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BRIO Results Report - Soil and Ground Water Investigation March 1996 (9647-0011) ' - TPH-g was detected in soil sample MW-I @ 16' at 0 5 ppm Soil boring MW-1 is located in the hydraulically upgradient direction between the former UST location and the ' adjacent property boundary Soil samples collected from the downgradient soil boring SB-Al did not detect the presence of petroleum hydrocarbon constituents at or above the laboratory reporting limit ' Ground Water Assessment ' Ground water was encountered at a depth of approximately five feet bgs Ground water level data collected on February 15, 1996 is presented in Table 4, Water Level Data The results of collected ground water samples are summarized in Table 5, Analytical Results Water, and the ' Report of Laboratory Analysis is presented in Appendix B Relatively low levels of TPH-g were detected in ground water samples collected from I monitoring well MW-1 (110 ppb) and in well MW-2 (56 ppb) BTEX was not detected in ground water samples MW-l or MW-2 at or above California Department of Health Services (DHS) drinking water standards, referred to as maximum contaminant levels (MCLs), using EPA Method 8020 Laboratory analysis of ground water samples collected from well MW-3 did not detect the presence of TPH-g or BTEX, at or above the reporting limit using EPA method 8015 modified and 8020 The distribution of TPH-g and benzene in ground water from the February 1996 sampling event is represented in Figure 3 ' CONCLUSIONS AND RECOMMENDATIONS IThe extent of soil contamination appears to be limited within the boundaries of the former UST pit The highest TPH-g concentrations were identified at a depth of 16 feet bgs Relatively low levels of TPH-g were detected in the ground water samples collected from both the ' hydraulically upgradlent well and the inferred downgradient well Benzene was not detected in any of the three ground water monitoring wells at or above DHS MCLs ' Tri-Valley Growers occupies the property located adjacent to and south of the subject property This site is a known Leaking Underground Storage Tank (LUST) site It is Fugro's ' understanding that assessment activities have been conducted at this site since 1987 and that remediation activities (ground water pumping) were started in 1991 ' Prior to ground water pumping activities conducted at the Tri-Valley Growers property (beginning in 1991), historical ground water flow directions were recorded Between the years 1987 and 1990, ground water flow directions have fluctuated from a south-southwest to north- 96470011 396 orth-96470011396 4