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1 <br /> GEOMATRIX <br /> FOURTH QUARTER 2003 <br />' GROUNDWATER MONITORING REPORT <br /> UST Site No 3 — Port of Stockton <br /> Stockton, California <br /> 1.0 INTRODUCTION <br /> This report summarizes the fourth quarter 2003 groundwater monitoring event at Port of <br /> Stockton's (Port) former underground storage tank (UST) Site No 3 Monitoring was performed <br /> on October 16, 2003, 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 in 1988, along with approximately 180 cubic yards of soil <br /> 10 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 <br />' Nilsen, 1990) Site-specific data collected to a maximum depth of 49 feet indicate a soil profile <br /> consisting of interbedded sand and clay layers Site data indicate that depth to groundwater has <br />' ranged from 9 to 16 feet bgs since 1999 Groundwater is confined to semiconfined below the <br /> site <br />' 2.0 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 /> I (MW3-1, MW3-2, MW3-4, MW3-5, and MW3-6) Well MW3-3 could not be sampled because <br /> I TR07$CT160OW6437 000/6437 15 doc 1 <br />