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> 3 i1 f 1 15 November 2004 AGE-NC Project No 96-0235 ' Page 3 of 5 - L t . 31 GROUNDWATER GRADIENT AND FLOW DIRECTION Depths to ground water ranged from,18`35 feet to 21 40 feet below the tops of the well casings, ' ground water was within the screened Intervals of the shallow wells,but was approximately 10 feet above the screened Interval of Intermediate wells MW-3 and EW-2 and between 18 and 46 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 ' 13 3 Heet(MW-12A)to 14 99'feet(MW-2)below mean sea level(MSL) The average ground water elevation at the site was approximately 13 78 feet below MSL The average ground water elevation In the wells decreased by approximately 1T56 feet since the May 2004 ground water monitoring" ' event 4 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, ground water flow direction at the shallow- screened data was Inferred to be towards the northeast at a gradient of 0 002 ft/ft,the deep-screened ` data delineated a ground water flow direction toward the south-southwest at a gradient of 0 006 ft/ft ' Near the former UST No 3 excavation groundwater flow direction at the shallow-screened data was Inferred to be towards the southeast at a gradient of 0 003 ft/fl, ground water flow direction at the deep-screened level was Inferred to be toward the southwest at a gradient of 0 014 ft/ft 32 ANALYTICAL RESULTS OF WATER SAMPLES f TPH-g was detected In the samples collected from MW-1, MW-2, MW-9, MW-14B and EW-2 at concentrations ranging from 100 micrograms per liter (µg/1) in samples,MW-9 and MW-14B to 13`,000 µg/1 in sample MW-1 TPH-d was detected In samples collected from MW-I and MW-2 at concentrations of 1,800 µg/1 and 6,140 µg/1, respectively ` Vanbus BTEX compounds were detected In samples MW-1,` MW-2 and EW-2 at maximum concentrations of 2,900 µg/1 benzene(MW-1), 240 µg/1 toluene (MW-2), 1,600 µg/1 ethylbenzene ' (MW-1) and 2,285µg/1 xylenes (MW-2) f MTBE was detected in the water samples collected from MW-9, MW-10, MW-11B, MW-12B, ' MW-13B and MW-14B at concentrations ranging from 24'µg/1 (MW-12B) to 110 µg/1 (MW-9) ' Water samples analyzed from MW-2, MW-11B, MW-1213, MW-13B, MW-14B and EW-2 contamcd detectable concentrations of 1,2-DCA ranging from 2 5 µg/1 (MW-12B) to 40 µg/l ' (MW-14B) EDB�was detected at a concentration of 3 3 µg/1 in the sample collected from MW-5 Concentrations of DIPE, ETBE, TAME, TBA, methanol and ethanol were not detected above, r Advanced GeoEnviron mental,Inc 1 �