Document jVd1odjk3R0Q6B5doYVrqwZp

^?CT^^*w'Tffi^^l.'W..?S*^r'r>^*'"<W^.l<^^ AR226-2539 - -,^ UNITED STATES ENVIRONMENTAL PROTEC'TION A6ENCY mSSlQNIII .^^"^ J 841 Chestnut Building ^JSLIi Philadclphi-, P*nnylvml 19107-4431 May 5, 19$7 In reply Refer to: 3HW90 CERTIFIED MAHt RETURN RECEIPT REQUESTED DATI JIKCIIVKD 57/3^7 ENVIRONMENTAL owci W.M. Stewart Sr. Environmental Control Consultant DuPont Washington Works P.O. Boae 1217 Parkersburg, Wv 26102-1217 Re; Notice of Deficiency Verification Investigation Report Washington Works WVD 045 87 5291 Dear Msr. Stewart; The Vex-lflcation Jnvestigatioa, S.J. du Font de jyeznoures lE Co., Washington Works (Report), dated April 1992 has been reviewed and, although the Environmental Protection Ageaey (SPA) finds deficiencies in the Report, sufficient information i@ included to warrant proceeding with the RCRA Facility Investigation (RFI). Therefore, a RFI work plan ia due within 90 days of receipt of this letter. GENERAL COMMENTS Enclosed is a table identifying deficiencies in the Report. While the comments are written as though the Report is to be revised, EPA is not requiring that the Report be revised. It is considered more important to proceed with the RFI than expend resources revising the Report. However, the items (in the table) in bold do need a response. Please provide a-response within 30 days of receipt of this letter. It is difficult to locate the precise locations of sampling points using the Report's Figure 6. The Report contains a divider marked "Plates" but that section is empty. Please provide three copies of the plate locating the actual sampling points on the Celebrating 25 Years of Environments! Progress CF032526 EID481623 topographic map used in the Verification Investigation Plan, Page 4. Permit Requirement The Corrective Action Permit Attachment 1 required soil and groundwater analyses for inorganics, volatiles, and semivolatiles. The Verification investigation Plan, Table 18 listed the EPA Constituent List but omitted chromium. EPA's September 30, 1991 .conditional approval letter required.surficial soil sampling and analysis at the DuPonfc Road Landfill and referred to parameters listed"in the permit, which includes chromium. DuPont modified Table 18 but added chloride instead of chromium. In addition, ERA'S conditional approval, and DuPont's acceptance, specifically identified chromium as an analyte for the Polyacetal Product Incinerator. The Report failed to include chromium as required. Therefore, the Report in deficient and additional sampling and analysis ifl required, see below. Gz-oundwater Section 7.1 discusses the use of dissolved versus total metals when evaluating groundwater quality. The second paragraph incorrectly paraphrases the referenced EPA Directive submitted in Appendix P. The EPA Directive, upon which is based the justification for looking at dissolved metals concentrations only, states that, "if the historical information shows inconsistency between the filtered and untiltered' data, and high levels of aluminum are present in the unfiltersd data, only filtered samples are needed." Neither historical information nor has aluminum analyses been included in previous or present sample analysis. In addition, the field sampling logs indicate that almost all wells are "muddy," "thick muddy," or have "medium to high turbidity." Evaluating groundwater quality with respect to metals when the samples are turbid is difficult. The practice is tending to total metals, or unfiltered samples, often using low-flow sampling techniques. Redeveloping a groundwater monitoring well and sampling with low-flow techniques can reduce total metals from above the groundwater protection standard in 40 CFR 264.94 to nondeteet levels. Therefore, no metal may be eliminated from further consideration at this time. Section 7.2 discusses that C-0 and TRITOM*, found in wells at the Riverbank Landf-ill, the Anaerobic Digestion Ponds, and the .Burning Grounds, are not 40 CPR Part 264, appendix IX constituents Celebrating 2S Yews of Environmental Pivpess CP032527 BID481624 and PALs or MCLs assigned to them. toxicological information. S>AL Please provide known The Report uses EEA proposed action levels (PALs) (July 27, 1990) for screening purposes, a more current list used by Region III III is the Region Risk-Based Concentrations; R.L. Smith (4/18/96) using the residential exposure scenario for soils. The significant difference between the Region table and the Report III Table 4 is arsenic. The value in Table 4 fails to consider arsenic as a carcinogen. As reported values for arsenic in the soil exceed the Region HI number, it may be necessary to determine a site- specific soil arsenic background number. Background Soil Samples III Determination of inorganic, soil background levels becomes important when the inorganic constituents exceed the Region Risk-Based Concentrations. Soil arsenic levels exceed the residential/industrial values for arsenic as a carcinogen of 0 .43/3.8 nig/kg. A statistically valid determination for background levels of arsenic is needed. A one-sided tolerance levels is appropriate. Seven samples were taken to represent background inorganic constituent conditions. Seven samples is less than the minimum number generally required (eight samples are generally necessary to calculate an upper tolerance level to represent background) but more importantly, the background samples need to be from the same soil series and horizon as the samples taken to evaluate releases from a solid waste management unit. in addition, background soil samples must be taken from areas unimpacted by facility operations Enclosed is a copy of EPA's Engineering Forum Issue paper, DeterndBStiozi of Background CMceoitrations of Inorcyanica in Soils and Sediments at .Hazardous wsiste Sites, BPA/540/S-96/500, December 1995. The paper identified some of the concerns in determining inorganic soil background levels. EVAMtBSIOH O? SSCOiamslDATIONS Eelyaoetal Waste Incinerator The Work Plan specified soil analysis for cadmium, chromium, lead, selenium, m-Cresol, and phenol. The Report, Table 3, fails to provide results for chromium and m-Cresol. Provide the missing data. Celebrating 25 Tears of Eiivinnniental Progress CF032528 EID481625 Local Landfill DuPont's "no further investigation" recommendation may be unacceptable given that the groundwater protection standard of 40 CFR 254.94 is exceeded for arsenic, barium, and lead. In 1995 DuPont notified EPA that the Local Landfill was being closed and one additional groundwater monitoring well was being installed, and in January 1997 DuPont notified BPA that the landfill surface impoundment is to be closed. Please provide the Local Landfill closure information and the schedule and plans regarding closure of the surface iinpoundment (a). RiverbanJc fc.mdfill A RCRA Facility Investigation (RFI) needs to b@ performed while maintaining the pump-and-treat for the methylene chloride spill. The statement that groundwater contamination is limited to the western and central parts of the Riverbank Landfill is inaccurate as extreme eastern groundwater sampling point exceeded the groundwater protection standard of 40 CfR 264.94 for arsenic and mercury. The RFI shall include the DuPont-Lubeck well field/ the Ranney water production wells, and well 336. Wells 331 through 335 and 337 shall be included in the RPI with' respect to groundwater elevations. The Report contains insufficient data to evaluate the effectiveness of the pump-and-treat system. Although DuPont submits quarterly seepage reports, please submit a report, within 60 days of receipt of this letter, on the punrp-and-treat system which includes a complete description of the system, a discussion of attempts to locate the source of the spring and to reduce its .flow, a demonstration that the contaminated groundwater i intercepted, and a summary of treated seepage quality. Anaerobic! Digestion Ponds : The Anaerobic Digestion Ponds ar essentially located within the Riverbank Landfill and ahall therefore be included in the .RFI. The Report states that DuPont has initiated a study to evaluate the uae of electrochemical techniques for in-situ stabilization of the C-8 contaminated soils. Please submit a report on your investigation to date within 30 days of receipt of this letter. Bura-ing CiroimdB The groundwater protection standard at 40 CFR 264.94 is exceeded for arsenic, lead, and mercury, therefore, the burning grounds shall be included in the Riverbank Landfill RPI. Excavation for a drainage ditch in March l9$0 uncovered hazardous waste and DuPont's April 4, 1990 letter submitted soil CeUbrttting 2S Years of Environmental Progress CB'032529 EID481626 analytical soil. The results Report, for "excavated soil" and "Burning Ground Trench" page 22, states that "(p)ostt-excavation soil sample analytical results . . . demonstrate that the pot- excavation levels of contaminants were significantly lower," however, DuPont's March 16, 1990 letter states that all of the hazardous waste encountered was not excavated. Therefore, soil contaminated to the "excavated soil" level are remaining at the Burning Ground and soil ia a medium of concern for the RPI. SuBMITTALS SuteLttal e>( the SPI Work Plan of reAceccipotrdoinfgtthoispelremttitercoonrdiAtuiognusItI.1D1,.I.1,99w7,ithwihnic9h0evcearlenisdalratdeayr,a submit to EPA and the Protection a work plan West Virginia Department of Environmental for the RCRA Facility Investigation for the Local Landfill. Riverbank Landfill including the Anaerobic Digestion Ponds and Burning Orounds, and the Polyacetal Waste Incinerator. EPA'8 portion action contains, in permit of the RCRA permit condition II.D., for corrective provisions (or requirements) enclosed is a for cop t y he o f RFI EP . A ' i A s s c a u r supp rent l ement permi t t o R t F h I e r permi equire t m langu ents. a ge, Of particular importance are attachment conditions D.2. and g regarding screening risk assessment and base-line risk assessment. Within 30 days of receipt of this letter, for by June 11, 1997, - whichever is later, submit to EPA and WVDBP information identified above or in the enclosed table. Within 60 days of receipt of this letter, or by July 11, 1997, whichever is later, subnu.tt to EPA and WVDEP a report on the puropand-treat system as identified above. It is Plan, that strongly suggested DuPont meets with that prior to submitting the EPA in the Regional office. RFI Work Please call me at 215-566-3429 to set up a meeting. Sincere!) "w^y/. Mary/F. Beck Remedial Project Manager RCRA Operations Branch enel. ee; G.S. Atwal, WVPEP Celtbrdting IS Years of Environmental Progress CF032530 EID481627