies

10 Full references are missing for many sources referenced in the text All primary references and text references should be checked for completeness and accuracy

11 Tables should follow a standard format and truly summarize all data not just selected aspects Most tables in Volume I more appropriately belong in the appendices

12 Summary statistics for data are often misapplied either summarizing between inappropriate data sets or between


areas of different exposures Often the full range of necessary summary statistics is not included

13 Dissolved oxygen depletion and sulfide concentrations identified in the report as probable contributors to toxicity are likely influenced significantly by the MGP waste at the site Conclusions regarding adverse effects due to either of these factors cannot be separated from site contaminant issues No BOD or COD measurements were made in fact language throughout the report alludes to the likelihood of biodegradation occurring along the edges of the contamination in the aerobic zones These organisms are also stimulated by temperature increases therefore it is logical to consider that this or other chemical degradation processes may contribute to the decrease in DO It has been well documented that sulfur compounds are a significant byproduct of the MGP and that in addition to direct disposal of sulfides an increase in sulfides is a likely byproduct of biological activity on organic sulfides

14 Data have demonstrated that a lack of mercury toxicity can not be predicted by AVS Please remove all references to mercury in discussions of SEMAVS (simultaneously extracted metalsacid volatile sulfide Not all inorganic toxicity can be discussed in terms of SEMAVS This only has predictive power for divalent metals

15 Remove the discussion of the avian dietary model An avian dietary model based on data from the ARI studies will be part of the Supplemental Baseline Risk Assessment All parties have had an opportunity for input into the risk assessment avian model

Specific Comments

EXECUTIVE SUMMARY

1 General Rewrite the Executive Summary to accurately reflect the text of the report and conclusions supported by data The Executive Summary should address position paper conclusions as well as field studies

2 General It would be helpful to direct the reader to the sections which contain data and analyses that support each conclusion

3 Page i paragraph 1 The last few sentences suggest that inclusion on the site on the NPL resulted in reshyestablishment of habitats at the site While the discovery

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of contamination at the site may have prevented development habitat on much of the site was re-established well before 1981 Revise

4 Page i paragraph 2 A fourth broad category of study was the remedial alternatives evaluation and it should be mentioned here

5 Pages ii and iii Conclusion 2 Preliminary SoilSediment Screening The fifth objective in this section is to determine the nature and extent of contamination at the Landing Pad The conclusion for this objective does not address nature and extent of contamination but relates Landing Pad contaminants to the Human Health Baseline Risk Assessment Analytical results presented in the text and summary tables in section 4326 for concentrations of metals and other contaminants appear to be consistent with (or lower than) concentrations in the general area called east of canal central area Although this information addresses the issue of nature and extent of contamination there is no supporting discussion in section 4326 which refers to the baseline risk assessment as is stated in conclusion 2 of the Executive Summary Add additional data to section 4326 which supports the claim of the contaminants being within the ranges used in the Human Health Baseline Risk Assessment

6 Page iii Surface Water Investigations The observed dissolved oxygen depletion is the only variable measured which is indicative of eutrophic conditions No data were presented on the nutrient content of the surface water (total phosphorus and total nitrogen) or the total chlorophyll concentrations which are usually used to classify the trophic status of a water body Clarify

Eutrophic conditions including low dissolved oxygen and sedimentation are discussed as water quality parameters other than site related contaminants that may affect aquatic or benthic communities Considering the low dissolved oxygen as unrelated to site contamination is inconsistent with the view offered elsewhere in the ARI Report (eg on page 4) that biodegradation of site contaminants is an important process at the Site It appears that the rate of biodegradation needs to be quantified (eg in terms of mass of hydrocarbon metabolizedmineralized per unit time) and any corresponding depletion of oxygen in canal water needs to be quantified and related to its effect on water quality Such an evaluation would help resolve questions about water quality impacts from the site-related contaminants Remove the

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phrase other than site related contaminants

7 Page iii Surface Water Investigations Conclusions State conclusions regarding parameters other than DO

8 Page iv Groundwater Investigation Conclusions Conclusions summarized in this section should demonstrate the same degree of certainty as those provided in the text For example the second conclusion which states hydrodynamic dispersion is small does not coincide with the information stated on page 245 hydrodynamic dispersion is not likely to be of great significance In the third conclusion it is stated that retardation factors are high given the presence of high organic carbon media at the site however the text on page 246 states that organic carbon has not been measured deeper than 2 feet and organic carbon content below that has been estimated by only visual observations The conclusions stated here must be consistent with the limitations presented in the text The text must also consider that fact that even if the contamination at MW-17 is in a state of equilibrium as implied by the relatively constant concentrations of contaminants this does not mean that contaminants are not migrating to Lake Champlain

9 Page iv Groundwater Investigation Conclusions The conclusion that biodegradation is significant in offsetting solute transport of contaminants (4) is overstated There has been no study designed to evaluate biodegradation of contaminants in groundwater The presence of BTEX and PAH degrading organisms in samples taken for the Retec study do not prove that biodegradation is significant although it is probably a factor See additional comments on Section 50 and revise this conclusion

10 Page iv Groundwater Investigation Conclusions Anisotropy of hydraulic conductivity which is listed as a factor contributing to the prevention of downward migration of contaminants in groundwater is not discussed in the text of section 34 Hydrogeology The degree to which anisotropy of hydraulic conductivity is a factor may be questionable since geometric means of hydraulic conductivities provided in section 34 indicate successive units are generally within 1 order of magnitude of each other The supporting information for this conclusion must be provided in the text or the conclusion must be revised

11 Page v Groundwater Investigation Conclusions The first sentence LNAPL has largely dissipated from the Site is overstated LNAPL is certainly localized and ephemeral Revise

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12 Page v Groundwater Investigation Conclusions A major purpose for evaluating the potential of contaminant migration to the lake was to evaluate potential human health risks from ingestion of lake water The Position Paper Data Gap for Lake Champlain Drinking Water Scenario in Appendix 1 contains a proposed approach for evaluating human health risk using the data from the groundwater investigation This screening approach and its conclusions must be included in the ARI report

13 Page v StormwaterSediment Investigation Conclusions The conclusion which states that contaminant migration via sediment transport from the Canal to the Lake is not a significant process may be correct for normal conditions observed during on-site sampling events However the uncertainty discussed in section 70 regarding the effects of extreme storm events and another potential beaver dam breach should be reflected here In addition rationale is not presented which supports the claim that a velocity of 2 ftsec is insufficient to resuspend settled sediments Clarify in the text and conclusions

14 Page v StormwaterSediment Investigation Conclusions State the conclusion regarding the preliminary assessment of contaminants entering the Canal via stormwater inflow (see objective)

15 Page v StormwaterSediment Investigation Conclusions Address how the conclusions respond to the Data Gap for Lake Champlain SwimmerWader Scenario Position Paper in Appendix 1

16 Page v Preliminary Air Assessment Please provide more information in the conclusions section (what contaminants were monitored what the results were and how the conclusions about human health were reached) Qualify the conclusion that the Pine Street Site does not have an adverse effect on the local ambient air quality because of apparent outlier values in the data

17 Page vi Avian Dietary Study See general comment regarding the avian model In addition the conclusion states that adverse effects were not expected from exposure to PAHs cadmium or mercury for either tree swallows or red-winged blackbirds nesting at the Site Based on the data presented no adverse effects were predicted using the Red-winged Blackbird Field Observation-based Dietary Model however adverse effects were predicted using the Red-winged Blackbird Energy Assimilation-based Model

1^ EPA Comments on Pine Street Draft ARI Report - October 15 1996

18 Page vi Fish Studies Another objective of the fish studies was a qualitative evaluation of diversity and abundance This data is absent from the draft ARI report and must be added

19 Page vi Fish Studies The objective was to evaluate subshylethal effects of PAH contaminants on bottom feeding fish at the Site A study was performed in August 1995 which included not only the fish biomarker study as presented in the text of this section but also analyses for PAHs organochlorine compounds aromatic hydrocarbon metabolites in bile and metals The fish tissue contaminant data was not part of the original ARI scope of work and therefore is not discussed in the report Please reference studies conducted by the State of Vermont and the US Fish and Wildlife Service

20 Page vi Fish Study Conclusions In addition to stating the results of the studies respond to the objective State whether or not sublethal effects are occurring to bottom feeding fish

21 Page vii Sediment Sampling and Toxicity Tests Conclusions The data do not fully support the conclusion that Areas 3 and 6 do not exhibit biologically significant toxicity (see Comments on Section 60) Toxicity to one or more organism were documented in the test results for one or more samples Revise

22 Page vii Sediment Sampling and Toxicity Tests Conclusions The data presented in the ARI Report are not sufficient to conclude that cadmium copper lead nickel and zinc do not cause toxicity in the canal sediments because the causative agent(s) cannot be determined directly from the toxicity tests In fact toxicity documented in the toxicity tests and SEMAVS data indicate that in many of the sediment samples (SEMAVS results greater than 1) metals may be bioavailable This would indicate that these metals have the potential to contribute to some of the observed toxic effects In addition the cumulative effects of the metals should also be considered Although it is fair to speculate that the toxicity of the metals may be mitigated to some unknown degree by the presence of organic material in the sediments study results are not sufficient to conclude that metals do not contribute to toxicity Also SEMAVS does not account for metals that are not divalent It should be noted that the body of literature regarding the predictive power of SEMAVS has not concurred on the absolute ratio of 1 as a decision point Revise this discussion

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o 1^ EPA Comments on Pine Street Draft ARI Report - October 15 1996

Overall ConclusionsConceptual Model

23 General See comments on the Executive Summary and revise overall conclusions accordingly

24 Page viii This section is missing a discussion on a major objective of the ARI studies which was to determine the extent and magnitude of contaminants in surficial soils and sediments and measure site-specific ecological toxicity Please add a summary of conclusions relating to this objective

25 Page viii paragraph 2 This paragraph overstates what has been documented about water quality in the canal The canal may provide some nutrient and sedimentation retention functions but the degree to which these occur is not documented in the ARI Report Speculation on processes not documented by the ARI data must be omitted from the Executive Summary

26 Page viii paragraph 2 There is no evaluation in the text comparing inflow water quality to outflow water quality In addition this could only be done for PAHs since the outflow samples were only analyzed for PAHs A review of Section 54 shows that PAHs were not detected above the Method Detection Limit (MDL) in either the inflow or the outflow Therefore it does not seem that any statement can be made regarding the effect that the canal has on inflow water A similar analysis cannot be done for metals so the effect of the canal in relation to metals retention is unknown Add a discussion of this topic to the report and revise this section accordingly

27 Page vii last paragraph The conclusion that the contamination is becoming less accessible to animals as a result of natural processes is not supported by data There were no studies designed to evaluate the rate of canal sedimentation or historic sedimentation Soil formation processes were not documented in these studies and rates of sedimentation in the canal were not measured Therefore data are not sufficient to document trends over time In fact one could argue the opposite - that in the decades since the disposal of MGP wastes sedimentation has not isolated the contaminants from organisms in a large portion of the canal based on the results of the sediment sampling and toxicity tests Speculation on processes not documented by the ARI data must be omitted from the Executive Summary

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If EPA Comments on Pine Street Draft ARI Report - October 15 1996

INTRODUCTION

28 paragraph 1 It should be noted that although the Baseline Risk Assessment did consider potential future risk from use of groundwater as a drinking water source the recommended remedy in the Proposed Plan was not based on the assumption that groundwater would be used as a potable source Maximum Contaminant Levels (MCLs) were not considered ARAR and the previously proposed remedy was not intended to restore groundwater for use as drinking water Revise the text

29 Page 2 paragraph 3 See General Comment 3 The discussion of the ARI contractors should be moved to Section 22 otherwise all contractors for all investigations should be listed

30 Page 2 paragraph 3 It appears that not all of the contractors hired by the PRPs are listed GEI and Alcyon are not listed Please ensure that the list reflects all the contractors hired by the Performing Respondents and not only the contractors subcontracted by the Johnson Company

31 Page 3 Contaminant Fate and Transport Add two issues which were evaluated as part of the ARI - the presence and likelihood of migration of LNAPL and the potential for vertical migration of contaminated groundwater

32 Page 4 paragraph 2 The bioremediation study is not discussed in this ARI report therefore this section should refer to the future bioremediation report and not make conclusions which are unsubstantiated in the ARI report

33 Page 4 paragraph 2 Revise the conclusion regarding sedimentation See previous comment

34 Page 5 paragraph 2 Stormwater sampling was limited and only represents specific precipitation events Overall loading from the storm sewers has not been documented sufficiently to make conclusions regarding significance of inflow of inorganics Please note here that inorganics were not measured in the outflow sampling

35 Page 6 paragraph 2 Section 11 of the ARI Report summarizes the future health risk if groundwater at the Site was ever developed as a potable water source However the risk assessment is incorrectly summarized in the PSBCCC recommended response presented in this section The response states that the EPA Human Health Baseline Risk

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it EPA Comments on Pine street Draft ARI Report - October 15 1996

Assessment determined that there were no unacceptable health risks at the Site It would be more accurate to state that estimated upper-bound cancer risks exceeded EPAs target risk range only for the pathway of ingestion of site groundwater as a source of potable domestic water (MampE Baseline Risk Assessment Final Report Pine Street Canal Superfund Site prepared for US EPA May 1992 page 4-3) To be more complete it could further be added that the estimated risks were subject to uncertainty Site-specific uncertainty included elevated detection limits due to matrix effects (MampE 1992 page 4-4) and the lack of an estimate of the risk of localized (rather than systemic) effects due to dermal contact with PAHs (MampE 1992 page 2-40) Please clarify in the text

36 Page 6 last paragraph Provide supporting datadiscussion for the conclusion that there are no short term risks associated with acute or chronic health effects at the Site that would require that access to the Site be restricted

37 Pages 5-7 Human Health Risk The pathways which were listed by the PSBCC as requiring additional consideration also included exposure to the lake Champlain swimmerwader potential exposure of individuals who might use the Lake as a drinking water source and potential exposure of consumers of fish to metabolites of PAHs Add discussion related to these questions

38 Page 6 first question This section states The additional data does not indicate any higher reported concentrations than those used in the HHBRA therefore the original findings of no human health risk still stands This statement is incorrect for surficial soils and sediment There were numerous contaminants measured in surface soil during the ARI which exceeded previous concentrations as reported in the 1992 risk assessment This does not mean risks need to be recalculated but the results should be reported correctly and the rationale for any conclusions clearly conveyed

For other data collected during the ARI such as groundwater in the sand lens and fish the above statement does not apply since these media were not previously evaluated For the landing pad the above statement is correct and for surface water in the Lake it is incorrect Please be clear about which media had higher concentrations of contaminants as measured during the ARI as opposed to those reported in the 1992 HHBRA

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EPA Comments on Pine Street Draft ARI Report - October 15 199 6

39 Page 7 paragraph 2 The statement that there are no unacceptable risks associated with worker exposure to contamination at depths below five feet is misleading A reader could easily conclude that it is safe for workers to work below five feet In fact the conclusion of the position paper is based on the fact that excavation below five feet was found to be unlikely and was therefore not evaluated The position paper specifically notes that if excavation were to occur below five feet the risk should be reevaluated Revise

40 Page 7 Ecological Risk This section does not list one of the primary questions relating to potential exposure of ecological receptors - the magnitude and extent of contamination in shallow surface soils at the Site Correct

41 Page 7 Ecological Risk Add a summary of conclusions to this section regarding exposure and effects of site contaminants

42 Page 7 Ecological Risk Note that the Ecological Workgroup agreed that the terrestrial exposure pathway was not likely to be significant as determined in the SRI and was excluded from further consideration

43 Page 8 1st question Delete the last sentence in the response It has not been demonstrated that the depletion in DO and sulfide concentrations are not contaminant related in fact they likely are

44 Page 8 Section 13 It is suggested that the Purpose of Report be moved to Section 11 in order to clearly explain to the reader how the report will be structured to present the results of the ARI while utilizing all RI datainformation as appropriate to present a comprehensive nature and extent of contamination

45 Page 9 1st paragraph This section should have a discussion of the changing of the site Boundaries The original site boundary and area of investigations included the Blodgett and Maltex properties

46 Page 9 2nd paragraph Section 751 does not exist Please revise

47 Page 10 paragraph 1 Include a mention of the Martin Marietta landfill including location and dates of operation

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-7 EPA Comments on Pine street Draft ARI Report - October 15 1996

48 Page 13 paragraph 3 The February 10 1995 PSBCCC position paper on synergy and antagonism between coal tar contaminants at the site states that the EPAs baseline risk assessment is sufficiently conservative to accommodate the possibility of some synergistic effects between chemicals It changes the meaning to state in the ARI Report that the baseline risk assessment accommodates any possible synergistic effects that may exist among site contaminants This statement must be modified to reflect the original intent of the position paper

49 Page 14 4 Explain the screening approach agreed upon by the PSBCC and outlined in the position paper Add a table to the position paper comparing the range of measured concentrations frequency of detects maximum detected values location of max and lowest of EPAs MCLs PCMLs or risk-based level Explain why all 46 COCs were not analyzed for (as stated in the position paper) and how this impacts the conclusions

50 Page 15 6 Replace this section with the Summary from the position paper

51 Page 15 Literature survey This section should be combined with Section 22112 on page 33

52 Page 17 References The list of references is incomplete Correct

20 SITE INVESTIGATIONS

53 Page 18 Section 21 It is suggested that the title be changed to Overview of Previous Investigations Include the exact title and dates of the previous investigation reports It is this section that allows the Performing Respondents to incorporate by reference the previous investigations In order to accomplish this a clear cross reference system is necessary

54 Table 21-1 Collection of air samples was performed by EPA and not MampE Please correct See and reference EPA 1990a reference in the Supplemental RI report

55 Table 21-1 The text in the Type of Investigation column for CERCLA Baseline Risk Assessment belongs in the description of the Supplemental Treatability Study

56 Page 23 paragraph 1 Add a reference to the SonarROV study report here and in the reference section

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57 Page 24 Field Sampling It would be helpful if the sampling methodology was summarized here since it is important in the evaluation of differences in the 1994 and 1995 data

58 Page 29 Preliminary Air Assessment Summarize the meteorological criteria

59 Page 30 Avian Dietary Study See general comment regarding the avian dietary study

60 Page 32 paragraph 1 Also reference fish tissue and bile analysis completed by USFampW

61 Page 41 Section 23 See General Comment 2 Section 231 should include a discussion of the entire database including all investigations In order to present a comprehensive report identification and description of all data sources is essential Include the sampling party designations other than the Johnson Company since other designations are referenced throughout the text

62 Page 44 1st paragraph Reference the database user manual by name and date

63 Page 46 paragraph l The presentation of laboratory flags may cause confusion with respect to the difference between laboratory flags and data validation Although presentation of the laboratory flags is useful information data validated in accordance with EPA validation guidelines should not retain any laboratory qualifiers The summary tables in the ARI Report should contain validated data without laboratory flags and the only unvalidated data in the report should be presented on laboratory summary forms It is suggested that this section focus on data validation rather than laboratory flags

30 ENVIRONMENTAL SETTING

64 Page 50 2nd paragraph Suggest using more current demographics

65 Page 50 4th paragraph See General Comment 3 Include key figures in the ARI report such as property lines Do not refer the reader back to previous reports for information other than detailed information regarding the previous studies and the actual data

66 Page 51 Maltex Suggest using more recent demographics

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67 Page 52 6th paragraph Current zoning Use the same language used in Revision 1 of the AFS work plan and include a figure of the current zoning

68 Page 52 paragraph 2 Briefly explain balanced using the least-squares methods and what is meant by an accuracy of 150000

69 Page 54 Bathymetry Before presenting elevations for above mean sea level of ground surfaces and the canal bottom it is recommended that the range of typical elevations of Lake Champlain be provided in order to furnish more context for understanding surface elevation relationships

70 Page 58 Subglacial Sands and Silty Gravels Please correct the spelling of Wisconsinan in the text throughout this section when referring to the Pleistocene-aged glaciations Also provide references for information stated in this paragraph In addition state where on the Site the till(s) may be located

71 Page 61 paragraph 2 The reference to Hunt 1980 is not in the reference list for this section Please add

72 Page 62 paragraph 1 In the fourth sentence the text should state that the sharp decrease in grain size is more likely associated with a rise in the Lake stage not a drop in the Lake stage The text should include a discussion of this possibility

73 Page 63 paragraph 2 According to Stewart and MacClintock (1969) a reference cited earlier in the text a post Lake Vermont erosion interval occurred before the invasion of the Champlain Sea resulting in weathering and fracturing of the lake clays prior to deposition of the marine sediments This information should be included in the discussion on potential vertical migration pathways in the silt-clay

74 Page 68 paragraph 5 Since the Hydrogeology at Maltex Pond is presented in section 341 it would be useful if the text in this section included a more detailed discussion of the geology at that particular location

75 Page 70 paragraph 2 For the purpose of comparison provide an estimate of bedrock hydraulic conductivity in feet per day

76 Page 72 last paragraph Please provide a reference for the groundwater maps

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77 Page 78 paragraph 3 The depression in the potentiometric surface for fill that appears to persist southwest of the Maltex Building is potentially important because it indicates the possible presence of a groundwater sink to which contaminants could migrate The most likely cause presented is leakage downward through boreholes into a deeper silty layer that serves as a conduit to Lake Champlain This explanation is not totally satisfactory because water levels are generally below lake levels The possibility of a response to pumping from nearby groundwater production wells should be considered It is noteworthy that water levels in Well MW-109 parallel water levels in deep gravel and bedrock wells during the period from March through September 1995 suggesting a connection between the two units The possibility of erroneous water-level measurements or measuring point elevations should also be considered For example a measurement reported in Appendix 34-1 for 51295 indicated the well was dry but measurements a week before and after this date showed at least 6 feet of water in the well It seems unlikely that the well would have dried and refilled in such a short time interval This observation prompts questions about other water-level readings for this well Expand the discussion to address these alternative explanations

78 Page 82 paragraph 4 Add the source for the information that MW12 and MW13 are hydraulically connected with the Silty Gravel and Bedrock Aquifers

79 Page 85 paragraph 3 The text should state if additional wells were monitored during the test and if so what observations were noted

80 Page 87 paragraph 2 The last sentence states that there are consistently upward vertical gradients observed in the silt-clay and refers the reader to Table 34-2 However this table indicates that downward vertical gradients have been observed in the silt-clay The text and the table should be clarified

81 Page 90 paragraph 1 Does this total watershed acreage of 150 acres include the 70 acres of the site If so state that the site accounts for a significant portion of the drainage area If not the site should be included in the total watershed acreage

82 Page 90 2nd paragraph Note that the beaver dam is an ephemeral feature over the history of the site and will likely be as well in the future In fact in a number of years it is to be expected that the beaver will deplete

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their food source at the site and be forced to move on

83 Page 97 second paragraph It is unlikely that a larger monitoring duration would account for the pH range in the deep turning basin unless the snowmelt event were included Explain why these pH readings are so high

84 Pages 98-99 Dissolved Oxygen This section indicates that low dissolved oxygen in the canal in warm weather is unrelated to contamination In actuality biological degradation of some contaminants probably does contribute to oxygen consumption during these periods Chemical oxygen demand may also be a contributing factor Neither was measured Revise

85 Page 100 Specific Conductance The relatively high specific conductance readings exceeding 1000 micromhoscm most of the time at all monitoring points are unusual for water bodies even polluted water bodies in New England Specific conductance readings exceeding 4000 micromhoscm at time at the deep turning basin seem especially high Please discuss the relatively high conductances and compare with specific conductance readings for groundwater

There are some questions regarding the accuracy of these measurements During the week of August 14 1995 the USFWS and EPA staff were conducting the electroshocking activities in the canal Conductivity measurements were taken and while elevated they did not approach the levels documented in the ARI It also should be noted that on the 15th the peak measurement recorded likely was due to the disturbance in the canal due to the electroshocking activities

86 Table 36-1 It is recommended that note number 3 be eliminated as it is unnecessary and confusing since the period reported by the table does not include 81195

87 Page 104 paragraph 3 Provide a citation (Environmental Laboratory 1989) for the Federal Manual for Identifvinq and Delineating Jurisdictional Wetlands and include this in the Reference List for section 3

88 Page 104 paragraph 4 Provide a date of publication in the text for Cowardin et al (1979) and include this in the Reference List for section 3

89 Page 105 paragraph 1 Provide a citation in the text for the Soil Survey of Chittenden County Vermont and include this in the Reference List for section 3

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90 Page 106 paragraph 2 Include a full reference for Fitzgerald 1993 in the Reference List for section 3 In addition it should be noted that the action was conducted by EPA Region I not Vermont DEC

91 Page 106 paragraph 4 Clarify the second sentence by defining xenobiotic chemical contaminants

92 Page 107 paragraph 2 See previous comment on dissolved oxygen measurements

93 Page 108 paragraph 1 Nutrient inputs were not measured therefore this is supposition Revise


40 NATURE AND EXTENT OF CONTAMINATION

95 Page 123 Section 40 Section 40 should not focus only on the ARI results Having presented the ARI investigation in Section 22 Section 40 should draw upon all investigation to create the nature and extent of contamination For example Section 40 presents many tables showing ARI data If it assists the discussion to summarize portions of data be sure to summarize all data that is relevant to the topic Similarly a discussion of why previous data is not utilized should be presented

96 Pages 124-125 Manufactured Gas Plant Make sure all wastes and byproducts are discussed here The text fails to mention the use of fuel oils by the MGP plant and the presence of metals and sulfides as byproducts Please see the Supplemental RI Report (MampE1992) for a complete description

97 Page 126 paragraphs 2 and 3 State the basis for the assertion that the wastes from the coal sheds and asphalt plants would have contributed PAH contamination to the site If there is no site-specific knowledge you should only state that these operations may have contributed contamination Paragraph 4 Provide a full reference for Weston 1996

98 Page 127 paragraph 1 Include a map of the Pine Street watershed and a description of industrialcommercial land uses within the drainage area See previous comment regarding the question of whether the site is included in this watershed

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73 EPA Comments on Pine Street Draft ARI Report - October 15 1996

99 Page 127 paragraph 1 Add a statement referencing site-specific stormwater data

100 Page 127 paragraph 4 The term free phase refers to a separate non-aqueous phase and should not imply mobility unless it is preceded by the term mobile Revise the text

101 Page 129 2nd paragraph The term FS (p 1-14) is a non-descriptive reference Please use more complete references

102 Page 130-194 The text of this section references Phase I and II data presented in the Appendices The data in these appendices is the unvalidated laboratory data Replace this data with the validation reports including the summary tables of validated data

103 Page 135 last paragraph How are the areas of the Site described here related to the numbered Phase II sampling areas within the Area of Focus This is confusing Please clarify

104 Pages 147-149 Screening Methods Evaluation In evaluating the correlation of the Quantix immunoassay kits to laboratory data the ARI appropriately used a pairwise correlation as described in Appendix 43-2 However Table 43-2 and the accompanying text appear to compare means and ranges for the two complete data sets for each study area This comparison does not seem meaningful and should be explained or removed

In addition the correlation described in Appendix 43-2 appears to be based on the logs of the data pairs Taking the logs of the data results in better correlation However the resulting best-fit straight line shows that the Quantix results are 66 higher than laboratory results (using the graphical presentation and the best-fit straight line shown in the appendix) not 25 as reported by Idetek For example using the best-fit straight line a Quantix result of 10000 ppb corresponds to a Laboratory result of 6000 ppb Using the best-fit straight line with the outlier removed results in an even greater discrepancy

The ARI Report discusses the better correlation between immunoassay screening results and the laboratory confirmation sample results for low molecular weight PAHs such as for the samples from the Canal and the Turning Basin If this correlation is superior to the overall correlation noted above then the statistics should be presented for this subgroup While in general it appears

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that the Quantix PAH results were reported at concentrations higher that the laboratory results PAHs with high molecular weights were under-reported These are two opposing trends which should be discussed

The ARI Report concludes that the X-Ray Fluorescence (XRF) metals screening data provided a useful screen for elevated concentrations of copper lead nickel silver and zinc A statistical analysis should be presented correlating XRF data and laboratory data for these elements

105 Page 148 Table 43-2 Also include a table summarizing results from the 10-25 cm stratum

106 Page 154 paragraph 2 The proper citation for ERLs and ERMs is Long and McDonald 1995 Make sure that these updated values are the ones used throughout the document

107 Page 157 paragraph 2 The third sentence refers to a very heterogeneous area Please clarify if this refers to physical or chemical heterogeneity

108 Page 165 paragraph 5 The text states that based on a comparison of Quantix immunoassay and laboratory results presented in table 43-2 there are no areas of potential concern in the wetlands However based on a review of table 43-2 laboratory results in the wetlands south of north road had a minimum reported result of 661 ppm total PAHs which exceeded the 40 ppm total PAHs threshold defining areas of potential concern In addition other reported values in the table indicate that the 40 ppm threshold was exceeded at other wetlands locations The text should be explain the rationale for the use of only part of the data or be revised to reflect all the reported data

109 Page 173 paragraph 1 The highest concentration of total PAHs shown in Table 43-9 for a laboratory analysis of a Turning Basin sample is 217 ppm not 15 ppm as stated in the text Please correct whichever value is in error

110 Page 173 paragraphs 1 and 2 In both paragraphs it is recommended that the term these areas be defined in the text as it is unclear if the term refer to all six access areas or areas H5 and H6 which were mentioned in the text previous to these paragraphs

111 Page 173 paragraph 2 The first sentence of the paragraph introduces lead and zinc as contaminants however the subsequent text presents information regarding only the

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contaminant lead without a further discussion of the zinc results Please include a discussion of the zinc results

112 Page 173 paragraph 2 A comparison is made to urban industrial background values for lead Please present a typical range of urban industrial background particularly in Vermont and provide a reference

113 Page 174 paragraph 3 The text states that the results for semivolatile organic analysis for the landing pad were below the method detection limit Based on a review of the validated data semivolatile organic compounds were detected below the contract required quantitation limit (CRQL) but above the sample-specific detection limit (or method detection limit) and are considered usable data Please revise to use the correct term for the type of detection limit in the text and summarize the reported results in this section with the other laboratory data for the landing pad

114 Page 174 paragraph 3 and page 175 Table 43-10 The intent of the text regarding arsenic concentrations their comparison with concentrations in the area east of the canal and the laboratory confirmation sample concentration range is very unclear Clarification of the text should include the numerical values for arsenic concentrations used for comparison the criteria for evaluating the data against data from the area east of the canal and an explanation of the laboratory confirmation sample concentration range defined in the text as 135-27 mgKg

115 Page 181 third paragraph The difference in vertical distribution of inorganics versus tPAHs in the two data sets could also likely be due to biodegradation occurring for the tPAHs in the aerobic zone leaving the inorganic concentrations unaffected Discuss

116 Page 182 second paragraph This conclusion regarding the metals concentrations can not be stated without performing a statistical test to determine if in fact these concentrations represent a distinct population from those observed elsewhere on the site the area being referenced is not clearly defined

117 Page 188 paragraph 2 Soil concentrations of total PAHs less than 100 ppm are referred to as low even though this concentration could pose risks to various receptors Subjective descriptions must not be used unless a comparison is made such as comparison to background or comparison to risk ranges

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118 Page 189 Table 43-14 This table inappropriately groups all sediment and surface soil data and compares them indiscriminately with benchmark information regardless of exposure scenario and or applicability Revise into a series of tables making the appropriate comparisons (ie ecological exposure site visitor industrial workers in north and south of site recreational use) Use correct current and primary references For example risk-based levels (EPA Regions 3 and 10) should be used for human health comparisons for the appropriate exposure scenario

Add the maximum minimum and mean concentration detected in surface soils and sediments so that a comparison to the risk-based soil levels can be made Without this comparison the data gap regarding accessible surface soil areas and human health cannot be answered

119 Page 195 paragraph 1 For the purposes of calculating sums and means a non-detected result is usually not assigned a value of zero but rather the value of one-half its detection limit This could be significant in situations such as the evaluation of data from the Pine Street Site because elevated detection limits may mask obscure contaminants present below the sample-specific detection limit It appears from some figures that the ARI Report did use one-half detection limits for non-detects Use one-half the detection limits throughout the report Clarify and revise

120 Page 197 paragraph 3 According to Table 34-2 both downward and upward vertical gradients were observed within the silt-clay unit however the table does not mention neutral gradients as is stated in the text of this section It is recommended that the text be revised for consistency

121 Page 198 paragraph 1 Change the term metals to inorganics as cyanide is not a metal

122 Page 212 paragraph 4 Section 53 discusses potential contaminant migration via the deltaic deposits in the vicinity of MW-17 however a detailed discussion of the geology at that location has not been included Please provide a description of the geology around MW-17 in this section

123 Page 213 paragraph 3 The term sand lens is introduced for the first time in this section and is referred to extensively in Section 4523 It is recommended that the term be presented and defined earlier in the report (ie in sections 33 or 34)

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124 Pages 217-220 EPA agrees that contamination found in groundwater at MW-17 has not significantly changed in four years and that contamination at this point may be in a state of equilibrium An equilibrium state does not imply that contaminants are not continuing to migrate However the report uses PSP2 which is not impacted by contamination although it is downgradient of a NAPL source to support the claim that sorption and biodegradation are effectively limiting contaminant transport at the site It is not appropriate to use this example to characterize contaminant transport at the entire site A more plausible explanation is that migration occurs principally in more discrete preferential pathways that were not sampled during this investigation The study does not provide adequate support to quantify attenuation processes or conclude that contamination detected in MW-17 does not reach the lake

125 Page 217 paragraph 4 The paragraph regarding metals migration to MW-17 is not clear in the point it is making The supposition is apparently that metals are not migrating to MW-17 however the distribution of organic contaminant concentrations does not seem relevant to metals migration Description of metals as hydrophobic on page 220 is inappropriate metals may be more or less immobile based on which form they are found Revise the text

126 Page 218 Table 45-4 Please account for blanks in the MCL column (ie none established etc)

127 Page 219 Table 45-6 Please reference the meaning of dashes in the MCL column

128 Page 220 paragraph 2 This paragraph states that the sand lens is found only in the northern end of the Site and that sand reported at the Martin Marietta property is not related depositionally to the sand lens This conflicts with the text in Section 33 on page 67 which appears to state the opposite Please clarify the text

129 Page 224 paragraph 3 and page 226 bullet 1 Surface water samples are not normally filtered prior to analysis The text should state whether sampling notes indicate that samples contained significant amounts of suspended sediment since samples collected in still water would not be expected to have significant suspended sediment Also PAHs and metals sorbed to suspended sediments may still be available to receptors and should not be discounted Revise the text accordingly

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130 Page 227 paragraphs 1 and 2 and page 228 paragraph 2 Correct the text to note that EPA conducted the air sampling described not MampE The PEER air data was not validated or used in the SRI report because of data (juality problems

131 Page 228 The 1990 air sampling was performed by EPA Please correct and reference source documents

132 Page 235 Table 47-4 Identify the source of Hazardous Ambient Air Standards in this table

133 Page 236 paragraph 3 When discussing the anomalous benzene concentrations it would be relevant to include information regarding the unusually high toluene result at station J_A-004 reported for 722-2393 despite the fact that it was detected at a different sampling station on a different sampling date

134 Page 237 paragraph 2 The text should clarify what is meant by outlier since in the previous paragraph it was concluded that the benzene result was a real value An explanation should be provided on the usenonuse of this data

50 FATE AND TRIOISPORT

135 General The report builds a coherent hydrogeologic conceptual model based on currently available data This model is used to evaluate potential contaminant transport The report concludes that the potential for significant migration of nonaqueous phase liquids under current hydrologic conditions is very low This appears to be a reasonable evaluation based on the physical data and the geologic model for the site However several conclusive statements are made regarding aqueous-phase contaminant migration potential and other site processes As noted below significant uncertainty regarding several of these issues exists due in part to subsurface heterogeneity and lack of detailed studies to define processes and rates Detailed comments regarding these areas of uncertainty and other concerns are discussed below Please discuss uncertainties related to all conclusions

136 General The report makes several general statements regarding subsurface biological degradation processes at this site In general many of the compounds of concern particularly the lower molecular weight and more mobile organic compounds are potentially degradable through biotic processes Such processes are likely occurring to some extent in some parts of the site However studies to

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obtain data to define the geochemical environment in specific areas of concern and estimate these rates have not been conducted Therefore significant uncertainty exists as to the extent to which these processes may be relied upon to limit contaminant transport or reduce contaminant concentrations in specific areas within reasonable time frames Revise the discussion on subsurface biological degradation to reflect the significant uncertainty

137 Pages 239-242 DNAPL Migration The text should provide a sensitivity analysis of the equations presented For example explain how the capillary pressure barrier would change if the assumed grain size of the siltclay or the sand were to increase or decrease by half an order of magnitude (a reasonable range)

138 Section 53 The report makes conclusive statements regarding the potential for benzene migration to Lake Champlain The studies which were conducted between the canal and the lake serve to further limit estimates of the potential area impacted by such migration and may be used to limit estimates of contaminant flux to the lake However these studies did not characterize transport and fate processes in sufficient detail to fully support the transport calculations and conclusions drawn in this report

The calculations used to evaluate transport to Lake Champlain are based on relatively homogeneous assumptions As at most sites uncertainty exists in the characterization of site conditions As indicated in cross sections the geology between the canal and the lake is relatively heterogeneous This generally results in significant heterogeneity in the hydraulic conductivity distribution and the potential for significant impact on contaminant migration In addition the range of potential half lives for benzene used in this report was developed from a very limited literature base and may not be fully representative of site conditions

The range of rates used in this document was based on the assumption of aerobic degradation Geochemical conditions in this area of the site have not been studied Aerobic conditions may not exist throughout the zone in which benzene is transported In the current setting (ie NAPL contamination relatively high natural organic carbon etc) the potential exists for oxygen depletion Transformation time frames in other geochemical settings may be longer than anticipated in this analysis It should also be noted that relatively few in situ studies have been conducted in sufficient detail to allow accurate estimation

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of degradation rates Therefore the maximum half life used in this analysis may not be as conservative as indicated in the report

Calculations of contaminant concentrations at discharge also depend in part on the assumed initial concentration It appears that benzene transport may be through a relatively limited portion of the formation in this area possibly through relatively higher conductivity pathways In this case contaminant concentration in these zones may be significantly higher than concentrations in samples obtained from a monitoring well that samples a mixture of waters from different zones Such mixing results in dilution in the well Please acknowledge these uncertainties be acknowledged and qualify definite statements regarding contaminant migration

139 Page 244 Table 53-1 Footnote 2 regarding inaccurate hydraulic conductivity calculations in MampE 1992b should include the complete reference for the MampE report including the page number Neither EPA nor MampE are aware of any inaccurate calculations

140 Page 246 paragraph 1 The estimated fraction of organic content of 0005 to 001 (05 to 1 by dry weight) appears to be high for the silty sand lens which has not been exposed to organic soil forming processes A lower value should be used as an upper bound

According to Table 34-2 both downward and upward vertical gradients have been observed within the silt-clay unit This information seems to differ from the that which is stated in the last sentence of the paragraph Revise the text for consistency

141 Pages 251-255 Sections 535 The report indicates that biodegradation prevents benzene detected in well MW-17 from reaching the lake This conclusion is based solely on a contaminant transport calculation using an assumed half life for benzene in groundwater As noted above data necessary to fully characterize the potential role of biotransformation at this site have not been obtained The actual half life may be significantly greater than the value chosen to represent the site (23 days) and may be greater than the value chosen as the potential maximum (100 days) The sensitivity analysis provides some idea of the uncertainty associated with this parameter

The hydraulic conductivity chosen for this evaluation also will significantly affect the results The number chosen to

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represent the silty sand may be a good estimate of the bulk or average hydraulic conductivity in the vicinity of well MW-17 In this respect it may be an appropriate number for estimating average contaminant flux to the lake However geologic logs and cross sections indicate significant heterogeneity in this area The hydraulic conductivity of the units may vary by several orders of magnitude In this setting calculations based on homogeneous assumptions are limited in their predictive power At a minimum the sensitivity to this parameter should be tested by varying hydraulic conductivity by one and then two orders of magnitude

142 Page 253 paragraph 1 last bullet The last variable states that peat occurs immediately below the sand however it is possible that the reverse is true If the later is the case then the text should be corrected

143 Page 256 Section 542 This model was not agreed to by the Fate and Transport group as part of the Statement of Work It is unclear whether the model is intended to be a conceptual model or a quantitative model It is unclear how the model principals were applied to the site The site-specific calculations must be provided for review

144 Page 257 Section 5421 Use of an asterisk to symbolize multiplication is confusing in this calculation because the same symbol is used later on the same page as a footnote marker It is suggested that the symbol x should be used to represent multiplication

145 Page 257 Section 5421 This discussion of stream power does not provide quantitative support for the authors belief that resuspension of organic sediments would not occur during a 25-year storm A calculation or reference must be provided that supports that statement

146 Page 257 Section 5421 The last equation on the page does not account for differences in sediment grain density A discussion of the applicability of the model to highly organic sediments that may be closer to neutral buoyancy (in water) than to the density of typical mineral grains should be presented in this section

147 Page 260 paragraph l Sufficient data are not available to fully evaluate the extent to which sedimentation is occurring in the canal and potential rates Sedimentation processes may take relatively long periods of time (eg decades or longer) to sufficiently limit potential contact with contaminated sediments Under low-flow conditions the

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canal probably is a relatively effective sediment trap as indicated by the relatively low turbidity measured during some rainfall events and the canal configurations However the total suspended solids content of the water entering the wetlands from the storm sewers also appeared to be low during these events The extent to which these conclusions may be applied to periods of higher flow (eg major rainfall events or breaching of the beaver dam) is not clear Limited data obtained during the rainfall of August 11 1995 indicated significantly higher turbidity in the canal than during the events analyzed in detail in this report

148 Pages 260 -261 Section 5422 The discussion of sediment transport in the canal states that a decrease in flow velocity occurs in part because of the decrease in water surface slope caused by beaver damming at the canal outlet In fact between 1989 and 1991 the beaver dam was not present at the outlet and the canal was open to Lake Champlain The text should discuss what would be expected to occur in the absence of a beaver dam In fact in the near future the beaver will have depleted their food source and will be likely to move on

149 Pages 260 -261 Section 5422 Since the text relates sediment removal efficiencies to watershed area the report should show a map of the watershed area and estimate its area The calculation of canal flow velocity from a 25-year 24-hour storm must be presented in an appendix A 24-hour storm is typically less intense than a shorter duration storm and could result in lower flow velocities The reason for choosing a 25-year 24-hour storm must be discussed

150 Pages 260 -261 Section 5422 It would be instructive to calculate the theoretical canal flow velocity that would have occurred during the August 11 1995 storm and beaver dam breach since that resulted in a high sediment load and to estimate the frequency of such a storm

151 Pages 263-272 Section 5441 The report is not clear regarding exactly where the outflow surface water sampling location was performed and if it was upstream or downstream of the beaver dam This information must be included because it would significantly impact sediment loading

Conclusions regarding ARI outflow sampling should be included in this section On page 5 the report concludes that site contaminants are not transported to Lake Champlain based on outflow sampling however samples were not collected during the storm which created the maximum

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turbidity (off-scale) on August 11 1995 It appears that a major storm event and beaver dam breach could create contaminated sediment discharge to the lake (This is noted in a conclusion in Section 7)

152 Page 276 paragraph 1 Clarify the first sentence Were the metals detected in stormwater inflow samples ubiquitous at all locations of Inflow seunples or at the entire site

153 Page 278 Add a discussion comparing inflow sample results to outflow sample results

60 ECOLOGICAL IMPACTS

154 General This section is missing a discussion of the results of the C tentans 28-day test Add this discussion and conclusions

155 Page 287 Table 6-21 Clarify the sample numbering scheme for the proposed locations in Area 6 Table 62-1 indicates locations proposed for toxicity testing were J_T11-1 J_T13shy3 and J_T15-4 while Figure 62-1 shows Tll-1 T13-53 and Tshy15-4 It appears that locations T13-52 and T13-53 were mislabeled on Figure 62-1

156 Page 290 Table 6-22 Clarify in the text why 28-day emergence tests for C tentans were conducted for samples with survival greater than the reference site

157 Page 290 Toxicity Test Results Explain what constitutes statistical significance for each test

158 Page 290 paragraph 2 The text indicates that survival of C tentans was generally greater than 75 except in Area 8 This summary is not consistent with data in Table 62-3 Two of three samples had survival values of less than 75 in Area 7 and one of two samples in Area 5 were also below 75 The text must be corrected to more accurately reflect the data in Table 63-3 In addition the results should summarize the C tentans data indicating where both survival and growth of C tentans were significantly less than the controls (Areas 1 2 5 7 and 8)

159 Page 292 paragraph 1 Clarify the text summarizing the H azteca survival results Data were collected only for areas 1 2 4 5 and 8 The conclusion that survival was generally greater than 80 except in Areas 1 amp 8 does not address the 71 value recorded in Area 5 These results could similarly have been summarized as the survival was greater than 80 only in Areas 2 and 4 In addition the

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results must summarize the H azteca growth data indicating where growth was significantly less than the reference or controls (Areas 1 2 5 and 8)

160 Page 292 PAH Results and Table 62-4 Include an explanation or reference to explain how the values were adjusted for TOC

161 Page 294 paragraph 2 Are there differences in metals concentrations between Phase I and II sampling

162 Page 294 paragraph 2 An explanation is provided for the Ontario Guidance LOEL Provide explanations of what the other benchmark values mean

163 Page 297 paragraph 1 Metals found consistently above the NOAA ER-L (with the exception of silver) may be found in typical gas plant wastes as well as typical urban runoff (Supplemental Remedial Investigation Final Report MampE March 1992) Please compare the concentrations of metals in surface samples to metals in subsurface samples in the location of known gas plant wastes This has already been partially completed in Figures 43-23 through 44-15

164 Page 301 Table 69-9 Data in this table indicate that the sediment composition of the reference location sample (J_T17-1) is dissimilar from the other sediments used in the toxicity testing with a much higher percent solids concentration and possibly a higher sand content This result must be highlighted in the text and the implications of this for the interpretation of the toxicity test results must be discussed

165 Page 302 paragraph 2 The statement that the previous toxicity studies are not indicative of baseline ecological conditions is misleading Although these soils were collected deeper than the sediments in the ARI studies some of the soils were collected as few as several inches from the surface a depth at which earthworms certainly would be exposed Revise

166 Page 303-316 Section 623 The discussion of the results focuses on the survival data from the toxicity tests The growth data are presented in Table 62-3 but are not referred to or summarized in the text or the summary tables (Table 62-10 through 62-17) Analysis and interpretation of these data must be provided

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167 Page 303 paragraph 1 The data analysis includes correlations of toxicity test results between organisms This makes the assumption that the organisms are potentially responding to the same set of variables which cause or mitigate toxicity in the sediments Since the sensitivity of the test organisms to the physical and chemical conditions in the sediments is not precisely known it should be pointed out in the text that correlations between survival of two different test organisms may or may not be expected since they may be responding to different variables present in the test conditions It would be ec[ually valuable for the interpretation of the toxicity data to examine correlations or patterns of individual toxicity test results fc tentans survival for example) against data collected on sediment characteristics (Total PAH concentration SEMAVS results etc)

168 Page 213 paragraph 3 The conclusion that the sediments in Area 3 are generally not toxic is not appropriate Sample T-16-51 with the highest TPAH value (42 ppm) for Area 3 exhibited significantly reduced survival In addition all of the Frog Embryo Teratogenesis Assay - Xenopus laevis (FETAX) results for Area 3 indicate significant differences from controls for survival growth and abnormal embryos The text correctly points out that the FETAX results were not significantly different from the on-site Reference Control however the bioavailability of metals in the Reference Control is elevated Due to the data limitations for the Reference Controls in the FETAX tests conclusions made about significant differences with the controls should riot be made without qualification Since all of the FETAX results from Area 3 are significantly different from the laboratory controls and show high mortality and high rate of abnormalities the appropriate conclusion is that FETAX tests indicated toxicity Revise

169 Page 312 paragraph 5 Since the toxicity tests do not allow distinction between potential agents causing the observed effects the implication that the observed toxicity is more likely to be due to sulfide or ammonia than to PAHs is not appropriate without additional supporting data Revise

170 Page 312 Section 623 The data do not support the conclusion that the sediments in Area 6 are generally not toxic Significantly reduced survival in sample J_T13-3 was recorded in the FETAX tests The remainder of the results from this sample are qualified as outside laboratory QC control limits Toxicity of the sediments for sample

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J_T14-1 is also indicated by the high mortality and increased rate of abnormalities in the FETAX tests These results were significantly different from laboratory controls and within laboratory acceptance criteria See previous comment regarding interpretation of FETAX results with respect to Reference Controls The summary of the results must be amended to reflect that two of the four samples in the FETAX tests showed toxicity

171 Page 314 paragraph 1 Clarify and document the discussion of ammonia concentrations Did the laboratory indicate problems associated with ammonia

172 Page 316 paragraph 3 The data do not fully support the conclusion that Areas 3 and 6 do not exhibit biologically significant toxicity (see previous comment) Toxicity to one or more organisms were documented in the test results for one or more samples It is clear from the discussion that ammonia and sulfide concentrations in the sediments may have the potential to affect the results of the toxicity tests However the data interpretation does not address the issue that toxicity due to ammonia and sulfide may mask the effects of the other contaminants present but if the toxicity form these compounds were absent toxicity from other contaminants may also be detected

173 Page 320 paragraph 3 Provide additional information on the statistical tests performed to determine differences between the reference and control sites If parametric statistics were applied to the Hepato-Somatic Index (HSI) data provide results to show that the data meet the test assumptions (normality homogeneity of variance)

70 SITMMARY AND CONCLUSIONS

174 General Rewrite this section to accurately reflect the text of the report and conclusions supported by data

175 Page 342 Environmental Setting third bullet The text notes eutrophic conditions in the canal however the discussion must acknowledge that chemical residues at the site contribute to the organic enrichment that leads to oxygen deprivation

176 Page 343 Contaminant Distribution Bullet 5 It is not likely that LNAPL has been dissipated by becoming immobile if it is still being detected in on-site monitoring wells This section must also include a discussion of LNAPL measured in wells B-lOlB B-104B and MWll-B during a sampling event in 1989 and NAPL discovered in the during the

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installation of PZ-3 (this fact must also be reported in the ARI Report)

177 Page 343 Add conclusions regarding ambient air

178 Page 344 Migration Potential-Sediment Transport bullets 1 and 2 The qualifications presented in this section must also be reflected in the Executive Summary Section

179 Page 345 bullet 1 This section must also include information regarding the retardation factors in the sand lens which would be expected to be lower since a lower organic content would be anticipated

180 page 346 Toxicity bullets 1 and 2 This summary of the results of the toxicity testing is incomplete and must be expanded based on the data Evidence for toxicity was also documented in Areas 3 and 6 (see comments on Section 60) Since the acid volatile sulfide-simultaneously extracted metals (AVSSEM) values at the reference site were relatively high indicating metals bioavailability it is not appropriate to make unqualified conclusions about the significant levels of toxicity based on comparisons to reference data alone Revise

181 Page 346 Toxicity bullet 6 The data presented in the ARI report are not sufficient to conclude that cadmium copper lead nickel and zinc do not cause toxicity in the canal sediments The causative agent(s) can not be determined directly from the toxicity tests In fact toxicity was documented in the toxicity tests and SEMAVS data indicate that in many of the sediment samples (SEMAVS greater than 1) metals may be bioavailable This would lead to the conclusion that metals have contributed at least some of the observed toxic effects Although it is fair to speculate that the toxicity of the metals may be somewhat mitigated by the presence of organic material in the sediments study results are not sufficient to conclude that metals do not contribute to toxicity It is likely that metals do contribute toxicity in at least some of the sediments Data do not exist to conclude otherwise Revise

182 Page 346 Avian See general comment regarding the avian model In addition this conclusion is not consistent with the results presented in Section 64 Predicted dietary intake of total PAHs for red-winged blackbird using the energy assimilation-based model resulted in an exposure that exceeded the predicted No Observable Effect Level (NOEL) of 1 mgkg body weightday for benzo(a)pyrene

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183 Page 347 Air bullet 1 Without additional data and based on high benzene and toluene values measured onsite there remains some uncertainty with the conclusion that the site does not have an adverse effect on local ambient air The text must be modified to acknowledge this current uncertainty

184 Page 347 Air bullet 1 Page -v- indicates 24 samples were collected Be correct the appropriate page

185 Page 347 Air bullet 1 Without additional data and based on high benzene and toluene values measured onsite there is too much uncertainty to conclude definitely that the site does not have an adverse effect on local ambient air The text must be modified to reflect the current uncertainty

186 Page 347 Section 743 This section is written in a somewhat misleading manner For example Therefore it does not pose a risk to the public as a drinking water supply is incorrect If the groundwater under the entire site or even just in the sand lens unit was used as drinking water supply it would pose a significant risk to the public and the future worker respectively The current groundwater classification only allows for nonpotable commercial uses of groundwater at the site Thus the risk analysis in the ARI for this route only evaluates dermal and inhalation exposures for a future worker for which significant risks were concluded to be unlikely This section must be rewritten to clearly convey this information

FIGURES

187 Figure 33-12 Provide a reference for the information provided in the figure Also the Lake VermontChamplain Sea contact is shown on the figure however page 61 of the text states that this contact has not been determined at the site Revise the textfigure for consistency

188 Figure 33-2 Although it is stated in the figure title a note should be added to the figure clarifying that the contours were generated using both verified bedrock and assumed bedrock data points Several contour lines in the southern portion of the site are difficult to follow and appear to be mislabeled The figure contains many contour lines that end abruptly in the central portion of the figure The figure should be corrected

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PLATES

189 Plate 2 A note should be added to the plate to explain that data for the canal bottom contours were collected by USGS separately from the data used to generate the land topographic contours

APPENDICES

190 Appendix 1 Position Papers Attachment F Attach Figure 1 to this paper

191 Appendix 1 Position Papers Position Papers on Human Health Fish Consumption and the Landing Pad are missing and should be added It is unclear if the Landing Pad paper was ever revised or finalized

192 Appendix 1 Position Papers on Data Gap for Lake Champlain Drinking Water Scenario and Lake Champlain SwimmerWader Scenario present approaches to evaluating ARI data An appendix should be added to these papers with the data evaluation and conclusions

193 Appendix 34-1 Maps 1 through 4 which show hydrologic subunits should define the delineation of the subunits in the legend or refer to where the delineation is covered in the text

Please reference the symbol e which is used in the table of groundwater elevation data Also depth to water measurements are missing from the table for some wellsdates and should be added

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SENDER I also wish to receive the laquo bull Complete itema 1 raquomor 1 for additio ^ laquo bull Complete items 3 end 4a It b following service (for an extra M bull Print your name and addraaa on the reverse of this form so that we can fee) bull return this card to you gt

bull Attach this form to the front of the mailpiace or on the back if space 1 D Addressees Address (0 does not permit bull Write Return Receipt Requested on the mailpiace below the article numlgter 2 n Restricted Delivery bull The Retutr) Receipt will show to whom the article was delivered and the date S

odelivered Consult postmaster for fee bull

3 Article Addressed to 4a Article Number

Mr Chris Crandall Z 276 578 5A9 Vice President 4b Service Type tc

1 Registered G Insured Pine Street SF Project 0oordinat(j) [ 3 Certified D COD s The Johnson Company G Express Mail bull Return Receipt for 3100 State Street Merchandise

Montpelier W 05602 7 Date ofifjjalivei 3 O gt bull

5 Signatlve (Addressee) L f ^ 8 Addressees Address (Only if requested Jt and fee is paid) C

S J i Ishy6 Signsfure (Agent)

gt PS Form 3 8 1 1 December 1991 UA QPa i9eraquo-a6a7i4 DOMESTIC RETURN RECEIPT

shyAlthough EPA has concerns with some of the conclusions reached in the report we do think that the data collected as part of the Additional Remedial Investigation are sufficient to respond to the data gaps identified by the Pine Street Barge Canal Coordinating Council and its workgroups

There are two enclosures with this letter The first attachment sets out EPAs general and specific comments on the ARI Also enclosed is a disk which contains additional corrections and clarifications marked in red-linestrike-out format

If you have any questions regarding the comments please contact Sheila Eckman at (617)573-5784

Sincerely

Mary Jane ODonnell Chief CTMEVT Superfund Section

Enclosures

cc Sheila Eckman EPA Ross Gilleland EPA Margery Adams EPA Susan Svirsky EPA Martha Zirbel MampE Pine Street Coordinating Council



























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28 Page 1 paragraph 1 It should be noted that although the Baseline Risk Assessment did consider potential future risk from use of groundwater as a drinking water source the recommended remedy in the Proposed Plan was not based on the assumption that groundwater would be used as a potable source Maximum Contaminant Levels (MCLs) were not considered ARAR and the previously proposed remedy was not intended to restore groundwater for use as drinking water Revise the text

29 paragraph 3 See General Comment 3 The discussion of the ARI contractors should be moved to Section 22 otherwise all contractors for all investigations should be listed







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31 Contaminant Fate and Transport Add two issues which were evaluated as part of the ARI - the presence and likelihood of migration of LNAPL and the potential for vertical migration of contaminated groundwater





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32 paragraph 2 The bioremediation study is not discussed in this ARI report therefore this section should refer to the future bioremediation report and not make conclusions which are unsubstantiated in the ARI report




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34 paragraph 2 Stormwater sampling was limited and only represents specific precipitation events Overall loading from the storm sewers has not been documented sufficiently to make conclusions regarding significance of inflow of inorganics Please note here that inorganics were not measured in the outflow sampling


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35 paragraph 2 Section 11 of the ARI Report summarizes the future health risk if groundwater at the Site was ever developed as a potable water source However the risk assessment is incorrectly summarized in the PSBCCC recommended response presented in this section The response states that the EPA Human Health Baseline Risk

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39 paragraph 2 The statement that there are no unacceptable risks associated with worker exposure to contamination at depths below five feet is misleading A reader could easily conclude that it is safe for workers to work below five feet In fact the conclusion of the position paper is based on the fact that excavation below five feet was found to be unlikely and was therefore not evaluated The position paper specifically notes that if excavation were to occur below five feet the risk should be reevaluated Revise









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43 1st question Delete the last sentence in the response It has not been demonstrated that the depletion in DO and sulfide concentrations are not contaminant related in fact they likely are





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45 1st paragraph This section should have a discussion of the changing of the site Boundaries The original site boundary and area of investigations included the Blodgett and Maltex properties



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47 paragraph 1 Include a mention of the Martin Marietta landfill including location and dates of operation

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94 5 paragraph 1 Provide a date of publication in the text for Cowardin et al (1979) and include this in the Reference List for section 3






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95 3 Section 40 Section 40 should not focus only on the ARI results Having presented the ARI investigation in Section 22 Section 40 should draw upon all investigation to create the nature and extent of contamination For example Section 40 presents many tables showing ARI data If it assists the discussion to summarize portions of data be sure to summarize all data that is relevant to the topic Similarly a discussion of why previous data is not utilized should be presented




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48 paragraph 3 The February 10 1995 PSBCCC position paper on synergy and antagonism between coal tar contaminants at the site states that the EPAs baseline risk assessment is sufficiently conservative to accommodate the possibility of some synergistic effects between chemicals It changes the meaning to state in the ARI Report that the baseline risk assessment accommodates any possible synergistic effects that may exist among site contaminants This statement must be modified to reflect the original intent of the position paper










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49 4 Explain the screening approach agreed upon by the PSBCC and outlined in the position paper Add a table to the position paper comparing the range of measured concentrations frequency of detects maximum detected values location of max and lowest of EPAs MCLs PCMLs or risk-based level Explain why all 46 COCs were not analyzed for (as stated in the position paper) and how this impacts the conclusions









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50 6 Replace this section with the Summary from the position paper








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108 5 paragraph 5 The text states that based on a comparison of Quantix immunoassay and laboratory results presented in table 43-2 there are no areas of potential concern in the wetlands However based on a review of table 43-2 laboratory results in the wetlands south of north road had a minimum reported result of 661 ppm total PAHs which exceeded the 40 ppm total PAHs threshold defining areas of potential concern In addition other reported values in the table indicate that the 40 ppm threshold was exceeded at other wetlands locations The text should be explain the rationale for the use of only part of the data or be revised to reflect all the reported data




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52 References The list of references is incomplete Correct






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115 1 third paragraph The difference in vertical distribution of inorganics versus tPAHs in the two data sets could also likely be due to biodegradation occurring for the tPAHs in the aerobic zone leaving the inorganic concentrations unaffected Discuss



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119 5 paragraph 1 For the purposes of calculating sums and means a non-detected result is usually not assigned a value of zero but rather the value of one-half its detection limit This could be significant in situations such as the evaluation of data from the Pine Street Site because elevated detection limits may mask obscure contaminants present below the sample-specific detection limit It appears from some figures that the ARI Report did use one-half detection limits for non-detects Use one-half the detection limits throughout the report Clarify and revise





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122 2 paragraph 4 Section 53 discusses potential contaminant migration via the deltaic deposits in the vicinity of MW-17 however a detailed discussion of the geology at that location has not been included Please provide a description of the geology around MW-17 in this section


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128 0 paragraph 2 This paragraph states that the sand lens is found only in the northern end of the Site and that sand reported at the Martin Marietta property is not related depositionally to the sand lens This conflicts with the text in Section 33 on page 67 which appears to state the opposite Please clarify the text


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132 5 Table 47-4 Identify the source of Hazardous Ambient Air Standards in this table






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139 4 Table 53-1 Footnote 2 regarding inaccurate hydraulic conductivity calculations in MampE 1992b should include the complete reference for the MampE report including the page number Neither EPA nor MampE are aware of any inaccurate calculations





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142 3 paragraph 1 last bullet The last variable states that peat occurs immediately below the sand however it is possible that the reverse is true If the later is the case then the text should be corrected






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147 0 paragraph l Sufficient data are not available to fully evaluate the extent to which sedimentation is occurring in the canal and potential rates Sedimentation processes may take relatively long periods of time (eg decades or longer) to sufficiently limit potential contact with contaminated sediments Under low-flow conditions the

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152 6 paragraph 1 Clarify the first sentence Were the metals detected in stormwater inflow samples ubiquitous at all locations of Inflow seunples or at the entire site









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155 7 Table 6-21 Clarify the sample numbering scheme for the proposed locations in Area 6 Table 62-1 indicates locations proposed for toxicity testing were J_T11-1 J_T13shy3 and J_T15-4 while Figure 62-1 shows Tll-1 T13-53 and Tshy15-4 It appears that locations T13-52 and T13-53 were mislabeled on Figure 62-1





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156 0 Table 6-22 Clarify in the text why 28-day emergence tests for C tentans were conducted for samples with survival greater than the reference site




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164 1 Table 69-9 Data in this table indicate that the sediment composition of the reference location sample (J_T17-1) is dissimilar from the other sediments used in the toxicity testing with a much higher percent solids concentration and possibly a higher sand content This result must be highlighted in the text and the implications of this for the interpretation of the toxicity test results must be discussed



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169 2 paragraph 5 Since the toxicity tests do not allow distinction between potential agents causing the observed effects the implication that the observed toxicity is more likely to be due to sulfide or ammonia than to PAHs is not appropriate without additional supporting data Revise


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173 0 paragraph 3 Provide additional information on the statistical tests performed to determine differences between the reference and control sites If parametric statistics were applied to the Hepato-Somatic Index (HSI) data provide results to show that the data meet the test assumptions (normality homogeneity of variance)





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175 2 Environmental Setting third bullet The text notes eutrophic conditions in the canal however the discussion must acknowledge that chemical residues at the site contribute to the organic enrichment that leads to oxygen deprivation


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LETTER REGARDING DISAPPROVAL WITH MODIFICATION … · The Johnson Company . 100 State Street ....

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