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ti <br /> TreadwellMollo <br /> i <br /> 3.2 Previous Investigations <br /> In June 2003 Advanced GeoEnvironmentai (AGE) advanced eight borings (B-1 through B-8) <br /> and obtained groundwater grab samples from Borings B-1 through B-4; and B-6 through B-8 <br /> i <br /> (AGE, 2003a). AGE Boring B-3, located in the sidewalk adjacent to the Site along West <br /> Fremont Street, was the only boring with detectable concentrations of petroleum hydrocarbons as <br /> gasoline (TPI-1-g)and diesel(TPH d)..in soil or groundwater(AGE,2003a). Tables 1 and 2 <br /> summarize the analytical results for soil and groundwater,respectively. Following this <br /> investigation,the Site was enrolled in the San Joaquin County UST program overseen by the <br /> SJCEHD. <br /> Treadwell&Rollo prepared a 23 December 2003 workplan for the Site to advance up to six <br /> borings to collect soil and groundwater samples in the vicinity of AGE Boring B-3. Between <br /> 15 and 20 January 2004, six borings(CSB-1 through CSB-6).were advanced and soil samples <br /> were collected from all six borings, while.groundwater samples were collected from Borings <br /> 4 CSB-1-through CSB-4. Figure 2 shows the boring locations. The highest concentrations of <br /> petroleum hydrocarbons in soil and groundwater were detected in Boring CSB-2, located <br /> approximately 23 feet east of AGE Boring B-3. Tables I and 2 summarize the analytical results <br /> of Treadwell &Rollo's investigation for soil and groundwater;respectively. <br /> 3.3 Soil and Groundwater Remediation <br /> 3.3.1 UST Excavation <br /> On 28 April 2004, the three USTs present in the sidewalk adjacent to the Site were removed, and <br /> during June 2004, a shored excavation was dug 4.3 feet long by 14 feet wide by 23 feet deep <br /> .(Figure 2). Approximately 425 cubic yards of soil were excavated and disposed of, and <br /> 20,000 gallons of groundwater pumped out and disposed of under permit to the sanitary sewer. <br /> The excavation was subsequently backfilled(Treadwell&c Rollo, 2004b). Analytical results for <br /> the soil and groundwater samples collected at the bottom the excavation are presented in <br /> Tables 1 and 2 respectively. <br /> 3 <br /> 25970122.DGD 14 February 2005 <br />