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2.3 Groundwater Monitoring <br /> Groundwater monitoring has been performed at the site on seven occasions since June of <br /> 1987 The sampling events was performed by AGS and Nations Groundwater Associates <br /> (NGA) Groundwater contamination was detected in samples from the monitoring wells <br /> during each monitoring event Benzene, toluene and xylenes were detected during the most <br /> recent groundwater monitoring event (November 12, 1992) <br /> According to reports by AGS and NGA, groundwater flowed consistently to the southwest <br /> from 1987 to April of 1991 However, in a report dated February 2, 1993, NGA depicted <br /> a northeasterly groundwater flow on November 12, 1992 Discussions with Mr Harlin Knoll <br /> of the PHS/EHD indicate that the northeast flow direction may be a one-time anomaly or, <br /> more likely, may have resulted from incorrect calculations <br /> 2.3 UST Removal <br /> The UST's and product lines were pressure tested for leaks in 1987 The tanks and piping <br /> passed the pressure tests, however, a faulty vapor recovery valve was discovered and <br /> repaired <br /> Two UST's were removed from the site in March of 1990 Gasoline contamination was <br /> detected in soil samples collected beneath the tanks According to the San Joaquin County <br /> Public Health Services - Environmental Health Division (PHS/EHD), approximately 800 <br /> cubic yards of gasoline-contaminated soil were removed from the tank excavation and <br /> stockpiled on-site <br /> 3.0 DEPTH TO GROUNDWATER <br /> According to the "Groundwater Monitoring Report" dated February 2, 1993, prepared by <br /> NGA, the depth to groundwater in November of 1992 was approximately 72 feet Current <br /> depth is expected to be approximately 70 feet <br /> 4.0 SOIL BORING & MONITORING WELL INSTALLATION <br /> In a letter dated September 24, 1993, the PHS/EHD states that "the full extent of soil and <br /> groundwater contamination [at the site]must be identified and corrective action performed " <br /> GeoAudit believes that it may be possible to investigate the "full extent" of contamination <br /> at the site, with two additional soil borings and two additional monitoring wells The <br /> locations of the monitoi ing wells and soil borings are depicted in Figure 2 After the extent <br /> of groundwater has been assessed, a corrective action plan (CAP) can be proposed. <br /> ddnosI A.d„s.,..�,,!.. <br /> ^d h-. .wrnx 4nscas 2 <br />