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' EEC#ti 1462 2 Unifirst StQL M11 December 17 2001 now present at the site, several private homes were located on the northern half of the property These homes were removed in 2001 Physiography ' The subject site is located in Township 1 North, Range 6 East in the City of Stockton, County of San Joaquin, California (Figure 1) The most recent topographic map coverage of the site vicinity is provided by the USGS 7 5 minute Stockton West quadrangle, dated 1968, with photo revisions ' in 1987 The site elevation is approximately 15 feet above mean sea level (MSL) Geologic and Hydrogeologic Setting ' This Site is located in the northern part of the San Joaquin Valley at an elevation of approximately 15 feet above mean sea level The valley fill consist of late Mesozoic through Ecocene ' sedimentary deposits, predominately of marine origin These deposits are overlain by Tertiary sedimentary deposits which are composed primarily of sand, silt, gravel, and clay (CDMG, 1976) In the vicinity of the site, the late Cenozoic deposits are approximately 3,000 feet thick and ' generally consist of alluvial gravel, sand, silt, and clay Groundwater in these alluvial deposits is usually confined to semi-confined Dunng a previous Phase I Environmental Site Assessment (EEC, 1998), near surface groundwater condition in the site vicinity were reviewed for several sites within a 1/2 mile radius of the site The information was obtained from the California Regional Water Quality Control Board— Central Valley Region, leaking underground storage tank database The nearest of these ' sites is located approximately 0 11 miles southeast of the site Groundwater fluctuates between 29 and 45 feet below grade at this location and flows to the northwest and northeast Although this uppermost groundwater aquifer is considered to be a beneficial use aquifer, EEC did not find any indications that drinking water supplies are produced frorn the uppermost aquifer in the site vicinity ' Groundwater for municipal service is supplied by the California Water Service Company (CWSC) The CWSC operates 58 groundwater production wells in the Stockton area These wells are installed at depths between 250 and 603 feet bgs The nearest active well to the site ' vicinity are CWSC well number 53-01, and 26-01 Water quality data obtained from the State of California Department of Health Services (CDHS) shows no evidence that either of these wells has been impacted by petroleum hydrocarbons or the chlorinated compounds tetrachloroethene (PCE), trichloroethene (TCE), or dichloroethene (DCE) Four wells, located within one to two ' miles of the site and in the assumed upgradient direction of groundwater flow, contain detectable concentrations of PCE Several hydrocarbon constituents typically associated with solvents or petroleum product have also been detected in wells within one to two miles of the site ' Proposed Assessment and Remediation Strategy—Surface Oil Release ' EEC is proposing to conduct the following scope of work, on a fast-track basis • Prepare and implement a site specific Health and Safety Plan ' • Obtain approval of this workplan by the San Joaquin County Environmental Health Department (SJCEHD) 10 • Excavate petroleum-impacted soil and soil with obvious hydrocarbon odor to minimize potential health and safety concerns associated with construction occurring in the area i