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EXECUTIVE SUMMARY <br /> This Environmental Conditions Report summarizes the results of <br /> recent field activities performed at Catellus' properties located at the <br /> western terminus of West Weber Avenue in Stockton, California <br /> 1 These activities, which consisted of soil and ground water sampling, <br /> were performed to evaluate the extent of hydrocarbon occurrence in <br /> soil and ground water in the vicinity of two former underground fuel <br /> ' storage tank locations at 1515 West Weber Avenue (Tank Site #1) and <br /> 1325 West Weber Avenue (Tank Site #2) <br /> ' During previous investigations, the extent of hydrocarbon occurrence <br /> in site soils was delineated, and impacts to ground water were <br /> evaluated based on monitoring results These previous investigations <br /> indicated the need for remedial activities, which were conducted in <br /> 1993 and 1994 The remedial alternative selected for site soils consisted <br /> of excavation and ex-situ aeration The selected ground water remedial <br /> ' alternative consisted of extraction, which was performed during three <br /> separate events in December 1993/January 1994, May 1994, and <br /> September 1994 <br /> Subsequently, the San Joaquin County Public Health Services <br /> -, Environmental Health Division (PHS/EHD) expressed a concern that <br /> hydrocarbon-affected soils did not appear to have been removed in <br /> entirety during the excavation event To address this stated concern, <br /> ERM performed additional characterization of the excavation areas and <br /> r a ' immediately-adjacent areas beneath the warehouses on each site This <br /> report presents the results of this additional characterization and the <br /> ` ground water monitoring results generated during the most recent <br /> r monitoring period from January 1994 to February 1995 <br /> The soil data generated during the post-excavation sampling event <br /> ' indicate that hydrocarbon products are not present at detectable <br /> concentrations beneath the warehouse at Tank Site #1, however, a <br /> thin (less than 2 feet thick), localized layer of hydrocarbon-affected soil <br /> ' appears to be present beneath the base of the excavation backfill These <br /> sampling results confirmed that the majority of the hydrocarbon- <br /> affected soils were remediated during the 1993 excavation The extent <br /> of detectable TPH/BTEX concentrations in ground water appears <br /> limited to the immediate area of the former tank, and detected <br /> concentrations have decreased significantly since ground water <br /> monitoring events were initiated in April 1991. Therefore, the <br /> presence of residual hydrocarbon-soil does not appear to be <br /> significantly impacting ground water quality <br /> ' � vii <br />