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1 ' 13 June 1999 • AGE NC Project No 97-0333 Page 7 of 9 Utilizing EPA Method 8020, BTE&X were detected in ground water samples collected from P-1 though P-5 at concentrations ranging as high as 48,000µg11,the greatest benzene concentration was detected in P-4 at a concentration of 23,000 µg/l MTBE was detected in ground water samples ' collected from P-1, P-2, P-4 and P-5 at concentrations ranging as high as 810,000 µg/1 Utilizing EPA Method 8260, MTBE was detected in ground water samples collected from P-1 ' through P-5 at concentrations ranging as high as 310,000 µg/l, TAME was detected in a ground water sample collected from P-3 at a concentration of 3 6µg/1 No other fuel oxygenated compounds were detected during the laboratory analysis of ground water samples Analytical results of ground ' water samples are summarized in Table 3 The laboratory report (McCampbell Analytical Inc Lab ID 09585 through 09589) and chain-of-custody are included in Appendix B The estimated extent of dissolved total petroleum hydrocarbons and of dissolved MTBE concentrations are depicted in plan view in Figure Nos 7 and 8, respectively 5.0. SUMMARY AND CONCLUSIONS Rased nn review of a regional a ound water elevation *nap published by the SJCFCD the prevailing kD ground water flow direction in Manteca is generally toward the northwest Based upon data collected on 15 April 1999, AGE concludes the follov"ing ' First encountered ground water is approximately 14 feet bsg, first observed saturated soli was between 15 feet bsg and 20 feet bsg ' General lithology beneath the site is depicted in cross sectional view on Figures 3 and 4 • Faint to intense petroleum hydrocarbon odor and x apor were noted in soil and grab ground «eater samples collected from probings P-1 through P-5 • The approximate known horizontal and Vertical extent of petroleum-impacted soil is depicted in Figures 5 and 6 and is based on laboratory data and field evidence noted on boring logs ' (i e vapor detection petroleum odor) • TPH-g ,N as detected in soil samples collected from probe borings P-1 P-2, P-4 and P-5 at concentrations ranging as high as 390 mg/kg, TPH-d was detected in soil samples collected from P-1, P-3, P-4 and P-5 at concentrations ranging as high as 49 mg/kg The estimated xtent of known adsorbed TPH-g is depicted in cross sectional ,iew 4 -,4 ' in Figure 5 ' 131 EX vverc detected in soil samples collected from P-1 though P-6 at concentrations iai�gmp is high 1 tng/kg 4dianced(,cotnkironmentil ir�c