Document YGomRN0XjjR2a5Z9yYmmeYeD

NORTHERN KENTUCKY OFFICE SUITE 340 1717 DIXIE HIGHWAY COVINGTON, KENTUCKY 41011-4704 606-331-2838 513-381-2838 FAX: 513-381-6613 Ro b e r t a . Bilott (513) 357-9638 bilott@taftIaw.conn Tm FT, STETTINIUS & HOLLISTER LLi" 1800 FIRSTAR TOWER 425 WALNUT STREET CINCINNATI, OHIO 45202-3957 513-381-2838 FAX: 513-381-0205 www.taftlaw.com May 7, 2002 f CLEVELAND OHIO OFFICE 3500 BP TOWER 200 PUBLIC SQUARE CLEVELAND. OHIO 44114-2302 216-241-2838 FAX: 216-241-3707 COLUMBUS. OHIO OFFICE 21 EAST STATE STREET COLUMBUS. OHIO 43215-1221 614-221-2838 FAX614-221-2007 -- i ! S TELECOPY Chris Negley, Esq. West Virginia Department Of Environmental Protection Office Of Legal Services 1356 Hansford Street Charleston, WV 25301 Pam Nixon Environmental Advocate West Virginia Department of Environmental Protection 1356 Hansford Street Charleston, WV 25301 James Becker, M.D. Marshall University Center for Rural and Environmental Health 1600 Medical Center Drive Suite 1500 Huntington, WV 25701 William Toomey Manager of Source Water Assessment Program West Virginia Department of Health and Human Resources Bureau for Public Health 815 Qurrier Street, Suite 418 Charleston, WV 25301 Dr. Dee Ann Staats West Virginia Department of Environmental Protection 1356 Hansford Street Charleston, WV 25301 cUz>) CXe_* rri cn "----QfoTl rx C) pn ho CO Jan R. Taylor, Ph.D. National Institute for Chemical Studies 2300 MacCorkle Avenue, S.E. Charleston, WV 25304 Joan Dollarhide, Ph.D. Toxicology Excellence for Risk Assessment 1757 Chase Avenue Cincinnati, OH 45223 Barbara Taylor Director, Office of Environmental Health Services West Virginia Department of Health and Human Resources - Bureau for Public Health 815 Quarrier Street, Suite 418 Charleston, WV 25301 C O N TA IN N T 000099 May 7, 2002 Page 2 Jennifer Seed U.S. Environmental Protection Agency 410 M Street, S.W. Washington, DC 20460 Samuel Rotenberg, Ph.D. (3WC11) U.S. Environmental Protection Agency 1650 Arch Street Philadelphia, PA 19103-2029 Roger Reinhart U.S. Environmental Protection Agency Region III 1650 Arch Street Philadelphia, PA 19103-2029 John Wheeler, Ph.D. (E-29) ATSDR 1600 Clifton Road, N.E. Atlanta, GA 30333 Janet E. Sharke, Esq. (3EC00) U.S. Environmental Protection Agency Region III Office Of Enforcement, Compliance and Environmental Justice 1650 Arch Street Philadelphia, PA 19103-2029 Garth Connor U.S. Environmental Protection Agency Region III 1650 Arch Street Philadelphia, PA 19103-2029 John Cicmanec, DVM U.S. Environmental Protection Agency 26 West Martin Luther King Drive Cincinnati, OH 45220 Laura Werner (3HS00) ATSDR U.S. Environmental Protection Agency Region III 1650 Arch Street Philadelphia, PA 19103-2029 Re: CAT Meeting To Discuss C-8 Screening Levels/Risk Factors Ladies and Gentlemen: Attached hereto is Section 6 of DuPont's June 1999 RCRA Facility Investigation Report for its Washington Works facility in Wood County, West Virginia, which sets forth DuPont's calculations in support of a 3 ppb "preliminary screening level" for C-8 in drinking water. Although we assume that each of you have been provided with a copy of this document by May 7, 2002 Page 3 DuPont (we understand that the document was submitted to at least the USEPA and WVDEP back in 1999), we wanted to make sure that each of the CAT Team members is aware of the existence of this document in the publicly-available files. Thank you. RAB/mdm Attachment 000101 cf l T O ) OuPoni Woshimjwn '.Vurtcs ? O. Bot 1217 Pjfkcfsmug, WV 26102-1217 CERTIFIED M AILRETURN RECEIPT REQUESTED June 24,1999 Mr. Martin Kotsch Project Manager U.S. EPA, Region ID 1650 Arch Street Philadelphia, PA 19103-2029 RE: Permit WVD045875291 Dear Mr. Kotsch: Please find enclosed the RCRA Facility Investigation (RFI) Report o f Findings for your review and comment If you have any questions or comments, please contact me at (304) 863-4271. Very truly yours, Attachment CC: Mr. Mark Priddy Office o f Waste Management WV-DEP 1356 Hansford Street Charleston, WV 25301 Mr. B. F. Smith, Chief* Office of Waste Management Charleston, WV 25301 1356 Hansford Street cover letter only R. L. Ritchey Sr. Environmental Control Consultant Washington Works Ms. Barbara Taylor, Chief* Office o f Water Resources WV-DEP 1201 Greenbrier Street Charleston, WV 25311 EID 109642 000102 @ V .I -: GLK002614 RCRA FACILITY INVESTIGATION REPORT DUPONT WASHINGTON WORKS WASHINGTON, WEST VIRGINIA USEPA PERMIT NUMBER WVD04-5 87-5291 June 30, 1999 Project No. 0D6W7205 CORPORATE REMEDIATION GROUP An AUmncm between DuPont nti The W C Diamond Gmup Bailey M il P le a . Building 27 VAnington, Delaware 194804027 (A juJisuI/ ,A C EteabeSaSSop W O Diamond Project Manager -~- " (% Andrew Harttan OuPontCRG Project O irictar EID 109643 l y J. SApftanO pp ! W-C Diamond Deputy Project Manager 000103 SECTIONSIX Screening Level RiskEvaluation 6.1 OBJECTIVES AND APPROACH The overall objective o f this risk evaluation is to determine whether identified releases from the SWMUs are a potential concern for human health or the environment and whether further evaluation or action is warranted. ." In the screening-level health risk evaluation, concentrations ofconstituents detected in soil and groundwater were compared to generic health-protective screening levels for soil and groundwater, in order to identify constituents and exposure pathways o f potential concern. The ecological evaluation focused on characterizing the habitat within the RFI study area and identifying whether complete exposure pathways exist between SWMU releases and significant ecological resources or receptors. This approach allows identification of the constituents and exposure routes o f concern early in the RFI/CMS process, and avoids expending effort on m inor constituents and exposure routes that do not influence overall risk (USEPA Region IE, 1993). The risk evaluation has been prepared consistent with the screening-level approaches outlined in the following documents: RCRA Facility Investigation Plan, DuPont Washington Works (DuPont, 1997). RCRA Facility Investigation Requirements (included as Attachment D to the RCRA Facility Investigation Plan). USEPA Region EH Technical Guidance Manual "Selecting Exposure Routes and Contaminants o f Concern by Risk-Based Screening" (USEPA Region HI, 1993). USEPA Region IH Risk-Based Concentration Table (USEPA Region HI, 1999). USEPA guidance for ecological risk assessment (USEPA 1997; 1998a; 1998b). In keeping with the above guidance documents, the risk evaluation includes: Description o f on-site and adjacent land use (Section 6.2). Evaluation o f data used in risk screening (Section 6.3). Screening-level health risk evaluation, in which analytical data were compared to generic health-based screening levels for soil, to drinking water criteria for groundwater, or to background levels (Section 6.4). Identification o f constituents and exposure pathways o f concern screening step (Section 6.5). Ecological exposure evaluation (Section 6.6). Summary and conclusions (Section 6.7). EID 109687 000104 6-1C:MYIAftY\7205V7205RFtOOC\30-JUN-W\7205l GLK002659 SECTIONSIX ScreeninglevelRiskEvaluation 6.2 SITE DESCRIPTION AND LAND USE This section provides an overview o f land use at the Washington Works site and identifies potential human and ecological receptors. Additional information on current and future land use is provided in Attachment 1, Land Use Report. / 6.2.1 OnSite and Adjacent Land Use The Washington Works facility has been the site o f ongoing industrial activities since the initial plant was first constructed in 1948. It occupies 1,200 acres, extending about a mile along the Ohio River seven miles west o f Parkersburg, WV. Most o f the facility is developed for manufacturing purposes and is covered with paving, rail tracks, and buildings. Open areas include lawns, mowed fields, and a few areas o f natural growth along portions o f the riverbank. The developed portion o f the property is fenced, and access is rigorously controlled by a security system. The riverbank itself lies outside the security fence, but is regularly patrolled. The riverbank adjacent to the facility is relatively inaccessible, due to its location and the regular security patrols, and there is little to attract casual visitors to the river's edge. Adjacent land use is a mix o f industrial, commercial, agricultural, residential, recreational, and open space. Adjacent industrial or commercial properties include GE Plastics and two warehouses to the w est Nearby residential areas include the unincorporated town o f Washington, whose eastern extent is adjacent to the DuPont property, and individual homes and subdivisions within about a mile o f the property to the east, south, and w est Figure 2.2 show the Washington Works site and adjacent land use. The W ashington Works facility will continue to be used for industrial purposes in the future. Likewise, adjacent land use is expected to remain a mix o f industrial, residential, and other uses. Land use issues are addressed in more detail in Attachment 1, Land Use R eport 6.2.2 Groundwater Uses The alluvial terrace unconfined aquifer is the principal regional aquifer and is used locally for industrial, municipal, and rural water supplies. Depth to groundwater is approximately 60iio 70 feet in the main plant area, and the saturated zone is about 30 to 40 feet deep, extending to bedrock at roughly 100 feet BGS. As indicated in previous sections o f this report, DuPont Washington Works operates several production well fields on the plant property that provide industrial process water and potable water to the plant (potable water is provided by Wells 331 (AO08, PW01), 332 (AQ09-PW01), and 336 (AM07-PW01), in the East Well Field). Off-site well fields in the downstream direction include eleven industrial and five potable water wells on the GE Plastics site located just to the west o f Washington Works and the Lubeck Public Service District (PSD) well field located about 2.3 miles south (downriver) o f the plan t The Lubeck PSD provides water to nearly 99 % o f the population in this portion o f Wood County (Lubeck PSD, 1999). Other private wells or small community wells o f unknown status were identified during a well search, but they are suspected o f being inactive (see Section 4.3 o f Attachment 1, Location o f Wellhead Protection Areas and Drinking W ater Wells). - EID109688 6-2C:\MARY\720S720SRF1.00029vAM49\720R 000105 SECTIONSIX ScreeningLevelRiskEvaluation As discussed in Section 5, pumping o f the Washington Works well fields controls groundwater flow, so that groundwater affected by SWMU releases is contained on-site. 6.2.3 Surface Water Surface water o f the Ohio River provides water to the cities of Parkersburg, West Virginia, and Belpre, Ohio, about seven miles upstream o f the Washington Works facility. There are no permanent streams or surface water bodies on the main plant area at Washington Works. Precipitation in the main plant area is directed toward drains and storm sewers, which ultimately discharge to the Ohio River. Two drainage swales that convey surface runoff to the Ohio River during rainy weather are located on the property, one in the facility's southwest com er and the other on the extreme eastern (upgradient) end o f the property. The former BG and PWI have been excavated, backfilled, and resurfaced, so there are no surface water impacts from these SWMUs. The slopes o f the RBL/ADP above the Ohio River are heavily vegetated, and the SWMUs have been covered with clean fill, so surface water impacts via surface runoff from these SWMUs are considered negligible. As indicated in the previous sections, SWMU-impacted groundwater does not discharge to surface water because o f production well pumping. 6.2.4 Ecological Setting The Washington Works site itself is largely developed and used for manufacturing activities, with manicured lawns, mowed fields, and a few areas o f natural growth along portions o f the river bank. These areas provide a narrow and intermittent terrestrial habitat for a variety o f birds, small mammals, and other animals. The upper terraces upstream and downstream from the plant are kept in grassland with some small areas o f trees and brush. A small chestnut grove is being developed by the facility's Wildlife Habitat Enhancement Program, in conjunction with the American Chestnut Foundation. There are no known records o f any federal or state listed species in the vicinity o f the Washington Works Site (West Virginia Division o f Natural Resources [WVDNR], 1999). In addition, no wetlands or critical terrestrial habitat were identified at the W ashington Works: facility during field observations conducted at the site. Section 6.6, Ecological Exposure " Evaluation, provides additional site-specific information about ecological resources and exposures at the site. GLK002661 OB ^ EID 109689 O O O IO S CAMARY\720720Sfl0002JUN-9720a 6-3 SECTIONSIX ScreeninglevelRiskEvaluation 6.3 DATA AND MEDIA EVALUATED Soil and groundwater analytical data collected during the RFI were discussed in Sections 4.2 and 4.3. No quality assurance or quality control issues were identified that would affect data usability in risk assessm ent Tables 6.1 through 6.4 show the soil data included in the risk evaluation. These data were from samples collected between 0 and 20 feet BGS at the BG and RBL/ADP units. The depth o f 20 feet is considered a conservative estimate o f depth o f excavation for future construction or utility work. Two soil intervals were evaluated: 0 to 2 feet (surface soil) and 2 to 20 feet (subsurface soil). Table 6.5 shows the groundwater data included in the risk evaluation. These data were from water quality samples collected at the five production wells sampled during the RFI investigation: K16-PW01, L17-PW01, AM07-PW01, VO5-PW01, and LO4-PW01. Water from these wells is used to supply process water to the manufacturing area, and water from Wells AM07-PW01 (336) provides potable water to the plant Therefore, groundwater drawn from these wells is representative o f the exposure medium to which humans are or could be exposed. 6.4 SCREENING-LEVEL HEALTH RISK EVALUATION The purpose o f the screening-level health risk evaluation is to identify the constituents and exposure pathways that may be a concern for human health and that may warrant further evaluation or action. Constituents whose maximum concentrations do not exceed healthprotective screening levels and environmental media that have no constituents exceeding screening levels are concluded to pose no concern for human health and can be eliminated from further evaluation. Potential exposure to multiple chemicals and multiple media also is considered in the risk evaluation, in order to strengthen conclusions drawn from the risk-based screen. 6.4.1 Potential Human Receptors Human exposure to hazardous constituents released from the SWMUs is minimal or non existent, because they have been removed and regraded or paved (BG, PWI, ADP) or covered and vegetated (RBL). However, for the risk evaluation it was assumed that potential on-site human receptors include site workers, occasional trespassers along the riverbank, and construction workers performing excavation work. O f these, the on-site worker is the most exposed individual, because he or she is assumed to be present on a daily basis for the duration o f his/her career. Therefore, evaluating presumed on-site worker exposure to soil at the SWMUs is protective o f construction workers and trespassers, whose exposure would be short-term and intermittent. Likewise, workers are the only receptors who are exposed to production well water. Construction workers would not be exposed to groundwater during excavation because the water table is about 60 feet BGS. 4BD >--ig E ID 109690 000107 CAMARY\720720SWI.00O-JUN-9tf20 6-4 SECTIONSIX Screeninglevel RiskEvaluation 6.4.2 Screening Levels Used in the Evaluation Soil data were compared to the following screening levels: USEPA Region HI RBCs for industrial soil (soil ingestion pathway) (USEPA Region HI, 1999). The RBCs are based on a target excess cancer risk o f IC r (1 in I million) and a noncancer hazard quotient (HQ) o f one. These RBCs represent chemical concentrations in soil that would be expected to pose no adverse impacts to health under the exposure conditions evaluated. Industrial soil RBCs were used because the current and future use o f the property is industrial (Section 6.2.1 and Attachment 1, Land Use Report). A screening level for lead in industrial soil o f 1000 mg/kg. This level is a conservative (low) estimate for industrial soil screening purposes, because it is below typical screening levels calculated using USEPA's Adult Lead Exposure Model (1,200 to 1,800 mg/kg, using default parameters) (USEPA 1996a). Federal MCLs for drinking water or the federal action level for lead in tap water. USEPA Region E l RBCs for tap water (in the absence o f an MCL) (USEPA Region HI, 1999). Preliminary screening levels for FC-143 in soil and groundwater (see Section 6.4.3). Certain potential exposure pathways are not included in the derivation o f the screening levels, namely: Inhalation: The inhalation pathway is not included in the derivation o f the USEPA soil screening levels used in this evaluation. Nor are there USEPA-established "soil-to-air" screening levels for an industrial scenario. However, neglecting the inhalation pathway is not expected to significantly affect the results o f the risk screening for the following reasons. -- First, inhalation o f non-volatile constituents (such as metals or FC-143) that are adhered to soil particulate matter usually does not contribute significantly to overall risk because air emissions from wind erosion are, on an annual average basis, relatively low. This is represented in USEPA's default Particulate Emission Factor (PEF) o f 1.32 x 10^ m3/kg soil (USEPA 1996b). When applied in the denominator o f an equation to estimate air concentrations o f particulate matter, the resulting air particulate matter concentrations are negligible and usually do not contribute to overall risk. -- Secondly, volatile constituents, such as methylene chloride or trichloroethylene, were relatively infrequently detected in soil (see Tables 6.1 through 6.4), and would not be expected to contribute to a significant inhalation hazard. Therefore, the industrial soil RBCs are considered sufficiently conservative (protective) for the screening-level risk evaluation. If constituent concentrations in soil exceed the RBCs, the inhalation pathway may warrant consideration in the future. 000108 EID109691 C.AMARW20SV730SRFI.D002-A)N-97?05V 6-5 GLK002663 SECTIONSIX ScreeninglevelRiskEvaluation Dermal absorption: The dermal absorption exposure route is not included in the derivation o f the USEPA soil RBCs used in this evaluation. Although this adds a small uncertainty to the screening levels, it will not significantly affect the results o f the screening. In cases where constituent concentrations in soil exceed RBCs, dermal absorption may warrant further consideration in the future. Migration to groundwater Soil screening levels for protection o f groundwater used as drinking water were not included in the risk screening evaluation because groundwater data were compared directly to drinking water criteria. 6.4.3 Derivation of Preliminary Screening Levels for FC-143 USEPA-established screening levels are not available for FC-143. Therefore, preliminary screening levels analogous to Region HI RBCs for soil and groundwater were derived from a health-based Community Exposure Guideline (CEG) o f 0.0003 mg/m3 air (Haskell Laboratory 1991). The CEG was developed by Haskell Laboratory to be protective o f public exposure via the inhalation pathway. The CEG was derived from the DuPont Allowable Exposure Level (AEL) for workers o f 0.01 mg/m3. Both the AEL and the CEG are health-protective o f the exposure conditions to which they apply. For example, the AEL for workers is 100 times lower than a No Observed Effect Level in a laboratory animal inhalation study and is 1,000 times lower than a Marginal Effect Level in a laboratory animal feeding study (Haskell Laboratory 1991). Therefore, the AEL is considered to be a safe level for workers potentially exposed for eight hours/day. To derive a level protective o f sensitive subpopulations (such as infants and the elderly) and to account for a 24-hour/day exposure time, the AEL was reduced further by a safety factor o f ten to account for the presence o f sensitive subpopulations in the community and again by a safety factor o f three to account for a 24-hour/day exposure time, resulting in the CEG o f 0.0003 mg/m3. Therefore, the CEG is considered protective o f general public exposures that could include sensitive subpopulations, exposed 24 hours/day. : Exposure to the CEG o f 0.0003 mg/m3 would result in an allowable daily intake o f 0.006 ^ mg/day, assuming an inhalation rate o f 20 m3/day (USEPA Region DI default residential '" inhalation rate). From this allowable intake, preliminary screening levels for soil and groundwater can be calculated using USEPA default exposure assumptions for industrial soil ingestion and residential groundwater ingestion. Table 6.6 shows the calculation o f preliminary screening levels for FC-143 in industrial soil (120 mg/kg) and for groundwater used as drinking water (0.003 mg/L). These preliminary screening levels were used in evaluating site soil and production well water data for FC-143. GLK002664 EID 109692 000109 SECTIONSIX ScreeningLevelRiskEvaluation 6.4.4 Results of Risk-Based Screening for Soil Tables 6.1 through 6.4 show the sample analytical results for constituents detected in soil and groundwater and include the SLs for comparison. Table 6.7 summarizes the results o f the riskbased screening for soil. Table 6.7 shows that maximum observed concentrations o f all constituents at all SWMUs and soil intervals were well below their respective screening levels, with the exception o f arsenic (which is present at concentrations comparable to background levels). Therefore, it is concluded that constituents in soil do not pose a health concern for workers via the soil ingestion pathway. Potential exposure via other routes (e.g., dermal absorption or inhalation) and possible additive effects o f multiple noncarcinogens are also not a concern. Maximum observed concentrations o f all site-related constituents were lower than screening levels by factors o f ten to one million, except for FC-143 and methylene chloride in the 2- to-20-foot interval at the RBL/ADP, where maximum concentrations o f these two constituents were lower than their respective screening levels by a factor o f about 2.4. Because maximum observed concentrations o f site-related constituents are well below conservative health-protective screening levels, it is concluded that constituents in soil do not pose a health concern for workers or transient receptors. 6.4.5 Risk Screening for Production Weil Water Table 6.5 compares sample analytical results from production well samples to MCLs or other health-based screening levels for drinking water. Table 6.8 summarizes the risk-based screen for production well water. In well AM07-PW01, which supplies potable water for the plant, maximum concentrations o f all constituents were below their respective drinking water criteria. To confirm this conclusion, a third round o f analysis for FC-143 was conducted in May, 1999 (see Appendix D). Therefore, no unacceptable health risk would be associated with the observo! concentrations in the potable water well. In production wells providing industrial process water, maximum concentrations o f all constituents were also below health-based criteria for drinking water, with the exception o f TCE in production well V05-PW01 and FC-143 in production wells K16-PW01, V05-PW01, and L04-PW01. Specifically, the maximum concentration o f TCE (22 micrograms per liter (ug/L)) exceeded the MCL o f 5 ug/L, and the maximum concentration o f FC-143 (16.2 ug/L) exceeded its preliminary screening level for drinking water o f 3 ug/L (Table 6.8). For both constituents, maximum concentrations exceeded their respective drinking water criteria by factors o f four to five. Because water from these wells is not used for drinking, but rather for industrial processes such as non-contact cooling water or fire water where exposure is nonexistent or intermittent, it was concluded that the exceedances o f the drinking water criteria by relatively small factors is not likely to pose health concern for workers who may be exposed to process water. EID 109693 GLK002665 O O O il SECTIONSIX Screening Level Risk Evaluation 6.5 SUMMARY OF CONSTITUENTS AND PATHWAYS OF CONCERN (HUMAN HEALTH) All constituents in all media evaluated were below health-protective criteria, with the exception o f TCE and FC-143, whose maximum concentrations in industrial process well water exceeded drinking water criteria by factors o f four to five (see Appendices B and C). However, average concentrations in process water at the point o f use (which is a mixture o f water from several production wells) will be lower than maximum concentrations detected in one well. Therefore, these exceedances are not considered a concern for worker health under exposure conditions typical for industrial process water. As demonstrated in Section 5, SWMU-impacted groundwater is contained on-site by production well pumping and does not migrate off-site or to surface water. In summary, the identified releases from the SWMUs are not a concern for human health. Siterelated constituent concentrations in soil (0 to 20 feet) did not exceed screening levels. While TCE and FC-143 somewhat exceeded screening levels in production well water used for industrial process water (but not in potable well water), there is limited exposure to industrial process water. In addition, SWMU-impacted groundwater is contained on site. These findings are summarized in Figure 6.1, Human Exposure Pathway Evaluation. The figure indicates that potential exposure routes for site receptors (workers, riverbank trespasser, and construction worker) are either incomplete or insignificant and that groundwater migration t o . surface water is an incomplete pathway due to pumping. 6.6 ECOLOGICAL EXPOSURE EVALUATION The ecological evaluation focused on identifying whether significant ecological resources may be exposed to site-related constituents released from the SWMUs. According to USEPA guidance (USEPA 1997,1998a, 1998b), valued ecological resources are those that either provide critical habitat (such as wetlands or fisheries), are critical to sustaining populations o f species o r habitat, are reflective o f public concerns (e.g., wildlife habitat for game animals), or are federal or state listed species that could be exposed and susceptible to site-related constituents. The study area for the ecological evaluation included the four SWMUs and surrounding terrestrial habitat The ecological evaluation included a day and a half o f field reconnaissance for habitat characterization (April 6 to 7,1999), principally along the portion of the property adjacent to the river, which includes the RBL/ADP. 6.6.1 Exposure Areas and Media Surface soil at the RBL/ADP is the only potential ecological exposure medium within the RFI study area. The PWI and BG SWMUs are covered with gravel, asphalt or buildings and do not provide ecological habitat Subsurface soil (greater than 2 feet) and groundwater are not exposure media o f concern for ecological receptors, and groundwater does not discharge to surface water at the site. EID 109694 000111 GLK002666 SECTIONSIX ScreenWevetRiskEvaluation 6.6.2 Habitat Characterization at the RBUADP The RBL/ADP lies in a narrow band between the river and the main nnaf& turing area. It runs approximately 4,500 feet and rises 30 feet above the floodplain, c o v erq p p p rtio n o f the alluvial terrace on which the main plant is located. A layer o f clean fill 6 to 3 6 ich es lhick was placed over the RBL upon closure in the 1960s. The southern side o f the RBLitwithin the active manufacturing area and is covered with gravel or buildings. The ADPsmrexIosed in 1988 and removed. The ponds were filled and capped and are now covered w ifh p esy vegetation. The slope o f the RBL/ADP is covered with hardwood trees, shrubs, g n ^ a n d io th e r dense vegetation that has grown in the 30 years since the landfill was closed. ItiEarea between the RBL/ADL and the river is manicured grass, with a few trees and shrub*. Aether upstream end o f the RBL, the grassy area gives way to natural vegetation o f trees and sUbs;. Major vegetation species include beech, maples, oaks, ash, cottonwood, black willow, aai^weetgum. Wildlife observations, including tracks, burrows, and scat, included snail mammals (woodchucks, cottontail rabbits, squirrels) and deer tracks along portion o f the river. It can be assumed that other small animals such as mice, voles, raccoons, and various reptile and amphibian species would inhabit the area near the riverbank. Birds dbsseved in the area were primarily bank swallows, crows, and redwing blackbirds. Other passcrisrbirds will likely occur during different seasons. Hawks were observed hunting over the area asKseveral species o f waterfowl were observed on the river that might feed on vegetation on riverbank. Ospreys, reintroduced by DuPont's Wildlife Habitat Enhancement Program, w a n ep o rted by a plant employee to nest in the area. Bluebird and wood duck nesting boxes emplaced near the river, but these species were not seen. 6.6.3 Identification of Significant Ecological Resources While numerous plant and animal species were observed along the rivafemk area, no significant ecological resources such as wetlands, game habitat, or threatened or endangered species were identified within the RFI study area. In addition, according to the WVBNR, Wildlife Resources Section, no rare, threatened, or endangered species are recorded for the vicinity o f the Washington Works p la n t Table 6.9 lists the terrestrial species that are fistfcd as Rare, Threatened or Endangered (RTE) by both the U.S. Fish and Wildlife and the West Virginia Natural Heritage Program. In conclusion, no significant ecological habitat or species o f special concern were identified within the study area, and therefore potential ecological impacts from constituents in soil at the SWMUs are expected to be insignificant. GLK002667 E ID 109695 CiMARW207209RFI.OOOaN)UN^*720 6-9 000 2 s SECTIONSIX ScreeningLevelRiskEvaluation 6.6.4 Ecological Exposure Pathway Evaluation In conclusion, there appear to be no significant ecological resources or exposure pathways o f concern related to soil at the SWMUs. Groundwater is not an exposure medium for ecological receptors, because there are no surface expressions o f groundwater at the site (water table is about 60 feet BGS). / These findings are summarized in Figure 6.2, Ecological Exposure Pathway Evaluation. The figure indicates that potential soil exposure pathways are either incomplete or insignificant, primarily due to the absence o f significant ecological resources in the study area. 6.7 SUMMARY AND CONCLUSIONS Soil at all SWMUs is not a medium o f concern for human health because maximum observed concentrations in soil were below health-protective screening levels. In the well supplying potable water (AM07-PW01), constituent levels were below MCLs or other health criteria, so the water is not a significant source o f exposure for workers. In wells supplying industrial process water, maximum concentrations o f two constituents somewhat exceeded MCLs or health criteria for drinking water, but the water is not ingested, and therefore, the production well water is not considered a health concern under exposure conditions typical for industrial process water. SWMU - impacted groundwater is contained on site by production well pumping. Ecological habitat in the study area is limited to a narrow band o f woody o r grassy vegetation along the river bank and slopes o f the RBL/ADP, inhabited or visited by small mammals, birds, and other animals. No significant ecological resources were identified within the RFI study area, and no rare, threatened, or endangered species have been recorded for the vicinity o f the Washington Works site. Because o f the absence o f significant ecological resources and the limited potential for exposure, ecological exposure pathways were concluded to be incomplete or insignificant. Table 6.10 summarizes the findings o f the screening-level risk evaluation and ecological exposure evaluation. * GLK002668 EID 109696 6cizooyno EID 109767 TABLe. 4.6 FC-143 RESULTS FOR GROUNDWATER SAMPLING RCRA FACILITY INVESTIGATION DUPONT WASHINGTON WORKS PLANT Groundwater Results for November Sampling Groundwater Results for February Sampling AA04-MW01 AA05-MW0I AB07-MW02 AC07-MW02 AEII-MW0I AI06-MW01 AM07-PW0I EI3-MW0I F06-MW0I GI7-MW0I KI6-PW0I L04-PW0I L06-MW0I LI7-PW0I M04-MW02 M04-MW03 MI6-MW0I N04-MW02 N05-MW0I NI3-MW0! P04-MW02 P05-MW02 P06-MW02 P08-MW01 Q04-MW02 Q05-MW0I R04-MW02 S05-MW02 TI3-MW0I U04-MW0I V05-PW0I V06-MW01 11/12/98 0.1 1l/l 1/98 0.77 11/16/98 0.2 i 1/16/98 0.79 11/10/98 0.41 11/16/98 0.1 11/18/98 1.9 1l/l 1/98 2 1l/l 1/98 0.1 11/11/98 13 11/18/98 0.46 11/J8/98 7.9 11/13/98 870 11/18/98 0.33 11/12/98 0.2 11/12/98 0.1 11/10/98 0.86 11/12/98 380 11/13/98 13 11/11/98 0.1 11/12/98 8300 11/13/98 1200 11/13/98 31 11/13/98 36 11/13/98 660 11/13/98 38 11/12/98 1300 11/13/98 690 11/17/98 0.1 11/12/98 1.6 11/18/98 0.66 11/16/98 1.7 UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L UG/L 0.1 0.1 0.2 I 0.1 0.1 0.1 0.1 0.1 0.1 2 0.1 1 50 0.1 0.1 0.1 0.1 20 2 0.1 800 100 2 5 50 2 too 50 0.1 0.1 0.1 0.2 AA04-MW0I AA05-MW01 AB07-MW02 AC07-MW02 AE11-MW0I AI06-MW0I AM07-PW0I EI3-MW01 F06-MW01 G17-MW01 KI6-PW0I L04-PW01 L06-MW0I L17-PW0I M04-MW02 M04-MW03 M16-MW01 N04-MW02 N05-MW0I N13-MW0I P04-MW02 P05-MW02 P06-MW02 P08-MW01 Q04-MW02 2/6/99 5.43 UG/L 0.028 0.095 2/4/99 1.46 UG/L 0.032 0.II 2/4/99 0.535 UG/L 0.030 0.099 2/4/99 0.356 UG/L 0.028 0.095 2/2/99 0.69 UG/L 0.030 0.1 2/3/99 0.13 UG/L 0.030 0.1 2/3/99 0.082 UG/L 0.030 0.1 J 2/2/99 0.59 UG/L 0.030 0.1 2/2/99 0.35 UG/L 0.030 0.1 2/2/99 2.11 UG/L 0.030 0.1 2/9/99 16.2 UG/L 0.29 1 2/7/99 5.89 UG/L 0.028 0.094 2/5/99 4.91 UG/L 0.028 0.095 2/9/99 2.76 UG/L 0.029 0.098 2/7/99 17.0 UG/L 0.14 0.47 2/7/99 21.1 UG/L 0.16 0.53 2/3/99 3.66 UG/L 0.030 0.1 2/7/99 329. UG/L 3.1 10 2/5/99 815. UG/L 28. 95 2/2/99 29.6 UG/L 0.60 2 2/6/99 13600. UG/L 320. MOO 2/5/99 434. UG/L 2.8 9.5 2/5/99 414. UG/L 3.1 10 2/4/99 43.4 UG/L 0.70 2.3 2/4/99 994. UG/L 6.1 20 R04-MW02 S05-MW02 TI3-MW01 U04-MW0I V05-PW0I V06-MW01. 2/6/99 9420. 2/5/99 174. 2/3/99 0.64 2/6/99 4.20 2/7/99 12.4 2/4/99 1.91 UG/L 280. 950 UG/L 3.1 10 UG/L 0.030 0.1 UG/L 0.033 0.11 UG/L 0.14 0.47 UG/L 0.029 0.095 Page 1 of 2 .! { 000114 Gwmcls.xls TABLfc 4.6 FC-143 RESULTS FOR GROUNDWATER SAMPLING RCRA FACILITY INVESTIGATION DUPONT WASHINGTON WORKS PLANT Groundwater Results for November Sampling Groundwater Results for February Sampling W05-MW0I YI4-MW0I Z06-MW02 Z07-MW0I Z09-MW0I 11/17/98 0.31 11/10/98 12 11/16/98 4.5 11/16/98 3.8 11/17/98 0.1 UG/L UG/L UG/L UG/L UG/L 0.1 2 0.5 0.5 0.1 Preliminary Screening Level (SL): 3 ug/L W05-MW01 YI4-MW0I Z06-MW02 Z07-MW01 Z09-MW01 2/6/99 0.729 2/2/99 4.95 2/4/99 0.803 2/4/99 2.05 2/6/99 2.74 UG/L 0.028 0.095 UG/L 0.030 0.1 UG/L 0.029 0.097 UG/L 0.028 0.095 UG/L 0.029 0.095 ,! * E ID 109768 OttZOfDHO Page 2 of 2 000115 Gwmcls.xls TAtL.E 6.5 PRODUCTION WELL GROUNDWATER CONCENTRATIONS COMPARED TO MCLs OR OTHER SCREENING CRITERIA SRCNAME Date K16-PW01 11/18/98 K16-PW01 2/9/99 L17-PW01 11/18/98 L17-PW01 2/9/99 AM07-PW01 * 11/18/98 AM07-PW01 * 2/7/99 V05-PW01 11/18/98 V06-PWD1 2/7/99 L04-PW01 11/18/98 L04-PW01 2/7/99 Maximum Concentration MCL or Other Criterion Maximum cone. Exceeds Criterion? Arsenic Qual m g/L 00013 J NO 0 0043 J NO 001 ND 0.0025 J 0 0017 J 0 0068 J 00028 J 0.01 005 MCL No PQL 001 001 001 001 001 0.01 0.01 0.01 001 0.01 Barium mg/L 0 15 0 14 0 13 013 0 0672 00743 0 0845 0 0848 0.16 0.14 0 16 2 No Qual J J J J MCL PQL Cadmium Qual m g/L 0 1 ND 01 ND 0.1 ND 0.1 ND 0.1 ND 01 ND 0.1 ND 0.1 ND 01 ND 0.1 NO ND 0.005 MCL No PQL 001 001 0.01 0.01 0 01 0 01 001 001 0.01 0.01 Lead m g/L ND ND 00022 ND ND ND ND ND ND NO 00022 0.015 No Qual J D) PQL 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 N icke l m g/L ND ND ND ND ND ND ND NO NO NO ND 0.14 No Qual MCL PQL 005 0.05 0.05 0.05 0.05 0)05' 0.05 0.05 0.05 0.05 SRCNAME Date K16-PW01 11/18/98 K16-PWD1 mm L17-PW01 11/18/98 L17-PW1 2/9/99 AM07-PW01 * 11/18/98 AM07-PW01 * 2/7/99 V05-PW01 11/18/98 V05-PW01 2/7/99 . L04-PW01 11/18/98 L04-PW01 mm Maximum Concentration MCL or Other Criterion Maximum cone. Exceeds Criterion? FC-143 ug/L 0.46 16.2 0.33 276 1.9 0.082 066 12.4 79 5.89 16.2 3 Yes Qual J (2) PQL 0.1 1 0.1 0.098 0.1 01 0.1 047 1 0.094 PCE Qual PQL ug/L ND ND 4J 5 4J 4J 5 5 MCL No 5 5 5 5 5 5 TCE Qual PQL ug/L ND ND 22 22 5 5J 22 5 MCL Yes 5 5 5 5 5 5 MeCI ug/L ND ND ND ND ND ND ND ND ND ND C No Qual MCL PQL Freon 113 Qual u g /L 5 5 5 5 5 ND 5 ND 5 64 5 56 5 5 270 270 59000 (3) No PQL 10 10 10 10 10 J ' Estimated value below PQL. M C I = Federal maximum contaminant Level for drinking water NO * Not detected. PQL * Practical quantitation limit. * Plant potable water supply (well 336). 'Observed concentrations did not exceed screening levels. (1) Federal action level for lead in tap water. (2) Preliminary screening level; see Table 6.6 and Section 8.4 2. (3) Risk-based concentration for Freon 113 (1,1,2-trlchloro-1,2,2-trifluoroethane) In tap water (USEPA Region III, 1999) O O O ii EID 109781 SITM44,>7!H' r>Mhsh>ih.*wnui>UAM ESJZOOXIO Pape I of TABLE 6.6 CALCULATION OF PRELIMINARY SCREENING LEVELS FOR FC-143 IN SOIL AND DRINKING WATER CEGair (1) mg/m3 0.0003 Inhalation* Rata (2) m3/day 20 Allowable Daily Intake (3) mg/day , 0.006 Water Ingestion Rata (4) L/day 2 PSL water (8) mg/L 0.003 Soil Ingestion Rata (6) mg/day SO Conversion Factor mg/kg 1.E+06 PSL soil (7) mg/kg 120 Lx p a n d : Allowable Daily Intake 3 CEGair x Inhalation Rate PSL w ater - Prelim inary Screening Level for drinking w ater 3 Allowable Daily Intake / W ater Ingestion Rate PSL s o il Prelim inary Screening Level fo r industrial soil Allowable Daily Intake x 10** mg/kg / Soil Ingestion Rate HQHt (1) CEG air = Community Exposure Guideline for air exposures (Haskell Laboratory. 1991). (2) USEPA Region III default residential inhalation rate (USEPA Region III. 1999). (3) Allowable Daily Intake 3 CEG air x Inhalation Rate. (4) USEPA Region III default residential groundwater ingestion rate (USEPA Region III, 1999). (5) PSL w ater 3 Allowable Daily Intake / W ater Ingestion R ate.' (6) USEPA default industrial soil ingestion rate (USEPA region III, 1999). (7) PSL soil 3 Allowable Daily Intake x mg/kg / Soil Ingestion Rate. GLK002754 I-"* * (Vito si* |r-A *> I \\l E ID 109782 000117 I nt I Taute 6.7 RISK-BASED SCREENING FOR SOIL C o n stitu e n t A rse n ic Barium Cadmium Lead N icke l Carbon Tetrachloride FC-143 Freon 113 M ethylene Chloride Tetrachloroethytene Trichloroethylene M axim um D etected C oncentration .m g /kg BG 0 - 2 ft 12 7 BG 2-20 ft 13 RBL/ADP 0 - 2 ft 15 RBL/ADP 2-20 ft 22 562 150 972 830 2 088 7 4 11 8 26 17 . 80 114 17.3 22.6 46.3 44.6 NO (<0.241 0.84 - - 0.082 0.14 9.5 48 - - 1.6 1.6 - - ND (<0 3) 320 - - 0.51 1.4 - - 0.16 8.8 Industrial Soil S i. (1) Max > Soil mg/kg SL? 3.8 AUSWMUs 140000 1000 1000 (2) No No No 410C No 44 No 120 (3) No 6.10E+07 No 760 No 110 No 520 No Not analyzed, na = not available. BG = Burning Ground. RBL/ADP * Riveibank Landfill and Anaerobic Digestion Ponds SL = Screening Level Notea: (1) Industrial soil SL - Risk-based concentration (RBC) fo r industrial soil. USEPA Region III 1999. (2) Conservative SL for lead in industrial soil; see Section 6.4.1. (3) Prelim inary screening level, see Table 6.6 and Section 6.4.2. EID109783 zoo>nD l I D i b ' l A f W . ' l v a i e M %M 000118 Page I of I TABLE 6.8 HEALTH-BASED SCREENING FOR PRODUCTION WELL WATER C onstituent --:J J n its Potable W ater W ell (1) Process W ater W ells (2) Screening Level Type Max > SL? Arsenic mg/L 0.01 0.0068 0.05 MCL No Barium md/L 0.07 0.16 2 MCL No Cadmium mg/L NO (<0.01 ) NO (<0.01) 0.005 MCL No Lead mgA. ND (<0.003) 0.0022 0.015 MCL No Nickel mg/L ND (<0.05) NO (0.05) 0.14 MCL No FC-143 ug/L 1.9 16.2 3 PSL Potable - No Process - Yes (3) Tetrachloroethylene ug/L ND (<5) 5 5 MCL No Trichloroethylene ug/L ND (<5) 22 5 MCL Potable - No Process - Yes (4) Methyene Chloride ug/L ND (<5) - 5 MCL No Freon 113 U9'L ND <<10) 270 Legend: MCL Maximum Contaminant Level for drinking water. PSL * Preliminary Screening Level; see Table 6.6 and Section 6.4.2. RBC = Risk-based concentration for tap water (USEPA Region III, 1999) - * Not analyzed. 59000 RBC No N otes: (1) Well 336 (AM07-PW01) (2) Process Water Wells: K16-PW01 K16-PW01 L17-PW01 L17-PW01 V05-PW01 V05-PW01 L04-PW01 L04-PW01 (3) Trichloroethylene exceeded the MCL in production well V05-PW01. (4) FC-143 exceeded the preliminary SL in production wells K16-PW01, V05-PW01. and L04-PW01. GLK002756 s Tjbi-i\j. (:am EID109784 000119 faire I .> I v TA BLE 6.10 RISK EVALUATION RESULTS Do Constituent Levels Pose Potential Concern? Exposure Medium BG Soil PW1 Soil RBL7ADP Soil Potable Water Wells (2) Process Water Wells (3) SWMU Impacted Groundwater Soil 0 - 2 ft No No No Soil 2 - 20 ft No No No Groundwater No No Contained on site (1) No All constituent concentrations were below health screening levels or (for industrial process water) were below levels that would be expected to pose a concern under intermittent exposure during manufacturing operations. Ihere were no significant ecological resources or listed species identified within the RFI study area. (2) Potable water well =*Well 336 (AM07-PW01). (3) Process water wells - K16-PW01, L17-PW01. V05-PW01, L04-PW01. GLK002758 E1D109786 000120