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0 • McLaren/Hart Soil sampling during monitoring well construction was conducted at the Site on November 3 through November 5, 1992 A total of four monitoring wells were installed (MW 1 through MW4) along the perimeter of the former underground storage tank farm, and a single monitoring _ well (MW5) was installed at the northeast corner of the Site in the inferred downgradient direction (Figure 2) Soil borings were drilled to a maximum depth of 45 feet below ground surface, and monitoring wells were installed within these boreholes to a maximum depth of 40 feet below ground surface (bgs) i The analytical results of the soil samples collected during monitoring well drilling indicate that concentrations of TPH-G were detected in the soil collected from monitoring wells MM2 through MW5 BTEX compounds were detected in the soil samples collected from monitoring wells MW2, MW3 and MW4 The soil analytical data are presented in Table 1 The maximum concentrations of petroleum hydrocarbons detected in soil samples were from the samples I collected at 25 feet bgs Groundwater samples were collected from the five monitoring wells on November 19, 1992 and submitted for laboratory analysis The analytical results indicated that no detectable concentrations of TPH were present in the groundwater samples collected from the five monitoring wells at the Site BTEX compounds were detected in groundwater samples collected from monitoring wells MW2, MW3 and MW4. . Following the initial groundwater sampling event, a quarterly groundwater sampling program was established and the second quarter of sampling commenced on June 4, 1993 Groundwater elevations were approximately four feet higher in June than when last measured in November 1992, as shown in the summary of groundwater surface elevations in Table 2 Concentrations of TPH-G were detected in groundwater samples collected from monitoring wells MW 1 and MW4 Petroleum hydrocarbons as kerosene, diesel, and motor oil have not been detected in any samples analyzed All quarterly groundwater analytical data are presented in Table 3 Concentrations of benzene were detected in groundwater samples collected from monitoring wells MW2, MW3 and MW4 The groundwater flow direction was determined to be to the northeast during the June 1993 groundwater sampling event In September 1993 groundwater elevations had decreased by less than five tenths of a foot from the June 1993 readings The groundwater flow direction remained the same as in rune 1993 In June 1993, McLaren/Hart removed the reported 180 cubic yards of soil stockpiled on plastic sheeting from the excavation A final total of 360 cubic yards of soil was ultimately removed and transported off-site for disposal at the Forward Class M Landfill in Stockton, California. At this point McLaren/Hart ascertained that all potential sources for continued release had been removed from the subject site (ie USTs and piping) The excavation was backfilled and resurfaced to restore the property to a functional condition The excavation and soil disposal procedures were observed and approved by San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) 11141cd3 3