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SIERRA <br /> 2. SUBSURFACE INVESTIGATION <br /> On June 24, 1991,Soils Exploration Services of Vacaville, California drilled one soil boring <br /> at the site, SB-1, using a CME-55 hollow-stem auger drill rig (Figure 3,Appendix A). The boring <br /> was drilled to determine the presence or absence of selected chemicals in the soil and ground <br /> water. <br /> 2.1 Soil Boring and Soil Sampling <br /> Soil samples were collected from boring SB-1 in accordance with SES Standard Operating <br /> Procedure-Soil Sampling(Appendix Q. The boring was logged in accordance with SES Standard <br /> Operating Procedure - Logging Method (Appendix Q. Soil samples were screened for volatile <br /> hydrocarbons during drilling in accordance with SES Standard Operating Procedure - OVM <br /> Readings (Appendix Q. <br /> Soils encountered from the surface to approximately 25 feet below grade (total depth) <br /> generally consisted of clean, well graded and poorly graded sand with lenses of silty sand and <br /> sandy silt. Ground water was encountered at approximately 20 feet below grade during drilling. <br /> The soil classification chart used for logging, details of subsurface sediments encountered, OVM <br /> readings, and the water level in the boring are shown in Appendix D. <br /> Drill cuttings were temporarily stored on-site in 55-gallon U.S. Department of <br /> Transportation (DOT)-approved drums pending analytic results. Each drum was sealed and <br /> labeled. The drill cuttings were spread over the site after receipt of the analytic results. <br /> The steam-cleaning rinseate remains on-site in 55-gallon DOT-approved drums pending <br /> disposal at an appropriate waste receiving facility. The drums were sealed and labeled. <br /> 2.2 Ground Water Sampling <br /> A grab ground water sample was collected from boring SB-1 with a steam-cleaned teflon <br /> bailer. The water sample was decanted into the appropriate containers for the analyses to be <br /> Page 5 <br />