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The project site is located on the south side of the City of Tracy, located near the <br /> northwestern edge of the San Joaquin Valley (see Figure 1). Holocene alluvial fan and <br /> fluvial deposits eroded and dissected by streams draining from the nearby Coast Range <br /> Hills to the northwest underlie the area. Surficial native soils in the region are mapped <br /> as Capay-Stomar-Zacharias, moderately well drained and moderately fine textured with <br /> gravel forming on alluvial fans, interfan basins and stream terraces. Capey soils are <br /> mapped as moderately slow permeability. Historic urban development and railroad use <br /> hits greatly altered or removed the shallow (surface to several feet deep) native soils in <br /> the project site vicinity. The underlying alluvial sediment may generally consist of <br /> weakly consolidated and irregularly interbedded sand, silt and clay deposits. These <br /> subsurface strata may show variable lateral and vertical continuity and extent (Page, <br /> 1986; Bertoldi, et al., 1991). <br /> Shallow groundwater in the Tracy area may occur about 10 to 20 feet below the surface. <br /> Very large groundwater aquifers underlie the Tracy region at depth and these aquifers <br /> produce very large quantities of agricultural and municipal drinking water. Regional <br /> groundwater flow in the large aquifer is estimated as northerly. The largest nearby <br /> surface water body, Paine Slough occurs about three miles northeast of the site. <br /> The Wright GeoProbe borings were advanced on February 5, 2003 to a maximum depth <br /> of 26.5 feet into native soil. Sandy silt underlies the asphalt road surface and underlying <br /> road gravel and thin fill soil to depths of about 12 to 15 feet. Interbedded sand, clayey <br /> sand, and sandy silt occur from depths of about 15 feet to 25 feet and these show vertical <br /> and lateral variability under the site (see Figures 2, 3 and 4 and Exploratory Boring <br /> Logs). The aquifer strata are composed of sand and silty sand that may contain sandy <br /> clay interbeds. Groundwater was encountered in the shallow aquifer at depths of about <br /> 12 to 14 feet below grade in each boring, and appeared to be unconfined. Three <br /> groundwater wells were installed on December 11, 2008. Some contaminant staining and <br /> soil vapor odor was present at MW-2 (near Boring B-3) near the capillary fringe and/or <br /> approximate occurrence of groundwater. A summary of the soil, reconnaissance <br /> groundwater and monitoring well information are presented in Tables 2, 3, 4, 5, 6 and 7 <br /> below. <br /> 2.3 Sensitive Receptors,Water Well Search and Surface Water <br /> The City of Tracy supplies drinking water to residents and commercial properties in the <br /> site vicinity. Wright did not locate any drinking water wells in the 2000-foot search, and <br /> the shallow aquifer is not known for use as drinking water, or for agricultural, municipal, <br /> recreation or any other use. The sensitive receptors in the area include rental residences <br /> and light commercial concerns. The nearest large surface water body is Paine Slough <br /> about three miles northeast of the site. <br /> 2.4 2000-Foot Well Search <br /> A 2000-foot radius well search was performed in 2003. Wright performed a 2000-foot <br /> PnaP 4 of 17 <br />