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i 26 April 2002 AGE-NC Project No 95-0173 Page 4 of 8 ' 4 1 GROUND WATER ELEVATION AND GRADIENT During the December 2001 ground water monitoring event,depths to ground water in the monitoring wells were measured between 25 68 and 29 43 feet below the tops of well casings, ground water elevations were calculated to be between 15 76 feet and 19 45 feet below mean sea level Ground water elevation at the site decreased an average 0 07 feet between the September 2001 and the ' December 2001 ground water monitoring events Nine of the wells were"drowned", the screened- interval was approximately 2 feet below the water table in wells MW-1 through MW-4,between 10 and 30 feet below water in wells AW-IA through AW-2B and approximately 70 feet below water in well MW-13 The ground water elevation data for the December 2001 ground water monitoring event is depicted in Figure 3 Ground water flow direction at the site was inferred to be toward the northeast at a gradient of 0 003 ft/ft or less, or approximately 16 feet per mile (Figure 3) ' 4 2 LABORATORY RESULTS OF GROUND WATER SAMPLES ' . A total of seventeen ground water samples were submitted to a DHS-certified laboratory for analysis TPH-g was detected in ground water samples collected from wells MW-I through MW-4, MW-6, MW-9,MW-13, and AW-1A through AW-2B, at concentrations as high as 95,000 micrograms per ' Iiter(µg/1) in the sample from AW-2A BTEX compounds were detected in ground water samples collected from wells MW-1 through ' MW-4, MW-9, MW-13, and AW-lA through AW-2B at concentrations as high as 22,000 µg/1 (toluene, AW-2A) The maximum benzene concentration was detected from sample AW-2A at a ' concentration of 7,900 µg/1 MTBE was detected in water samples collected from MW-3, MW-4, MW-5 and MW-11 at concentrations as high as 14 gg/l (MW-4), DIPE was detected in a water sample collected from MW-5 at a concentration of 0 77µg/1, 1,2-DCA was detected in water samples collected from MW-3 and MW-5 at concentrations of 13 and 3 8 µg/l, respectively No other fuel components were detected in the samples analyzed Previous and current analytical results of ground water monitoring well samples are summarized in Tables 3 and 4, respectively, the estimated extent of dissolved petroleum hydrocarbons is depicted in cross sectional view C-C'(Figure 5) The laboratory reports ' (Castle Analytical Laboratory Reference No 4310) and chain-of-custody forms are presented in Appendix C ' Advanced GeoEnvironmental,Inc