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Project No 034-98081 <br /> Page No 2 <br /> excavation The first boring (B-la) was discontinued because it was not located within the former tank <br /> excavation The second boring (B-1), which did penetrate the former tank excavation, was advanced to a <br /> total depth of 20 feet below ground surface (bgs) Analytical results of soil samples collected from <br /> boring B-1 revealed minor concentrations of PHCs Based on the results of the January 1998 drilling and <br /> sampling activities, and prompted by UBOC, four additional Geoprobe® borings (P-1 through P-4) <br /> ranging in depth from 20 to 40 feet bgs were advanced in the vicinity of the former UST excavation on <br /> February 2, 1998 The analytical results of soil samples collected from the Geoprobe® borings <br /> established both horizontal and vertical attenuation of PHCs in soils beneath the former UST However, <br /> because groundwater was anticipated to be within 10 feet of detectable concentrations of PHCs and <br /> impact to groundwater was unknown, the property lender (UBOC) requested an additional assessment to <br /> determine potential groundwater impact by PHCs associated with the former UST Please refer to Figure <br /> 2 for borehole locations <br /> On March 13, 1998, Krazan advanced a 46-feet deep Geoprobe© boring and collected a grab <br /> gioundwater sample (P5-W) at the location of the former UST The groundwater sample was analyzed <br /> for PHCs and common fuel oxygenates, as the former UST was in place during the period of time when <br /> oxygenated fuels were being initially introduced into the market The groundwater sample contained <br /> elevated concentrations of PHCs, but no concentrations of fuel oxygenates or chlorinated hydrocarbons <br /> Upon receiving a copy of Krazan's report for the March 1998 investigation, the San Joaquin County <br /> Environmental Health Department (SJCEHD) requested in an April 13, 1998 letter to Wilbur-Ellis the <br /> installation of monitoring wells to complete the assessment process <br /> During Phase I of the present investigation in August 1998, Krazan advanced two 60-foot deep soil <br /> borings (13-2 and B-3) to determine the maximum vertical extent of possible PHC soil and groundwater <br /> impact, and four (13-4 through B-7) 34 to 40-foot deep borings to determine the maximum lateral extent <br /> of PHCs in groundwater Soil and groundwater samples were analyzed for benzene, toluene, <br /> ethylbenzene, and xylenes (BTEX) and for total petroleum hydrocarbons as gasoline (TPH-G) by EPA <br /> Methods 802113 and 8015M, respectively Methyl tertiary butyl ethyl (MTBE) was analyzed by Method <br /> 8260 in one groundwater sample One confirmation sample was also analyzed for volatile organic <br /> constituents using EPA Method 8260A The results of the August 1998 investigation are presented in <br /> KRAZAN& ASSOCIATES, INC <br /> Of Serving the Western United Stales <br /> 3498091 sg2 <br />