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' 24 May 2001 • AGE-NC Project No 96-0254 IPage 3 of 4 I MW-6 Ground water elevations at the site increased an average 0 08 feet between the January 2001 and April 2001 sampling events The ground water flow direction for the 25 April 2001 sampling event was inferred to be flowing towards the north at an average hydraulic gradient of 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 remaining wells Figure 3 illustrates the contoured ground water elevations 3 2 LABORATORY RESULTS OF GROUND WATER SAMPLES I TPH-g was detected in samples collected from wells MWAB and MW-4 at concentrations of 1,300 micrograms per liter (µg/1) and 120 4g11, respectively TPH-d was detected in the water samples collected from wells MW-113 and MW-7 at concentrations of 84 µg/1 and 130 µg/l, respectively ' 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 monitoring wells MW-1B, MW-4 and MW-7 at concentrations as high as 400µg/1 benzene, 27,ug/1 toluene, 43 µg/l ethylbenzene and 22 µg/1 xylenes I MTBE was detected in samples collected from MW-1B and MW-4 at concentrations of 12µg/1 and 1 5µg/l, respectively No other fuel oxygenates were detected in the ground water samples analyzed The analytical results are summarized in Table 2 Copies of the laboratory reports (MAI Laboratory ID 66187 to 66195), QA/QC reports and chain-of-custody forms are in Appendix B 4.0. SUMMARY AND CONCLUSIONS IBased on the data collected during this monitoring period, AGE concludes • The depth to ground water at the site was between 6 87 to 8 61 feet below the well casing tops The average ground water elevation was 0 08 feet higher than the average ground water elevation last quarter The prevailing ground water flow direction at the site is generally northward which is consistent with the previously determined flow directions • Petroleum hydrocarbon-impacted ground water was encountered in samples from monitoring wells MW-1B, MW-4, and MW-7 with benzene concentrations exceeding the State of ICalifornia maximum contaminant level (MCL) of 1 ppb in samples collected from MW-1 B • and MW-4 Low concentrations of MTBE were detected in the ground water samples collected from MW-1B and MW-4 MTBE concentrations did not exceed the State of California primary maximum contaminant level (MCL) of 13 ppb In general, overall Advanced GcoEnvlronmental Inc