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1 li <br /> • contaminant concentration with depth, with a benzene concentration of 17,000 µg/L at 74 to 78 feet bgs <br /> and 150 4g/L at the refusal depth of 107 feet bgs The results of the deepest groundwater samples <br /> collected from the hydropunch borings associated with the CPT borings indicated that the vertical extent <br /> of petroleum hydrocarbon contamination was not fully characterized No soil horizon was encountered <br /> during the investigation that apparently had substantially impeded the vertical movement of gasoline <br /> contamination <br /> Laboratory analytical results from hydropunch groundwater samples indicated that shallow groundwater <br /> northeast of the site was not impacted by gasoline constituents at or above the laboratory reported <br /> detection limits Results of the groundwater samples collected north of the site indicated that the shallow <br /> groundwater immediately north of the site was impacted by moderate and low concentrations of gasoline <br /> constituents Results of the groundwater samples collected wells screened below the water table indicated <br /> that the lateral and vertical extent of groundwater contamination was not fully investigated north of the <br /> site <br /> The highest concentrations of gasoline constituents were detected in the shallow groundwater sample <br /> collected near the former location of the USTs with benzene at 15,000 µg/L MTBE iso-concentration <br /> contours constructed with the shallow groundwater data from the investigation indicated a low <br /> concentration MTBE plume The plume was apparently from an off-site source located southwest of the <br /> site and not from the former USTs at the site The low concentrations of benzene detected may also have <br /> been from an off-site source located southwest of the site based on the distribution of the benzene <br /> contamination in that area <br /> Based on the results of the March 2002 investigation, Condor recommended additional groundwater <br /> investigation at the site to further evaluate the vertical distnbution of the contaminant plume Condor is <br /> currently preparing a work plan to further evaluate the lateral and vertical extent of gasoline <br /> contamination at and near the site The work described includes additional CPT borings, discrete depth <br /> sampling, and monitor well installation <br /> P 12038 Canepa ParklQuarteriy Monitonng Reports12002 OctoberlStte Background 10-2002 doe <br />