Document DjqmQOK2Zgzb8Q4L4N1vkL25

AR226-2545 WVD045875291 DUPONT WASHINGTON WORKS RESPONSE TO EPA RFI WORK PLAN NOTICE QF DEFICIENCY (KOD) COMMENTS An NOD letter dated 1/15/98 concerning the 9/24/97 DuPont Washington Works RFI Workplan, was received from Region III EPA on 1/20/98. EPA and DuPont personnel held a phone conference call to review and discuss the NOD comments on 2/3/98. Our response to the NOD comments presented below include the understandings and agreements reached during the 2/3/98 conference call. RESPONSE TO GENERAL COMMENTS General Comment <1 As agreed with Region III EPA on 2/3/97, DuPont will conduct the following investigations concurrent with RFI Work Plan implementation: A. Monitoring Data Evaluation B. Slope Stability Investigation C. Leachate and Perched Water Investigation D. Process Lines and Waste Stream Lines Investigation Please note, the EPA basis for these investigations specifically pertains to NOD general connients 2, 3, 4, and 5, respectively. Our detailed comments and clarifications are provided in those specific response sections. With regard to items A, B, C and D, listed above, it is our intent to complete this work either prior to conducting the preliminary groundwater modeling activity, or concurrent with RFI field work implementation. The RFI Implementation Schedule has been revised to reflect these additional items and a copy of the revised schedule is included in the Attachments. General Comment #2 We agree that current and previous site groundwater flow conditions are significantly influenced by production well installation and pumping. The groundwater system's transient nature is the primary reason for conducting preliminary groundwater modeling activities prior to performing the RFI field work. (Note: "preliminary" implies that further model refinement will be completed after the field investigation). It is our belief that only through groundwater modeling can an accurate evaluation of current, historical and future site groundwater flow conditions be conducted. EID911320 ASH0GI977 groundwater flow^nditiona8w m faiaborioal and future site and/or investigation focS ^ K h data n * a investigation. Refinement Med? if4fcL nfS be added fco fclMS RH field (e.g., aquifer hydraulic proDertiea constructed groundwater model through collection of ddiKSFStS; Q ^ heads) wlU be a3333*i needs^will^be^comtwnieate^to^EF^in^the additional data Technical MemoranSm S be iSiJ i 6 P12al RFI ^ P U n g locations provided in Appendix A.^roleet S a i L ^ r p ? 6"08 ^ th the 3Chedule issued to IPA for review and P^an` 71113 memorandum will be implementation. M aod approval ^ ioe to ^ginning RFI field work investigaUoi%S1ir^liteda%wJviiteagJeUndWa6er flow 100(161 33 ach model will be constructed very accurate groundwater Data validat?or S S w PS WOrk Cities. further defined in the QAPP. Integral step in this process and is IMnt 1. currently input into the groundwaterSi S h ? ? ^ 0?1 flb# W a n g l e data for to: site geology, monitor will ^ deludes, but Is not limited well pumping rates, and aquifertproperUearlCThftd mea3ureB*nfc3* Production asneJd oPtrhiemrarieluyrreexnits/htissttohrrioouaglh fcfoPnOidmurfcuSrSig.Lct?hee 1991 vverSifiicaStironh?InnSviesVtfi4gdaattiaon i19n9c7l.udes site 6gro^d3SS"elue5vaStiSo2nsr ^taLkennnaIseartelc8eantttil?yn aasctfiovulrttlh33quwahritcehr General Cornent 3 However ft indicates riverbank sloce inst-ain prevented by the^ell r lS ^ r ' that13 Investigation a. repeat*, ? *no evidence currently exists that J lope Ratability is largely Riverbank ar8a alon the a*1TM Sinmteirmtit^tenntlSyyclTeared to expose soils,i5f !prract^ic*alh.f Ulty ^ * E i ^ i ^ T \ w nspeotion o the site production wells (e a production wellaar* at insfcanc the site situated on areL SverSf ncrebe platfot'a3 and are to evaluate. by cemeT)t or aPhalt and may be difficult ASH001978 EID911321 CoMuefe an evaluation o the ultimate dynamic factors, such as heavy precipitation (e.g,, 25, 50, and 100 year floods) to determine their potential impact on the site. DuPont intends to consult with various agencies such,as the WVDEP, national Weather Service and OS Army Corps of Engineers as needed during completion of this evaluation, .W.ork, Plansj,r0eppor8tta,bllifcy aaseanent results will be included in the final RFI General Comment 4 As proposed in RFI Work Plan section 3.5.2.1, a thorough soil and groundwater investigation of the RBLL1 seep area will be conducted This investigation is designed to determine whether the current "french drain" type leachate collection system effectively captures the perched groundwater containing methylene chloride. The investigation in this area will also aid in delineating the extent of soil and groundwater impact* The leachate source elevation will be surveyed in conjunction with other RFI survey work. As noted previously in the quarterly reports submitted to USEPA, all collected groundwater is passed through an on-site carbon adsorption unit where greater than 99% methylene chloride removal is typically achieved prior to discharge to the Ohio River through an BPPES permitted outfall. As requested during the 2/3/97 phone conference call, we will prepare a unit operation performance summary of the RBLL1 leachate collection and treatment system to supplement the information previously submitted on 7/11/97. This information will be included in the RFI Work Plan report. With regard to investigation of RBLL2, we will proceed with the activities proposed In the RFI Work Plan, which include collecting a soil boring sample and installation of a groundwater monitor well located downgradient of RBLL2. In addition to these activities, a survey of the leachate source location and flowrate will be completed during the RFI field work. General Comment #5 ' As reviewed during the 2/3/97 conference call, we plan to first conduct known oi*suspected source areas (i.e,, the site SWMOs). The 1991 Verification Investigation (VI) did not generally include soil sampling at locations within known SWHU boundaries, but instead was focused on sampling locations outside the SWHU perimeter. For this reason, the RFI Work Plan has been designed to primarily foous on SWMU source area characterization and delineation. Analysis of the data collected from the RFI field work will determine if there is a basis to ivestigate any underground process lines as possible release sources. Any need identified for further process line evaluation will be recommended in the RFI Work Plan Report, ASH00I979 EID911322 General Comment #6 DuPont has now received EPA guidance documenta EPA/S40/4-91/001, "Soil Sampling and Analysis for Volatile Organic Compounds" and EPA/540/S-95/504, "Low flow (Minimal Drawdown) Ground-Water Sampling Procedures". DuPont intends to conduct all RFI Plan field activities in accordance with these guidance documents, site conditions permitting. Any field deviations from this guidance will be communicated to EPA. \; EID911323 ASH001980 HVD045875291 DUPONT WASHINGTON WORKS RESPONSE TO 1PA RFI WORK PLAN NOTICE OF DEFICIENCY (NOD) COMMENTS RESPONSE TO SPECIFIC COMMENTS Documents mentioned below are Included located at the end of this section. in the "List of Attachments" Specific Comment 7 The DuPont Washington Works 100 year floodplain elevation is 60S 2 feet above mean sea level (MSI). This information has been added to Section 2.3*3 and revised text is included in the Attachments* Specific Comment *8 ... sfcl?n 3.5,3 has been revised and the revision is included in the Attacnnisnws* Specific Comment #9 Figure 1 has not been revised since Lock and Dam No, 19 was removed years ago and is no longer in service. It has no impact on determining the pool elevation of the Ohio River adjacent to Washington Works. The n l0,cated approximately 12 miles down river from the Waf u B rka 3ifcf' wel1 beyond the area covered in Figure 1, now controls the Ohio River pool elevation adjacent to DuPont Washington Works. Specific Comment #10 Figure 2 has been rvised to include the location of outfall #005 and the seepage collection and treatment unit, A revised copy of Figure 2 is included in the Attachments; Please refer to the 7/11/97 seepage treatment treatment unit afnd; c,a<pWtutrleoMalrea, u locati?oHS. 6 Specific Comment #11 _ scheteatle has been created to indicate the general location of the DuPont Washington Works flueropolymer manufacturing area. The location of DuPont Washington Works and its associated warehouses, General Electric Plastics and the Shell Chemical and Huntsman Chemical manufacturing site are shown on a modified schematic of Figure 1, included in the Attachments. Amoco is located approximately 12 miles up river in Ohio, well beyond the area covered in Figure 1, and we have removed it from Section 1.2. Revised text is included in the Attachments, J8610HSV EID911324 Specific CoBBient 12 A revised RFI Implementation Schedule is included in the Attachments. Specific Comment 13 Table B-2 has been revised to replace method 8240 with 8260 and is inoluded in the Attachments. Specific Comments #14, 15 & #16 The QAPP has been revised to reflect the information in comments #14, #15 and #16. Revised QAPP text is included in the Attachments. } EID911325 ASH001982 WVD045875291 DUPONT WASHINGTON WORKS RESPONSE TO EPA RFI WORK PUN NOTICE OF DEFICIENCY (NOD) COMMENTS LIST OP ATTACHMENTS { to be added } EID911326 ASH001983 aI }W >.5..,c - 2- WC^ a it^ T n teV- >5 ^ 14 ` svstern co capture Che water leaking Through the second quarter of 199?, ^S^oraeeaalog area. In ehe --- *--S million gallons of Sllearthlther'or"not'iii-l is Opaci V VW rf*J wortcp^- seepage have been processed. still seeping or not, please measurement of elevation and Big* quantity fea w S S ot m u b P l L should Include the (Attachments c eontamlnated water and D) and other seeps found. Also, the percnen concarow* <* -U.S should be investigated for the extent and source control. s. sjftt*PirS+'t Tainnhedtvhfee) rgWifriohcuearnetdiwiosanttehtrtevs*asom^upirflce*est,(l.)^butotlf^nafo|tr^in t^heersgooilrias !. ^Ic^soe^eu^Acintbetvadec.shtmigIebantitisso nS on fjo l Che v5 formed*n rier^ to conducting th e model: 6, publications, which Are included, snouro o w. lidered l*A/540/4-9l/00i toll F^ $ lfflal volatile Organic compounds and EPA/540/3-95/504 wow ' Drawdown) olound-water Sampling Procedures, , -Vtau ^clodt *? fja w spsczvzc comnwra S.cti -- t mclud. O . . I * Of <* W * * " 'Win to, the Washington works. / Section 3.5.3 must include ^a^ | 3^a^ rtort|ppc^iafrom1t h r w tDBpn|3 wells designated for closure must have prior appro ,^u well as the O.S. EPA. q |<( )&o4 . <**' `W FtihgeuOrheio1 sShivoeurl,d ainndclusdheoulthdea?lsgo^fin^cilJudde ^tLneaectcu^li *location*of the site, Figure 2 should include the seepage collection and treatment unit as well as outfall 005. All described locations in |^e "!gtn^u|acturing1arerete^ h o u l d j i * Huntsman chemicals, Amoco, nuropolyroer . \ ' *\a(i of (Jescr.bd loCC*.+ appear to>nn a map. ,, ________ _ OW ,i^F to (pE_>o0_Ps*A_siabnledj.* ttahue* 0r Wuy WJt3WU r'iJW SnigPp mtnuusstC bbee pPe0\'A*'+*?v'w! Saddddeeddic Jo?C<vb*n tchhee ^ISilLSSSU otf _ Table B-2 in Appendix 8 oe.!h*fSa^ 3ln9p ^ a^ lSote1thatathis method i ! S i : 2lnd^ f s r i 8eplaced by method 8250. ^ K^* The Quality Assurance oject Plan incluirfratlonale I n ^ ^ t e r i ^ f o r how these samples ill be selected. fA<kc l ^cS^Tm^a^ Sara r.dfor ssssffissi?asa <*\ The narrative describing trip blanks ^ o r T ^ hime 3language should be Appendix c. * " * ' ^ (Sft.Vc ^ ^ ^ ,iSS ' T)\ r * t u* - ** ^ V-1^ sW- *3" ilop(45 *J J/\/as(4n^fne tA/orirS Cb 1 EID911327