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s influence on the local groundwater flow direction in the vicinity of WESMW-1, is not known_ One soil sample collected from the upper portion. (B-1 @ 13.5-15 feet) of the shallow aquifer was tested for permeability by Wright in 2003 and revealed a. relatively low hydraulic conductivity (1.56 x 10-- cm/sec)and bulk density of 117.9 lb/ftl. 2.2.1 Subsurface Conditions Sandy clay underlies the surface road gravel and fill soil to depths of about 10 feet. .interbedded sand, clayey sand, and sandy silt occur from depths of about 10 feet to 25 feet, showing vertical and lateral variability under the project site (see Figures 2 and 3, Exploratory Boring Logs and Well Detail). Areas of the WWTP have been altered by construction and excavation for nearby impoundments. Groundwater was encountered in the shallow aquifer at a depth of about 13 feet below grade and appeared to be unconfined at the time of drilling. Groundwater measurements were collected on October 2.2, 2009 from well MWWTS-1 and the existing CH2M Hill wells. The 2009 groundwater contour plot indicates a. northwest groundwater flow direction at a gradient of about 0.0007 in the vicinity of the new well. A, small gfo'undwater mound rn.ight be present in the vicinity of VIWWES-1 (located near two impoundments). The amount of seepage from the impoundments and its possible effect: on local groundwater levels are not known. A summary of the soil, reconnaissance and groundwater monitoring well chemical information are presented in Tables 2 through 8 below. 2 3-SenAtive Receptors.1 aftr well Ne—gr—eh and Surface Water The City of Tracy supplies drinking water to residents, schools and commercial properties in the site vicinity. Wright, did not locate any drinking water wells within a 2000-foot radius of the site, and the shallow aquifer is not known for use as drinking water or for agricultural; municipal., recreation or other use (see Figure 1 and Table 1). Wells were located just outside the radius as shown on Figure 1. The sensitive receptors in the region (outside of the WWTP boundaries) include residences, agricultural irrigation and light commercial concerns. With the exception of nearby City of Tracy industrial waste ponds, the nearest large surface bodies of water are the Sugar Cut just north of the WWTP and the Paine Slough, located about one mile north northeast of the site. 2.4 2000-E"t Mjil arch-Results j Wright performed a 2000-foot radius search,far welts around the WWTP study area. The search used the available information from the Department of Water Resources files and. i City of Tracy files to document imtnicipal:, domestic, agricultural, industrial wells in the j search radius. The infortnatian is presented in the summary table together with a map showing the well locations (see Figure 1 and Table 1). The: well locations are approximate and based upon the information on the individual well logs; in some cases the State Well Completion Reports well location,as well as logging and well construction information, may not be precise or may be incomplete. Groundwater monitoring wells � I 4889/CSR/Rep( Page 5 of t.7 t