Laserfiche WebLink
i <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 /> soil 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 2004a). <br /> 3.1 Previous Investigations <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 /> (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 /> borings 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 /> j <br />