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' . 04 April 2002 AGE-NC Project No 96-0235 ' Page 3 of 5 . ' 3 1 ' GROUND WATER GRADIENT AND FLOW DIRECTION The elevation of ground water in each well was calculated by subtracting the depth to ground water from the surveyed casing elevations (Table 1) Depths to ground water ranged from 16 09 feet to t 18 76 feet below the tops of the well casings, ground water was within the screened intervals of the shallow-screened wells,but was approximately 12 feet above the screened interval of intermediate- screened wells MW-3 and EW-2 and between 2124 and 23 38 feet above the screened intervals of the deep-screened wells Ground water elevations at the site ranged from 10 69 feet (MW-8A) to 12 26 feet (MW-2)below mean sea level The average ground water elevation in the wells increased by approximately 1 67 feet Figure 3 illustrates the groundwater potentiometric surface based on the shallow-and deep-screened data sets Near the former UST cluster, the shallow-and deep-screened data delineated a dominant ground water flow direction toward the southeast, ranging from northeast to southeast Near the former UST No 3 excavation groundwater flow direction was inferred to be flowing radially toward the northeast to the southeast using shallow-screened data and toward the south-southwest using deep-screened data The inferred ground water gradient in the shallow zone was 0 003 ft/ft near both the former UST cluster and the former UST No 3 location,the inferred ground water gradient in the ' deep zone was 0 002 ft/ft near the former UST cluster` and 0 012 ft/ft near the former UST No 3 ' 32 ANALYTICAL RESULTS OF WATER SAMPLES TPH-g was detected in the samples collected from MW-1, MW-2, MW-10, MW-I IB, EW-1 and I EW-2 at concentrations as high as 39,000 micrograms per liter(µg/1) in the sample collected from EW-1 TPH-d was detected in samples collected from MW-1,MW-2, MW-10,MW-11B and EW-1 at concentrations as high as 5,900 ltg/l(EW-1) Various BTEX compounds were detected in samples ' from nine of the twenty wells,the maximum concentrations were detected in the sample from EW-1 (1,300 µg/1 benzene, 5,400 µg/1 toluene, 1,800 µg11 ethylbenzene and 6,700 µg/1 xylenes) ' MTBE was detected by EPA Method 8260 Modified in the water samples collected from MW-9, MW-10,MW-11 B,MW-12B,MW-13A,MW-13B and EW-1 at concentrations ranging from 17µg/l (MW-1 1B) to 310 µg/1 (EW-1) TBA was detected in the water sample collected from MW-6B at ' a concentration of 21 µg/l Water samples analyzed from MW-1, MW-2, MW-5, MW-6B, MW-7, MW-I IB, MW-12B, MW-13B,,EW-1 and EW-2 contained detectable concentrations of 1,2-DCA ranging from 1 I gg/l (MW-1) to 16 µg/1 (MW-11B) EDB was not detected in any of the samples ' collected from the 20 on site wells Concentrations of DIPE, ETBE or TAME were not detected ' • above laboratory reporting limits in any of the water samples collected during the February 2002 1 Advanced GeoEnvi ron mental,Inc f