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TABLE 1 RELATIVE GROUNDWATER ELEVATIONS Western Lift 3430 S. EI Dorado Street, Stockton, CA Relative Depth to Groundwater Relative Groundwater Well No. CasingElevation Elevation 10-8-93 2-9-94 -9-94 5-31-94 -31-94 10- -8 93 2-9-94 5-31-94 ' MW-1 101.62 40.28 38.30 37.57 61.34 63.32 64.05 MW-2 101.62+ 40.24 38.33 37.50 61.35 63.29 64.12 rMW-3 101.17+ 39.55 37.54 36.89 62.52 63.63 64.28 MW-4 102.02 40.75 38.76 38.04 61.27 63.26 63.98 , t MW-5 101.54 40.11 38.19j 37.35 61.43 63.35 64.19 •AH measurements in feet + Re%ised 7,15/94 4.3 Groundwater Sample Results TPH as gasoline, diesel and. benzene were detected in monitoring well MW-1 at concentrations of 100 ppb, 58 ppb and 5.5 ppb respectively. Benzene was also detected in ' MW-4, at 0.82 ppb. Toluene was detected in MW-5 at a concentration of 0.62 ppb. No other petroleum hydrocarbons were detected in any of the samples collected. The analytical results ' of the groundwater samples are summarized in Table 2. The laboratory results and chain of custody are included in Appendix A. 4.4 Stratigraphy and Field Observations Clayey silts were logged in soil boring B-6 from the surface to 20 feet,with a silty sand layer at 10 feet. A pebbly lens was present at 20 feet. Silty clays were encountered from 21 feet to approximately 38 feet and from approximately 42 feet to the bottom of the boring (45 feet). Sandy silts were encountered from 38 feet to 42 feet. Soils were dry to slightly damp above the current water table. Slight hydrocarbon odors were noted in the samples from 40 ' and 45 feet: The boring logs are included in Appendix B. 4.5 Analytical Results of Soil Samples I Three samples, from depths of 35, 40 and 45 feet, were analyzed for TPH as gasoline and ' diesel and BTE&X. No petroleum hydrocarbons were detected in any of these samples.The W-yen liL QRO-WI,16