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w :r 26 February 2003 s AGE-NC Project No. 96-0254 iPage 3 of 4 I July 2002 and October 2002 sampling events; the ground water elevation.in well MW-7 increased 0.37 feet between the July 2002 and October 2002 sampling events. The ground water flow direction for the 31 October 2002 sampling event was inferred to be toward the north at an average hydraulic gradient of 0.007 feet/feet; data from the deeper-screened.wel Is MW-IA, MW-2A and MW-7 was not used to determine the ground water gradient. Figure 3 Iillustrates the contoured ground water elevations. r3.2. LABORATORY RESULTS OF GROUND WATER SAMPLES TPH-g was detected in the samples collected from wells MW-1B and MW-4 at concentrations of 390 micrograms per liter(pg/l) and 1,200 µg/1, respectively (Figure 4). TPH-d was detected in the water samples collected from wells MW-1B and MW-4 at concentrations of 610 �tg/l and 75 gg/l. ' TPH-g and TPH-d were not detected in the remaining samples. Benzene and xylenes were detected in the ground water samples collected from monitoring wells ' MW-1B and MW-4 at concentrations as high as 390µg/1 and 63 µg/1,respectively(MW-4).Toluene was detected in the sample collected from MW-4 at a concentration of 6.2 µg/l. Ethylbenzene was not detected in the ground water samples collected during the October 2002 monitoring event. MTBE was detected in the samples collected fron, MW-1B, MW2B and MW-4 at concentrations of 66 µg/l,0.64µg/1 and 5.3 gg/l,respectively(Figure 6). TBA was detected in the sample collected ' from MW l-B at a concentration. of 22 µg/1. No other fuel additives were detected in the ground water samples. The analytical results are summarized in Tables 2 and 3. Copies of the laboratory reports (MAI Laboratory IDs 0211024-001,0211024-002 and 0211025-001 to 0211025-007),QA/QC reports and chain-of-custody forms are in Appendix B. 4.0. SUMMARY AND CONCLUSIONS 1 Based on the data collected during this monitoring period, AGE concludes: • The depth to ground water at the site was between 7.05 and 8.12 feet below the well casing tops. The prevailing ground water flow direction at the site was generally toward the north, I consistent with the previously determined flow directions. • Petroleum hydrocarbon-impacted groundwater was encountered in samples from monitoring wells MW-1B, MW-2B,MW-4; benzene concentrations exceeded the State of California's Advanced GeoUnrironmental Inc.