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1 <br /> TreadvvelOWIo <br /> there was a regional rise in groundwater of at least 10 feet recorded in nearby wells, and <br /> additional rise in groundwater elevation was reported to have occurred prior to 1994 The rise in <br /> groundwater after the fuel release at the Site (and documented at adjacent sites) has resulted in <br /> Isoil exhibiting a smear zone of significant total petroleum hydrocarbons as gasoline (TPH-g) <br /> concentrations to at least 10 feet below the water table (AGE, 2003b,c) (Wallace, Kuhl & <br /> Associates, 2003) (Treadwell & Rollo 2004x) <br /> 1 3.1 Previous Investigations <br /> i <br /> In June 2003 Advanced GeoEnvironmental (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 TPH-g and diesel (TPH-d) <br /> in soil or groundwater (AGE, 2003a) Tables 1 and 2 summarize the analytical results for soil <br /> and groundwater, respectively Following this investigation,the Site was enrolled in the San <br /> Joaquin County UST program overseen by the SJCEHD <br /> Treadwell &Rollo prepared a 23 December 2003 workplan for the Site to advance up to six <br /> bonngs to collect soil and groundwater samples in the northern portion of the Site 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 /> 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 1 and 2 present the analytical results of <br /> Treadwell &Rollo's investigation for soil and groundwater, respectively <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 to the dimensions at 43 feet long by 14 feet wide <br /> by 23 feet deep (Figure 2) Approximately 425 cubic yards of soil were excavated and disposed <br /> of, and approximately 20,000 gallons of groundwater pumped out of the excavation and disposed <br /> 25971024 DGD 3 7 June 2005 <br />