Document 2jeeo549JL3vyBYdmvOMy2Ln7

` ' AR226-2537 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY Region III 841 Chestnut Building Philadelphia, Pennsylvania 19107 OATS RECEIVED 10-3'tL bnvironmentai omcB In Reply Refer To: (3HW52) CERTIFIED-MAIL RETH1N.RECEIPT REQUESTED W. M. Stewart E.I. du Pont de Nemours and Company, Ine. P.O. Box 1217 Parkersburg, WV 26102 gjrp 3 0 1991 P U H F iU I COPY io NOT KtMOVt /X(f0 R e : Washington Works WVD 04 587 5291 Dear Mr, Stewart: The Environmental Protection Agency (EPA) has completed the review of the second draft of the RCRA Verification Investigation (VI) Work Plan submitted December 14, 1990 by Du Pont for their Washington Works Plant. The VI Work Plan has substantively met the VI Work Plan requirements of the RCRA permit issued to Du Pont on December 13, 1989 and e p a conditionally approves the Work Plan subject to the following requirements: I. Unit A-i, Du Pont Road Landfill The leachate sampling program is accepted as proposed. The groundwater sampling program is accepted as proposed. In addition, Du Pont must conduct surfioial soil sampling (o 2 feet) as called for in permit condition ll.B.l.b.(1)(a)(i). These samples must be tested for the parameters listed in Table 18 of the RCRA permit. Use the appropriate soil sampling plan developed for other solid waste management units; such plan may be modified as necessary for this unit. For figure 2 of the Work Plan; Currently the scale of this map is 1"=30Q. The map scale must be changed to express the scale Printed on Recycled Paper CF033537 EID482263 either as a fraction, ex. 1:24,000, or the units for the 300 must be included. II. Unit A-2, River Bank Landfill Soil, groundwater, and leachate sampling plans are accepted as proposed. III. Unit 8-4, Anaerobic Digestion Ponds The plan for soil and groundwater samples to be taken outside the ponds is acceptable as proposed. For the cores taken inside the ponds, samples must be taken every 5 feet (starting 0-2 feet below the level of backfill), where soil characteristics change, and taken until groundwater is encountered. Groundwater samples must be taken from each boring and tested for the parameters listed in Table 18, IV. Unit C-6, Polyacetal Product Incinerator For this unit, it is sufficient to sample one upwind and one downwind soil sample at the specified locations. In addition the sampling parameter list for this unit must include the metals burned in this unit, specifically, cadmium, chromium, lead, and selenium. ' V. Unit F-ll, Injection Wells This submission and plan are accepted as proposed. VI. Unit H-13, Burning Grounds . number and location of the soil borings are approved but soil samples must be taken every 5 feet, where soil characteristics change, and until groundwater is encountered, VII. Trigger levels for a RCRA Facility Investigation , Permittee must conduct a RCRA Facility investigation (RFI) if a release of a hazardous waste or hazardous constituents from a SWMU to groundwater, surface water, soil or sediment exceeds: 1. The Practical Quantitation Limit (PQL) where the PQL is at or below the health-based level (available upon request). PQLs are the lowest concentrations of analytes that can be reliably deter- 2 CF033538 EID482264 mined within specified limits of precision and accuracy by SW-846 (Test Methods for___Bvaluati m .Sol Id Wastes^--- Physical/Chemical Methods) methods under routine laboratory operating conditions. Should the PQL not be practical, the Permittee must justify the use of a higher number. This justification must be in the Verification Investigation Report. 2, The method detection limit where the PQL is greater than the health-based limit. VIII. QA/QC E.j. Clugston of EPA's Annapolis Laboratory has completed the review of the second draft of Du Font's QA/QC plan. The plan is approved subject to the reviewer's comments which are enclosed and the following comments: If groundwater monitoring wells are pumped dry during the well evacuation, sampling must be performed within two hours, not the 24 hours specified in Appendix B of the VI Work Plan? and Where groundwater samples for metal analyses are taken, both filtered and unfiltered samples shall be taken and analyzed. IX. Effect of Public Water Supply Wells Prom investigations already performed, it is obvious that the public supply wells have a significant impact on the groundwater flow at the site. Therefore, provide available data on the those wells such as size, depth, screened interval, pumping rates, etc. X. Data Management and Models All raw data must be kept in an easily retrievable form for the duration of the HSWA permit and provided to EPA upon request. EPA recognizes the legitimacy of using computer models to determine the extent of or risk associated with contamination. However, approval of any conclusions of this study which are based on computer models necessitates that EPA have access to the same models. Du Pont must provide the name and distributor for any commercially available package and make the necessary arrangements for IPA access if a custom designed package is used. 3 CF033539 EID482265 i XI* Schedule Within 180 days of receipt of this approval of this VI work Plan or by April 6, 1992, Du Pont shall execute the Plari and submit the VI Report to EPA for approval. Du Pont shall also submit the VI Report to WVDNR. Acceptance of the above conditions may be addressed by submitting revised pages and/or a s u p p l a n t to the VI Work Plan within 30 calendar days of receipt of this letter. snouia exception be taken to all or part of the above < ^ h a l *' written statement of the grounds for the exception shall be submitted within 15 days from receipt of this letter. XII. other comments The supplement to the VI Work Plan must include JL Proposed schedule for field and sampling activities. W V D N R _ a n d I P A u s t b e notified of any changes in this schedule at least 14 cal Y in advance, if you should have any questions, please do not hesitate to contact John J. Humphries III at (215) 597-0320 or Mary 7. BecK at (215) 597-7239, S in 'c e r e ! ' y /Rbert L. Allen, chief RCRA Programs Branch enclosure cci 6.S. Atwal (WVDNR) 4' CF033S40 IID482266