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19 January 1998 AGE-NC Project No 96-0229 IPage 6 of 8 Benzene was detected in soil samples collected from MW1, MW3 and MW6 at concentrations up to 6 ppm,toluene, ethylbenzene and xylenes were detected in samples collected from MW1, MW3 and MW6 at concentrations as high as 140 ppm The analytical results of selected soil samples are summarized in Table 2 MTBE was not detected in soil samples submitted for laboratory analysis utilizing EPA methods 8020 and 8260 DIPS,TAME, ETBE and TBA were not detected in selected soil samples utilizing EPA method 8260 The laboratory reports (Castle Analytical Laboratory Reference No 1346) and chain-of-custody forms are included in Appendix D 3 5 ANALYTICAL RESULTS OF GROUND WATER SAMPLES During the November 1997 ground water sampling event, TPH-g was detected in ground water Isamples collected from MW1 through MW6 at concentrations as high as 150,000 parts per billion (ppb, reported as micrograms per liter) Benzene was detected in ground water samples collected from MW1 through MW6 at concentrations as high as 10,000 ppb Toluene, ethylbenzene and xylenes were detected in samples from MW 1 through MW6 at concentrations as high as 21,000 ppb MTBE was detected in ground water samples collected from MW1 and MW2 at concentrations of 1,800 ppb and 950 ppb, respectively, as analyzed by EPA Method 8020 analysis MTBE was also confirmed from MW1 and MW2 at ' concentrations of 1,200 ppb and 1,100 ppb utilizing EPA method 8260, which also detected MTBE from MW3 and MW6 at concentrations of 83 ppb and 81 ppb, respectively TBA was detected from MWI and MW6 at concentrations of 320 ppb and 72 ppb, respectively TAME, DIPE and ETBE ' were not detected in the laboratory analysis of any ground water samples Analytical results of the ground water samples are summarized in Table No 4 The laboratory report (CAL Reference Number 1349) and chain-of-custody forms are presented in Appendix E 4.0. SUMMARY AND CONCLUSIONS Based on review of depth to ground water maps and the results of ground water monitoring and sampling activities and monitoring well installations performed in November 1997,AGE concludes • Depth to ground water maps dating back to 1971 and published by the San Joaquin County I Flood Control and Water Conservation District indicate that historical ground water dcpths for the area of the site to have been as low as 55 feet bsg • General ground water flow direction at the site was calculated to be in a northeast direction at the site with a general ground water gradient calculated at approximately 0 004 fl/ft • Laboratory ground water data Indicates that the greatest concentrations of dissolved Advanced GcoEm ironmental,Inc