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'FAFC j,�e'P# NC. SACRAMENTO <br />' 3 . 0 SOIL-VAPOR EXTRACTION WELLS <br /> The interim remediation/pilot study involved the drilling of <br />' four boreholes and installation of soil-vapor extraction wells; <br /> the installation of a soil--vapor extraction and abatement system; <br /> and the collection of soil and soil-vapor samples for analysis. <br /> The following sections detail the methods and procedures utilized <br /> in the installation of the soil-vapor extraction wells. <br /> 3 . 1 Soil Sampling and Analysis <br /> During the period June 28 , 1991 to July 2 , 1991 Versar <br /> supervised the drilling of four boreholes at the site by Woodward <br />' Drilling Company of Rio Vista, California, and the installation <br /> of four soil-vapor extraction wells. The permits for the wells <br />' are included as Appendix A. All of the soil borings were <br /> advanced using a CME 55 drilling rig and the hollow-stem auger <br /> technique. Three of the borings (EW6, EW7 and EW8) were drilled <br /> using 10. 25--inch outside diameter (O. D. ) by 6 . 25-inch inner <br /> diameter (I. D. ) hollow--stem augers. The fourth boring (EW9) was <br /> drilled using 8--inch O. D. by 4 . 25-inch I. D. hollow-stem augers. <br /> Figure 4 presents the locations of the soil borings. <br />' California-modified split-spoon samplers were used to <br /> collect soil samples for lithological description, field <br />' screening and on-site chemical analysis. Soil samples collected <br /> for chemical analysis were collected within brass liners inserted <br />' into a two-inch I. D. and 1 . 5-foot long split--spoon sampler. The <br /> sampler was driven approximately 18 inches into the subsurface <br /> using a 140-pound, free-fall drive hammer with a 30-inch drop. <br /> tDrilling and sampling equipment were steam cleaned prior to use. <br /> Soil cuttings generated during drilling were stored on site in <br /> 55-gallon Department of Transportation-approved drums. The soil <br /> cuttings were subsequently disposed of at a Class II landfill . <br /> Soil samples were collected in all borings at a maximum <br /> interval of approximately 5 feet. The soil samples were examined <br /> 6 <br />