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3.0 SITE DESCRIPTION <br />3.1 PHYSICAL SETTING <br />The site is located at the Port of Stockton on West Washington Street, one mile west of <br />Interstate 5 in Stockton, California. The site is situated in Township 1 North and Range 6 East and <br />topographic map coverage is provided by the Stockton West Quadrangle, 7.5-Minute Series. The San <br />Joaquin River is approximately '4-mile to the west. The site is flat at an elevation of 5 feet above mean <br />sea level. The site location and topographic coverage of the vicinity are shown on Plate 3. <br />3.2 GEOLOGIC AND HYDROGEOLOGIC SETTING <br />The site is located at the Port of Stockton near the intersection of the Stockton Deep Water <br />Channel and the San Joaquin River. The area lies within the flood plain of the San Joaquin River. <br />California Division of Mines and Geology geologic maps indicate that typical sediments include relatively <br />permeable Quaternary aged stream channel, alluvial fan, and river basin deposits. Groundwater flow in <br />the area is strongly influenced by tidal action and can vary significantly. No site specific hydrogeologic <br />assessment was undertaken as part of this environmental assessment. <br />Several geotechnical investigations have been carried out on the subject property and <br />immediate surrounding areas. These investigations included the drilling of soil borings. Two borings <br />reaching depths of 80 and 90 feet were drilled on each side of the rotary railcar dumper on site. These <br />borings indicate that the surface soils on site consist of loose sandy material extending to approximately <br />five feet below ground surface (bgs). The surface material is underlain by approximately 30 feet of <br />medium stiff to stiff silty clay/clayey silt. Underlying the silty clay/clayey silt are alternating layers of <br />silty sand and clayey silt extending to 90 feet bgs. One of these borings was used for the installation of <br />a piezometer; groundwater was measured at 6 feet bgs (Dames & Moore, June 1982). <br />Based on the California Department of Water Resources Division of Planning, the average <br />annual precipitation for Stockton is about 14.5 inches. The majority of the rain falls between the months <br />of December and March. Some infiltration of these waters likely occurs in unpaved areas. <br />PSA04.007 4