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i Four exploratory borings (B-1, B-2, B-3 and B4) were drilled and sampled in April 2003 around the former underground tank pit at the Wastewater Plant. The soil samples collected showed that contaminants were not detected. Groundwater samples showed very low levels of dissolved TPHD, with one relatively elevated level of 33,000 micrograms per liter(ug/1) TPHD in B-2 in a downgradient location. BTEX, MTBE and related oxygenates were not revealed in any groundwater sample. On the basis of this data collected for this study, limited leakage from the former underground tank had occurred, and is attributed to overspill. The dissolved plume has migrated a short distance downgradient of the former tank pit to the north-northwest. Scope of Work 2.0 2000-foot Radius Well Survey and Sensitive Receptor Survey Wright will perform a 2000-foot radius search for wells around the Wastewater soil borings site. The search will use the available information from the Department of Water Resources files and City of Tracy and County files to document municipal, domestic, agricultural, industrial and other wells. The information will be compiled into a summary table together with a map showing the well locations. Additional information will include a brief review of potential sensitive receptors in the area. 3.0 Field Methods—Drilling and Sampling Exploratory Borings Exploratory borings will be drilled at the locations shown on Figure 1. Drilling permits will be secured from SJC/EHD, and the above referenced underground utility clearance will be performed prior to doing the fieldwork. The soil borings will be advanced to a depth of about 20 to 25 feet but not below the aquitard. Soil borings will be drilled at the following locations: • One boring to resample at the B-2 location. • One boring approximately 20 feet northwest of the B-2 location. • One boring north of the B-1 location. • One boring south of the B-3 location. • One boring east of the B-4 location. The boreholes will be drilled with truck mounted :GeoProbe direct-push drilling equipment. All drilling equipment and sampling tools will be cleaned prior to arriving, between each sampling borehole and before leaving the site. The probe will collect continuous cores of soil in each borehole. The sampler will then be retrieved and dissembled and soil sample intervals retained for chemical analysis will be cut from the liners at the desired depths. Each soil sample will be Page 2 of 4 I