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' 18 October 2002 • AGE-NC Project No 95-0128 ' Page 4 of 7 ' 3.0. FINDINGS Ground water elevations were determined by subtracting the measured depths-to-water from the surveyed casing elevations Ground water flow directions were determined by contouring the water elevations on a scaled site plan Contaminate Impact to ground water samples was assessed by laboratory analysis The mass of hydrocarbons removed by ground-water extraction was calculated from the volume of water treated and the concentrations of contaminants from laboratory analysis 3 1 GROUND WATER ELEVATION AND GRADIENT The ground water elevation on 14 August 2002 ranged from 20 01 feet (MW-7) to 2177 feet (MW-14) below mean sea level (MSL), the average ground water elevation was approximately 1 65 feet lower than the average ground water elevation during the May 2002 monitoring event The ground water table occurred within the screened interval of the shallow-screened monitoring wells (Table 1), wells MW-1 to MW-3, MW-11B and MW-12B were deeper-screened wells and are currently drowned The depth to ground water and ground water elevation data is summarized in • Table 1 ' The areal ground water flow direction was inferred to be northeast at gradients of between 0 003 ft/ft i to 0 004 ft/ft An approximately 90-foot diameter cone of depression was observed at the northeast corner of the site due to drawdown of the water table by extraction well EW-1 (Figure 3), ground water gradients greater than 0 05 ft/ft were observed within this depression i 3 2 ANALYTICAL RESULTS OF MONITORING WELL GROUND WATER SAMPLES iTPH-g was detected in ground water samples MW-4, MW-5 and VW-1 at concentrations of 2,300 micrograms per liter(µg/1), 36,000 µg/l,and 1,200 µg/l,respectively, TPH-d was detected in i the same samples plus sample MW-11A at concentrations of 1,500 µg/1, 4,800 µg/l, 430 µg/1 and 71 µg/1, respectively iVarious BTEX compounds were detected in samples MW-1,MW-4,MW-5 and VW-1,at maximum concentrations of 160 µg/1 benzene, 170 µg/1 toluene and 1,900 µg/1 ethylbenzene in sample MW-5 and 180 µg/1 xylenes from sample VW-1 IMTBE was detected by EPA Method 8260M in ground water samples MW-2 through MW-6 MW-8,MW-11 A,MW 11 B,MW 12A,MW-12B,MW-15 and VW-1 at concentrations ranging from • IAdvanced GeoEnvironmental Inc E