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13 June 1997 AGE-NC Project No 97-0330 Page 4 of 5 ' Moderate petroleum hydrocarbon odor was detected in soil probe boring P-2 at depths from 15 to 30 feet bsg, while faint petroleum hydrocarbon odor was detected at depths from 35 to 45 feet bsg Organic vapor was detected in P-2 soil sample duplicates (15 to 45 feet bsg) at concentrations as high as 58 0 parts per million 43 ANALYTICAL RESULTS OF SOIL SAMPLES A total of six soil samples were submitted to a state-certified laboratory for analysis of TPH-d and BTEX The laboratory analysis did not detect benzene or toluene from soil samples collected at P-1 or P-2, however, ethylbenzene was detected with concentrations up to 0 26 mg/kg, while xylenes were detected in a sample collected from P-1 at 20 feet with concentrations up to 0 52 mg/kg TPH-d was detected in a soil sample collected from P-1 at 20 feet at a concentration of 9 400 mg/kg, P � � g, and from P-2 at depths between 25 and 50 feet at concentrations as high as 12,000 mg/kg Analytical results of soil samples are summarize in Table 1 -Analytical yt p d ab eResults of Soil Samples The laboratory report (Castle Analytical Laboratory Reference No 1118) and chain-of-custody are included in Appendix B 5.0. CONCLUSIONS AND SUMMARY Based upon field and analytical data collected at the site on 14 May 1997, AGE concludes Substantial concentrations of TPH-d were detected from soil probe boring P-1 at a depth of 20 feet bsg and from P-2 at depths of 25 and 35 feet bsg Reduced concentrations of TPH-d were detected from P-2 at 45 and 50 feet bsg Therefore, it appears that soil impacted by TPH-d in the UST area is limited in vertical extent to depths of approximately 50 feet bsg • According to a depth to ground water map published by the San Joaquin County Flood Control and Water Conservation District, the estimated depth to ground water at the property is 80 feet below surface grade (bsg) However, according to PHS-EHD observations of ground water wells located nearby, the long term rise of ground water near the site is at approximately 50 feet below surface grade (bsg) • Although ground water samples were not collected, concentrations of xylenes and ethylbenzene detected in soil samples from P-1 and P-2 were detected below the concentration equivalents of the State of California Maximum Contaminant Levels (MCLS) for drinking water of 1,750 and 700,ug/l (micrograms per liter or parts per billion) • The Central Valley Regional Water Quality Control Board (CVRWQCB) has declared