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wWs'EFS ES\ERS GG`45`U.5 Note that petroleum impacted soil associated with the former USTs has been removed to a depth - of 31 ft below grade, therefore, the shaded results in Table 1 are for soil that is no longer present at the site. 3.2 1991-1993 QUARTERLY MONITORING WESTON began a quarterly groundwater monitoring program on behalf of the SJCMVCD in December 1991 Only one of the three existing monitor wells (MW-1) at the site was found to have enough water to sample at that time Consequently, an additional monitor well (MW-4), was installed in July 1992 northeast of the former tank area This monitor well was installed to evaluate the possible downgradient migration of hydrocarbons in groundwater All analytical results for groundwater samples collected from monitor wells at the site have been Y g p non-detect for total petroleum hydrocarbons as gasoline (TPH-G), and benzene, toluene, ethylbenzene and xylenes (BTEX) compounds A complete summary of groundwater analytical results is presented in Table 2 lie 3.3 1994 SOIL AND GROUNDWATER INVESTIGATION WESTON conducted a field investigation from 5 through 7 July 1994 to evaluate the horizontal and the vertical extent of soil contamination at the site and to assess the presence of contaminants in groundwater Twelve soil samples were collected from four soil borings and were submitted for analysis of TPH-G (EPA 8015) and BTEX (EPA 8020) Two groundwater samples were collected using a bailer and Hydropunch® groundwater sampling tool, at soil borings SB-3 and SB-4 (Figure 1) The groundwater samples were also analyzed for TPH-G and BTEX compounds The results of the soil and groundwater analyses are summarized in Tables 1 and 2 TPH-G was detected in only two soil samples, one from SB-1 and the other from SB-2. The concentration detected in SB-1 at 50 ft bgs was 0 014 mg/kg The 20 ft bgs sample from SB-2 was analyzed twice because the surrogate recovery from the initial analyses was high due to background matrix interference The second analysis was completed one day past holding time The initial result, 6,000 mg/kg, is most likely biased high, based on high surrogate recovery, and the second result, 210 mg/kg 1s not reliable because the holding time was exceeded. However, it can be concluded that the 20 ft sample from SB-2 contained TPH-G at concentrations between 210 mg/kg and 6000 mg/kg. LW0jECTSNSAM0Q\L0DI ACT 5 15 May 1995