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AR226-2610 I I I I I SAMPLING INVESTIGATION RESULTS LITTLE HOCKING WATER I ASSOCIATION WELL FIELD I WASHINGTON COUNTY, OHIO I I Date; April 2003 I Project No.: 7482 18983762.00010 I I CORPORATE REMEDIATIOIM GROUP I An Alliance between DuPont and URS Diamond I Barley Mill Plaza, Building 27 Wilmington, Delaware 19805 I I ASB025862 EID779150 EID779150 I Sampling Investigation Rasute Table of Contents I TABLE OF CONTENTS I Executive Summary........................................ ............................................................ Hi 1.0 fcitroduction.......................................,..,................,.........................,,.....,,.....,..,....,,..,.! I 2.0 Environmental Seating............................................................................................3 2.1 Geology......................................................,,,,,,,.,,.,,,,,,,,,,.,,..,,.,,.,,,,,,..-..,,...,,.....,3 I 2.2 Hydrogeology................,......,..,..,,.............,.,.......................,,.........,.,.........,.....,,4 3.0 Sampling Approach...................................,......,.......,...,.,..,...,.,.,.,...,,..,.......,..,.........,.5 4.0 Groundwater Sample Results......................................................................................6 I 4.1 C-8 in Groundwater from Temporary Borings .....,...............,...........................,6 4.2 C-8 to Groundwater from Production and Test Wells........................,.,,.........,6 I 4.3 Groundwater Blevatfons in Production and Test Wells and Ohio River Stage...................,.......................................................................................,.......8 I 5.0 Soil Sample Results ....................,.........,...................,...........,...,......,.,,.,.....,...,.,.........9 I 6.0 Site Conceptual Model..............................................................................................lO 6.1 Geology.......................................................................................................10 6-2 10 Hydrogeology........................................................................................... 6.3 C-8 Transport Mechanisms and Migration Pathways.............,........................! 1 7.0 Conclusions and Recommendations .,,..,,..,......,..,.....,............,,....,,.............,..........,..13 I 8.0 R6ferences.....................,,,............,............................................................................15 I TABLES Table 1 C-8 in Groundwater from Temporary Borings I /Table 2 C-8 in Production and Test Wells Table 3 Oroundwater Elevation Data for Production and Test Wells August 21. I 2002 Table 4 C-8 in Soil from Temporary Borings I I I LHSIreportI ABC. 17. 03 I Wllnilngion, 06 A3H025863 EID779151 EID779151 Sampling Investigation Results Table of Contents f FIGURES 1 Figure 1 Site Location Map Figure 2 Production and Test Well Locations 1 Figure 3 C-8 in Groundwater - January 2002 Figure 4 Idealized Ohio River Valley Cross-Section and Block Diagram 1 FigureS Generalized Geologic Cross-Section at River Mile 190 Figured Temporary Boring Locations 1 Figure 7 C-8 Concentration Ranges in Groundwater FigureS Groundwater Blevation Contour Map - August 2002 1 Figure? C-8 Concentration Ranges in Soil Figure 10 Cross-section Location Map 1 Figure 11 Cross-section A-A' Figure 12 Cross-section B-B' 1 Figure 13 Cross-section C-C' APPENDICES 1 Appendix A C-8 Analytical Reporting Appendix B Geologic Logs for Little Hocking Water Association Well Field r L Temporary Borings Appendix C Geologic Logs for Production and Test Wells (Provided by Little Hocking) 1 1 , 1 1 1 1 1 LMSlrepom Apr. 17,03 i 1 WiliTilngton, DE ASH025864 EID779152 EID779152 I sampling invMtiflatien Results___________________^Executive Summary w EXECUTIVE SUMMARY DuPont conducted a field investigation of the Little Hocking Wats- Association well field in August 2002 in order to delineate ammonium perfluorooctanoate (C-8) concentrations in soil and ground-water near a test well, TW-4. Groundwater sampled from TW-4 in 2002 showed a C-8 concen^ation range of 12.3 to 37.1 ug/L. This report summarizes the work performed, presents results, and provides conclusions and recommendations. Recently, pursuant to a multi-media consent order issued by the West Virginia Departments of Environmental Protection and Health and Human Resources to DuPont on November 15,2001 (Order No. GWR-2001-019; Consent Order), DuPont had submitted summary reports to the Ohio Environmental Protection Agency detailing the off-site investigation activities near the Washington Works facility. These reports assessed media-specific C-8 transport from the facility and concluded that migration of air emissions is the only probable transport mechanism for C-8 found in the Little Hocking Water Association well field. The field investigation of the Little Hocking Water Association well field focused on delineating depth-specific C-8 concentrations in soil and groundwater near TW-4. Concurrently, additional geoprobe borings, test wells and production wells were sampled in order to develop a site conceptual mode! for deposition and migration of C-8 in soil and groundwater at the Little Hocking Water Association well field. The following conclusions are drawn from the investigation results and other available data: Q All groundwater results are below the C-8 Assessment ofToxicity Team (CATT) established human health protective screening criteria for water (water C-8 SL; WVDEP 2002) of 150 ug/L. Q The C-8 concentrations in groundwater decreased with depth within the aquifer. I The C-8 concentrations in groundwater at the top of the aquifer, within the silty clay, ranged from ND (<0.01 ug/L) to 78 ug/L, while C-8 concentrations at the I bottom of the aquifer, within the sand and gravel, ranged from ND (0.01 ug/L) to 8.58 ug/L (excluding results for TW4). Q Consistently high pH values measured in TW-4 and other field observations I indicate that this test well's construction is likely compromised, possibly due to a failed grout seal or to a failed well easing. Higher concentrations of C-8 measured in this well (ranging from 12.3 to 37.1 ug/L) we likely attributed to shallow I groundwater that contains higher C-8 concentrations migrating downward into the deeper monitoring zone or into the well itself; which could happen if the grout seal or the well casing were to have failed. C-8 concentrations measured in this I well are not likely to be truly representative of the deep aquifer, 0 Drinking water is pumped from the bottoin of the sand and gravel aquifer through I the four production wells. The highest C-8 concentration measured in the four production wells was 8.58 ug/L, significantly lower than the human health protective water C-8 SL, The C-8 results for finished water, a combination of I LHSlreportI Apr. 17, 03 III I Wilmlngton, DE ASH025865 EID779153 EID779153 I Sampling Investigation Results Executive Summary f waters from the production wells that is distributed to Little Hocking customers, ranged from 1.69 to 4.29 ug/L, also significantly lower than the water C-8 SL. 0 All soil results are below the CATT-established human health protective screening criteria for soil (soil C-8 SL) of 240 nig/kg (WVDEP 2002). The highest soil C-8 concentration measured is 170 ug/kg (0,170 mg/kg). Most results for soil sampled below the water table are nondetectable. Q Overall, the very low concentrations of C-8 measured in the soils indicate that C-8 does not readily adsorb to soil, especially soils below the water table. Q C-8 results for soil and groundwater sampled immediately adjacent to TW-4 do not distinguish this test well as a source for higher C-8 concentrations in soil and groundwater. Q Overall, this investigation as completed, combined with the air emission modeling and groundwater modeling results and the available physiochemical data for C-8, are sufficient to understand the migration pathways of C-8 from the Washington Works facility and within the Little Hocking Water Association well field. Q Revised groundwater modeling by DuPonI supports the previous conclusion that no potential groundwater migration pathway exists beneath the Ohio River to the Little Hocldng Well field. Q Based on the current data available, DuPont believes the following pathway does exist C-8 from the DuPont facility is transported via air emissions by wind and is deposited on the Little Hocking well field surface soils. Precipitation then leaches the C-8 downward through the unsaturated zone to the aquifer. Dissolved C-8 r then migrates with groundwater within the aquifer, Groundwater containing low levels of C-8 is then pumped from the aquifer through the four production wells, Water from the production wells is mixed and the finished water, containing even I lower levels of C-8, then alters the Little Hocking Water Association distribution system. I Q This investigation as completed, combined with the overall understanding of C-8 migration pathways within tfae Little Hocking well field, is also sufficient to understand (he distribution of C-8 in the test wells, including TW-4, in the I production wells and in the finished water that enters the Little Hocking distribution system. 0 In order to assess the impact of recent C-8 air emission reductions at the I Washington Works facility, DuPont recommends continuing quarterly monitoring of C-8 in the four Little Hocking Water Association production wells and finished I water for a period of two years. I I LHSlreportI Apr. 17.03 tv I WllmlnQtofi, DE ASH025866 EID779154 EID779154 I Sampling Investigation Rasulte ____ _____Introduction 1.0 INTRODUCTION Pursuant to the multi-media consent order issued to DuPont on November 15, 2001 (Order No. GWR-2001-019; Consent Order), groundwater was sampled at public water supplies (PWS) along the Ohio River in West Virginia and Ohio. Groundwater was sampled to detamine if releases ofC-8 from the DuPont Washington Works facility (located in Washington, West Virginia) have impacted groundwater in the PWS. The PWS sampling was performed under the direction of the Oroundwatcr Investigation Steering Team (GIST) which was established under the Consent Order. The Little Hocking Water Association well field, located across the Ohio River from the Washington Works facility in Washington County, Ohio, was included in this sampling. The locations of tine-Little Hockmg'Water Association well field'afid'the'DiiPont " Washington Works facility are shown in Figure 1. Four production wells at the Little Hocking Water Association well field (LHPSD1 through 4) were sampled in December 2001. The C-8 concentrations measured in the production wells ranged from 0.844 to 7.66 ug/L. To better understand the distribution of C-8 in the Little Hocking well field, a more extensive sampling event was conducted in I January 2002, that included the sampling of finished water (the water distributed to customers) and booster station sampling points, and groundwater from all production and test wells in the well field. The locations of the production aad test wells sampled in the I Little Hocking well field are shown in Figure 2. A total of 19 groundwater samples, including one duplicate, were collected and analyzed from Little Hocking during the January 2002 sampling event. The concentrations of C-8 r in finished water and booster station sampling points ranged from 1.69 to 1.94 ug/L The C-8 concentrations measured for the production wells ranged from 0.744 to 6.22 ug/L. i The C-8 results for nine of the ten test wells ranged from 0.364 to 4.48 ug/L. In test well 4 (TW-4), the concentration measured was 37.1 ug/L. Figure 3 shows the January 2002 distribution of C-8 results in the production and test wells. Based on the elevated result at i TW-4 compared to the surrounding wells, the Ohio Environmental Protection Agency (OEPA) requested that DuPont conduct a focused field investigation to delineate C-8 > concentrations in soil and groundwater near TW-4, i In August 2002, DuPont conducted the field investigation at the Little Hocking Water Association well field. During this investigation, the following activities were performed: i 0 Advanced ten temporary soil borings Q Continuously monitored geologic information during the advancement of the ten i temporary borings Q Sampled soil and groundwater and monitored groundwater parameters at various i depths within the temporary borings i LHSlrBport-l Apr. 17.03 i Wllmlngton. D ASH025867 EID779155 F.Tn77qi^e; I Sampling Invasllaatlon Results Introduction _ I 0 Sampled groundwater in all production and test wells and recorded groundwater elevations I 0 Measured Ohio River stage The C-8 Assessment of Toxicity Team (CAT!), was assembled as required by the I Consent Order to establish human health protective screening criteria for water (water C8 SL) and for soil (soil C-8 SL). In August 2002, while the field investigation was being conducted at Little Hocking, the CATT issued its final report and established the water I C-8 SL at 150 ug/L and the soil C-8 SL at 240 mg/kg (WVDEP, 2002). Following (he completion of the field activities at Little Hocking, groundwater samples I were analyzed to measure C-8 concentrations. C-8 analytical results for groundwater were then compared to the CATT-established water C-8 SL. In August 2002, an analytical method for measuring C-8 in soils was still under development; therefore, soils I sampled during the investigation were placed on-hold in a secure manner. The method development was completed in February 2003. C-8 analytical results for soils were finalized in March 2003. C-8 analytical results for soil were then compared to the CATT- I established soil C-8 SL. The analytical results were then evaluated in conjunction with geologic data available from Little Hocking Water Association and with geological data obtained from the temporary borings. A site conceptual model was then developed. I This report documents the field investigation activities and the results of the investigation. Tn this report, the following sections are discussed: Q Environmental Setting (Section 2) 0 Sampling Approach (Section 3) 0 Groundwater Results (Section 4) 0 Soil Sample Results (Section 5) I 0 The Little Hocldng Site Conceptual Model (Section 6) Q Conclusions and Recommendations (Section 7) I Q References (Section 8) I I I I I LHSIreportI Apr. 17, 03 I Wilminslon. DE ASH025968 10779156 EID779156 sampling investigation Results Environmental Setting I 2.0 ENVIRONMENTAL, SETTING 2.1 Geology I The Little Hocking well field is located in the Ohio River Valley and consists of Quaternary alluvial sediments that overly the Permian-aged Dunkard Group, The two predominant fades of the Ohio River alluvium that have been identified in this area include coarse-grained Ohio River Alluvium (Pleistocene-aged glacial outwash deposits) and fine-grained Ohio River Alluvium [Holocene overbank deposits (Simard, 1989)]. The Pleistocene deposits consist primarily of coarse-grained sand and gravel while the Holocene depositsconsist primarily of interbedded and laminated silt, clay and fine I grained sand. The Dunkard Group (bedrock) consists primarily of red and varicolored sandy shale; gray, green and brown sandstone; gray and light-gray siltstone; and minor beds of coal, claystone, black carbonaceous shale and limestone. I The facies of the Ohio River Alluvium formed in response to the glacial advances and retreats of the pre-, early- and late-Wisconsinan and were deposited as successive phases ofaggradation and degradation of river valley alluvial materials. The coarse-grained I Pleistocene alluvium was deposited as glacial outwash during the primary valley aggradation event following the glacial scouring of the valley into the bedrock floor. I During the subsequent degradation and aggradation cycles of the Pleistocene, the glacial outwash sediments were partially removed, re-worked and then redeposited to a lower elevation than the previous cycle, thus forming a terrace. This process formed a series of Pleistocene-aged terrace surfaces within the Ohio River Valley. These surfaces were designated (youngest to oldest) as S4, S5, and S6 by Simard. With each subsequent degredation/aggradation cycle, additional fines were incorporated into the Pleistocene I deposits due to continual influx of finer-grained fluvial sediments from tributaries of the Ohio River. As a result, the Pleistocene deposits become more highly re-worked and progressively finer-grained toward the center of the river valley, particularly in locations I downstream of significant tributaries (Simard, 1989). The total thickness of Pleistocene sediments at Washington Bottom (located immediately south across the Ohio River from Little Hocking in West Virginia) ranges from about 80 feet beneath the highest I Pleistocene terrace surfaces to about 15 feet beneath the current channel of the Ohio River, I The Pleistocene alluvial deposits are overlain by the finer-grained Holocene sediments. The silts, clays, and fine sands were deposited on the surface of the Pleistocene terraces as well as on a series of more recent floodplains, which formed in the center of the Ohio I River Valley during the Holocene. The thickness of the Holocene sediments typically ranges from 5 to 15 feet over the Pleistocene terrace surfaces and 25 to 35 feet over the Holocene floodplains. Sunard designatedthe Holocene floodplain surfaces as Sl through I S3 and the modem floodplain of the Ohio River as SO. Figure 4, modified from Simard (l989) is a block diagram and idealized cross-section through the Ohio River valley depicting me complex set of Pleistocene terraces and Holocene floodplains which have I formed in the valley. LHSIreportI Apr. 17.03 3 I Wllmlngton, 06 ASH025869 EID779157 EID77&157 I sampling invMiigation Resuite___^____________Environmental Setting II A generalized north-south cross-section from the Little Hocking Water Association well field in Ohio, through the Ohio River and across the Washington Works facility, is I presented in Figure 5. This cross-section shows the floodplain and terrace surfaces, the Holocene silt and clay ova-bank deposits overlying the Pleistocene sand and gravel outwash deposits and the re-Worked Pleistocene alluvium in the center of the river valley. I The alluvial terrace deposits are underlain by a flat, river-scoured bedrock surface of the Dunkard Group that rises steeply and forms the valley walls to the North of Little I Hocking Water Association and to the south of the Washington Works facility (Figure 1). 2.2 Hydrogeology I Groundwater supplies in the region are obtained from the Dunkard Oroup bedrock and Ohio River alluvial terrace deposits. However, the saturated portion of the Ohio River I alluvial terrace 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 (Schultz, 1984). Based on these high yields, numerous industrial I and commercial water supply companies obtain water from the alluvial aquifer. The Ohio River Alluvial Aquifer is the primary water-table aquifer in the area. This aquifer occurs at a depth of 15 to 30 feet below ground surface in the Little Hocking well I field. The saturated zone is approximately 30 to 40 feet thick, extending approximately to the surface of the underlying Dunleard Group bedrock. Numerous pumping tests have I been completed in the alluvial aquifer m the Washington Bottom area as part of water supply investigations. The hydraulic conductivity of the alluvial aquifer in the area typically ranges from 100 to 300 ft./d (Legggette, Brashears & Graham, me., 1986; Burgess & Niple Ltd., 1988). In contrast, the hydraulic conductivity of the underlying Dunkard Group bedrock aquifer is typically between 0,05 and 5 ft./d (Kozar and Mathes, 2001). I Natural recharge to the alluvial aquifer comes from various sources, including; 0 Infiltration of precipitation falling directly on Ihe alluvium I Q Lateral movement of the river water through the alluvium Q Seepage from scream tributaries that discharge to the Ohio River I Q Surface run-off from the outcrop areas of the Dunkard Group, which form steep slopes adjacent to the uppiscmost Pleistocene terrace. I I I I LH8lreBOrt1 Apr. 17. 03 I Wllmlngton. DE ASH025870 EID779158 EID779158 I f I I I I I I I I h. I I I I I I I I Sampling InvBSllgatlon Rasijte SamplJng Approach 3.0 SAMPLING APPROACH fa order to evaluate the elevated C-8 concentrations in TW-4. DuPont implemented a focused sampling approach that delineated horizontally and vertically the C-8 concentrations in groundwater near this test well. This sampling plan was developed with assistance from the OEPA and was submitted to and approved by the OEPA in early August 2002 (DuPont, 2002a). The locations of temporary borings advanced are shown in Figure 5. TW-4 was used as the center point, and six radial sampling segments were established north, northeast, southeast, south, west, and northwest. Along each segment, soil and groundwater or only groundwater were sampled from the temporary borings, Figure 5 shows the locations of the two borings where soil and groundwater were sampled and the locations of the eight borings where only groundwater was sampled. In two borings where soil and groundwater Were sampled, sampling was planned ai the following depths from ground surface. Q Soil at the surface at 5-foot intervals below ground surface to the top of the sand and gravel aquifer (approximately 30 feet below grade) " at 5-foot intervals from the top of the sand and gravel aquifer to the bottom of the aquifer (estimated at 50 to 55 feet below grade) at the geologic interfaces Q Oroundwater at first encountered water (approximately 17 to 20 feet below grade) at 5-foot intervals from first encountered groundwater to the bottom of the sand and gravel aquifer (estimated at 50 to 55 feet below grade). at the geologic interfaces At all other temporary boring locations, groundwater sampling was planned at two depths, at first encountered water (approximately 17 to 20 feet below grade) and at the bottom of the sand and gravel aquifer (estimated at 50 to 55 feet below grade). In addition, DuPont scheduled the Consent Order-required 3Q02 PWS sampling event, which includes sampling the four production wells and TW-4 at Little Hocking, to coincide with the field investigation. The Little Hocking test wells, that are not required sampling points in the quarterly PWS sampling, were sampled as part of the field investigation, including TW-l through TW-6 and TW-9 through TW-12 (Figure 2). Oroundwater elevations were measured in the test and production wells prior to sampling the wells. Ohio River stage was also measured using the datum located on the Kraton Polymers property, located immediately east of the UtUe Hocking well field, with the assistance of a Senior Environmental Engineer from Kraton. LHSIiwortI Apr. 17, 03 Wllmtnaton, DE ASH025871 EID779159 EID779159 Sampling invasHgafen Results ___________ Groundwater Sample Results 4.0 GROUNDWATER SAMPLE RESULTS For groundwater sampled from production wells, test wslls and the temporary borings, sampling was conducted as described in the Quality Assurance Project Plan (DuPont 2002b) and in the Sampling Investigation Plan for Little Hocking Water Association Well Field (DuPont, 2002a). Appendix A provides infonnation on C-8 analytical reporting. 4.1 C-8 In roundwater from Temporary Borings Oroundwater sampled at various depths from the ten temporary borings was analyzed for C-8. Table 1 presents the C-8 results for the groundwater samples. The first part of the sample name indicates the investigation and the sample type (WWO-G; Washington Works, Ohio, groundwater). The second part of the sample name indicates from which temporary boring the sample was collected (i.e. LHWAN1 is boring LHWAN-1; see Figure 6 for temporary boring locations). The third part of the sample name indicates the depth below ground surface from which the groundwater was sampled. Figure 7 shows the range in C-8 concentrations measured in each of the temporary borings. In total, 18 samples (including one duplicate sample) were collected from the ten temporary borings (Table 1). Samples of first water encountered were collected from all ten borings. Samples from greater depths were collected from three borings. At the boring closest to TW-4, LHWASW-1, samples were collected every five feet from the first water encountered to the bottom of the sand and gravel aquifer. Note, not all planned sampling was completed. The field investigation proceeded slower than expected due to changing field conditions (stabilization of field parameters, particularly turbidity, took much longer than anticipated) and interruptions by the oversight consultant. As a consequence, not all groundwater and soils targeted in the work plan were sampled. The C-8 concentrations measured in the groundwater sampled from temporary borings ranged from non-detectable (<0.01 ug/L; ND) to 78 ug/L and do not exceed the CATT- established human health protective water C-8 SL of 150 ug/L. In general, C-8 concentrations are higher at the first water encountered than at greater depths within the aquifer or at the bottom of the aquifer. The distribution of C-8 vertically and horizontally within the well field is discussed in detail in Section 6 which presents the site conceptual model for C-8 in soil and groundwater at Little Hocking. 4.2 C-8 in Groundwater from Production and Test Wells Table 2 presents the PWS sampling C-8 results for the Little Hocking Water Association. The data for the well field investigation conducted to August 2002, including the data from the four production wells and all ten test wells are highlighted in blue. At the bottom of Table 2 are data from finished water and booster station sampling points, These are samples of the water that is being distributed to Little Hocking Water Association customers. Finished water was inadvertently not sampled during the well l.HStraport1 Apr. fT, 03 Wilmington, DE ASH025872 EID779160 EID779160 sampling investigation Results_________________Groundwater Sample Results field sampling. Table 2 also provides data from the 4Q02 and the 1Q03 PWS sampling events in which the four production wells, TW-4 and finished water were sampled. I During the well sampling and PWS sampling, all of the C-8 concentrations measured in the production and test wells sad in the finished water were well below the water C-8 SL I of 150 ug/L that was established by the CATT (WVDEP, 2002). Figure 7 shows the range of C-8 measured at each production and test well using alt the data for each well summarized in Table 2. The highest concentration of C-8 measured in I a production or test well, excluding TW-4, was 8.58 ug/L. C-8 concentrations measured in TW-4i which was the focus of this investigation, have I been variable. The C-8 concentration in this test well has ranged from 12.3 to 37.1 ug/L. These levels are higher than in any other test or production well in the Little Hocking well field. However, field and laboratory measurements and field observations, discussed I below, suggest that the integrity of this test well is compromised. Table 2 provides the pH data for the groundwater sampled collected from the production and test wells. The pH measured for all production and test wells, except for TW-4, has I ranged from 6.72 to 7.94. However, the pH values measured in TW-4 are much higher, and have ranged from 9.22 to 12.61. High pH values are commonly associated with I cement-bentonite grout (Colangelo et al. 1986). Bentonite, which is commonly used as grouting material in well eonstroction, is a clay mineral containing calcium, aluminum and iron. A comparison ofgroundwater analytical results between TW-4 and Well #2, one of the four production wells, also showg that TW-4 has approximately twice as much calcium and three times as much iron and aluminum than Well #2 (OEPA. 2002). Field activities show that a three-inch pump that fits in the upper portion of the below- surface PVC pipe of TW-4, gets stuck in the PVC pipe at depth. The one and one half- I inch pump, on tbs other hand, can be lowered to the bottom of the well. This observation indicates that the PVC pipe is not completely straight. A bent PVC pipe may indicate a problem with the joint between lengths of PVC pipe that could allow grout contamination I into the well. Furthermore, particles of a crusty, white material, which may be grout, are frequently found on the pump when it is removed from the well. In addition, water from TW-4 also is frequently a milky to grayish color. I The consistently high pH values, water chemistry, and other field observations from this well likely indicate the integrity of the well is compromised, most likely by a failed grout I seal or a failed well casing related to the bend in the PVC pipe. A failed grout seal or a failed well casing would allow shallow groundwater, which contains higher concentrations of C-8, to migrate into the deeper monitoring zone and would result in I unusually high C-8 concentrations in the test well compared to C-8 concentrations measured in other production and test wells. Because of the compromised integrity of TW-4, it is likely that samples ofgroundwater from this well are not representative of I typical conditions within the deeper portions of the sand and gravel aquifer. I I LHSIreportI Apr. 17,03 Wllmington, D6 ASB025873 EXD779161 T.:Tr>77Q1 fil I sypiinginvesagaiionResute Groundwater Sample Results The distribution ofC-8 in the production and test wells in the Little Hocking well field is discussed in detail in Section 6, which presents the site conceptual model for C-8 in soil I and groundwater in the Little Hocking Water Association well field. I 4.3 Groundwater Elevations In Production and Test Wells and Ohio River Stage I Groundwater elevations were measured in all production and test wells sampled in the Little Hocking well field. In addition, the Ohio River stage was measured. Table 3 provides the surveyed measuring point elevations of the production and test wells, the I depths to water measured and the calculated groundwater elevations. The Ohio River stage is also presented in this table. Figure 8 presents the groundwater elevation contour map of the Little Hocking well field I for August 21,2002. The pumping of the production wells results in the development of a cone of depression surrounding the production wells with groundwater flowing towards the production wells from all directions. Because the four production wells are cycled on I and off, the cone of depression shifts its position depending on which production wells that are pumping at the time. Groundwater elevations and flow directions within the I Little Hocking well Held aquifer are discussed in more detail in Section 6, which presents the site conceptual model for C-8 in soil and groundwater at the Little Hocking well field. I r i i i i i i i LMSIreport-l Apr. 17,03 Wllmlnglon. DE ASH025874 EID779162 EID779162 I p I I I I I I I I '[ I I I I I I I I Sampling investigation Results Soil Sample Results 5.0 SOIL SAMPLE RESULTS For soil sampled from the temporary borings, sampling was conducted as described in the Sampling Investigation Plan (DuPont, 2002b). h total, 22 soil samples, including one duplicate sample, were collected from two temporary borings, LHWASW-1 and LHWANW-1. Table 4 provides the sample names, sample dates, the C-8 concentration measured and comments. The sample nomenclature is similar to that employed for the groundwater samples. The first part of the sample name indicates the investigation and the sample type (WWO-S; Washington Works, Ohio, soil). The second part of the sample name indicates from which temporary boring the sample was collected (i.e. LHWASWl is boring LHWASW-1). The third part of the sample name indicates the depth below ground surface where the sample was collected. The Comments column, on the far right, provides a brief description of the sample. The C-S concentrations measured from the two borings ranged from ND (<2 ug/kg) to 170 ug/kg in LHWASW-1 and from ND to 110 ug/kg in LHWANW-1 (Figure 9). In general, the concentrations of C-8 measured decreases with sampling depth in both of the temporary borings. The C-8 concentrations measured in soil from the temporary borings are significantly lower than the human health protective soil C-8 SL (240 mg/kg or 240,000 ug/kg) that was established by the CATT (WVDEP, 2002). C-8 concentrations measured in soils from the Little Hocking well field arc discussed m detail in Section 6, which presents the site conceptual model for C-8 In soil and groundwater at the Little Hocking Water Association well field. LHSIreportI Apr. 17.03 WllnilnBton, OE ASH025875 EID779163 EID779163 I ________________Site sampling investigation Ftesuite Conceptual Model I I 6.0 SITE CONCEPTUAL MODEL 6.1 Geology I Using the geologic data available from the temporary borings and the production and test wells, three cross-sections (A-A1, B-B', and C-C') were generated for the Linie Hoeking I well field. Appendix B provides the geologic lop for the temporary borings. Geological lop for the production and test wells (made available to DuPont by the Little Hocking Water Association) are provided in Appendix C. The cross-section location map is I provided in Figure 10, Cross-sections A-A' and B-B' generally run north to south and CC' runs west to east. Cross-sections A-A', B-B', and C-C* are presented in Figures 11, I 12, and 13, respectively. These cross-sections show that the stratigraphy of the Little Hocking well field is comprised of three lithological units (from ground surface downward): I Q Holocene overbank deposits(approximately 25-40 feet of a low permeable silly clay or sandy clay or sand and clay) I a Pleistocene glacial outwash deposits (approximately 20-35 feet of sand and gravel which is the site aquifer) Q Dunkard Group bedrock (shale) I The composition of the Holocene overbank deposits is variable, hi the western part of the well field, silty clay and clay are observed, while in the eastern portion sand and clay and/or sandy clay is found. The contact between the upper silty clay and the underlying y sand and gravel is an erosional surface, characterized in some locations by channels cut into the sand and gravel (Figure 13). The composition of the sand and gravel unit is also I variable, consisting of sand, sand and gravel, sjlty sand, and clayey sand. Where encountered in the temporary borings, the underlying bedrock is a micaceous, greenish gray siltstone. The logs for the production and temporary wells indicate that bedrock I consists of red and blue shale, red clay and sandstone. I 6.2 Hydrogeology Cross-sections A-A', B-B' and C-C' also show the groundwater elevation for August 21, 2002 based on data measured at the production and test wells. At the time water levels I were measured. Well #1, Well #2 and Well #3 were being pumped and Well #5 was not being used. The cone of depression around these three wells can be seen most obviously on cross-section C-C" (Figure 13), but can also be observed on B-B' (Figure 12). The I groundwater contour map, which also shows Ac drawdown from the pumping wells, is provided in Figure 8. The hydraulic conductivity of the alluvial aquifer in the area I typically ranges from 100 to 300 ft/day. Because of the high hydraulic conductivity, it is likely that the cone of depression shifts its position rapidly with the cycling on and off of the four production wells. Ohio River stage, 582.24 ft mean sea level, is higher than in I LHSlTOortI Apr. 17. 03 10 I WllmlnBton, DE ASH02S876 EID779164 EID779164 I Sampling Investigator Results_________________Site ConggptUal Modal I the test production and test wells. Therefore, water from the river flows into the site aquifer. Precipitation also is a minor recharge source for the Little Hocking well field, 6.3 C-8 Transport Mechanisms and Migration Pathways Based on our current knowledge, the following paragraphs describe the transport mechanisms and migration pathways for C-8 from the Washington Works facility. A groundwater model was developed for the Washington Works facility as part of the RFI report for Washington Works (DuPont. 1999). The Consent Order required refinement of the groundwater model for the facility to re-evaluate the extent of groundwater captured by the pumping wells at the site and to confirm that off-site migration of C-8 impacted groundwater is not occurring. To meet these requirements, refinement of the groundwater modeling work was completed with input, guidance, and critical review from the United States Geological Survey, the USACOE, the West Virginia Department of Health and Human Resources, and GIST members during the model development, calibration, and finalization process. The report of final findings for the revised groundwater model for me facility and the surrounding area was submitted to the GIST in January 2003 (DuPont, 2003). The revised groimdwater model supports DuPont's previous conclusions that no off-site migration of groundwater is known to be occurring and that no potential groundwater migration pathway exists beneath the Ohio Biver to the Little Hocking weU field. However, DuPont had released, and continues to release, C-8 in air emissions from the Washington Works facility. C-8 is emitted to the atmosphere in two phases, a vapor phase, and a particulate phase. In May ,2002, additional control equipment was installed f-- at the facility to reduce C-8 emissions. There has been approximately a 65 percent decrease in total C-8 air emissions since the installation of this equipment compared to levels measured for 1999, when C-8 emission levels were at their highest. Continued I reductions in C-8 emissions from the facility are anticipated during the next few years as abatement efficiency improvement projects are completed. I The Little Hocking well field is located directly north of the Washington Works facility across the Ohio River into Ohio. Wind direction data show that the Little Hocking well field is downwind of the facility and the predominant wind flow. Air emissions modeling I by DuPont indicates that some C-8 in emissions from the Washington Works facility migrate over the Little Hocking well field. Some C-8 in the vapor and paniculate phases, emitted from me facility and transportedby I wind, is deposited on the surface soil at the Little Hocking well field. The concentrations of C-8 measured in surface soils (i.e. 0-1 foot depth) sampled during this investigation I were 110 ug/kg and 170 ug/kg (Figure 11). C-8 is then leached by the precipitation from surface soils to surface-water bodies and/or infiltration into surface soils. Dissolved C-8 continues migrating downward in the unsarurated zone with the infiltrating I precipitation. The C-8 concentration in the soils below the surface, in the unsaturated zone, ranged from 3.4 to 13 ug/Tcg, almost an order of magnitude lower than the concentrations of C-8 measured at the surface (see LHWAN-1 and LHWASW-1 in I LHSIreportI Apr. 17,03 11 I WIIminglon, DE ASH025877 EID779165 EID779165 SairipllnglnvesBgaaonRasulB Site Conceptual Model Figure 11). The low permeability of the upper silly clay lileely slows the rate of downward migration of precipitation. In-addition, the rate and direction of migration of I precipitation likely changes with the different lithologies encountered in the Holocene overbaok deposits. For example, precipitation might migrate slowly downward through the silty clay and then migrate laterally in a sand lens at a much faster rate. Soil-type I differences may also be responsible for His highly variable C-8 concentrations measured within the groundwater in silty clay unit (compare LHWAS-1 with C-8 concentration of nondetectable to LHWAS-2 having C-8 at 78 ug/L), In addition, the rate of precipitation I and the level of the water table likely have some control over the rate of migration of dissolved C-8. However, because C-S is highly soluble (Fluoropolyniers Manufacturers I Group, 2001), it does not tend to precipitate or sorb to particles in the soil but it remains in solution and migrates with groundwater. The concentrations ofC8 in groundwater at the top of the water table are higher than the I concentration of C-8 just below at the lithologic contact between the silty clay and the sand and gravel (Figure 11). These data indicate that the overall the concenteation of C-8 decreases with depth in the water table within the silty clay. Alternatively, these data also I may reflect the increased permeability in me sand and gravel compared to the silty clay. The C-8 concentration measured in a single boring at various depths show that the I concentration of C-8 in groundwater and soil decreases with depth within the aquifer (Figure 11) as the dissolved C-8 migrates within the sand and gravel aquifer. However, the C-8 concentration at the base of the sand and gravel aquifer (i.e. position of (lie well I screens) is somewhat variable and does not seem to show a trend with groundwater flow direction towards the pumping wells. Table 2 shows that C-8 concentrations are consistent within a single production well but (hat the concentrations are different between the production wells. Well #3 consistently has the lowest C-8 concentration (less than lug/L) whereas Well #5 consistently has the highestC-8 concentration (ranging froin5.69 to 8,59 ug/L). Because the four production wells are cycled on and off and the C-8 concentrations measured in the wellg are not the same, the C-8 concentration in the finished water is variable. Table 2 shows the concentration of C-8 in finished water has ranged from 1.69 to 4.29 ug/L. Briefly summarized, DuPont currently believes that C-8 from the DuPont facility is * transported via air emissions by wind and is deposited on the Little Hocking well field surface soils. Precipitation leaches the C-8 downward throughthe unsatwated zone to the aquifer. Dissolved C-8 Aen migrates with groundwater within the aquifer. Groundwater containing low levels of C-8 is then pumped from the aquifer through the production wells. Water from the four production wells is mixed and water containing even lower levels of C-8 (the finished water) then enters the Uttle Hocking Water Association distribution system, C-8 concentrations in mushed water from Little Hocking are significantly below the human health protective water C-8 SL of 150 ug/L (WVDEP 2002). LHSIiepOrtI Apr. 17. 03 Wllmlnston, DE 12 ASH025878 EID779166 EID779166 I sampitng inwsBgsBon Resuis ___ __ ____Conclusions and Racommendati'ons I 7.0 CONCLUSIONS AND RECOMMENDATIONS Based on the investigation at the Little Hocking Water Association well field and other I data available, the following conclusions can be made: 0 All groundwater results are below the C-8 Assessment ofToxicity Team (CATT) established human health protective screening criteria for water (water C-8 SL; I WVDEP 2002) of 150 ug/L. Q The C-8 concentrations in groundwater decreased with depth within the aquifer, I The C-8 concentrations in groundwater at the top of the aquifer, within the silty clay, ranged Stun ND (<0.01 ug/L) to 78 ug/L, while C-8 concentrations at the bottom of the aquifer, within the sand and gravel, ranged from ND (0.01 ug/L) to I 8.58 ug/L (excluding results for TW-4). Q Consistently high pH values measured in TW-4 and other field observations indicate that this test well's construction is likely compromised, possibly due to a I failed grout seal or to a failed well casing. Higher concentrations of C-8 measured in this well (ranging from 12.3 to 37.1 ug/L) are likely attributed to shallow I groundwater that contains higher C-8 concentrations migrating downward into the deeper monitoring zone or into the well itself, which could happen if the grout Seal or the well casing were to have failed. C-8 concentrations measured in this I well are not likely to be truly representative of the deep aquifer. Q Drinking water is pumped from the bottom of the sand and gravel aquifer through the four production wells. The highest C-8 concentration measured in the four production wells was 8.58 ug/L, significantly lower than the human health protective water C-8 SL. The C-8 results for finished water, a combination of waters from the production wells that is distributed to Little Hocking customers, I ranged from 1.69 to 4.29 ug/L, also significantly lower than the water C-8 SL. 0 All soil results axe below the CATT-establighed human health protective I screening criteria for soil (soil C-8 SL) of 240 rng/kg (WVDEP 2002). The highest soil C-8 concentration measured is 170 ug/kg (0.170 rng/kg). Most results for soil sampled below the water table are nondetectable. I Q Overall, the very low concentrations of C-8 measured in the soils indicate that C-8 does not readily adsorb to soil, especially soils below the water table. I Q C-8 results for soil and groundwater sampled immediately adjacent to TW-4 do not distinguish this test well as a source for higher C-8 concentrations in soil and groundwater. I 0 Overall, this investigation as completed, combined with the air emission modeling and groundwater modeling results and the available physiochenricaldata for C-8, I are sufficient to understand the migration pathways of C-8 from the Washington Works facility and within the Little Hocking Water Association well field. I LHSlreportI Apr. 17,03 13 I WBtninglon. DE ASH025979 EID779167 EID779167 I and Recommendations sampling invMBgatimRwuite________Conclusions r Q Reviged groundwater modeling by DuPorit supports the previous conclusion that no potential groundwater migration pathway exists beneath the Ohio River to the Little Hocking Well field. i Q Based on the current data available, DuPont believes the following pathway does exist. C-8 from the DuPont facility is transported via air emissions by wind and is deposited on the Little Hocking well field surface soils. Precipitationthen leaches i the C-8 downward through the unsaturated zone to the aquifer. Dissolved C-8 then migrates with groundwater within the aquifer. Groundwater containing low i levels of C-8 is then pumped from the aquifer through the four production wells. Water from the productionwells is mixed and the finished water, containing even lower levels of C-8, men enters the Little Hocking Water Association distribution i system. Q This investigation as completed, combined with the overall understanding of C-8 migration pathwayswithin the Little Hocking well field, is also sufficient to i understand the distribution of C-8 in the test wells, including TW-4, in the production wells and in the finished water that enters the Little Hocking distribution system. i Q hi order to assess the impact of recent C-8 air emission reductions at the Washington Works facility, DuPont recommends continuing quarterlymonitoring i of C-8 in the four Little Hocking Water Association production wells and finished water for a period of two years. i i i i i i i i tHSIrepom Apr.17.03 i Wilrniiaton, OE 14 ASH025880 EID77916e EID779168  sampling invMiigattort Rosute w References 8.0 REFERENCES I Burgess & Niple, Ltd. 1988. Blennerhassett Island Water SupplyWell Drilling and Test Pumping, unpublished report. " Colangelo, R. V., Cannestra, R. B., and Morehouse, J. T. 1986. The Effects of Water _ Quality Data Due to Annular Space Material and Monitoring Well Specifications, | Proceedings of the Ifrnth Annual Madison Waste Conference on Municipal and Industrial Waste, Madison, WI, pp. 100-120. DuPont 2003. Revised Groundwater Flow Model, DuPont Washington Works. Washington. WV January 2003. DuPont Corporate Reroediation Group and URS Diamond. 2002a. Sampling Investigation Plan for Little Hocking Water Association Well _____Field. Washington County, Ohio August 2002. DuPont Corporate Remediation Group and URS Diamond. ___ I 2002b. Groundwater Investigation Quality Assurance Project Plan for Washington Works Plant, Washington Works, West Virginia January 2002. DuPont Corporate Remediation Group and URS Diamond. ____ 2001. Project-Specific Waste Management Procedures for Letart Landfill, Local Landfill. Dry Run Landfill, Washington Works Plant and Designated Off-Site Areas November 2001. DuPont Corporate Remediation Group and URS Diamond. 1 1 9 9__9_ .1999. RCRA Facility Investigation Report, DuPont Washington Works, June 30, DuPont Corporate Remediation Group and URS Diamond. 1999. RCRA Facility Investigation Report, DuPont Washington Works June 30,1999. DuPont Corporate Reroediation Group and URS Diamond. Fluoropolymer Manufacturers Group 2001. Guide to the safe Handling of I Fluoropolymer Dispersions October 2001. The Society of the Plastics Industry, Inc' ILeggette, Brashears &. Graham, Inc. 1986. Water Supply from Blennerhassett Hydrogeologic Evaluation/or Island, unpublished report. Additional | Kozar, M.D. and M.V. Mathes, 2001. Aquifer-Characteristics Data for West Virginia. Water-Resources Investigations Report 01 -4036, United States Geological M Survey, 74 p. LHSlrBportI Apr. 17.03 15 B Wllmlrgton, DE ASH025881 EID779169 EID779169  Sampllnfl liivasBgatton Results_______________________________________References ' Ohio Environmental Protection Agency, 2002. Fax dated May 28,2002, from Steve Williams (OEPA) to Andrew Hartten (DuPont) providing sampling results from Little Hocking TW-4 and Well #2 conducted on April 23,2002. Simard, C. M. 1989 Geological History of the Lower Terraces and Floodplains of the Upper Ohio River Valley, Open File Report, West Virginia Geological Survey, " 160 P. I Schultz, R.A. 1984. Ground-water Hydrology of the Minor Tributary Basins of the Ohio River. West Virginia. " WYDEP, 2002 Final Ammonium Perftwrooctanonate (C8) Assessment ofToxicity Team I (CATT) Report August 2002. West Virginia Department of Environmental Protection. I I I r \ I I I I I I _ _ Final LHSI r V/ilmington, _eport DE _Apr. 1 _7.03 _ _ _ _ _ _ _ _ 16 ASH025882 EID779170 EID779170 ASB025883 EID779171 EID779171 Table 1 C-6 In Gcoundwater from Temporafy Borings Little Hocking Water Association Wasliiniglon County, OMo WWO-G-IL^^ WWO-G- LHWANE1 "WWO-G- LHWANE1 WWO-Q- LHWANE2 WWO-G LHWAE1; WWO-G- LHWAS1 WWO-G- LHWAS2 WWCM3- LHWASW1 WWO-G- LHWASW1 WWO-G- LHWASWt WWO-G- LHWASW1 WWOG- LHWASW1 WWO-G- LMWASWl'' WWO-G. LHWAW1 WWO-G- LHWAW2 WWO-G- LHWANWIi WWO^G- LHWANW1 WWO-G- LHWANW1 t7-22 21-27 * (56-58) (20.7-25.7) (21-26) (25-30]L (25-30) (2.8..&-3a) (35-40)* HO-45} (45-60) (50^-55} (55-56)* (29-341 j[33-3B) (18-25) (24-29) (24-2&)-2<DUP] * Sample spM with the Ohio EPA. 8/2aro2 8/2Q/02 8/22/02 8/30/02 8/30/02 8/28/02 8/27/02 8/23/02 B/26/02 6/28/02 8/28/02 BC8/02 aJ2W02"' 8/29/02 8/29/02 8/29/02 8ffi9/02 8/29/02 5 5 5.58 . 8 f i r s tfirsi waterencountered" water encountered 0.682 bottom of sand and gravet 1.26 first water encountered 0.416 first wafer encountered ND (<0.01) first water encountered 78 first water encountered 0.0912 first water encountered '""1.32 1.02 every 5 ft groundwatBr sample every 5 ft oroundwater sample 0.376 evary 5 ft groundwateT sample 0.166 ' " "0'-254 ev8(y5ftjproundwatersampte boitorn of sand and gravel ND(<0.01) i first water encountered 3.35 first water encountered 34.6 first water encountefed 5.9 6.22 top of sand and gravet top of sand and gravel Paga 1 of 1 Table 2 C-8 in ProducUon and Test Wells Little Hocking Water Association Washingon County, Onto I ; '- Well Sample Nainfli ;i?-.' Sample Data ''i"wsWc-B UB/I fc ^Comments .' - - PH WelW LHPSD1 12QO/01 1.02 ProAiQlonWell 7.19 I LHPSD1 LHPSD1 1/21/02 202/02 1.72 237 PitiducttonWall ProducBonWell 7.6S 6.97 LMPSD1 3/26/02 2,99 Production Well 7.30 I LHPSD1 : LHP5bl ' '' . LHPSD1 403/02 aaic? ioe/a2 :':"' ''.."'!. 2.02 3.66 <, .. 3,A1 Prnductton Well ProducBonwal) Production Wall 8.03 6.79 6.97 LHP8D1 2G6/03 3.38 Production Well 6.72 I Well #2 mPSD2 LHPS02 1220/01 12/20/01 3.72 3.S2 Producfion Well auplicata 7.06 -- LHP8D2 1/21/02 2.97 PnductionWdl 7.74 I LHPSD2 LHPSDZ 2/22/02 202/02 2.03 2.07 Production Well duplicatB 7.61 -- LHPSD2 3/26/02 3.31 PfOdualonWal 7,56 I wm. -^"^ LHPSD2 '" WPSV& w' LMPSD2 4/23/02 .""- io/ie/oz 3.4 3.98 Production Wai Producllon WBll Production Well T.7B 7.3S 7,5 I WetKQ LHPSD2 LHPSD3 LHPSD3 2/26/03 1200/01 1/21/02 3.62 0.84+ 0.744 Production Well Prodiictien Well Producton Well 7.2 7.2S 7.63 LHP803 2/22/02 0.42 Producllon WBII 7.03 I LHPSD3 LHPSD3 3/Z&02 4/23/02 o.te7 0.783 Production well Production Wall 7.73 7.94 I.HPSD3 V: : &21/02 "'-.^rfcgsz PfOtluetton We 7.89 V LHPSD3 10/18/02 0.495 Production wen 7.77 mPSD3 10/16/02 0.434 duplicato -- LHPSD3 2/26/03 0.733 Pioduetlon wall 7.44 I Wall #5 mpeos 1-HPSD5 mpsos 12/20/01 1/21/02 1/21/02 7.66 6.22 $.14 Production Well Production wa duplicate 7.04 7.4 7.3E LHPS05 2/22/02 5.6S Production well 7.26 I ss LHP8D5 LHPSDS azs/oa 4/23/02 8.11 Production Well Production Well 7.40 7.52 : ,LHPSD5 was LHPSDS I mpsos io/ie/oz 2/26/03 " ;,';;?. 8,08 8^8 6.93 Productfan'Wan PioduaionWell Production Well 7.2 7.41 7.16 I.HPSD5 2QB/03 7,ie duplicate -- I TW.1 . LHPSOTW1 LHPSDTW1 1/22/02 BQ1/02 2.16 0^1 Twt well Tsstwell 7.87 7.41 TW.2 LHPSDTW2 MWi 0,103 Test well 7,62 I TW-3 LHPSDTW2 LHP8DTW3 LWSDTW3 8/21/B2 1/22/02 8B1/02 .. ' O.OB1 4.48 . ,. -....^7 Tsatwell Test well Tetwell 7.03 7.42 7.13 I I I 4/17/03 Page I of 2 LH samples ASH025B85 EID77&173 EID779173 I Table 2 C-8 in Production and Test Wells II Little Hocking Water Association Washingon County, Ohio I Sample Ham* Sample Nama ';'?!; SaimilaDate -f:--:r..-C.Ssigft "A^-if Comment* PH TW-4 LMPSOTW4 1/22/02 37.1 Test well 12,61 I LHPSDTW4 LHPSDTW4 LHPSDTW4 3/26/02 4/23/02 a'21/02 33.3 28.7 1Z3 Test well Test well Test will 12.26 12.35 11.32 I TW-5 LHPSDTW4 LHPSDTW4 LHPSDTWS 10/16/02 2/26/03 8/21/02 14.B 22.S 8.28 Test wall Test well Test well S.22 10.54 S.7 Tw-e LHPSDTW6 1/22/02 1-79 Test well 7.03 I LHpSDTwe ' 'aoi/oz LHPSOTW6 8/21/02 ' .'31.15 . '- 1.23 Testwell 8.81 dupleate 6.81 WS LHPSDTW9 loaoz 0.364 Test well 7.33 I LHPSDTWS TW-10 LHPSDTW10 ' LHPSOTVi/10 ' ' - 8(21/02 1/21/02 6/21/02 0.812 l.a . '' 1.1 ' Twiwell TBI wit Test 'ACJI 7.06 7.43 6.8S I TW-11 TW-12 LHP8DTW11 LHPiDTWH LHPSOTW12 1/21/02 1- 6/21/02 1/21/02 1.41 1.73 0.7S8 Tssi well TasI well Test well 7,38 7.07 7.39 I LHPSDEP001 LHPSDEP001 LMP6DTW12 LHP5DEP001 LHPSDEP001 8/21/02 1/22/02 3/26/02 0.824 1.89 2.62 Teglwtill 6.5 Finlshad Water FInithsd Walar LHP8DEP001 LHPSDEP001 4/23/OZ 1.93 Finished Water I LHPSDEP001 LHPSDEP001 LHPSDEP001 LHPSDEP001 10/16/02 2/26/03 4.29 2.33 Finistiad Water Finished Water LHTORCHBS LHTORCHBS 1/22/02 1.85 Booster Station Sample 8ARTLETTCC BARTL6TTCC 1/22/02 1.94 Booster Station Sample 339B STA ssaa STA 1/22/02 1.81 Booster Station Sample Shaded cells indicata groundwater sampled for the Little Hocking Sampling Investigation in August 2002. 4/17/03 Page 2 of 2 LH samples ASH025886 EID779174 BID77&174 I I I I I I I I I I I I I I I I 4/17/03 Table 3 Groundwater Elevation Data for Production and Tsst Wells August 2002 Little Hocking Water Association Washington County, Ohio ..^;&;^ '.Well.lD^'^ Well#1 Well #2 Well #3 Well #5 TW-1 TW-2 TW-3 TW-4 TW-5 TW.5 TW-9 TW-10 TW-11 TW-12 '^^J^''"' .-'*''A'1?. ':i^;' ",W.i; " Surveyed Elevation*' 613.47 B13.71 613.54 813.18 698.13 599,92 599.75 598.52 60828 698,7 698,53 5BS.83 603.79 602.22 Depth to ^ .Walflir, (8fi1/03) 58.88 42.BB 39.88 35.62 17.38 18.83 22.78 18.18 30.63 19.03 21.44 17.77 26,57 23.95 Girouritjwater Elevation (feet :"" MSL) 556.59 570.83 573.88 677.56 580,75 581,29 578,97 580.36 577.65 579.67 577.09 678.08 577.22 578.27 Ohio River 684.7 2.46 582.24 Elevations were survsyed by Bob Griffin of LHWA on 8/23/02 using 610,0 as reference assumption for PW-1 well house top of floor slab, Page 1 of 1 LH samples ASH025887 EID779175 EID779175 Tafc!(?4 C-8 in Soil froni 1 w'oorery Borings Litlle Hocking Vaa .e- Associattori Washingiw f:oui"'Ey. Ohio wwo-swwo-s- WMO-S- WWO-3- WWO-S- wwo-swwo-swwo-swwo-swwo-swwo-swwo-swwo-swwo-swwo-s- WWO-S- WWO-S- wwd-s-' wwb-swwo-swwo-swwo-s- LHWASW1 LHWASW1 LHWASW1 LHWASW1 LHWASW1 LHWASW1 LHWASW1 LHWASW1 LHWASW1 LHWASW1 LHWASW1 LHWASW1 LHWASW1 LHWASW1 LHWASW1 LHWANW1 LHWANW1 LHWANW1 LHWAKW1 LHWAHW1 LHWAMW1 LHWANW1 3-.9) (5.0-5.6) (11.2-11.7) (15.5-16.0) (22.1-22.6) (2B.5-27.0) (30.0-30.5) (30.5^1.0)' (37.0-37.5) (37.&-3B.O) (44.3-44,5)'" (47-5-48.0) (53.5-54.0) (53.5-54.(1>-2 (55.5-56.6) (0.1_-05) (5^0-5J5)' (10.0-10.5) (15.0-15J5)_ (2d;0^20.5S' (2'1,0-21.5) (25.0-25.5]i aQ3ffl2 8Q3/02 8;23X)2 ' 8Q3/02 8/23/02 '8/23/02 8f2W2 6t2W2 8/26/02 ffl26/02_ "8KCT2 '8/26/02' 8/26/02 8/28/62" " a/2B/02" 8/29/02 8/29/02 '8/29/02 8/29/02" 8/23/02' "8/2Sffi2 8/2affi2 170 '13[ ' 3.4 3.3 NQ_ N0(0.18) N0(0-18) ND^.igi' "NQ^_ NDiOISS "NQ N0(0.18) N0(0.18) N0(6.17)" N0(017) 110 _e.r ' 7.5 6.9' "'17" '"W" "8.4" surface soil every 5"ftscn!_sampte every 5 ft soil sample every 5 (t soil sample _evieiy 5 ft soil sample _ every_5 ft soil sampte geotogte Werfac _' SiH6^h!o?t9otgoyJc"1hearitgeB( __IS^sisay.^i^s8' every 5 ft soil sampta, charcoal w wy 5 ft salt saraple ev ay 5 ft soil sample ^ every 5 ft soli sampte, duplic "'' airy 5 ft soil saraple surface soil ev ary 5 ft so& sample ev sry S ft soil sarnpie w siy 5 fl so-a sample geologic Interface _ geologic interface every 5 ft soil' sample ND = nol detected at iho listed method dateclion limit (MOL). NQ = detected at a level between the MDL and the reporting limit (RL); result ts not quanirable. ND<MDL<NQ<RL RL = limit of quanititatlon (LOQ) adjusted for aclual sample weight and % moisture, nominal LOO = 2 ug/kg. Paae 1 of 1 -n fi> a K ASH025889 EID779177 EID779177 ASH025890 EID779178 EIE>77917fi ASH025891 EID779179 EID779179 ASH025892 EID779180 EID779180 ASH02S893 EID779181 ;EID779181 ASH025894 EID779182 EID779182 AS8025895 EID7791B3 EID779183 ASH025B96 EID779184 EID779184 ASH025897 EID779185 EID779185 ASa025898 EID779186 EID779186 ASH025899 EID779187 EID77&187 ASH025900 EID779188 EID779188 r ASH025901 EID779189 EID779189 "a^ ?u1 III 1 s- | o MM *IBsC?T M sli2g i I J a a a 5S. 59z ? 4s,-A- ASH025902 EID779190 EID779190