Document QkYmeKbO584p0VnRMQJ8ye0V6

AR226-2507 COMPILATION OF HISTORICAL C-8 DATA DUPONT WASHINGTON WORKS MAIN PLANT AND LANDFILLS Kate: Jattttiay 2002 Projtct Mo; D6WW7423 h ^ CORPORATC R6MEDIAT1CW GROUP ftnAlSancobetttwin DuPci^ and OfiS DimwntI Bailey Ml PteHi. Buikllna 27 WIlnrilngton, DelEnraro 1M05 JS0015042 EID620777 1.0 Introduction ,..........,.,.........,...^.....................,...,,......;^s^^^...........^........... 1-1 1.1 Document Organization |................................^4..^^^.--........,,....----.. !! 1.2 C-8 Historical Laboratory Analysis ..........,,........l^^^,.ft ,,..........,,.,,,,-.... 1-1 13 PhysicoehemicalData for Ammoriium Perfluoro^^^te(C-8) ,,..,,........-- 1-2 1.4 References ........,.^....,...t"."---"--.-.."""---..i^^^^----""**----"* 1-2 2.0 Washington Works Main PIaiit...............-.................i^^^--.........."--........2"l 2.1 I[^troduetion..,,..........,,....:-.........,......,,.,,............,,.<^^....,,.,,,.............,,..2-2 2.2 EmTroiDttnent3lSetting..(.......,.........,........,......fe^^^^............,.,..........,2-3 2.2,1. Oeology.,......,....|.....,.....,....................;a^^...........................2^ 2.2.2 Hydtolo^, Hydipgeology and Oirotuidwa!^tt^'...........,.......--....2-3 2.3' WaterQuality....,...........,.l.......-.........-..,.........J^^^&.........-.........2-6 2.3.1 Surface Water Quality .,>...................,,,,.....:.;..;^,;.....,,,,...........,,,.,.,2'-6 2.3.2 Gtoundwater Quality .......,...,........,.......-.^.^.!::;...,..................^.2-6 2.3.3 Drinldng/Tap Water Quajity...,,....................a,^...-....................2-7 2.4 Site Conceptual Model .................,...............,.........,.......................,,,.........,.2-7 2.5 DataGaps,...,............,.......................;.......^..........,,,.,.......,...........,...........2-8 2.6 ReferetCes.................,.....................,,..-.......,........,.........,.............,,............2..S 3.0 Local LandfiU..............................,...,.......................................,..........,.,..........,.3.1 3.1 Iatrodiiction...,............,............,...............,...........................,...,.,............3.2 3.2 EnvironineDtalSetting...........,............,...,.......,.........,.....^...,,.,........,,..,,.......,.3-2 3.2.1 Geology.........,....--.....,......^,.......,.,,.^....,,.........................,.........,3-2 3.2.2 Hydrology, Hydrogeology and Groundwater Flow-- ,...........,.........3-3 3.3 WsterQuality ..........,,,.....,,.,,.....,,..,,.....,,.........,..,,,,..,,.,,.,,..,,....,,,,,,,,...,,,,_3-4 3:3.1 Surface Water Quality ..,.,............,.......,..............,,.........,....,,,,......3-4 33.2 Groundwalter Quality ......................,........,,.......,,,..........,,,.......,.,.....3rit 3.4 Site Conceptual Model^.................,...........,............,...........,......................3.-5 3.5 Data Oaps ...>.........;.....,..,.................,...,.....................,.........,..........,........,.,,,..3.6 3.6 References.^......,.......,.....,.....,,.......,...,........,,.,......,....,.......,........,...........,,3-6 4.0 LetartLaiidfill...........................,,............,........,.,..,..,...................,,,....,...................4-l 4.1 Introduction ,,,,......,,,,..,,..............--.,....--,.,..,.......,,................................,.,.,..4-2 4-2 EnvironaientalSettmg...........,..................,.,.......^.,......,.....................,.....4"2 4.2.1 4^-2 Geology........,,...-...........................,.>..............,,,,......,...........,.,...4-2 Hydrology, Hydrogeology and Growidwatar Flow.....-..,...............4-3 4.3 WatwQuality..............................,...........,............,.^.......,..,.................,^^..4-4 4.3.1 Surface Water Quality ...,..........^.........,,..,.........,........................^..4-4 4.3.2 Giouttdwater Quality .....................-........-..............,....,................4-5 4.4 Site Conceptual Model -.-.....---...........................,,.............................,..........,4-6 4.5 Data0aps....-..,...........,.......--.,..............,...^...........,,.,......,.......,...............4-7 4.6 References....-.,.........--,,.....--.........................,................,..,..............,......4"8 .780015043 EXD620778 Main Plant and Landfill? Table of Contents 5.0 Dry Run Landfill ..-..^^................................,..,...............................................,..,5-1 5.1 Introduction......--.....,,,,..........,,.,,,,...............,,..,,.--...--............"--....,...,........5"2 5.2 BnviroiBnentalSettitig..............................................................."......--"...5-2 5.2.1 5.2.2 Oeology..........,,..........,..^.^...-...--.....,..*.....---......".-.............."--5-2 Hydrology, Hydrogeology and Groundwater Flow....... ,......,,..,.......5-3 5.3 Water Quality......................................................,,.........,,,,.............--....,......5-4 53.1 Surface Water Quality........................................,............,......,.........5*4 5.3.2 Groundwater Quality...,,.,.........,,,.,...............,..........,......................5-4 5.4 Site Conceptual Mode! ...............^........-...........,..............-..........................5-5 5.5 DataGaps.............,.,.,........--.......--.......,,.......--...........".--............--.--,...5-6 5.6 Refwences....,................,,,..........,.,,,............--,,.,.,.....--..,..............^.,...........5*6 TABLES Table 2.0 TableZ.lA Table 2.1B Table 2.1C Table 3.0 Table 3>1A Table 3.1B Table 4.0 Table 4.1A Table 4.1B Table 5.0 Table 5.1A Table S.IB Washington Works Main Plant Monitoring Wells Construction Data Washington Works Main Plant Analytical Data Table -Surface Water Washington Works Main Plant Analytical Data Table- Groundwater Washington Works Main Plant Analytical Data Table - Drinking Water Local Landfill Monitoring Wells Construction Data Local Landfill Analytical Date Tables - Surface Water Local Landfill Analytical Data Tables - Groundwater Letart Landfill Monitoring Wells Construction Data Letart Landfill Analytical Data Tables-Surface Water Letart Landfill Analytical Data Tables- Oroundwater Dry Run Landfill Monitoring Wells Construction Data Dry Run Landfill Analytical Data Tables-Surface Water Dry Run Landfill Analytical Data Tables - Groundwater Figure 1.0 Figure 2.0 Figure 2.1 Figure 22 Figure 23 Figure 2.4A Figure 2.4B Figure 2.4C Figure 2.4D FIGURES Solubilities ofC-jPis COOM m Water as a Function of Temperature Washington Worts Main Plant Location and SWMU Map Washington Worts Main Plant and Local Landfill 1-mile Radius Map Washington Works Main Plant Monitoring Well and Surface Water Sample Location Map Washington Worics Main Plant Cross Section Location Map Washington Works Mato Plant Cross Section A-A* Washington Works Main Plant Cross Section B-B' Washington Works Main Plant Cross Section C-C' Washington Works Main Plant Cross Section D-D' -- ConTaatlonofhistoiyclateDiaSZrev.doeMar.ll.CB __ .. Wn;iigton, DE JS0015044 E1D620779 Main Plant and landBlta Table of Contents Figure 2.4E Figure 2.4P Figure 2.5A Washington Works Main Plant Cross Section E-E' Washington Works Main Plant Cross Section F-F" Washington Works Main Plant Oroundwater Elevation Map - November 2000 Figure 2.5B Washington Works Main Plant Oroimdwater Bevation Map February 1999 Figure 2.5C Washington Works Main Plant Oroundwater Btevation Map - November 1998 ' Figure 2.oA Washington Works Main Plant C-8 ConcentrationMap" February 1999 Figure 2.6B Washington Works Main Plant C-8 ConcentrationMap - November 1998 Figure 3.0 Local LandfillLocationMap Figure 3.1 Local LandfillandWashington Works Main Plant 1-mile Radius Map Figure 3.2 Local Landfill MonitoringWell andSurface Water Sample LocationMap Figure 33 L a n d f i l l Cross S e c t i o n Location Map Local Figure 3.4A Local LandfillCross SectionA-A' Figu.rB3.4B Local LandfillCross SectionB.B' Figure 35A Local Landfill Oroundwater ElevationMap November 2001 Figure 3.5B Local LandfillGroundwater ElevationMap - December 2000 Figure 3.5C Local LandfillGroundwater ElevationMap - November 1999 Figure 3.5D Local Landfill GroundwaterElevation Map - November 1998 Figure 3.5B Local LandfillGrouadwater BlevationMap - November 1997 Figure 3.5F Local Landfill Groundwater Elevation Map -December 1996 Figure 3.50 Local LandfillGroundwater ElevationMap - December 1994 Figure 3.&A Local Landfill C-8 Concentration- May 2001 Figure 3.6B Local LandfillC-8 Concentration- May 2000 Figure 3.6C Local LandfillC-8 Concentitarion"May 1999 Figure 3.6D Local Landfill C-8 Concentration - May 1998 Figure 4,0 Letart LandfillLocationMap Figure 4,1 Letart Figure 4,2 Letart Figure 4.3 Letart Figure 4.4A Letart Landfill 1-mile RadiusMap LandfillMonitoringWell andSurfaceWater Sample LandfillCross SectionLocation Map L a n d f i l l CrossSection A - A ' LocationMap Figure 4.4B Letart LandfillCross SectionB-B* ConipBaBonrfMstwydBta tli Draft aw.itocMar-11.02 Wfcntngton.DE JS0015 BID620780 Main Plant and Landffls Table of Contents Figure 4.5A Figure 4.5B Figure 4.5C Figure 4.5D Figure 4.5B Figure 4.5P Figure 4.6A Figure 4.6B Figure 4.6C Figure 4.6D Figure 5.0 Figure 5.1 Figure 5.2 Figure 5.3 Figure 5.4A Figure 5.4B Figure 5.5A Figure 5.5B Figure 5.5C Figure S.5D Figure 5.5E Figure 5.6A Figure 5.6B Figure 5.6C Figure 5.6D Figure 5.6E Figure 5.6F Letart Landfill F-Zone Groundwater Elevation Map - November 2001 Letart Landfill F-Zone Oroundwater Elevation Map January 2001 Letart Landfill F-Zone Croundwater Elevation Map - October 1999 Letart Landfill F-Zone Groundwater Elevation Map " October 1998 Letart Landfill F-Zone Qioundwater Elevation Map - December 1994 Letart Landfill P.Zone Groimdwater Elevation Map December 1992 Letart C-8 Concentration Map July 2001 Letart C-8 Concentration Map - January 2000 Letart C-8 Concentration Map-July 1999 Letart 0.8 Concentration Map November 1991 Dry Run Landfill Location Map Dry Run Landfill 1-mile Radius Map Dry Run Landfill Monitoring Well and Surface Water Sample Location Map Dry Run Landfill Cross Section Location Map Dry Run Landfill Cross Section A-A' Dry RUB Landfill Cross Section B-B' Dry Run Landfill Groundwater Elevation Map October 2001 Dry RUB Landfill Groundwater Elevation Map Dry Run Landfill Groundwttet Elevation Map Dry Run Landfill Groundwater Elevation Map Dry Run Landfill Groundwater Elevation Map October 1999 October 1998 October 1993 April 1992 Dry Run C-8 Concenbation Map Bedrock Wells July 2000 Dry Run C-S Concentration Map Bedrock Wells July 1999 Dry Run C-8 Concentration Map Bedrock Wells July 1997 Dry Run C-8 Concentration Map Overburden Wells July 2000 Dry Run C-8 Concentration Map Overburden Wells July 1999 Dry Run C-8 Concentration Map Oveitwden Wells May 1998 Appendix Consent Order APP6NDIX CompaaUon o( history dBiB DISS 2w.ctoc WItnington.DE Mar. 11.02 iv JS0015046 ,BID620781 Main plant antiLantIBB? Introduction 1.0 INTRODUCTION A multi-media Consent Order was entered into between the West Virginia Department of Envnonmental Protection (WVDEP), the West Virginia Department of Health and Human Resources-Bunssu for Public Health (WVDHHR-BPH) and DuPont on November 14,2001. A copy of the Consent Order (Order No. GWR-2001-019) is contained h Appendix 1. The Consent Order identified a series of requirements to be perfonned by the Parties (WVDEP, WVDHHR-BPH, and DuPont) in order to determine whether there has been any impact on human health and the environment as a result of releases of ammonium perfluorooctanoate (0-8), CAS Number 3825-26-1, to the environment from DuPont operations at Hie Washington Works main plant and the associated landfills (Local, Letart and Diy Run), The 0-8 Oroundwater Investigation Steeling Team (GIST) was established ia the Consent Older to oversee investigationsand activities that will be conducted to assess the presence and extent of C-8 in drinking water, gtuundwater, and surface water at aid around the main plant, aad Ac Local, Letart and Dry Run Landfills. Pursuant to Attachment A of the Consent Older, three (asks will be performed by DuPont and evaluated by the GIST, Tasks A, B, and C. This report addressed Task B. The pmnary objective of Task B is to develop and implement a monitoring plan (hat detertntoes the presence and extent of C-8 in drinking water, groundwater aid surface water ia and around the main plant, aad the Local, Letart and Dry Run Landfills, and to provide a compilation of available ipoiaidwater/surface water monitoring results and hydrogeologie characterization date for each location. This document was prepared to meet the data compilation objective. 1.1 Document Organization Sections 2.0,3.0,4.0, aad 5.0 present the historical data available for the main plant and the Local, the Letart and the Dry Run Landfills, respectively. Each section includes text, tables, and figures specific to the site being discussed in that section. At die end of each section, data gaps are identified. The same outline is used for each section. Data presented in each section includes information (to the extent that information was available) as requested in Table A-l of me Consent Order. In addition, supplemental mfonaation is provided as needed to develop and present a site conceptual model for die four locations discussed. 1.2 C-8 Historical Laboratory Analysis of C-8 The analytical method, method detection limit, and laboratory utilized for C-8 analysis has changed over time. Prior to 1991, DuPont performed C-8 analysis at the DuPont Experimental Station in Wihmngton, Delaware, to 1991, when the RCRA Verification Investigation was conducted, the analysis was contracted to the CH^MHill Laboratory in Montgomery, Alabama: Both labs used a Gas Chromatography/BleetronCapture CompflaiJon of historydata Draft Zrev.doc hftr. 11,02 1-1 VVUmlnolBn.DE JS001S047 EID620782 _ _ _ _ ._ Main Plant and landttte Introduction Dectector (GC-ECD) based analytical method with detection limits for C-8 that ranged from 0.1 to 1.0 ug/1. CHzMHill conducted C-8 analysis for DuPont into the fall of 1998 when the laboratory ceased operation. At that time, DuPont had completed ooe round of analysis for the RCRA Facility Investigation (RPI). The analytical work was transferred to Lancaster Laboratories, Lancaster, PA, for the RFI second round analym in February 1999. Lancaster Laboratories continued to conduct C-8 analysis using GC-BCD forDuPont until October 2001, when development and testing was initiated on a new analytical method developed by Bxygen Research, Inc. (locatedin State College, PA) (hat utilizes Liquid Chtomato^phy/Tandein Mass Spectrometry (LC/MS/MS). DuPont adoptedthe use of LC/MS/MS for 0.8 analysis in November 2001. 1.3 Physicochemical Data for Ammonium Perfluorooetanoate (C-8) C-8, also identified as FC-143, is a fluorinated $wfactant used im the fluropolymer manufacturing at the main plant Figure 1.0 shows Ae solubilities pfCyFis COOM m water as a function of temperature (Figiwe 6.9 in Kssa 1994). The following summary lists the physicochemicaldate available for C.8 (Kissa, 194): Q Molwuar Ponnula ^ CF:(CF2)i,COO'NH4+ 0 Molecular wei^it =431.098g/niole 0 LDso acute oral rat'3 680 mg/kg 0 BC'F^U 0 pH~ 5 (0.5% aqueous) 0 pKa"2.8(-COOH) 0 Melting Point = 56.58-C (-COOH) 0 COD^700nig/kg 0 Kocia25 0 Water Solubility > 1000 ioagC-8/L 0 Vapor pressure (at 22C)" 7.1 x 10"05mm Hg 0 Kraft Points 2.5 C 0 Critical Micelle Concentration 33 nimol/L LD: lxttalDw)50-DothtviiigiOtipfctabiBtyofcB5il)gilalh BODr: Buicbiiaijtt) Osyjcn I3nnnd -SttHtliadtntMWtincnt tirilnfi)r5()a)20degrein C DCF; Btoccotculiiilion Factor ate pKK Ncgalrw log rftlwiomz^oncCTUtaa-MtiBuni of ^iilily of tea MtOgth Cttttifd Oxncn DNiaad Kcc: OrimieCtttenPBti&nteg Coefficient 1.4 References Kissa, E. 1994. Fluorinated Surfactants. New York: Marcel Dekker, lac. Comptetfrn of history data OraR^w^oc Mar. 11,02 1.2 WStistee/tcn.tK JSOOIS048 ZID207B3  Figure 1.0 Solubilities of CyFis COOM in water as a function of temperature (Kissa, 1994). JS0015049 EID620784 Main Plant and Landfill!! Washington Works Main Plant 2.0 WASHINGTON WORKS MAIN PLANT lBiro!tndionTM,-.TM.,TM, EttvirCTtDnital Setting--- Wtttr QiiaBly--,_.-,,.,,,, Site Conctptiitl Mo<lc! -- EKdA Gfp9l^u.MJtttftKTr> ItelenzEciu--------,.-- Table iJd ia>te2.JA Tablo2.1B Tbte2.1C Ttbte WasAingtoi Woritt Main Pisnit Monitoraig W<sl|t CMftnution Dato WiBhtogtM) Wor)aMBniPlwtAatlwealDalTabte~Staftc<!Wattr WMhfaKt(WoiteMmnPI)nrtAa)il>ticdt)Btarbls-ChwDilwilaWoliirtpCTt Worta Mate MMK Amaytiial Dt Table - DiiiiUBBrfap Water Pigiire?.9 figure 2.1 Figure 2.2 rtgml.t Rguw2.4A rigiOTl2.4B HglBB&4C FigHrt>2.4D Figure 2.4E HgliiB2.4P Rgiirea^A HgiBZ^B RguHcZ.SC Pigiac2.6A FiSaSfsiM Figinn Wiriiitigttn Woika Msto Plwt locatlcn aad WvW MV Washington Ww)tt Main PiBnt and Ittal landfill l-mtte RadiiB Map Wtohinglon Wolifll MBBI nant MonilMlttg Wett imd Stuftee Water Silmpb Location lAp Wahgt(m Wiata Mattt MNrt Ciw Scatfoa Lcilion Map Wasliinglw Wt Mahl Pbnl OWt Scctiun A-A" Wilshinglon Wate htoBi Omit CKW SwtiMi B-B' WashlngiCB Winks Main Plant C0t Secttoo C-C' VMimigtm Wcito Man) PImit Crow Section t)-D' Waibingtiw Wwk Main Plait Crow Scclion E-6' Wiuhington Wortai Min PItiit CKIBI Seclion p.F' Wsuhington Wafts Ufam PteitOHiun4wrEhatica Map -Mwianber 2000 Wiahiiiglon Woilu Mato Platti Owuidwatfr EIcVitfioo Map . Wnwey 19!>9 WitthmgiDnWoitaMBta FiBntGrouailwiito-Elevation Map-Noycmbtr 199? Waditagton WortB MBBI Plant C-S CoMflhadim Map - TiSMuarf 1999 WMl^tton Wirio Mrti PliaitC-8 CcoeaiMlica Mnp- Nwtaba1 998 .,^.2-2 ,.M .,,.2"< .-..2-7 _2-4 .,...i4 (^inpllalton of Malory date Drat Srov.doc htar. 11,02 WKmIneton.DE 2-1 JS001S050 EID620785 Main want and tandfiiia Washington Works Main Plant 2.1 Introduction The Washington Works Main Plant (main plant) is located along the Ohio River in Washington, West Virginia, approximately seven miles southwest of Parkeisburg, West Virginia (Figure 2.0). A water use and well survey is currently being conducted for the area within a 1-mile radius of the main plant aid Local Landfill property boundaries (Figure 2.1). Significant historical hydrogeologic and groundwater quality data for C-8 at the main plant is available from previous investigations that have been conducted. The most significant studywas a Resource Conservation and Recovery Act (RCRA) Facility Investigation (RFI) conducted in tfae fall of 1998 on four Solid Waste Management Unite (SWMUs) at the main plant to satisfy requirements of the RCRA Hazardous sad Solid Waste Amendments (HSWA) Permit Number WVD 04-587-2591 (DuPont, 1999). A brief descriptionof each of the SWMUs investigated is presented below. SWMU locations are shown on Figure 2.0. 0 SWMU A-3, Riverbank Landfill: The Riverbank Landfillis about 4,500-feet long and lies along tfae northern edge of the site near the Ohio River. It was operated between 1948 and the late 1960s and received powerhouse ash, incineration ash, plastics, nibble, and plant trash. After closure, it was covered with 6 to 35 inches of soil. Ciwaitly, the Riverbank Landfill is covered with dense vegetation (on the sloped area) or by buildingssod pavement in the manufacturing area. 0 SWMUB-4, Anaerobic Digestion Ponds (DigestionPonds): Thrw former digestion ponds ans co-located withia a portion of the Riverbank Landfill. One pond dates ftom the 1950s and two others from the 1970$. The ponds received waste fi-om the fluorocaxbon manufacturing process (including C-8) until 1988, when the pond contents and upper few feet of clay liner and pond benn material were removed and disposedof off-site. The pond area was backfflled and capped with topsoil, and the area is currently vegetated witfa grass. Q SWMU C-6, Polyacetal Waste Incinerators (Waste Incinearatora): The former Waste Incinerators consisted of two brick-lined pits in the western portion of the manufacturing area. The Waste Incinerators operatedbetween 1959 and 1990. The Waste mcineirators have been excavated and backfilled with clean soil. 0 SWMU H-14, Burning Ground: The Burning Ground is located in the central portion of the manulbcturmg area and was operated between 1948 and 1965. Since 1990, the Burning Ground has been leveled, backfilled with clean nil and gtavel, and covered by buildings and asphalt, A previous Verification Investigation (VI) found evidence of releases of C-8 to soil and groundwater at the Riverbank Landfill, Digestion Ponds, and Burning Ground (DuPoat 1992). little evidence of releases were found in soil at the site of the foimer Waste Incinerators. Further investigations and evaluations were performed during the RPI to detemune the extent of releases in groundwater. ConipBatonotmawd^aDtBtZw.dochte. 11.02 2-2 WttmlngtonDe JS0015051 EI&620786 Main Plant ana LandBlis Washington Works Main Plant Plant-wide groundwater sampling was also conducted during two separate monitoring events, the first in November 1998 and the second in February 1999, during the RFI. The sampling events focused on evaluating groundwater quality at existing and newly installed wells associated with the Burning Ground and Riveibank Landfill/ Digestion Ponds SWMUs. All plant wells sampledduring the RFI were analyzed for C-8. C-8 was detected in all gioundwater samples. C-8 concentrations and the extent in groundwater is discussed in Section 2,3 Water Quality. 2.2 Environmental Setting 2.2.1 Geology The geology of the main plant is shown on six geologiccross-sections developed during the VI (DuPont, 1992) and revised based on additional findings ftoro the RFI, The locations of the geologic cross-sections are shown in Figure 2.3. Two east-west crosssections, A-A' and F-F, are shown on Figures 2.4A and 2.4F. Four north-south crosssections, B.B', C-C', D-D', and E-B' are shown on Figures 2.4B, 2.4C, 2.4D and 2.4B, respectively. The cross-sections were developed from detailed geologic logs recorded during the VI and RP1, and than less detailed historic geologic logs from test and production wells and geotechnical boringsdrilled m the late 1950s through &e early l$80s. Some monitoring wells shown in Figure 2-3, were later abandoned. The current site map (Figwe 22) shows the monitoring wells that currently exist atlhe site. The main plant nests on Quaternary alluvial terrace deposits in (he Ohio River Valley. The alluvial tenrace is topographically flat and lifts approximately 50 feet above the Ohio River, which flows east to west past the main plant (sec Figure 2.0). The alluvial terrace is underlain by a Hat, river-$coured bedrock surface of the Dunfcard Series that rises steeply and outcrops in the southern edge of the site to form the valley wall. The Quaternary alluvium ranges fitun 60 to 100 feet in depth and consists of Coarsening downward unconsolidat^d river deposits of poorly to well-sorted, brown and gray sand, silts, clay and gravel. The Dsmksid Series bedrock consists primarily of red and varicolored sattdy shale; gray, green and brown sandstone; and minor beds of coal, claystone, black carbonaceous shale, and limestone. The average river water elevation is about 580 feet above Mean Sea Level (MSL) and die elevation of Ac Ohio River tenace deposits under the main plant are about 630 feet above MSL. Due to riverbank undercutting, some slumping of clay and silt exists along the northern boundary of the main plant along the river's edge. Figure 2.4C shows an example of (he relationship of fill and clay layers along the riverbank. 2.2.2 Hydrology, Hydrogeology and Groundwater Flow Hydrology Regional water needs are primarily satisfied by tte Ohio River and Little Kanawha River near Parkersbuig, These sources provide water to the cities ofParkei-sburg, CMnpMIonorhhilofydata Draft 2iw.doc Mar. 11, VS. 2-3 Wlhiington.DE JS0015052 EID620787 jMn plant and landgia Washington Works Main Plant West Virginia and Belpre, Ohio. In less populated areas (i.e., near tile main plant), the local communities receive water from small local water companies that obtain their water feom production wells screened in the Quaternary river alluvium. Surface water at the main plant dischargesthrough drains and storm sewera, mid drainage swales. Seeps located along the riverbank may originate firon precipitation that has infiltrated topsoil or fill and that flows along the top ofthe underlying shallow clay and dischargesalong the riverbank. Two drainage swales, one located in the facility's southwest comer, and the other located on the extreme eastern end of the facility, convey surface runoff duringrainy weather to tfae Ohio River. During dry weather, the drainage swales are dry. Hydrogeology Regional groundwater supplies are obtained from the Dunkard Group bedrock and Ohio River alluvial ten-ace deposits. The saturated portion of the Ohio River alluvial tenace depositscomprise the principal regional aquifer used for water supply purposes. Production wells completed in this aquifer have been known to yield up to 500 gallons per minute (gpm) (Schulte, 1984). Based on these high yields, numerous industrial and coaiioercial water supply companies obtain water Aom the alluvial aquifer. The yield ftom alluvial aquifer wells is related to the well's position with respect to the river, as well as formation grain size and thickness, The Ohio River alluvial terrace deposits contain a single key aquifer underlying the main plant. The water table occurs at a depth of about 60 to 70 feet below ground surface in the main plant area. The saturated zone is approximately 30 to 40 feet thick, extending to the surface of the underlying Dimkard Group. The on-site production water wells completed in the site aquifer yield 200 to 450 gpm. The underlying Dunkard Oroup is not a major aquifer. The upper zone of the Dunkard Group (Washington Fonnation), which consists primarily of shale and silt, likely bounds the lower extent of the site aquifer, h addition, regional groundwater communication between the Ohio River and bedrock will likely result itt upward gradients to the alluvial aquifer. Gioundwater quality in me alluvium in this region tends to be naturally poor, having the highest taedian chloride, sulfate, hardness (as calcium carbonate), iron, and manganese conctartrathms of all hydrogeologie units m the region (Schiiltz 1984). Water fiom the alluvium gcneMJIy is a calcium bicartonate type, wifll near neutral pH and highdissolved solids content Natural recharge to the alluvial aquifer comes from various sources, iacluding: U Infiltration of precipitation falling directly on the alluvium 0 Uteral movement of the river water through the alluvium via pennaable sand and gravel zones 0 Seepage from stream tributaries that discharge to the Ohio River The maximum amount of water available to the alluvium depends on the degree of hydraulic conaectioa to the river. The degree of hydraulic connection is a function of the penneability and thickness ofthe riverbed, penneabiuly and thickness of the alluvium, and hydiaulic gradient between the groundwatw and the river. Pumping of on-site active CwnplaBon of h)i.l(xy data Oral! Zrev.tloc Mar. 11,02 2.4 WWngton, DE J8001S053 EID620788 Main Plant and Landfilta Washington Works Main Plant well fields near and parallel to the river (i.e., the Ranney Welj. Field, and the East Well Field sho^nin Figure 2.2) lowers tt| alluvial aquifer to below river stag4. This induces water ftoi|| alluvium toward the wells, which r iplaces water pumped fiofi helps sustain high-yield pumping vi ells. ys-sy- -g ^ puPont-LubeckWell todwater level in the iver to flow into the |ge in the aquifer, and Groundwater Plow Groundwater generally flows to the south-southwest in the;a (aquifer. However, giottttdwater elevations, flow directions, and flow rates on-si the Ohio River and by pumping of bn-site pr&ductiofl wells.%] ^igly influenced by 1-siteproduction wells include (he Karmey Well, a radial collector well which pt ill,000 gpn; the seven wells in the East Well Field, which pump a combined af^a^s rate of 2,000 gpm; and the five DuPont-Lubeck wells, which pump about 700 %nfe^|abined. Groundwater elevation contour maps for the alluvial aquifer developed fron data measured in November 2000, February 1999, and Noverobei?||998p^resentedas Figures 2.5A, B, and C, respectively. The direction ofgrouinawate^Sowis indicated by ttie flow affows. As shown on the growidwater elevation contour maps, groundwater flow in the northeast part of the site is toward the East Wll Field wells, to the north" central portion of&e site, groundwater flow is toward the Ranaey WeM. 61 the central and western portion of the site, groundwater flow is south-southwest towards the DuPontLubeck Well Field. Pumping of the production wells (Ranney Well, East Well Field, and the DttPont-Lubeck Well Field) eliminates off-site iiaigicationof impacted groundwater that may originate ftom the SWMU areas. Additional groundwater elevation data was obteiaed lErcanthe General Electric (OE) property located to the west of the main plant. Data ftom (he main plant and GB were used in calibrating the Washington Works gcoundwater model (DuPont, 1999). 'The groundwater model conclusions indicated that groundwater ftOBil (he main plant area is contained to the DuPont property by operation of the site production wella. In a 1990 hydrogeologic assessment, production well specific capacity testing of the DuPont.Lubeck Well Field and the East Well Field was conducted. The results were used to calculate the transmissivity and the hydraulic conductivity of the alluvial aquifer (DuPont 1990). to the vicinity of the DuPont-LubeA Well Field, tiansmissivity values xanged between 114,900 and 127,500 gallons per day per square foot (gpd/ft2). In the vicinity of the East Well Field, the transmissivity values ranged between 16,050 and 50,000 a?d/ft2. Hydraulic conductivity values were calculated ftom the transmissivity values for me East Well Field. For Wells AX13.PW01 and AZ13.PW01, the hydraulic conductivity values tanged from 0.013 to 0.055 centimeters/second (cm/sec) and fiom 0.01 to 0.049 cm/soc, respectively. Using the hydraulic conductivity values ftom the 1990 study and the hydraulic gradient values determined ftom groundwater elevations measured in 1990 and assuming an effective porosity value for sand and gravel of 35 %, me groundwater flow velocity for sevetal well pass was calculated. The groundwater flow velocity was estimated at 5 feet/day (fl/d) between monitoring wells Tl 3-MW01 and LI 8-MWO 1 in the southwest portion of the site, A gioundwater flow velocity of 3 ft/d was estimated between monitoring Wells P06-MW01 and K14-MW01 in the western central portion of the site. Cwipilation of history data Draft 2rev.c!oc Mar. 11,02 2-5 WliringtoaDE JS0015054 EID62078? Main plant and Landwia _ Washington Works Main Plant In the eastern portion of the site, a groundwater flow velocity of 2.5 fVd was estimated for the site aquifer between monitoring wells AL10-MW01 and A009-MWOL Groundwater seeps at the Riverbank Landfill were identified and sampledduring the VI (DuPont 1992). Ao active French-Drain groundwater collection has been in operation at the Riverbank Landfill since 1991. The RFI verified that the collection system effectively captures water at the seep area. 2.3 Water Quality 2.3.1 Surface Water Quality Historical surface water C-8 concentrations are presented in Table 2.1A. Surface water sample locations are shown on Figure 2.2. Surface water C-8 concentrations were measmed in 2000 and 2001 at two outfalls, 002 and 005 and at two river locations. The outfalls have been sampled monthly since February 2001. Outfall 005 C-8 concentrations have ranged from 1,43 ug/1to 199 ug/1, while Outfall 002 C-8 concentrations ovei'all have been much lower, ranging from 0.436 ug/1to 8.54 ug/1. hi general, Outfall C-8 concenteations have significantly declined in 2001. This is the result of installation of a carbon adsorption treatment system in the fhuopblymeis process. The system is designed to remove a major percentage of C-8 from the process wastewater. 2.3.2 Groundwater Quality Concentrations of C-8 in groundwater sampled at (he main plant have been evaluated sine? 1991 (Table 2.1B), however, the wells sampled and the sampling frequency has been variable. Some wells have been monitored annually since 1996 and otheia have been monitored quarterly starting in January 2001. Two plant-wide gioundwater" sampling events were conducted as part of the RFI (November 1998 and February 1999) and are discussed below. The sampling events focused oa evaluating groundwater quality from existing and newly installed wells associated with the Burning Ground and Riveibank Landfill/Digestion Ponds SWMUs. All plant wells sampled during the RFI were analyzed for C-8. At the Riveibaak Landfill/Digestion Ponds area (in the western portion of me Riverbank Landffll), c-8 was detected in groundwater and previous seep samples. Figures 2.6C and 2.6D depict the well locations and results for C-8. Measured concentrations ranged from <0,1 to 13,600 pg/L. Concentrations were below 40 y-g/L in 28 of the 37 wells sampled; in the other 9 wells, maximum concentrations ranged from 380 to 13,600 pgflL. The highest concentrations were measured m monitoring wells P04-MW02 and R04-MW02, near the Digestion Ponds awa. The RFI C-8 concentration values were utilized for contouring. Isoconcentran'on maps were prepared and are presented in Figures 2.6A and 2.6B. CofflpteBMi of htetoy data Orefl Sw.tjoc Mar. 11,02 WBfiiinBion.OE 2-6 JS001S05S ErD620790 Man piani and landfiiia____________^______Washington Works Main Plant 2.3-3 Drinking/Tap Water Quaiity Production Well AM07-PW01 (historically known as well 336) suppliespotable water to tiie main plant C~8 concentrations in drinking/tap water have been measured at four distdbution points on the plant periodically since May 1999 (Table 2.1C). Concentrations ranged ftoro 0.213 ug/1to 0.589 ug/1. C-8 coacentoations detected at three sampling points ia the distribution system on October 11,2001 were 0.507,0.45, and 0.423 ug/l, respectively. No obvious (rends arc seen in the data. 2.4 Site Conceptual Model The main plant site conceptual model describes the potential exposure routes for current and future human and ecological receptors, Potential exposure routes were evaluated and classified as complete or incomplete, Direct exposure to C-8 bearing materials contained within the SWMUs is minimal of non-existent, because these materials have been removed and rcgradsd or paved (Binning Ground, Waste Inciflerators, and Digestion Ponds) or covered and vegetated. Therefore, contact with these materials is considered to be an incomplete exposure pathway. A large portion of the plant site is covered with asphaltand concrete. Hence surface water contact with C"8 impacted soils or groundwater is not likely in these areas. Therefore, surface water contacting C-8 impacted soils is considered to be an incomplete exposure pathway. Much of the precipitation falling on site is routed toward drains and storoi sewera, which ultimately discharge into the Ohio River. Precipitation falling on the riverbank slope either percolates into the soil or was off to the riven The seeps (hat occur in places along the riverbank axe probably caused by percolated water that accumulates above the slumped, low-permeability clay and sflt of the Ohio River deposits that underlie topsoil and fill along the rivetbank. Contact with impacted seep water is considered to be an incomplete exposure pa&way due to the active fiench-drain youndwater collection system. Direct exposure to groundwater impacted by C-8 is also considered to be an incomplete pathway because groundwater is located at about 60 feet bgs. The only potential contact route for groundwater is via contact with water pumped ftona production wells. Water pumped from production wells is used for two purposes, supplying drinkmg water and providing industrial process water. Well AM07-PW01 is one of three production wells that provides drinking water to the main plant. Other wells are A008-PW01 and AQ09-PWOL AM07-PW01 was sampled eight times. Measured concentratioios of C-8 in this well suggested that this exposure pathway is considered to be complete. However, average concentrations of C-8 in drinkingwater at point of use (which is a mixture of water from the three wells) will be lower than the nniaximujn concentrations detected in any single well. Contact with impacted drinking/tap water is a complete expo$uire pathway. C-8 was detected in production wells providing industrial process water (K16-PW01, V05.PWOI, and L04-PW01). The maximum concentration of C-8 was detected in well K16.PW01 (16,2 vsft). Water from these wells is not used for drinking, but rather for industrial processes including non-contact and contact cooling water, fire water, process Compilation o history date Drall 2rev-doc Mar. 11,02 2-7 Wm^agton. DE JS0015056 Ein620791 Main ptoit and tagiiis__________________Washington Works Main Plant water, conversion to demmeralized water to generate steam, and/or consumption in the manufacturing processes. There is a potential for limited contact, however, this contact is expected to be minimal. Average concentrations of C-8 in process water at the point of use (which is a mixture of water from several production wells) will be lower than maxinaini concentrations detected in any single well. Therefore, while this exposure pattiway is complete, it is considered to be iniminal. The RPI ecological valuation focused on identifyingwhether significantecological resources may be exposed to site-related constituents released fiom the SWMUs. This evaluation concluded that surface soil at the Riverbank Landfill/Digestion Ponds is the only potential ecological exposure medium within the RFI study area. Surface water contact with C-8 impacted soils or groundwater is not likely because the Waste Incinerators and Burning Ground SWMUs are covered with gravel, asphalt, or buildings and do not provide ecologicalhabitat Subsurface soil (greater than 2 feet) and groimdwater are not exposure media of concern for ecologicalreceptors, and gwundwater does not discharge to sur&ce water at the site. 2.5 Data Gaps The following data gaps were identified for ft mam plant: Q Additional monitoring wells are needed to farther delineate C-8 concentrations in groundwater and to evaluate groundwater flow directions, particularly for groundwater flow in the bedrock below the unconfined alluvial aquifer. Q Continued refinement of the groundwater model for the roam plant is required to reevahiate that groundwater capture by (he pumping wells is occurring at the site and that no off-site migration ofC8 impacted groundwater is occurring. Q Surface water quality in the Ohio River should be evaluated. A separate work plan is currently being designed to address this issue. Activities to fill (he data gaps will be proposed and discussed ia the work plan, 2.6 References DuPont. 1990. Washington Work/1990 Preliminary Hydrogeologic Assessment. Solid Waste & Geological Engineering Department. ^^^- 1^2- Verification Investigation Worts April 1992. (Vol. 1). EJ. DuPont detfenwurs Co. Washington ^ 199. KCM Facility Investigation Report, DuPontWashington Wbrte,J\ms 30,199. Coiporate Remediation Group. HaskellLaboratory. 1991. Ammonium Perfluorooctanoate (PC-143). ComfsSlslOoofif htetoy data Draft 2rtiv.doc Mar. 11.02 2-8 Wilmlnglon, PE .ysooisos? K1D620792 MainMani^dLen^ia ' Washington Works Main Plant Schultz, R-A. 1984. Gromdwater Hydrology of the Minor Tributary Basins of the Ohio River, West Virginia. CMnpal)cnofh!steydaiaDre(iaw^loc Mar. 11,02 WInilngton.DS 2-9 jsooisosa EID620793 Table 2.0 Monitoring Well Construction Data DuPont Washington Works Main Plant Washington, WV liaonltoringiWells Surface New ID OldBO Elevation (fBt) Q04.MW02 Q05.MW01 P06-MW02 P08-MW01 N13.MW01 M16-MW01 AOOWWOl AQ09-PWOI ATlO.PWOl AV11-PW01 AX13.PW01 AM07-PW01 AZ13-PW01 L04-PW01 U7-PWOI K18-PWOI KIS-PWOI K16-PW01 J117-PW01 vos-ywoi m-wwrn Q07.MW01 Z07.MW01 010.MW01 T13-MW01 U16-MW01 A009-MW01 L18.MW01 V09.MW01 N04-MW01 P06-MW01 AR09-MW01 AX12-MW01 A007-MW01 AI06-MW01 AObs-MWOl Roa'sMW-t RorisMW-2 R.orfiMW-3 RorfsMW-t Ron's MW-5 RorfsMW-6 """^31"" 332 333 334 335 336 337 GALLERY Ll(351) L2(352) L3(353) MOM) LS(3S5]L RANNBY TW-1 (tw-28) TW-20 TW2l (307) TW.22 TW-23 TW-24 TW-25 TW-26 TW-27 TW.3(pW.3) TW-32 TW.33 TW-38 TW.30 TW-40 TW-41 Tff-46 TW-43 TW-5 TW-60 TW-<1 TW-E4 62939 598.76 629.29 630,82 625.87 627.14 632.91 634.36 634.37 633.49 630.69 634.26 628.04 589.75 633.93 634.92 634.2 623,24 624.78 632 630.21 630.35 632.49 631.4 632.69 638.23 632.89 635.82 628.5 594.48 630.63 635.27 635.23 632.87 635.09 636.02 Y05-MW01 ACOS-MWOl ALlft-MWOl TW-E5 TW-E6 TW-M1 631.16 635.22 631.61 Total Depth (feet) 71 42 71 75 70 70 95 9 91 933 90 96 91 92 9S,U W.4 193S.69 W,2i 99.5 US^f JSML. 191,61 Well Diameter Jnches) 2 2 2 2 2 2 18 18 18 18 18 18 18 18 . 18 18 18 NA 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 4 6 4 Slot Size (inches) Screen Length -a^L i 10 lO s s 10 20 20 20 19 13 2B 20 WA 18 1 W 19 M 20 t9 29 20 29 29 Elevation of Screen Interval (feet) $$&0-S5&0 sew -sszo 567.0-SS7.0 5S9S^5S4.9 560.0-S55.0 565.0. SS5.0 588.7 .538.7 5.8-m8 5S3S-S33JS SS5.7-53&7 saw" 543.0 SS5.0-S3&0 555.0. 535.9 542.0-541,0 SS5-S3f SS9-S30 SS9-SM S5P-SM S50-.S39 5S9-539 SM-S30 559'539 559'539 Page 1 of 2 JS0015059 EID620794 table 2,0 , Monitoring V^ellConstruction Data DuPont Washington Works Main Plan Washington, WV | Monitoring Welis ............_________i__.__ ___........ ._._.,_._._...as NewD) OldBtt TW-M2 "H- Total Depth J^StL Well Diameter (inches) ; Screen 1Length {ineHiea.l J[teea r-zff I07-MWI TW-M3 610.23 4 ^tet' K14-MW01 TW.M4 62734 97.34 4 D08-MW01 TV-US 600.67 4 r"' "''" F06-MW01 TW-M6 601.14 63.S 4 r' U03-MW01 U05.MW02 U05-MW01 TW-N2 TW.1P12 TW-W1 5&2.44 631.17 632.11 103.11 6 ^SsfK 'f- 6 ' -;.."', .-,-..-' 6 '% '^ '? 30 L04-MWOI AA04-MW01 AA05-MW01 AB07.MW02 woo-sn TW-70 TW-71 TW-72 597.4 43 630.8 70 630.6 72 2 ";ao^ 1 10 2 -w^ " 10 2 10 10 AC07.MW02 TW-73 633.2 74 2 10 10 AB11.MW01 .AI06.MW01 B13-MW01 TW-74 TW-75 TW-76 629,51 72 634.04 72 623.5 74 2 10 2 J1O0 .^, 10 2 10 10 017-MWOl TW-77 630.5 80 2 10 to L06-MW01 TW-78 629.85 77 2 10 10 M04-MW02 M04-MW03 TW-79 TW-80 593.5 25 593.6 26 2 10 10 2 '-"ir" 10 N04.MW02 TW-81 593.6 26 2 10 10 NOS-MW01 TW-82 633.48 82 2 10 to P04.MWtt2 P05-MW02 R!04-MW(& ^M^ TW-83 590.6 28 2 10 TW-84 631.68 80 2 10 10 TW-85 593.2 28 2 10 """To^1 S05.MW02 TW.86 631.18 78 2 10 10 Utt4-MWOI TW.87 593.1 27 2 10 10 V06.MWOI WC5^W01 Y14.MW01 TW-88 TW-89 TW-90 629.93 630.25 629.93 77 "76^ 90 2 ., ,,^. 2 10 10 10 10 10 10 ZOfrMW TW-91 640.1 72 2 10 10 Z07-MWOI TW-92 629.64 74 2 10 10 ZOS-MW01 TW-93 630.7 70 2 10 10 Elevation of Screen Interval (feet) 550-539 SS9 -S36 SSO-S39 5644-5S4.4 570.8-560.8 568.6-558.6 569.2-559.2 567.51 .557.1 572.04-562.04 559,5-.549.5 560,5 550.5 562.85-552,85 578,5-568.5 577,6-567.6 577.6-567,6 561.48-531,48 572.6-562.6 561.68-551.68 575.2-565.2 563.18-553.18 576.1.566.1 562,93-552.93 564.25-554.25 549.93-539.93 578.1-568.1 565,64-555.64 570.7-560.7 M16-MW01 N13.MW01 P08-MWOI Q04-MW02 TW-55 TW-54 TW-53 TW.50 627.14 625.87 629.29 598.76 Red arid italics - approximate Bold Taken from RF1 WP information taken off cross^sBction Page 2 of 2 JS0015060 EID620795 Table 2.1A Summary of Analytical Results: C-8 In Surface Water Samples DuPont Washington Works Main Plant Washington, WV <^;;^;>.Aaaii^':^;^^ OUTFALL 002 ^.-..ESSUS. 10CS01 B/19/01 ww imm S13VM 4/11/01 3Q1701 Z/14/01 OUTFAU.OOS laas/oi aiiaim 8/3(801 ~ , ^ ^ 7/11/01 ... 6/31/01 4/11/01 3/21/01 2/14/01 RIVER BELOW 005 RiteR BEIEWPABES RORI 6/1WI 6/14/01 'K Fai&.'i^i'ya.teif1 ;4,,a'i.i 2.8 0.118 O.S58 0.5&4 0.436 ,,,,.,,,,,.,,..^,. tM (.54 1 """""1""1" , . ^ 6S.7 ,,,,,.,,,,-.,.,,,, , ~ 2.18 120 74 1.43 4.31 199 1S3 0.634 J 0,076 it J TS estimated value (below laboratory quantltation lunil) JS0015061 EID620796 Tabte2,1B Summary of Analytical Results; C-8 in Groundwater DuPont Washington Works Main Plant Washington, WV WfW^-:. AAOMulWOI AAOWWOI '.y^g E^, RS"?^^ ?: . -----Wffiafl) aafw 5.43 . (1/1398 <&1 n'WWiB^. ,,,, . 24/SS ,,,,.,,,-^^ . 1.46 11/1 iroo 0.77 ^^5 AB07-MWC8 AC07-MW02 2/i/B9 ft/i&Ea- 2/4/99 11/16ffit --1"'" 0.533 ^i.^r'":"" '" 0.356 0.78 AE11-MW01 2/2/99 0.69L AID8-MW01 AM07-PW01 "^^W"""" 11/W88 nnaea 11/20/00 0.41 0.18 B , ,, M - 024 , .. BMawo S12B9 2Gfla 0071 J 0.878 0.062 B 11/1BfM " '"'wiaiw"-' -fi&rtfr 1.91. 0.4 0.7& 4/2/90 0.48 AOOWW01 11/20f00 0.4 11/2000 (dup) 0.28 W5/W 6/12/98 0.167 o-aoy 6/19^8 1 . %27 0.55 ---- ACK19PW01 B13-MW01 fW-MWiM S17-MW(n 4/2/98 W11/W 5/12^9 Bi(12/99 aizaB 11/)VB8 2099 11/11/9S ^ ^maaa ZC/99 11/11/98 0,52 0:496 or"1""" 0-832 0.89 L 3 ^.35 L O.I 2.47 --""'-" i- lu-- ^,iL 13 . K16.PW01 1,04^'WOI 11^& . 2/9/99 n/law .-.-.--^^.-..4/11/01 n/zaoo assa n/ie/aa 11/18/88 dup) --.-.-. 7.5 16.2 0.461. o^Q2 3.99 J3.8 S.B9 7.9 J 3.9 J LB6-MW01 L17-PW01 WW """"^iyi(aT"""" ^ ^ ,, 4/11/01 4A1 870 &31 1.68 W14fflft . ,, 6/3/99 -. - .aB19 1.63 ,,. 2WSS - 2.16 11/18/98 0.33 8098 19 5(29/97 7.9 4(11/98 3.7 316/84 2 JS0015062 BID620797 Tablo2.1B Summary of Analytical Results (con't.); C-8 In Broundwater DuPont Washington Works Main Plant, Washington, WV . .::...y^^NaaijFipK;. MM-MWOZ ,^ S'iS'iW. 0?^^..Si.3i?i iai5^. . 2/7/89 .WMW-SS;. s; 17 M04.MW03 M16-MW01 mwrnst 11/12/99 Wiaa 11/1898 ----1--1/1CaW^,,., '^""1<"" " 1/2STO1(dup) 0.2 21.1 O.I 3,66 L 0:80 BBS 698 2WW 329 NO&W01 """"''" Mi-Rip ------ - MW-M6M ' -"iKW-lW -J- MWBQ . .^.. ."""."- ".. ''MfSH^'^'-'^ pfe-iMwa POS-tWSt ~ "~"" urtasa z/areo n/ia^ 4/1&96 W8/98 4/18/86 vases 32/09 WWW-- 1/26/01 . ,,. ,^,....., ""WW-Sfsiaa n/ia/sis -....,,., 380 615 ,3 <0.4 0.09 -0:6^- <0,1 ,,..,,,.,.,,..^^^ <0,1 126b!> '- 13609 B300 434 1200 foe-VMS POB-MW01 Q04-MWfi2 Q05-MW01 aareB -"'----1--1/--13--/89^gy------------' nrta/s& 2M^9 11/13/99 ' urtA/sa 414 31 43.4 ! 994 660 38 R04*MWO 1/25/01 " a6ft 11/12^8 13800 9420 1300 vwjpwm 7/1 W1 4/11W HfflWOO 11.4 .,,,.,..,,,,.,....,. ^ 13:7 ' T13.MW01 %rw 2ff/99(dW) Hrt6S98 20/99 2B8((!UO) " ' " ' ia.4""" 3.95 0.66 L 0.64 L 1.301. U04-MW01 11/17/98 aiena <0.1R 4.2 U1lMtW01 ...1WS1W1/0S0 5n'0f99 wiwsft 1.6 4.7 2 11 S05-MWQ2 2/S/tB 174 11/13/98 690 VOM1WM w^)5^wftfa1 Y14-MWft) 2AV99 11/1Bf98 2/e/ro Wiffaa - 2a9 11/10/89 1.91 1.7 0.729 0.31 4.951. 12 Z06-MW08 Z07-MW01 ZOMBIW01 awa 11/16/98 . 2/4W- 11/16W ae/sa 11ffl7?9 0.66S 4.5 2.05 3.8 2.74 <0.1R ,180015063 EID620798 Table 2.1 B Summary of Analytical Results (con'k): C-8 in ereundwaler DuPont Washington Wortis Main Plant, Washlnaton, WV ^R i" unusabio deta rfesull (ralatiVBto CWOO) ) a esttnatetf value (btlcw lalioiatwy quantlficaton L = possibtelnwUa!> rMult ((Blattvato WQC) lirem) Bs compound dOlBCled InQC btank < s Hon-deUct at stated laboratory mWhod detacHon nmtt JSOO15064 EID620799 Table 2.1C Summary of d.8 Analytical Result^ Drmking/T&p Water Samples DuPont WasMr^gton Works Main Washington, WV as. BI.D61MMNI 8100231 BU3Q2W BLDQ5 ,^tgg(t.w,ggsg, ^.'- W11/01 wtiibidupy .,, ----m---- $/ias9(durt 10f1W01 mwa S/12/89 ttS(%n,. 'aww ..iBWt^,.*, " .; JD^,-^,, "ttaw??,^ ^wwwy 0.4^1- . ^WW*'"^ azia . JS0015065 EID620800 Man Plant and Landfills 3.0 LOCAL LANDFILL Wter Quaffly...-TM...__,,_.,,,,,,,,,,- Site Ctaltqitoal Model----------..,,.,.,----, Oatft Gaps...--.........._TM"_.--_ T*]?.0 Table 3.1A Table 3.1B VifSUv3.Q HgDIB3.1 Hgtfel^ Figuic3J RgiBt3.4A Figiim3.4B HgmeSJiA Rgie3^B FiglHti^C Fignre3JD Rgise3,5B Fipite3JF Rgwel^O RgiBe3.6A i^^fir^ 3r@ i^jflUB 3>6u Spirts 3.60 Tabte* IwalLandliUMonltertnaWcaCtttEtrualtifiDiitt Locnl Landfill Analytical Date Table* - Surfato Wnin' Local UadliU Annlylical DatiTabIa - Onxtfldwaa FigMN Loiial iLandfin Locta'oa Mnp Local LAadnU (rod WahinpCH Wtifcl Main Flam 1-mite Radim Map Lttal laidfiU MMiitWiiig Well aid Suiftce Wtter Sanpie Localion Map Local Landfill Cna Section Location Mtp Local tandfillCiw* Section A-A* Local LaadfiU Cnxa Section B-B' LottlUndfiB tinillBAraler EteWtrtoft M*p - Novanttt 2!)0( Locri ImffiU Givw&mus Btetttoo Mp . Dctcinbcr MOO It m^tt Or>im4wKr Kttt< Mtp - Neveoiba 19^ Local LandfiUGroimdwBUTElCTliooMtp-Ni)Vtnil)cr 1998 U>ftl ILMdfltl (ftwiBihiwter BIVHB Mi9 - Nimmber 1997 Local LandTiU OroimdwaterEIcvtk>a Mtp - Drccnilir 1996 Local LartdfiU GtfiUBdwma Eicvilitrti M.p . Duaata 1994 Local Landfi!)C-ConcCTtiiitlc"-May 20(1 Lotsl LBidfi!; C-8 CwmWim - May 2000 LoMlLandBU &8 Coiicentittiai-May 1999 Local iLwdfia C-8 C(eatn-May 19?8 Local Landfill -.3-2 -.3-2 ..3-4 -3-S -3-6 -Mi Conipiat)oni>fhi<ite(y(lataDrall2rtB/.do<; Mar. 11,02 Wlhilnaton.DE 3.1 JS001506S EID620801 MahPtonlandLandBb LandfJII ___ _______________________Local 3.1 Introduction The Local Landfill is located immediately adjacent to the main plant off the southern perimeter (Figure 3.0). The landfill and plant are located along ito Ohio River in Washington, West Vir^pnia,approximately seven miles southwest ofParkersbwg, West Virginia. A water use and well survey is cuwently being conducted for Ac area within a l-nu(? radius of the landfill pertsrotCT(Figure 3.1). The Local Landfill consists of three separate closed cells located on the heavily wooded 250-acre site. The cells were operatedfrom 19o4 to the middle 1980s under West Virginia/National Pollutant Discharge Elimination System (WVNPDES) Permit No. 0076538. The permit is currently undergoing renewal and is expected to be effective in January 2002. The permit requires monthly surface water samplingand semi-annual groundwater monitoring. Materials landfilled included scrap product, scrap metal, wood pallets and bins and Powerhouse ash. Approximately 144 tons of waste per year were disposed in the landfill. Powerhouse ash comprised about 70 percent of the total waste. The specific source ofC- 8 w historical groundwater and surface water samplescollected from on-site locations has not yet been determined. Tne cells were closed and covered with approximately two feet of low permeability soil. Figure 3.2 shows the location of the three cells, .monitoring wells, and surface water samplingpoints. The cells have no compacted or syntheticbottom liners. However, a hydrogeologic evaluation indicated that the natural soil present under the cell materials is ft composed of reddish brown clay and weathered shale having a very low hydraulic conductivity of about 5 X 1 cm/sec (DuPont, 1990) and ranges from 3.5 to 19.5 feet in thickness, 3.2 Environmental Setting 3.2.1 Geology The Local Landfill is situated in a hilly ares with relief of approximately 30 to 40 feet. The slopes appear to be a combination ofnatui'al topography with terraced outcrops of massive sandstone and siltstone underlying varying amounts of soil cover and roan-iogdc landfill plateaus. The locations of two cross-sections developed for the Local Landfill are shown in Figure 3.3. The two cross-sections, A-A' and B-B', are shown in Figures 3.4A and 3.4B, respectively. A shallow ti^it clay layer starting at ground surface ranges from three to 25 feet thick. The clay contains some minor sandy and silty zones, and some pebbles and fragments of sandstone m some locations. The clays are of low plasticity and appear to be well compacted, often displayinga laminar structure (DuPoot, 1990). Underlying the shallow clay layer is weathered shale ranging from 10 to 35 feet thick. Below mis competent be<irock is present at depths ranging from 21 to 40 feet below ground surface. Compialton of htetwydata Oralt Zw-doo Mar. 11.02 3-2 WtinliiglcaOE - - - . ..... ssooisoe'7 EID620802 Main Plant and LandflU landrab______________________________Local The bedrock at the Local Landfill consists ofinter-bedded red and varicolored sandy or calcareous shale, and gray, green, and brown sandstone of the Permian age Dunkard Group. The maximum thickness of the Dunlcard Group to this region is 570 feet. The cross-sections show that the sandstone layers dip gently towards the north. Most of the sandstone layers located in the upper portion of me stratigraphicsection are lenticular and laterally discontinuous. Two laterally continuous sandstone layers are located in the lower stratigraphic section. 3.2.2 Hydrology, Hydrogeology and Groundwater Flow Hydrology to general, infiltration of precipitation is limited due to the very low hydraulic conductivity (5 x 10"7cm/see) of the surficial clays (where these clays exist) and me weathered bedrock (DuPont, 1992). In addition, infiltration of precipitationinto the cells is limited by approximately 2-feet of low permeability soil and vegetative cover capping of the cells. Leachate from the southern cell and the eastern ecu flows from me seeps in the steep valley walla to leacnate collection ponds. Pond 1,2 and 3 (Figure 32). Leachate from these ponds is discharged into a pipeline and conveyed to the main plant where it passes through storm water Outfall no- 001 into me Ohio River. Monitoring of combined pond effluent conveyed in the pipeline is conducted at Outlet 101. Hydrogeology Groundwater underlying the Local Landfill occurs in two zones. The discontinuous npper zone consists of the clays and underlying weathered bedrock and has a very low hydraulic conductivity (DuPont, 1992). The lower zone consists of the continuous and discontinuous sandstone layers caving low permeability of 1 x lO'5 on/see. The sandstone layeis are separated by laterally continuous shale layers. Well yields from the sandstone layers are vwy low, ranging fiom <OJ gpm to 1.5 gptn (DuPoot, 1992). The upper (and thicker) oftfae two laterally continuous sandstone layers located in me loww zone at elevations between 710-740 feet above Mean Sea Level (Figures 3.4A and 3.4B) has been designated as the "underlying significant aquifer" and is currently monitored semianniially as required by the permit. m 1989, eight oionitoriog wells weie installed at the Local Landfill by Tetra Tech Richardson (LLMW-Jl through 8). However, flve oftfaese monitor wells (LLMW-1, -2, - 3, -5, and -7) were closed in 1996 because they were screened in the discontinuous shallow clays and underlying weathered bedrock. LLMW-8, a bedrock well, was closed in 1997 because it was dry. Two additional bedrock wells, LLMW-9 and -10 were installed in 1995 and 1997, respectively. LLMW-9 was installed as a background well. These wells are scirwned within the significant underlying aquifer. Table 3.0 summarizes the well construction date for the existing moaitoring wells. Groundwater Flow Oioundwater elevations have bwa measured senuannually since 1994. Groundwater elevation contour maps for the significant underlying aquifer have been prepared from this data as required by the WVNPDBS Permit No. 0076538. Figures 3.5A through 3.50 present maps for 2001 through 1996 and 1994. The groundwater contours were Cwiipt^dftothistoly data Diril2rCT.docMBr.11.02 3-3 Wllmlngion. DB JS001S068 BID620803 Main Plant wtltarmsite Local Landfill __________ transferred from (he original maps submitted for the permit to me updatedLocal Landfill basemap. Evaluation of limited groundwater elevation data for the closed wells (basedon well installation information) indicates a downward vertical gradient between the upper discontinuous water bearing zone and the lower sandstone layers containing the underlying significant aquifer. In addition, C-8 present in the underlying significant aquifer provides fiuther support for a downward vertical gradient The groundwater contour maps for the underlying significant aquifer show that flow is from the south to the north towards the plant The sandstones of the underlying significant aquifer outcrop in the valley walls where discharge may occur as seeps. However, groundwater may also How downslope within the fractured rocks of the valley waDs and ultimately enter the alluvial terrace deposit on the main plant. Groundwater dischargingto seeps ultimately migrates to the plant through a number of pathways. It can discharge downward to leachate collection ponds and pipesto me main plant where it enters stom SSWCTS and discharges to the Ohio River. Groundwater also can seep to snail streams draining (he property to the north and flowing to the Quaternary alluvial terrace uncoofined aquifer where pumping of on-site active well fields controls groundwater flow. Oroundwater flow in the alluvial aquifer, adjacent to the valley walls of the Local Landfill, is towards the pumping wells located near and parallel to the Ohio lUvcr. The pumping of these well fields also lowers ths groundwater level to below river stage, inducing surface water from the river to flow into me alluvium towards the pumping wells. Water from the pumping wells is used for non-contact cooling purposes and ultimately is discharged to the Ohio River. 3.3 Water Quality 3.3.1 Surface Water Quality Table 3.1 A presents the historical G-8 concentration data available for surface water. Figuto 32 shows the surface water sampling locations, if the location currently exists. Samples from two outfalls, four outlets, two streams, and one leachate sampling location have leen collected periodically since 1994. C-8 concentrations in the outfalls and outlets range from <0.2 ug/1to 80ug/L Steam sample C-8 concentrations ranged ftom 4.12 ugfllto 15 ug/L The leachate sample, collected in the pipe from the leachate ponds, bad a concentration of 31 ug/1(February 1994). For sample locations having more than two sampling events, the concentration of C-8 is decreasing with time although it is difficult to accurately identify treads in samples with the limited data set The C-8 concenteation at Outlet 101, located at the northeastern portion of the side, have decreased ftottt 54 ug/1to 12 ug/1 over (he course of three samplifig events. 3.3.2 Oroundwater Quality Analysis of C-8 in groundwater has been conducted annually on a voluntary basis since 1996. Table 3.1B presents the data available for C-8 in Local Landfill monitoringwells. Grouodwater was sampled annually in 1996, and 1998 through2001 foruaee wells, LLMW-4, -6, and-9. LLMW-10 was sampled twice in 1998 and 1999. The limited ComplaBon ofNrtW data Draft Zw.itoc Mar. 11,02 3-4 WDfuiinston.DE J!SOOl5069 810620804 Ma-n Plant and LandffliB j LpCai Landfill amount of data makes it difficult to i develop concentration !.!:- contomgnaps. la addition, the monitoring wells are located at three]separate areas (cells) of ^30af5U;therefore, annual data for the past four years isjpostedin Figures 3.6A tl^>|^3.6D but is not ' contoured. ' ''"!&lat'1 C-8 concentrations m LLMW-9 and rIO range &om aon-detec^fit|0^.22 ug/L The other two wells, LLMW-4 and -6, hsilvethe highest concentratfons,.^Bfgroimiog1.4 to 39 Mg/land fiom. 1.32 to 15 ug/1respectively. Although there is firoWd^a, the data shows a distinct seduction in C-8 concentration over time for wells Lt^^^, -6, and -9. 3.4 Site Conceptual Model 'sS^ The Local Landfill site conceptual model describes the potenrisfexposui-eroutes for cmient and future hTOnan and ecological receptors. Potentialexposure routes were evaluated and classified as complete or iacomplete. . Access (o the Local Landfill is restricted by electronic and locked gates at the load entrances. However, a posted nature trail has been established on the east side of the landfill property. The teail loops arouad the eastern part of me landfill starting and ending near the landfill's electrically operated gate. The nature trail is a marked trail and does not cross the cells. Access to the site from surrounding roads is possible but is discouraged due to the heavily wooded nature of the property and the hilly terrain. The three cells at the Local Landfill are covered with a low permeability soil and vegetative cover. This cover prevents human and ecological receptors' exposure to the laadfilled materials and to the soils potentially impacted by the landfill materials. However, these materials could potentially be exposed by extensive digging or rooting in the soil by animals or unauthorized people. Therefore this pathway is considered to be potentially complete but alisiitnal. An additional potentially complete exposure pathway exists if the soil and vegetative cap is eroded by precipitation, Pennit WV0076538 requires that the laadfill surface will be inspectedquarterly for evidence of cracking or erosion (which could allow surface water to enter the solid waste deposit) and evidence of settling of solid waste (causing ponding of surface water). Per Condition G-l 6 of the pennit, a stonawater erosion Inspection is conducted anttually. Therefore, this potentially complete pathway is considered to be minimal. At the landfill, precipitation is expected to take one of two paths. It may infiltrate downward through the vegetated soil cover and into the cells. However, the low penmeabilityof (ha soil cover reduces me amount of infiltration. If the precipitation infiltrates the soil cover, it will possibly encounter the landfill materials and will continue downwards. It may be prevented from further downward migration by roe low permeability clays and weathered bedrock. However, if this water migrated farther downward, it should encounter roe sandstones and shale layers. Groimdwater flowing through the sandstone layers mat outcrop m me valley walls located above the plant site's southern edge would be exposed at the surface in seeps, if seeps exist. The existence and location of seeps at some places on the property have been observed, particularly those mentioned near the leacbate collection ponds, Much of the site remains unexplored, Complfrttofi Of htstwydfileORsfiaev.itoc Mar.11.G2 3-$ Wimlnglon, PE JS0015070 EID62080S Main Plant and lantifflis Local Landfill ._ therefore, complete evaluation of this potential exposure pathway (surface water to groundwater to surface water) is currently not available. Another possiblemigration route for precipitationis direct flow as surface water via overland flow downslope. la this ease the water would not encounter the fill materials at any point it tune. This potential exposure pathway ia considered incomplete. Contact with ^oundwater impacted by C-8 is anotherpotenrialexposure route for current and future human and ecological receptors. However, contact with groundwater under the landfill is limited, although,contact with leachate that has reached the ground surface via seeps is possiblein the vicinity of Pond I, near the southern most cell. Ponds are open and accessible to limited number ofDuPont employees. As stated previously, groundwater flowing through the sandstone layers that outcrop fa the valley walls located above the plant site's southern edge would be a possible contact location. However, because seeps in this area are not evident, it is likely that groundwater flows dowaslope within the fractured rooks of the valley walls and discharges,to the main plant alluvial tesaace. Detcimixiingtheexistenceandloealionofseepsonthepropertyhasnotbeen completed therefore, this potential exposure pathwaycannot be fully evaluated. 3.5 Data Gaps The following data gaps were identified for the Local Landfill: 0 Identify me locations of seeps MX the valley walls and determine water quality with respect to C-8 concennation. Q Determine the C-8 concentration in streams and other surface water bodies. Q Acquire additional geological data to refine the Site Conceptual Model. Q Install additional monitoring wells to provide additional groundwater flow data and groundwater quality data. Cl Gather additional C-8 concentration data from monitoring wells for plume delineation. Activities to fill the data gaps will be proposed and discussed in the work plan. 3.6 References DuPont 1990. Washington Works 1990 Preliminary Hydrogeologfc Assessment. Solid Waste St Geological Engineering Department. . 1992. Verification Investigation EJ. JMPmt de Nwwws Co. Washington Works April 1992. (VoL 1). ComWattoo (rfhtetwy data Draft Znw.doc Mar. 11.02 Wairiflgton.OB M JS001S071 EID620806 Table 3.0 Monitoring Well Construction Data Local Landfli! Washington, WV Monitoring Wells UA1W- 4 LLMW- 6 LLMW. S LLMW- 10 Surface Elevation (feeti S44.7 79S.2 788.54 805.S4 Total Depth (iert> 155 SO 80 87 Well Diameter (Inches) 4 4 4 4 Slot Size (Inches) 0.020 0.020 0.020 0.020 Screen Length (tot 20 20 " 20 20 Etavationof Screen Interval fleet) 717.2-697.2 723.2-703.2 72&54.70B.54 738.S4-718.94 Table 3.1A Summary of Analytical Results: C-8 in Surface Water Samples Local Landfill Washington, WV S'SSi^3iiSi(fc'?- ; ^is-ay;:, ^y^ssiistssi9^:-. LgACHATE simw OUTFALL 004 s/asooo 1210/1999 601889 6W998 swsssr 4/2/1996 r ^11984 OUWALLOOS smivws iaW1699 6^3/1989 OUtUgTOOl cwiaaa ^iiafl^y *AHM<6*f-IIOtWOVa 2/iai994 6Q9f17 41996 OU-nBTW Srcgll lgt7f ^ "'""^l^"'"" OUTUsTOB OUTIBT101 S/2a/1M7 401998 a/i4aooo 03/1559 6Q/18B8 STREAM1 5/2OT987 4W18@6 STREAMS 9/146000 ia2S/1S99 6C/13&8 4/2/1998 ^- ^i.tefli 31 4.79 7.1 3.08 -"" ^"^ - ---13 13 11 """""" " 13.3 34 im"' liil 39 41 dVt&f -- 35 ' '-- -- -- n -- *92 72 23 20 1? 15- ,. ^ . 54 11 7^ 4.12 10.7 15. 14 JS0015073 EID620808 Table 3.1B Summary of Analytical Results: C-8 (n Grounctwater Local Landfill Washington, WV i-ifawK^aww'. UJHW-4 U11iWUWt^Ii^cVft UJMW-9 U.MW.10 ::^a'sri;-. "<^:r'BMe .^Wsffl 5/11BOOO aiwifi azmsBo W1/1880 6^f/l1^6yrCa0*01ji ^, .:.:''f -- swnwa ffwm simwi wwaoo S/20/1899 " s^rtate' " 4f11;1Bfi6 8ttO;1S89 608/1998 w^^^swsm^,..^ w 16^ 28 3Si 3 1.42 1A2 8 W1"1 . 0.039 J ^?9 0.0404 <0.1 "" 11111""IJ "T 0.14 0.18 032 J80015074 BID620809 Main Plant and lancllilta l-etart Landfill 4.0 LETART LANDFILL .all ^ m '-'saS..^ ..:.,';"-;"/ ^ ,-,:;-;,,;- rt~~----.-...--^.^..TM"^"':,>.;i.;:S-'cii,:'2;Ki-..----"..--.4-2 - Wi-fr Quility----k.^,,.------,,,,,...--, ' -':;. JIM . SUe CcMqitiut Modcl.^^...-------->^,^.------ ^ lei^siSSe. 4^ D6tft0kpa,j .....ir -,wTTtTT-."<",,,,*, -^. A.J ItefaBHa.......,...,,,,..,,.....,, ,,,,-i^^^5L....^^4,8 Tabld.O TaMtt !L<5taitLBiidfillMooilWflgWclliCtmstrtisliaiDBiB '^ TA14,)A l*aitLBiidfltlAltyliialDrtTttlt-SuriaceWIW ^ Tb)4.)B UtMtLfflodfi!lAn.ilyt5cilDataTtlle-GiCTBiAtter ngure4.0 F)gurt-(,l rigitre -t-2 riguic43 riginO'UA. RgBH!4AB HgiBe4^A BgBlt4.5B figm4^C FIBTM 4.50 fVte4S Hgim 4.SP rijm4M rigure4.6P RgBW 4.6C Rgtae^jED PISiBW LetartUBdfillLocatiflnMaji LctertLtiidfill l-ttBlsIUtliiuMlip Lctait lAndfill Moili! oring We)) ifflil Surface WMtr Sample Locakm Map IxtBrtl.<mdfiUCrtBScclionLocaliTMM!iip lLawtlairifillCtWtStcfiaiA-A* Loait I^mifill 0TM Stttfnn B-B* LctartU(UlBF-ZoiM)OrC]itndnmlcrElcyBttoiMsp-NwtBlliB-aBl lleteitLiriai)F-S;BBeGn)oiidaatnElevatiooMe-JBUy20(l Ut^LaiidfiUP-ZoneOroundwatciElcvaflcti Map-OcliibiS-1999 I-iA>rtLsiiflfillF-ZonGroai|dwtlCT Elevation Map-OttobcrlWB I-ctanLaiulfillF-ZoncOrouiidwatCtElevtiUonMap-Dccaiiba-liW Leitirt Laidfill F-Zono CitMdatr EItvaHwt Mtp - Dcttmlw t992 lait&SCattl!ttmtto<iMp-Jttty2(l01 Lctart 0-8 CCTiCtntnitionMp-Jtauaiy 21100 tuM Ca ConiantiitioB Mp - toty 1999 Lctart e-3Coiicaitratioo Mtp'Novcinbct 1091 CompaaHi.txrfhtototydata Dranzw-doc Mar. 11, WItafciBtoii.DE 4-1 JS0015075 EID620810 Main Plant and LandCTs Letart LandtU^ 4.1 Introduction The Letart Landfill is located just north of the town of Letart in Mason County, West Virginia (Figure 4.0), A water use and well survey is being cotopletedfor the area within a l-mfle radius from the landfill perimeter (Figure 4.1). The landfill covers approximatelyY1"asses of a 205-acre parcel of land owned by DuPont Washington Works. It was in operation from the early 1960s to 1995. The landfill was operated Mid closed under West Virginia Solid Waste /National Pollutant Discharge Elimination System Permit No. WV 0076066. This permit squires quarterly gtoundwater monitoring, outfall and surface water monitoring and engineered cap maintenance. Figure 4.2 shows the landfill extent, orientation, topography, and monitoring well locations. The landfill was constructed within a aatuial ravine and has no compacted or synthetic bottom liners. However, a hydrogeologic evaluation indicated ttat the natural sofl present under the landfill material is composed of highly plastic clay and silt having a paitoeability of about W1 cm/sec (DuPont, 1993). The soil thickness ranges from 4 to 14 feet, averaging about 8 feet in thickness. Letart Landfill received waste was ftoiia the Flwropolyroer manufacturing process at the plant that consisted primarily of scrap product, scrap metal, wood pallets and bins, and miscellaneous trash. Approximately 5,000,000 poundsof waste per year were disposed m the landfill. This waste is believed to be (he source ofC-8 in the historical gromidwater and surface water samples collected from on-site locations. The Letart Landfill was peaaaanently closed by installingan engineered multi-layer geosyttthetieand soil cap (DuPont, 2001). Included in the closure activnitss were the installation of a leaehate collection system, erosion and drainage control measures and chain-link fencing. The cap construction was completed in April 2001. 4.2 Environmental Setting 4.2.1 Geology The Letart Landfill la situated on a heavily dissected plateau consisting of several steep Y-shaped valleys. Residual soil covers most landfill areas. In general, the soil at the site has been described as residual in nature, consisting primarily of heavy clays derived from the weathering ofbedrock. At most landfill areas, the soil is less than ten feet thick, with a maximum thickness of 20.5 feet Ths underlying bedrock at the Letart Landfill consists otinter-bedded red and varicolored sandy or calcareous shale, and gray, green, and brown sandstone of the Permian age Dunkard Group. The majdsaum thickness of the Dunkard Oroup in this region is 570 feet The location of two cross-sections, A-A* and B-B% crossing the landfill are shown in Figure 4.3. The two cross-sectiona oflhc underlying geology are shown on Figures 4.4Aand4.4B. ComciiaBonOf Mstory data DraB aw-itoc Mar. 11,82 4-2 WllmKiflton.DE jr@00l5076 EID620811 Main Plant and Landfills _ Landfill _________________________Letart Geologic investigations conducted at the Letart Landfill identified six stratigraphic water- bearingzones that were designated as Zone A through Zone F, with Zone A being the shallowest zone and Zone F the deepest. These zones consist of massive, very fine to fme grainsd crystalline sandstone with occasional shale lenses. Zones A through P are separatedby locally continuous shale unite that are generally ten feet or greater m thickness. Zones A throughD/B are discontinuous. Zone F is the fust laterally . continuous zone under the landfill. Zones A, C, D/E and F outcrop on the valley sides and along the Ohio River near the southern end of the landfill. 4.2.2 Hydrology, Hydrogeology and Groundwater Plow Hydrology The Letart Landfill engineered cap system prevents surface water from contacting landfilled materials. Precipitation falling on the engineered cap system takes on? of two paths. It may infiltrate downward through the vegetated soil and encounter the impermeable geomenibrane and titea flow laterally downslope on top of the geoaiembraae. Alternatively, precipitation may now via overland flow on top of the vegetative layer downslope. In either situation, this surface water does not contact the landiilled materials and migrates downslope towards drainage ditches constructed in or adjacent to the cap system. Precipitation, fallingon the northwest side of the upper part of roe cap flows downslope towards the soufewest, away from fte landfill, into a drainage ditch that flows to a sediment trap near LMW-6. Precipitation falling on the reaiiainjng portions of the cap flow downslope and towards the south m drainage ditches. Hydrogeology Hydraulic conductivity testing [i.e., slug tests (Zone A) and borehole packer tests (Zones C, D/E and F)] of me bedrock zones indicates mat these zones display low hydraulic conductivity (Tetta Tech Richardson, 1990). Zone A hydraulic conductivity is low, rangfog from 10'* cm/see to less man 10'5 cm/sec. (There are no wells Monitoring Zone B, therefore, it wag not tested.) Zones C and F have very low hydraulic conductivities ranging from 10"* cm/sec to less than 10^ cm/sec. Zone D/B hydraulic conductivities are also very low and range from 10"5 cm/see to 10'8 cna/sec. Zone F has been designatedthe "underlying significant aquifer" as defined by to the West Virginia Solid Waste Management Regulations because it is laterally continuous under the landfill and is thought to be hydraulicaliy connected to the Ohio River south of the landfill. Most current groundwater monitoring is conducted in Zone F. The low hydraulic conductivity can be attributed to the very fine-grained nature of the water-bearing units. In addition, many sandstone mats in the region typically display effective porosity as low as 1 percent. This low porosity results from pore space being filled in by autbigenic minerals (e.g. kaolinite) sometime after original sediment deposition. Zone P groundwater average linear velocities were calculated for flow froni the north to the southwest and from the north to me southeast (DuPont, 2000). These values are relatively low, 0.01 and 0.003 fVdayrespectively. The low velocities calculated in the P zone indicate that groundwater flow beneath the landfill is very slow, attributable to the ConipBtitlonof histoi^ data Draft zmv.doc Mar. 11.02 witmkigtorvDE - - - - - - - - - -. - . . . ... 4.3 ^0015077 Ein620812 htehHgitandtancifilb_ _____Letart Landfill low hydraulic conductivity present in the F zone and all the overlying imits as well- Low vertical hydraulic conductivities in the overlying shallow zones limit infiltration and recharge down to the F zone. The sanitated thickness of Zone F ranges from 22 feet in the upgyadientwell (LMW-2A) to between 2 and 8 feet in five downgradientwells (LMW-5A, -6, -9, -10, and-11), In many instances, the monitoring wells at (he landfill cannot be sampled until 48 hours (or longer) after purging,when a sufficient quantity of groundwater has recovered in the weU screen interval. Groundwater Flow Thirteen monitoring wells have been installed at the Letart Landfill in the Zone A, C, D/E, and F sandstone mute (Tetra Tech Richardson, 1989; 1990). Two of these wells, LMW-lOandLMW.ll, were installed in October 2001. to provide additional data from ,, Zone F to the north and south offl landfill. Table 4.0 lists the wells monitoring each ^ zone and provides well construction infoimation. Water level measutsiaente and calculated groundwater elevations have been measured quarterly- Figures 4.5A through 4JF provide available annual groundwater elevation contour maps for Zone F as required for the DCTimt. This data was transferred from the original maps submitted for the permit to <faeupdatedLetart Landfill base map,. The location and limited number of monitoring wella within Zones A, C and D/E prevents determination of groimdwater flow directions within these zones. However, elevations measured in the monitoring wells indicate a downward vertical gradient within the site groundwater system. Wittnm Zone F, a groundwater divide exists under the center of the landfill in a north-south direction. Girwmdwater east of the divide flows southeast towards the Ohio River. Groundwater west of the divide flows towards <he west and southwest Groundwater elevation data, including the newly installed LMW-l 1, the most northern monitoring well, indicates a slight component of northward groundwaterflow in Zone F in this area. Rapid decreases in die observed volume of water discharging from the leachate collection system in 2001 indicate diat groundwater flow under the landfill is being greatly reduced in response to tfae installation of the engineered cap system, fo addition, this reduction indicates that a new equilibrium state for groundwater flow has not yet been reached. Continued monitoring of groundwater elevations of Zones A through P is required to evaluate long-term changes in groundwater flow resulting from closure activities. 4.3 Water Quality 4-3.1 Surface Water Quality Voluntary surface water sampling for C-8 has been performed periodically since 1991. This date is presented in Table 4.1A. The two locations sampled most frequently, the Upper and Lower ponds, no longer exist. During construction of the engineered cap system, these pondswere de-watered and the sediments underlying the ponds were excavated and placed in low areas of the landfill prior to the installation of the cap. Currently, only two surface water locations still exist (due to landfill cap construction) ConipaqtlOn(i(hi6toydataDrafl2rev-t)pc Mar.n.Itt 4"4 Wilmlnaton.De ,780015078 EID620813 HMn Ham and tandiiib Letart Landfill _ and at being sampled. These locations include the leachate from the landfill [location 002(leachate basto)] and the stream located slightly east of the property line along Rt 33. The locations of these surface water-sampling points are shown in Figure 4.2. 4.3.2 Groundwater Quality Groimdwater ftom the monitoring wells has also been voluntarily sampled and analyzed for C.8 periodically since 1991. However, samplingdid not take place on an annual . basis until 1996 and quarterly sampling began the second half of 1999, when C-8 was added to the permit as a monitoring parameter. Table 4.1B presents all historical analysis available for C-8 from monitoring wells at the Letart Landfill. The nmited data set makes contouring the values difficult, thetsfore, roe values were posted on maps and not contoured. Figures 4.6A through 4.6D present the 0-8 concenttatioD values for July 2001, January 2000, July 1999, and 'November 1991, respectively, An initial examination of the groundwater data does not show any obvious overall concentration trends (Table 4.1B). For wells having data from 1991 through 2001, it appeals (bat the concentrations measured in 1991 were the lowest Ftom 1991, the concentrations to an wells increased. Currently, concentrations ate now decreasing again in the most recent sampling events. However, identifying trends in the data is complicated by the fact that three different analytical laboratories have been contracted to perform me analyses between 1991 and 2001. In addition, (be effects of the installation of the engineered cap system (preventing further surface water infiltration) may or may not te observable in the limited recent data. For the most recent sampling event and analysis (October 2001), the sampling and analytical procedures, and the analytical instrumentation used were modified to gain better accuracy in the C-8 analytical results. These modified procedures will be utilized for all future analysis of groundwater samples for C-8. Continued monitoring of C-8 eoncenteanoins in groimdwater is required to accurately evaluate the long-term trends in groundwater quality. IS it Is assumed that impacted groundwater flows ftom Zone A downward to Zone F and ultimately migrates to the Ohio River, the C-8 historical mean for LMW-5B (Table 4.1B) can be used along with the estimated groundwater flux to calculate the C-8 loading to the rivet. ThB following assumptions were made ia this caJculation- Q The saturated thickness is 25 ft at LMW.5B. This is higher than the most recent groundwater elevation measurement and therefore, is a conservative value. Q The length of the aquifer discharging to the Ohio River is 1000 ft based on the geologic cross-scctioas. 0 The historical mean value of 855 ug/1for LMW-5B, a downgradient well, represents the concentration of C-8 in Ac aquifer. Q The velocity of groundwater in the aquifer is 0.01 ft/day. Groundwater average linear velocities for the F zone are calculated to be 0.01 fl/day from the north to the southwest and 0.003 ft/day from roe north to the southeast (DuPont, 2000). Using these assumptions, me calculation for loading to the Ohio River is shown below: Cotnpaaion rfKstofy data bran Siw.vloc Mar. 11, (B 4-5 WMngtoa.ce. .730015079 BID620814 Mainpi^^u.ndste Letart Landjm _ A = Area 1000 ft length x 25 ft saturated tfuckness for Zone F = 25,000 ft2 V Velocity = 0.01 ft/day (estimated) Q " flux- Ax V" (25,000 ft2)x (0.01 ft/day) x (7.48 gal/fl3)x (365 day/yr.) = 682,550 gal/yr Mass - (855 ug/l) x (lg/10'ug) x (llcg/lOOOgx) (I lb/1205 kg) x (4.785 Vgal) ^ 1.47xl04 Ib/gal x 682,550 gal^r = IxKT'lb/yr Estimated annual loading to the Ohio River is very low based on the calculated mass and should result in a veiy low C"8 concentration in the Ohio River. The low calculated mass is reasonable given the low hydraulic conductivities and low average linear velocities observed in the F zone. 4.4 Site Conceptual Model The Letart Landfill site conceptual model describes the potential exposure routes for current and future human and ecological receptors. Potential exposure routes were evaluated and classified as complete or iiacomplete, The Letart Landfill closure was completed in April 2001 with the installation of an engineered cap system. The engineered cap system prevents human and ecological contact with toe landfilled materials. Contact with landfilled materials would only be possible ifthecap system were to be intentionally breached by workers or trespassere or by extensive, vigorous digging by animals. However, dense vegetation and appropriately installed fencing restricts access by unauthorized individuals and animals. Therefore, direct exposure to laadfUled Materials is a potentially complete but very limited exposure paAway. Exposure of landfilled material because of erosion of the engineered cap system due to stonn runofifis also a potential human and ecological exposure pathway. However, cap system drainage controls were designed to convey the runoffftoEQ the landfill cap to a designated discharge point and to eliminate the potential for ranoff-related erosion of the cap. In addition, the landfill cap is required to be inspectedat least quarterly (permit requirement C.12.A) for evidence of erosion aa part ofthe site Stonn Water Pollution Prevention Plan. Therefore, this potential exposure pathway is also a potentially complete but minimal exposure pathway. The Letart Landfill engineered cap system prevents surface water from contacting landfilled materials. Surface water migrates towards drainage ditches constructed in the cap system and is dischargedat the southern edge of the landfill. Because this surface water does not contact me landfilled materials, it is not impacted by C"8. Therefore, contact with this surface water is an incomplete exposure pathway, Groundwater contacting the landfilled material has been impacted by C-8. Contact with tins impacted groundwater presents a possible human and ecological exposure pathway due to groundwater flow patterns. Groundwater flow under Ac landfill has shown that prior to the installation of the engineered cap, surface water impinging on the landfill ComplattwofKslflfydBta Dra(t2w.ikft Mar. 11.02 4-8 WIMnston.De JS001S080 E3:D620815 MainptemaftdtandBte_ 1 j ..___ _ Letart Landfl>[ mipated downward through the landfill material. These waters <?ontinuedto flow as gronndwater downward towards Zone F where ft then flowed la^ttyto the west and south. Cunently, the engineered cap prevents surface water fromispntactingthe landfilled materials although groundwater migrating laterally and vertically underneath the landfill may still contact the landfilled materials. Qroundwater under Aesnjpneered cap ungrate? to the leachate collection system. Discharge from the ieaeBateepUgction system is pipedto an outfall [002(lea6hatebasin)] where it enters a small,^haliow,wet weamer stream that flows approximately 400 feet before it dischargesto the Ohio River. Contact with leachate is a potential pathway exposure route for cwreat ^:fiiture human and ecological receptors, however, this pathway is considered complete but limited due to the ^ ^ restricted access to the area- Zones D/B and F occur at elevations lower than the leaehate collection system. Qroundwater flowing ftom these zones to the south dischargesto the Ohio River, Contact with (ha water is limited to the areas where these zones may outcrop on the valley walls. However, in general gfoundwater flows downslope witnimi the shallow soil, coHiavium, and fractured rocks of the valley walls and would only he exposed at the surface if seeps exist Currently, tbeie is no data available on the existence or location of seeps on the slopesadjacent to the landfill or along the Ohio River. Therefore, evaluation offhis potential pathway exposure route for current and ftrture human and ecological receptors is not possibleat this time. Qroundwater lhat flows to the west from Zone F is likely to discharge to nearby valley drainage systems and to ultimately migrate to the Ohio River. Again, groundwatef flows dowaslope within the fractured rocks of the valley walls and would only be exposed at ft8 surface if seeps exist Currently, (here is no data available on the existence Of location of seeps in the valleys south of the landfill. Therefore, evaluation of this potential pathway exposure route for current and future human and ecological receptors is not possible at this time. 4.5 Data Gaps The following data gaps were identified for the Letart Landiill: 0 Identify the locations of seeps in the vauey walls, particularly in the steep valley wall along the Ohio River, and determine water quality with respect to C-8 concentration. Q Determine the C-8 concentration in the Ohio River. !3 Detennuie die C-8 concentration in streams and other surface water bodies. Q Acquire additional geological data to refine the SSte Conceptual Model. Q Install additional monitor wells to provide additional groundwater flow data and groundwater quality data. 0 Gather additional C-8 concentration data ftom monitoring wells for plume delineation. Activities to fill the data gaps will be proposed and discussed in the work plan. ComplteDwipflliatofy data Draft 2rev.doc Mar. H, 02 4-7 W8mln9!Bn. DE JS0015081 3BIDG20816 Main Plant and lantifite Letartl-andflll 4.6 References DaPont 1993. Letart Landfill Hydrogeohgic Evaluation, My W3. Corporate Remediatioa Group. 2000. iefart Landfill Grwmifwater Protection Plan SW/NPDES Permit No. ___,,_.wyW?6066,JssQsixy7,2000. Coq>oi-ateRemediation Group. 2001. Certification Report Letart Landfill Cop Construction, June 2001. . Corporate Remediatioo Group. TettaTepb Richardson. 1989. Monitoring Well Installation Program, October 1989. ___. 1990. Monitoring Well Installation Program at Letart Landfill-Summary Report. August 1990. Comptelton of Malay data Draft Zw.ttoc Mar.11.02 W8mlf)BK>,BE 4-8 ^80015082 EID620817 5 c ilf 1X.S o Ufe||4>|^|ft|?|8||g|g|te ^S8 0 ipa 0 0 o|e|o 0' ei|ri <rfde S g gIt^l-^j-^'lNl'q-jcMi'^j'q-l'nrl'^l'tl''*!'* ^ ^ g ------ _-.---- -,,,,_ - Ii"l|l|5i __^^.^__..---^ ..--\ "' ll-gsag^s^ae^^stes 'b I S>-Bi>i%tSr>|S^d-S=^^|&B:;r|e-5-,|^Si)rTi4Oa^~^S^a|R^tl)^^~ap^[- s [lg>l"l't plis < 00 JS0015083 ElDg20818 Table 4.1A Summary of Analytical Results: C-8 In Surface Water Samples Letart Landfill Letart.WV aaMs'.NiB... gsswsiff& .'-:';:....! Ot&frEACHAT^BASIN) LEACHA7E ""LOWER POND Tff SCRIMS FtOW Rr33snR6AM STREAM MNRD SWSPRitlQPLOW UPPER POMP s.;-^ .tiA'iBirtf'*^-. :& ' T/assakir ' 4/3/2000 mv^w 1QB1/1W9 <1OT/2001 TMflM 7B5QOOQ Tfityi^ V34^000 4/3/2000 " loai/wa' 7rtW1999 iyza/i&aa itxanssr 4/^/1966 BB^IBM OT5M9S4 lactfrt'Bal HK2rt1 4/26(1991 " a^tten' J --siAMOal""" lOSttBBi . S/12/189Z OTaiSSiZ 7waooi 7/31^000 7Bffl999 7^f1W7 ""37iWS9 3/ISflM? 9BW1994 ahaisaz 7;iai99a 608/1398 7Q3H997 wwiasa 3/15/1994 12a7rt991 1102/1981 <M21991 3tt/1991 2/8/1991 1/18/1991 SBiis'A;; ISSSViSSf-'''s: 'iS^S 13SO 1900 920 3240 533 19 . 22S9 1030 1410 1260 2530 1190 1100 1600 1900 2200 730 13W 1000 70 340 -"""""" .iior1' J200 1 1 0,3 0.3 2.61 0573 2S ' ^2 ^., ^u.,^ . 1.8 , . 0.9 . 51J7..- 4BO -aoo 2100 4400 4100 700 830 500 2300 2900 JS0015084 EID620819 Table 4,1 B Summary of Analytical Results: C-8 In Groundwater Letart Landfill Letart, WV gi^ ^'",;'. -:%i(lBftt!?s.l-.e;a^,. LMW.2A LMW-SB LMW4 LMW81 :g gpSiiL 7/isBooi 1/3S2001 1EKOOO " ----7/25^000 4/3/2000 wtooo 10l/1999 7/2W1B89 &2a;1968 7(2tfi 4/17/1996 0/2tV1884 3/15/19B4 n/zaiflsi 3/221881 7/Sittaxrt 7QW1WW,} 1/3TB001 W5)00 1WSfOO((lupl wzaaooo 4/SV200Q 4Woa(*>Bi VKaxio 10Q1/19B9 ioai9i^i 7/20/1999 7%?1W a^1W 3/1^894 ^tSfW 3^1991 i/iasow a2W9 THa/19M 3/22/1991 IWaiBBB ,at^<affiWfe^..^asa 242 423 248 ^ .306 453 S70 350 690 460 4BO 270 266 63 50 46$ 592 615 , .. "" " 1190.J 780 800,^ 1TOO 1020 1030 17SO 1700 "44S 4SB "l ":-i53fl"--" 1200 380 - 'WO 9.4 """"'' ------so ~ S.4 2^ 92 J estimated valw (below laboratwy quantitatitin lEroit). B ^ " '-.;' """ ..<^^ts;i'^^^teMaKw^:a^;t^fey. .:.%:/a^.;s\- : 'sastWK: u33ZM l ::v:f ' ;..':'.."'" ^-ff'^te.' "-; 7/lfl?' 999- ^VS.'S-KC-WSi-ltt.'-^S 60a ?-.: 11/22/1991 3SO- -WSiiwi" - 380 UlW-4 40/5:006 272 1/14BOOO 172 iiWM ~ 11 830 3/Z8/1991 690 LMW.W 11/22/1991 0.8 3/22/1991 1A TS0015085 EID620820 Table 4.1B Summary of Analytical Results (Con't): C-8 in Gcoundwater Letert Landfill Letart,WV &;. ' ^^SBitSiffa;,. Lfaw-3 'A^l^^S^^l^^s^S^!,?;',-'--'^^..- ^::'.,; g..-'?:''D*W?S; pSS-^/ c-ateg^'. . 11C2/1&91 1000 302/1 B91 360 -^"-^ -^s3>.; g ^iw^sy.: ^ ,w-si?'E^tt LMW-1 LMW-7 IMW-B "^^^^gSbe-^ai.^'J':'^'- ":. '......SS^ .-f^fe. 5te;;E?^IMWS%'Wi fflaffiKn ^"s?:. oafBtrtt-"' w;,-;'%-; 8100 101/2001 10/4/ZOOO 7Q4/2000 4/3(2000 -B1B6-"'- .-10600 ?90 13600 1i13BOOO 10(21/1889 7/20/1993 8ffl1998' 7B3rtSW 17400 12600 6920 24000 8100 4/17/1996 IIBSaiflBl 1i22/lB9l 1700 68 60 7aW2001 wiaaai 10/4/8)00 tri^Sfibo"" 40^00" ' """"-i/isaibo"""' , 10/2W1999 , 700/1999 5CW1B9B 7B3tS93f 4/17/1999 1-I/2^1?B1 r/iaeool 1/300001 wwea 704/2000 242 249 231 1S8 ar'1"" ^ ,219 78.3 260 53 15 01 1120 2650 20X1 2160 4/3/2000 1/13&000 2180 2100 10CW1999 3260 7CQ/1999 1790 5f2B/1B98 2700 7/23M897 4/17rt886 ,..- ..iSSt.,- 2200 ..,.- ,,,,,,,,, 11/231891 280 080015086 EID620821 Main Plant and laridHs Dry Run Landfill 5.0 DRY RUN LANDFILL iBtroducticn.tl Setting,. WitoQiiiBty-, SilBConi.tj)tiitl Model.. IX* G^t.-..,--.--_ Kc{ataiCc^.,.,m---uu TdbkS.O TliMe 5-1A TablcS.lB Tablw I'Xy Rim LiindfillMCTiitonngWclbCoMlnictitm Data DiyRunLiindfaiAnalytHsalDattTibiB-SuifaixWBlaDiyRuaLandHUAnt>llAlDa>Tayct-Oroundw)itt? Flgun: 1.6 Rpw5.l RpBBSJ! Figures-* RgurtMA Figure 3.48 HguroS-SA FigurtiSSB Figare5^C Flgltt54!D fIgnrei-SB lPiglB5,(A RgnieS.SB Pigurej.GC FigimiS.tD Bglifti.SB KysmSSP Ofy Run Landfill LccationMfip Flaw E)|-yR.unUodfi!l!-miicRadiui!Mp [>^R^LjdffllMoTOt<^g Well si^SurEiMWaia-SartpleLocirtioMnap Dry RBiiLaiHinBCio-isStttitsi Location Map Dty Run LnndfiltCftB* Section A-A' Dry Rim LasMlfiU Cnas Section B-B' DryRBOlAndfillGiimnilwitlCTElcyatitrtMiip-Ol.tolxfZOO) Dry RmiLaDdfilJGicundwatCTElcvallon Map-Octobisr 1999 &yRwLndmiOrBtttdwtiEterafl<iBMwOctotiW8 DtyRunLiin!iraie3rtiun[hwitcrEl(-iiBcnMp-OctcI)Cr)%l3 Diy RIM LiiiiilffliGristiKlWilQ-Elcviitioli Map-April 1992 ' DfyRDnC-8Coia<ralIonMopBc<lreclcWi:ib-)uly2000 DiyIUia&8ConcaintiiMBpBti!lwltWell.Julyl99? DryRunC-8CcintoCa)MiM,yBnliocliWe)t-Julyl7 Diy Run &8C!)nccntraltonMiyOvcttiurdtflWelli-)ty 2000 DtyIlunC-8Coiu:nitrat)onM)<50vi!rtW!te!iWellt-July 1!><)< Dry RiittC-8Concni3ti(aMt(iOvc!twdtaWclli-My 1998 --.-.5-2 ..,5-2 --.M --.5.1 _S-t --w CMtipltetiMtorhblojydaia Draft aw.doc Mar. 11,02 W!MnahKi,G6 5-1 JS0015087 EID620822 Main Plant and Landate Dry Run Landfill 5.1 introduction The Dry Ron Landfill is located west of the towmofLubeck, in Wood County, West Virginia (Figrore5.0) and is about eight miles southwest of the Washington Works main plant and tfae Local LandRIl, A water use and weu survey search is being completed for the area wilfain a 1-infle radius from the Dry Run Landfill perimeter (Figure 5.1). ---- The Dry Run Landfill covers approximately17-acws of a 535-acre paiceclof land owned by DuPont. The landfill began operation in 1986 and a still active at present The landfill i8 operated under West Virginia Solid Waste /National Pollutant Discharge Hmnnanon System Permit No-WV 00?6244. This permit requires quarterly groundwater moiutDringattdfflOBtfaly&ut^'sari^'\^erm&nitoirirlg.-- --- Figure 5.2 shows the location of the landfill, monitoring wells and surface water samplingpoints. The landfill was constructed within the drainage bash of Dry Run, a tributary of the North Pork of Lee Creek, which is atributary of the Ohio River. The Dry Run Landfill has no compacted or synthetic bottom liners. However, natural soil present under me landfill material is composed of day and weathered shale. The Dry Run Landfill receives waste from the main plant consisting of non-hazardous waste including scrap product, scrap metal, wood paBcte, fly ash and bins, and miscellaneous ttash. Approximately 50,000,000 poundsof waste per year nave bwn disposedin me landfilL Currently, the C-8 source is believed to be the sludges from the closure of the main plant anaerobic digecsatipoancpitoyncdaslcthualattwioenrse floanr 2d0fi0ll1edshaot wDr4y,4Ryuenarins of r1e9m88a.inTinhgelDiferyoRn uthneLeaxnisdtfiinllgrceemllabinaisnegd oa a 128,000 ydVyrnet fill volume consumption (DuPont 2000). 5.2 environmental Setting 5.2.1 , eology The Dry Run Landfill is situated on a heavily dissected plateau consisting of several steep V-shflped valleys. Residual soil covers most landfill areas, to general, the soil at me site has been described as residual in nature, consisting primarily of heavy clays derived ftoni the weathering of shale. A geoteehnicalinvestigation for the Dsy Run Landfill was completedby DuPont (1996). The investigation consisted of advancing sou test borings, test pits, laboratory testing of soil physicalproperties, stability analyses, and sBttlement analyses. DuPont (1996) determined that the natural residual soil underlying the landfilled materials consisted of stiff to very hard silty clay and clayey silt with occasional rock fragments and a trace of sand. The thickness of this natural soil ranged from 12 to 28 feet itt the test borings within the landfilled area. A 1989 monitoring well installation program, prepared by Tetra Twh Richardson Inc., indicated similar silty clay and weathered shale overburden. Four Con)p(ittMiofhlttoy<a(aOr^t2iw.<too Maf.11,02 S.2 Wilinliiisinn.oe JS0015088 E1D620823 Main Ptent and Run Landfill landBJB_________________________Pry overburden wells (DRMW 12A, 12B, 13A, 6A) were installed to depthsranging from 11 to 17 feet. The underlying bedrock at the Dry Run Landfill consists of mter-bedded red and varicolored sandy or calcareous shale, and gray, green, and brown sandstone of the PetBdaa age Dunkard Group (Tetra Tech Richardson, 1989). The maximum thickness of the Dunkaid Croup in Ifais region is 570 feet The location of two cross-sections, A-A" Mid B-B', crossing the landfill and downgradient of the landfill are shown in Figure 5.3. The two cross-sections are shown in Rgurea 5.4A and 5.4B. There arc only a limited number of deep momtoringwells around and upgradient from the landfill (DRMW-14). Dashed geologic contact line$ were drawn on cross-section A" A' (Figure 5.4A) because there is not sufficient data to confidently extrapolatebetween DRMW-14, the upgcadbntwell, and DRMW-13, the downgradient well. More geological data is available (DRMW-6, -11, -12, and-13) and was used in developing the downgradient cross-section, B-B' (Figure 5.4B) with more confidence. Cross-section B" B' supports the Saterpretatbns made in cross-section A-A* of rather flat lying sttatigraphic'units of sandstone layers separated by shale layers. 5.2.2 Hydrology, Hydrogeology and Groundwater Flow Hydrology The Diy Run Landfill is situated on a heavily dissected plateau consisting of several steep Y-shaped valleys. Diy Run drains the valley in which the landfill is located. Many small tributaries dischargefrom the nearby valleys into Dry Run before it joins up with the North Pork ofUe Creek. Potesta & Associates, Inc. (1989) completed a hydiologic and hydraulic analysis of the receiving stream below the Dry Run Landfill. They determined that me watershed soils are split between hydiologic soil groups (HSO) C and D and estimated the flow capacity at 481 cubic feet p second (that is greater than the 100-year 24.hour stOKn). Potesta (1989) also evaluated the 24-hou? precipitation amount that would result in rail flow conditions at (he location where the capacity was estimated. Potesta determined that precipitation values between 5.25-5.99 inches in 24 hours would result in full flow. The installation ofaleaGDate collection system at the Dry Run Landfill encompassing ihe inactive lower halfoffba landfill was completed by Potesta & Associates me. to 1999. Leachate from the landfill discharges into a leachate collection sump located northwest of the landfill (Figure 5.2) through perforated pipes buried at the low edge of the fill area, The leachate is pumped from the collection sump to a 50,000-gallon collection tank located at the top of the hill. Leachate is pumped ftom the collection tank to a tanker truck, which is thea hawed to me main plant for n-eattnent in the site's wastewater treatment plant Hydrogeology OroundwatCT is found in the overburden and the underlying bedrock aquifer. The bedrock aquifer is considered the underlying significant aquifer for NPDES permit required groundwater monitormg. A total of 15 monitoring wells have been installed at Dry Run to monitor the overburden and bedrock aquifera. At mi's time, Tow ovefburoen Ccniptalton tit htelwy tfate Cwtl ZtBii.doc Mar. 11,02 5-3 Wilrington.DE .7gooisoa9 ETD620824 Main plant ami Utfuifite JDry Run Landfill wells 0&RMW-6A, -12A, -12B, and 13A), and four bediock wells (DRMW-12, -13, -14, and -15) still exist. The other seven wells were abandoned in 1999 by Potesta & Associates, Inc. as required by the permit because they were not being utilized for quarterly monitoring (Potesta, 1999). Table 5.0 provides the weU construction data for existingmonitoring wells. Groundwater Flow Water levels measured m "November 2001 indicated overburden groundwater was encountered between 4 and 6 feet below ground surface. Although 3 of tiw 4 wells completedin the overburden monitor the same hydrogeologieunit. well DKMW-6A is completed at a relatively higher zone, which is discontinuous at lower topographicareas. No groundwater How maps were preparedfor the shallow water encountered to the overburden section. Annual grouodwater elevation maps for the underlying significant aquiferwere available for the years 1992-1994, and 1998-2001. These maps are presented in Figures 5.5A through 5.5G. The groundwater contours werfi transferred from the original maps submitted for the permit to the updated Dry Ron Landfill base map. These maps show that groundwater in the bedrock aquifer flows from the southeast towards the northwest. The groundwater elevations measured for nested wells (DRMW-12, -12A, and 12B, and DRMW-13 and -13A) are similar and the screened zones are constructed relatively close to each other, indicating that the overburden and bedrock aquifers may be in hydraulic conunnnicationdowngradientoftbelandfiB. 5.3 Water Quality 5.3.1 Surface Water Quality 08 Historical surface water coneenttations are presented in Table 5.1A for six sampling points. Sampling location for surface water sampliog points still in existence can be found on Figure 5.2. Surface water samples have been collected periodically from these locations since 1996 and have been collected consistently for three locations (DRLeachate, Outlet 001 and at the property boundary) since 1998. The concentration of C-8 in the leachate Sampleshave been decreasing over time (ftonx 62 ugfl down to 27.4 ug/1)while concentration from the other locations are variable and do not indicate a clew trend (Table 5.1A). 5.3.2 Groundwater Quality Historical gi-oundwater sampling began in 1996. For wells that currently exist, sampling continues (DRMW-6 was abandoned in 1999; Potesta 1999). C-8 concentration were contoured for some of the sampling events for the overburden and bedrock wells. These concentration contours can be found ia Figures 5.6A through 5.6 P. Data shown in Figure 5.6B was plotted but not contoured due to the data spread. The data for DRMW12-B and DRMW13-A for July 1999 appears anoinalows compared to the other data for these two wells. The contour naps show that the highest concentration of C-8 exists in monitoring wells 13 and 13A, bedrock and overburden wells, respectively. CiimpBaaon o( Mslwy data Draft a-ev.doc Mat. 11.02 S-4 WlinIiDgton.DE JS00150&0 Eir>620825 Main Plant HjtBndBlte________________|____________________Py Run Landfill These two wells are located downgradient from the central axis of the landfill. For the majority of the sampling events for most of the other wells, both overburden and bedrock, the C-8 concentration has been less than 1 ug/L The C-8 concentration for fte 1999 sampling event in DRMW-14 was higher than other values measured for this well. Given that this weU is an open bedrock well, and is relatively close to the landfill, this higher concentration may indicate communication of surface or shallow aquifer waters through the open well* particularly because groundwater flow in the underiymg significant bedrock aquifer flows ftom DBMW-14 north west toward the landfill area as opposedto groumdwaterflowing from the landfill toward theDRMw-14 well. ;, $.4 Site Conceptual Model The Dry Run site conceptual model describes the potentialexposure routes for current and future ecologicalreceptors. Potential exposure routes were evaluated and classified as complete or incomplete. Access to the Diy Run Landfill by is controlled by electronic gates on the major roads and locked gates on smaller roads, to addition, because the landfill is active, there is a crew of wolkers on the landfill area during normal working hours. The daily activity discouragestrespassers on the site. Therefore, direct contact with landfilled materials is a complete but minimal exposure route, limited to Ac workers in active portions of the landfill. Direct contact with landfill materials in the inactive, lower half of the landfill is incomplete due to the leachate collection system's geotextile and geomembrane cover, Contact with leachate at the landfill (or at the main plant where the teachate is treated) Is consideied a potentially complete but limited exposure route for the landfill and plant workers and samplers. , Cunentty, the inactive lower half of the landfill is covered by geotextlles and geomembraaes of the leachate collection system. Therefore, precipitation falling on this portion of the landfill does not come in contact with the landfilled materials. This precipitation Sows downslope via overland flow and discharges into storm water drainage ditches and eventually reaches Dry Run Creek. Therefore, this potential exposure route is considered incomplete. Precipitationfalling in the upper half of Ac landfill may also How via overiaad flow down slope to (he drainage ditches, again, an incomplete exposure route. Alternatively, uus precipitation may infiltrate and come in contact with the laodfilled materials as it migrates downgradient. However, this impacted water flowing within the landfill may be collected by the leachate collection system. If this impactedwater migrates downward through the landfilled materials, it may eventually come in contact with the underlying shales and sandstone of the bedrock and migrate downgradient within the bedrock aquifer. Contact with impacted groundwater is a potentiallycomplete exposure route althoughcurrently, not enough hydtogeologiedata exists to accurately evaluate this exposure pathway. Plains are underway for the expansion of the leachate collection system and for a final cap/cover system. These activities in the future will farther reduce preeipitatfon infiltiaring and contacting laadfilled materials. Cornplation of hisloiydala Draft Zrev.doC Mar. 11,02 5-5 WBmInBton.EC jsooiso&i EID620826 Main Plant and LendBIa pry Run Landfill 5.5 Data Gaps The following data gaps were identified for the Dry Rim Landfill: 0 Identity the locations of seep in the valley walls and determine water quality with respect to C.8 concentration. Q Determine the C-8 concentration in streams aid other surface water bodies. Q Acquire additional geologicaldata to more accurately develop (be Site Conceptual Model. Q Install additional monitor wells to provide additional growdwater flow data and groundwaterquality data. 0 Oather additional C-8 concentration data from monitoring wells for plume delineation, Activities to fill the data gaps will be proposed and discussed in the work plan. 5.6 References DuPont. 1996. Report of Geotechnical Investigation Dry Run Landfill, Washington Works Main Plant, Paitesbwg.WV. Oeotecbmcal Group, Civil Bngineenng Systems, DuPont Engineering. April 23; 1996. 2000. 2000 Dry Run Landfill Operational Report. Subtnitted January 26,2001. ^ ,.--. Potesta & Associates, Inc. 1989. Hydrolo^c and Hydraulic Analysis of Dry Run, Area No. 1. October 9,1989. Letter j&oca R Mark Kiser to Dan Weber. 19S9. Monitoring Wells MW.1.MW-1A, MW-4, MW-4A. MW-6. MW-10. MW- ,,,-,-,, . 10 Abandonment Report^ Dry Rim Landfill, DuPoat Washington Works. March 1999. TetiaTech Richardson. 1989. Monitoring Well Installation Program, October 1989, CompBaUw of Malay !tetal>Bll2iw.itoc Mw.11,02 WBmIftgton.Oe s-e JS00150&2 Ein620827 JS0015093 BID620828 Table 5.1A Summary of Analytical Results: C-8 in Surface Water Samples Dry Run Landfill Lubeck.WV & '''^w'W^''fes|asvs!99Ss.fe'ff- D<sipilBy,i ^.;fc. <&<W> ,..,%:"? 4/9/1998 DRtEACHATB 1^2w(2a9t(s18s9s9 2874.4 OUTLETWI PROPERTY BQWDAW WWW6 ^naf\'? iwaisawi vwwa 6MOT998 Wt^ lorafzooo -ya/im ' :- ..1.^29s/1a9aB 56 --------------g ~ 31.S 6tf . ------ ,1a7s 10.3 9.9 0.88 ^ ..,,. STREAM SAMPLING POimriM STREAM. SAHWUN6 POINTW lo/azooo i2eafi9 WfWS ^WHsaao ia25/1&99 OJ58 054' ' 1 27.8 87 519/19B9 4.6 W0015Q94 EID620829 Table 5.1B Summary of Analytical Results: C-8 in roundwatar Dry Run Landfill Lubeek.WV ^^r?!-^. ^ DRMW-12 DRW-12A "ORMW.IZB DRMW-13 DRMW-13A DRMW-14 BRMW-'IS" DRIu|W- ----CRMW-W ., ^3^ ': 709/2000 yffirti^ai 5/36/1988 7/231997 4/W16 7/19/2000 7/21(1989 6/26/1DS8 7/22/1997 4/1W1996 71SS13000 71S.WSS9 6M6/1998 7/2W2000 7/21/1998 SB2B/1^B 7ffiB1fl877/200000 7/21/1899 5/26/19S8 7/29^1687 4/1W199B 4/10/1 es0(dup) 7/2012000 7/21/1899 alOTees 7/21/1997 ^ wimsso 7/20/2000 7/Z1/1999 7/22/19B7 4/1011398 7/2B/20M wsvss""" 5/28/1998 : "Ttea/iSOT 4/10/1998 wsg- -^aaiaBS?^^ .01.;1634 " --^~ <0.10 <0.1 ' <0.1 0.128 O.OB1J ^CT----"""""' <0.1 <0.1 ND(O.Q5g 5.4 <0.1 . &. 3.8 ----------------9^3--. ---------------- 9A 0.070 J 8.7 ir" "' - - - - " ' -- -- --,..--..,,---.,&- ^2-..-... (MIS """""-"""""a.s -<b.r 1'"1"" "" ,,,...,,,,,.., ^ ^.f^" " 0.7^ 05W i """" ^" 0.87 oaa 0.096 o^ 0.27 0.19 """ J = estimated value (below laboratory quantitation iimit). JS0015095 EID620830 FIGURES JS001BO&6 EID620831 Figures can be found on hard copy in central files. JS0015097 EID620832 APPENDIX 1 CONSENT ORDER (ORDER NO. GWR-2001'019) JS0015098 EI0620833