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i <br /> In July, 1995, groundwater (the first water-bearing zone) was encountered at a depth of <br /> approximately 48 feet bgs The hydraulic gradient was measured to be 0 0013 feet per foot <br /> to the east-southeast on August lb, 1995 (Thnfty, 1995) <br /> 4.0 FIELD ASSESSMENT <br /> 4.1 Soil Borings <br /> On May 28 through 30, 1996, six soil borings were advanced onsite by Western Strata <br /> Exploration of West Sacramento, California Two soil bonngs (MW-ll/VW-3 and <br /> MW-10/VW-1) were converted into dual-completion groundwater monitonng/vadose zone <br /> monitoring wells One soil boring (VW-2) was converted into a dual-completion vadose <br /> zone monitoring well and three soil borings (VW-4, VW-5 and VW-6) were converted into <br /> triple-completion vadose zone monitoring wells The location of these wells are shown in <br /> Figure 2 <br /> 4.2 Soil Sampling <br /> Soil samples were collected at 5-foot intervals from the borings in accordance with the <br /> protocol presented in Appendix A A sample log was maintained for each boring Sample <br /> lntholognes were described using the Uniform Soil Classification System (USCS). Soil boring <br /> logs are included in Appendix B. All onsite work was supervised by a California State <br /> Registered Geologist. <br /> Soil cuttings and decontamination water generated by the drilling and sampling operations <br /> were placed in labeled and sealed 55-gallon steel drums and stored on-site prior to disposal <br /> 4.3 Soil Sample Analysis <br /> Selected soil samples were transported under strict cham-of-custody procedures to American <br /> Analytics located in Chatsworth, California. American Analytics is a Thrifty contracted, <br /> California Department of Health Services (CADHS) approved analytical laboratory. Soil <br /> samples collected from each boring were analyzed for TPH (gasoline), methyl tertiary butyl <br /> ether (MTBE) and benzene, toluene, ethylbenzene and xylenes (BTEX) according to EPA <br /> method 8015 modified, EPA method 8020 and GC/PID, respectively A summary of soil <br /> laboratory analytical results collected during previous assessments are presented in Table 1 <br /> and analytical results collected during this assessment are presented in Table 2 Copies of <br /> the soil laboratory data sheets and chain-of-custody forms collected during this assessment <br /> are included in Appendix C <br /> 4 <br />