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r r 19 September 2001 s r AGE-NC Project No 96-0254 Page 3 of 4 rThe depths to ground water in wells MW-1 through MW-7 and GLMW-3 were measured between 6 91 feet and 8 68 feet below the tops of the well casings Ground water elevations at the site ranged from 28 64 feet above mean sea level (MSL) in well GLMW-3 to 30 30 feet above MSL in well rMW-6 Ground water elevations at the site decreased an average 0 04 feet between the April 2001 and July 2001 sampling events rThe ground water flow direction for the 27 July 2001 sampling event was inferred to be toward the north on-site and toward the northeast downgradient of the site at an average hydraulic gradient of r 0 006 feet/feet Data from MW-1A, MW-2A and MW-7 was not used to determine ground water gradient These wells are screened at a deeper interval than the remairung wells Figure 3 Illustrates the contoured ground water elevations r 3 2 LABORATORY RESULTS OF GROUND WATER SAMPLES rTPH-g was detected in the sample collected from well MW-1B at a concentration of 140 micrograms per liter (µg/1) TPH-d was detected in the water sample collected from well MW-7 at a r. concentration of 74 µg/l TPH-g and TPH-d were not detected in the remaining samples One or more BTEX compounds were detected in the ground water samples collected from rmonitoring wells MW-1B and MW-4 at concentrations as high as 24 µg/1 benzene, 11 µg/1 toluene, 4 1 µg/1 ethylbenzene and 11 µg/1 xylenes (MW-1B) rMTBE was detected in the sample collected from MW-4 at a concentration of 2 2µg/1 No other fael oxygenates were detected in the ground water samples rThe analytical results are summarized in Table 2 Copies of the laboratory reports(MAI Laboratory ID 73775 to 73783), QA/QC reports and chain-of-custody forms are in Appendix B r 4.0 SUMMARY AND CONCLUSIONS rBased on the data collected during this monitoring period, AGE concludes • The depth to ground water at the site was between 6 91 to 8 68 feet below the well casing tops The average ground water elevation was 0 04 feet lower than the average ground water elevation last quarter The prevailing ground water flow direction at the site is generally toward the north shifting toward the northeast downgradient of the site which is consistent . with the previously determined flow directions Petroleum hydrocarbon-impacted ground water was encountered in samples from monitoring wells MW-1B and MW-4 with benzene concentrations exceeding the State of California Advanced GeoEnvironmental Inc r