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FOURTH QUARTER 2004 <br /> D GROUNDWATER MONITORING REPORT <br /> UST Site No 3 — Port of Stockton <br /> Stockton, California <br /> D1.0 INTRODUCTION <br /> n This report summarizes the fourth quarter 2004 groundwater monitoring event at Port of <br /> Stockton's (Port) former underground storage tank (UST) Site No 3 Monitoring was performed <br /> U on December 17, 2004, by WGR Southwest, Inc (WGR), in accordance with directives from the <br /> alocal enforcement agency, the 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 I and 2) The site is catalogued by EHD as Site Code 1282-124 <br /> The site formerly contained two 12,000-gallon USTs, both of which stored unleaded gasoline <br /> (Figure 2) The tanks were removed in 1988, along with approximately 180 cubic yards of soil <br /> excavated to a depth of about I 1 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, 2003) <br /> a <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 />�J 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 Site-specific data <br /> collected to a maximum depth of 49 feet bgs indicate a soil profile consisting of interbedded sand <br /> and clay layers Since 1999, depth to groundwater beneath the site has ranged from 9 to 16 feet <br />] bgs Groundwater beneath the site is confined to semiconfined <br /> 20 FIELD PROCEDURES <br /> Starting with third quarter 2004, the method used to purge the groundwater monitoring wells <br /> before sampling was changed from vacuum evacuation to a dedicated submersible pump <br />