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' FIRST QUARTER 2004 GEQM.ATRIX <br /> GROUNDWATER MONITORING REPORT <br /> UST Site No 3 — Port of Stockton <br /> Stockton, California <br />' 1.0 INTRODUCTION <br /> This report summarizes the first quarter 2004 groundwater monitoring event at Port of <br /> Stockton's (Port) former underground storage tank (UST) Site No 3 Monitoring was performed <br /> on February 26, 2004, by WGR Southwest, Inc (WGR), in accordance with directives from the <br />' local enforcement agency, San Joaquin County Environmental Health Department (EHD) <br /> UST Site No 3 is located near the central portion of the Port in the City of Stockton, San Joaquin <br /> County, California, approximately 50 feet north of Port Road G and about 300 feet west of Port <br />' Road 14 (Figures 1 and 2) The site is catalogued by EHD as Site Code 1282-124 <br /> The site formerly contained two 12,000-gallon tanks, both of which stored unleaded gasoline <br /> (Figure 2) The tanks were removed 1n 1988, along with approximately 180 cubic yards of soil <br /> excavated to a depth of about 11 feet below ground surface (bgs) Detailed descriptions of the <br /> site, the site investigation history, and the site hydrogeologic setting are available in the Results <br /> of Additional Assessment and Remediation Evaluation of Petroleum Hydrocarbons in <br />' Groundwater (Geomatnx, 2003a) <br /> The site is located on the delta of the San Joaquin River, approximately 2 miles east of the <br /> confluence of the San Joaquin and Calaveras rivers The subsurface geology consists of a thick <br /> sequence of alluvial deposits of late Tertiary to Holocene age overlying sedimentary rocks of <br /> Cretaceous to Tertiary age, which in turn overlie crystalline basement rocks (Bartow and Nilsen, <br /> 1990) Site-specific data collected to a maximum depth of 49 feet bgs indicate a soil profile <br />' consisting of interbedded sand and clay layers Since 1999, depth to groundwater beneath the <br /> site has ranged from 9 to 16 feet bgs Groundwater beneath the site is confined to semiconfined <br /> r2.0 FIELD PROCEDURES <br /> A total of six groundwater monitoring wells are used to monitor groundwater quality below the <br /> site Groundwater samples were collected by WGR from five groundwater monitoring wells <br /> (MW3-1, MW3-2, MW3-4, MW3-5, and MW3-6) As during the fourth quarter 2003, well <br /> MW3-3 could not be sampled because it was covered with about 2 5 feet of soil forming a <br />' I TROJEC N60OW6437 000\6437 19 doc 1 <br />