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' 23 January 2004 AGE-NC Project No 97-0312 Page 3 of 4 ' 3 1 GROUND WATER ELEVATION AND GRADIENT Depths to ground water at the site ranged between 6190 to 68 80 feet below top of casing (btoc), ' ground water elevations were between 37 58 feet(UST-5) and 38 18 feet(UST-3)below mean sea level (MSL) The average ground water elevation had decreased by an average of 6 8 feet since the May 2003 momtonng event The ground water table occurred above the screened iritervals of ' monitoring wells UST-2 through UST-6 Monitoring well UST-7 was designed to monitor deeper ground water, with a 5-foot screened interval set at approximately 25 feet below the water table, since it possibly is monitoring a different hydraulic zone,UST-7 was not used to determine gradient ' and flow direction General ground water flow direction at the site was inferred to be north-northwest with an average ' gradient of approximately 0 002 ft/ft or less Figure 3 depicts the ground water elevation contours for September 2003 ' 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES ' During the September 2003 monitoring event,TPH-g,benzene,toluene and 1,2-DCA were detected in the sample collected from UST-5 at concentrations of 590 micrograms per liter(µg/1), 9 1 µg11, 1 8 µg/1 and 510 µg11,respectively MTBE and 1,2-DCA were detected in the sample collected from ' UST-6 at concentrations of 0 72 µg/1 and 4 4 µg/1, respectively Tetrachloroethene (PCE) was detected in the sample collected from UST-7 at a concentration of 2 0 µg/1 ' No other target analytes were detected at or above laboratory reporting levels in the ground water samples collected this quarter The laboratory,reports (MAI Lab IDs 0309482-001 through t 0309482-007) and chain-of-custody forms are included in Appendix B Analytical results of water samples collected during the third quarter 2003 are summarized on Tables 2 and 3 The analytical results of all water samples are summarized on Tables 4 and 5 Figures 4, 5 and 6 illustrate the areal ' extent of TPH-g-, benzene- and 1,2-DCA-impacted ground water ' 4.0. DISCUSSION AND CONCLUSIONS Based upon data collected from the site, AGE concludes •' Ground water elevation decreased approximately 6 8 feet at the site between the May 2003 PP and the September 2003 momtonng events The inferred ground water flow direction is ' toward the north to northwest The average ground water gradient was 0 002 ft/ft across the site Advanced GeoEnvironmental,Inc 1 r ,