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' 29 September 2000 AGE-NC Project No 95-0173 ' Page 4 of 7 ' 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT During the May 2000 ground water monitoring event, depths to ground water in wells MW-1 ' through MW-12 were measured between 22 30 and 26 40 feet below the tops of well casings,ground water elevations were calculated to be between 12 40 feet and 16 38 feet below mean sea level Ground water elevation at the site Increased an average 197 feet between the October 1999 and May ' 2000 ground water monitoring events The ground water elevation data for MW-1 through MW-12 during the May 2000 ground water monitoring event is depicted in Figure 3 ' Ground water flow direction for the area bound by wells MW-1,MW-6, MW-7, MW-8 and MW-12 was generally toward the northwest at a gradient of 0 004 ft/ft, or approximately 21 feet per mile (Figure 3), ground water flow direction for the area bound by wells MW-2, MW-3, MW-4, MW-5, ' MW-9, MW-10 and MW-11 was generally toward the southeast at a gradient of 0 002 ft/ft f3 2 LABORATORY RESULTS OF GROUND WATER SAMPLES . TPH-g was detected in ground water samples collected from wells MW-1, MW-2, MW-3, MW-4, ' MW-5 and MW-6 at concentrations ranging between 51 and 120,000 micrograms per liter (µg/1) TPH-d was detected in ground water samples collected from wells MW-1, MW-2, MW-3, MW-4, ' and MW-6 at concentrations ranging between 220 and 6,400 µg/1, however the laboratory reported that all five of the TPH-d sample chromatograms as not having typical diesel patterns ' BTEX compounds were detected in ground water samples collected from wells MW-1, MW-2, MW-3,MW-4, MW-5 and MW-6 at concentrations as high as 19,000,ug/l (toluene, MW-3) The greatest benzene concentration was detected from MW-3 at 13,000 ,ug/l MTBE was not detected ' in any of the six ground water samples by the EPA 8020 analysis MTBE was detected in ground water samples collected from MW-3 and MW-4 utilizing EPA ' Method 8260 Modified at concentrations of 66 and 38 µg11, respectively TBA was detected in a ground water sample collected from MW-5 at a concentration of 72 ,ug/l No other fuel oxygenated compounds were detected during the laboratory analysis Analytical results of the ground water 1 samples are summarized in Table 2 The laboratory reports (Castle Analytical Laboratory Reference No 3017 and McCampbell Analytical Inc Lab I D 38890 through 38895) and chain-of-custody forms are presented in Appendix C ' Advanced GeoEnvironmental,Inc