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TreadweWRdlo <br /> • 4.2 Environmental Impacts at Operable Unit 2 <br /> 4.2.1 Area 15 <br /> Previous studies indicate that soil and groundwater at this site has been impacted by petroleum <br /> fuel hydrocarbons caused by UST releases. The site is currently under the jurisdiction of the <br /> CVRWQCB and local oversight agency,the SJCEHD. This investigation confirmed the <br /> presence of significant quantities of petroleum hydrocarbons in the north central portion of the <br /> site that do not appear to be associated with a previously identified UST. No other significant <br /> additional soil or groundwater contamination was found at Area 15 during this study. <br /> Concentrations of TPH quantified as gasoline as high as 13,000 mg/kg were detected in soil from <br /> Borings 15B-4, 1513-6, and 15B-9. The chromatograph pattern of the petroleum hydrocarbon <br /> does not match gasoline and appears to be closer to mineral spirits. Long-term monitoring of <br /> groundwater by others has documented the presence of petroleum hydrocarbons and chlorinated <br /> • solvents in groundwater as summarized in Section 1.2.2.1. <br /> 4.2.2 Area 16 <br /> Area 16 has been the subject of an extensive soil and groundwater remediation program under <br /> the jurisdiction of the CVRWQCB and local oversight agency, the SJCEHD. A soil vapor <br /> extraction system reportedly began operation at the site during November 1999,with the goal of <br /> mitigating the known soil and groundwater contamination caused by a former UST release. <br /> AGE who is operating the system has not issued a report analyzing the effectiveness of the <br /> system. No significant additional soil or groundwater contamination has been found at this site <br /> during either Treadwell &Rollo study. Long-term monitoring of groundwater by others has <br /> documented the presence of petroleum hydrocarbons in groundwater as summarized in <br /> Section 1.2.2.2. <br /> 29 <br /> 25970309.DGD 24 August 2000 <br />