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, � v 4.1 Subsurface Conditions Borings were advanced to a maximum depth of 26.5 feet into native soil. Sandy silt underlies the asphalt road surface and underlying road gravel and thin fill soil to depths of about 12 to 15 feet. Interbedded sand, clayey sand, and sandy silt occur from depths of about 15 feet to 25 feet and these show vertical and lateral variability under the site (see Figures 2, 3 and 4 and Exploratory Boring Logs). The aquifer strata are composed of sand and silty sand that may contain sandy clay interbeds. Groundwater was encountered in the shallow aquifer at depths of about 12 to 14 feet below grade in each boring, and appeared to be unconfined. Some contaminant staining and soil vapor was present at MW-2 near the capillary fringe and/or approximate occurrence of groundwater. A summary of the groundwater monitoring well information is presented in the table below. Table 2. Groundwater Data in Monitoring Wells, December 19,2008 Well Number Depth to Top of Casing Groundwater Comments Groundwater(ft) Elevation(ft) Elevation(ft) MW-1 15.56 60.46 44.90 None N1W-2 16.36 61.07 44.71 None MW-3 16.64 61.15 44.51 None City of Tracy surveyed Top of Casing elevations in feet,NGVD. On the basis of the dissolved contaminant distribution from the 2003 study, the groundwater flow direction was inferred to be northerly. The initial groundwater monitoring wells elevation contour plot shows a northwesterly flow direction at a calculated gradient of 0.008. 5.0 Results and Discussion Soil sample MW-1 at 16.5 feet (upgradient of the former UST locations) showed 8.5 milligrams per kilogram (Mg/kg) TPHD. The soil chemical analysis from MW-2 at 16.5 feet showed that TPHD was detected at 4300 Mg/kg and TPHG at 220 Mg/kg. Very low levels of volatile organic compounds interpreted as related to fuels were also present in the MW-2 at 16.5' sample. The remaining soil samples did not reveal TPHG, TPHD, BTEX or MTBE or related oxygenates contaminants (see Figures 3,4 and 5 and Table 3). Groundwater samples showed 1300 Ug/l TPHD in MW-2. TPHG, BTEX or MTBE or related oxygenates were not detected in any sample (see Table 4). Dichlorodifluoromethane and Chloroform were detected at very low concentrations in all wells. Samples collected in 2003 in the former underground storage tank pits showed dissolved concentrations collected in temporarily cased boreholes of 34,000 Ug/l TPHG and 750,000 Ug/1 TPHD in B-3 (MW-2 is positioned within several feet of B-3 and down gradient of one of the former UST locations).