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14 May 2004 AGE-NC Project No 96-0235 Page 3 of 5 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION Depths to ground water ranged from 17.70 feet to 20 60 feet below the tops of the well casings, ground water was within the screened intervals of the shallow wells,but was approximately 10 5 feet above the screened interval of intermediate wells MW-3 and EW-2 and between 19 and 47 feet above the screened intervals of the deep wells The elevation of ground water in each well was calculated by subtracting the depth to ground water from the surveyed casing elevations (Table 1) Ground water elevations at the site ranged from. 12 41 feet(MW-15A)to 14 05 feet(MW-2)below mean sea level (MSL) The average ground water elevation at the site was approximately 12 86 feet below MSL The average ground water elevation in the wells increased by approximately 0 47 feet since the November 2003 ground water monitoring event Figure 3 and Figure 4 illustrate the ground water potentiometric surface based on the shallow- and deep-screened data sets Near the former UST cluster, the shallow-screened data delineate a radial ground water flow pattern, with a net flow towards the northeast at a gradient of 0 002 ft/ft, the deep-screened data delineated a ground water flow direction toward the east at a gradient of 0 009 ft/ft Near the former UST No 3 excavation ground water flow direction at the shallow- screened data was inferred to be towards the southeast at a gradient of 0 005 ft/ft, ground water flow direction at the deep-screened level was inferred to be toward the south-southwest at a gradient of 0 013 ft/ft 32 ANALYTICAL RESULTS OF WATER SAMPLES TPH-g was detected in the samples collected from MW-1, MW-2, MW-9 and EW-2 at concentrations of 11,000 micrograms per liter (µg/1), 19,000 µg/1, 140 µg/l and 190 µg/I, respectively TPH-d was detected in samples collected from MW-1 and MW-2 at concentrations of 4 1 µg/1 and 23 µg/1, respectively Various BTEX compounds were detected in samples MW-1, MW-2 and EW-2 at maximum concentrations of 750 gg/I benzene (MW-1), 200 µg/1 toluene (MW-2), 810 µg/l ethylbenzene (MW-2) and 1,570 µg/1 xylenes (MW-2) MTBE was detected in the water samples collected from MW-9,MW-11B,MW-12B,MW-13B and MW-14B at concentrations ranging from 22 µ.g/1 (MW-12B) to 140 µg/1 (MW-9) Water samples analyzed from MW-1,MW-2,MW-14B and EW-2 contained detectable concentrations of 1,2-DCA at 39 µg1l, 25 µg/l, 38 µg/1 and 10 µg/1, respectively Concentrations ofDIPE, ETBE, TAME, TBA and EDB were not detected above laboratory reporting limits in any of the water samples collected during the February 2004 monitoring event Advanced GeoEnvironmental,Inc.