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L <br /> I co <br /> E <br /> I AT <br /> A S S O C I A T E S I N C <br /> L. 2.1 Drilline Activities <br /> " On June 30, 1998, ATC personnel supervised advancement of five soil borings, SBI through <br /> G <br /> SB5, at the site to depths ranging from approximately 6 to 36 feet bgs at the project site to <br /> investigate the horizontal and vertical extent of petroleum hydrocarbon impacted soil and <br /> determine and define soil stratigraphy. The boring locations are shown on Figure 2. <br /> . 2_2 Soil Samplina and Analysis <br /> Drilling was conducted by Mitchell Drilling (State C57 license no. 672617) utilizing a hollow stem <br /> . auger drill rig. A field geologist continuously logged all drill cuttings and cored soil samples <br /> utilizing the Unified Soil Classification System. Descriptions of soil types encountered and sample <br /> collection intervals are included on the boring logs (Appendix A). Cored soil samples were <br /> collected at five foot intervals beginning at 14.5 feet bgs using a 2-inch diameter split-spoon <br /> sampler containing three brass tubes. Grab samples were collected from drill cuttings from the <br /> surface to 14.5 feet bgs. The cored samples and drill cuttings were characterized for soil type, <br /> fi moisture content, and visual evidence of petroleum contamination. A photoionization detection <br /> meter (PID) was used as a field screening device for the detection of petroleum hydrocarbon <br /> vapors in drill cuttings and cored samples. Drill cuttings were stored on site in 55-gallon DOT <br /> approved steel drums pending disposal. <br /> Selected soil samples were analyzed by Sequoia Analytical (ELAP #1210) of Walnut Creek, <br /> California for total petroleum hydrocarbons as gasoline, (TPHg) by EPA method 8015 modified, <br /> L- benzene, toluene, ethylbenzene, and xylenes (BTEX) and methyl tertiary butyl ether (MTBE) by <br /> EPA method 8020. Two soil samples were also analyzed for oxygenate fuel additives by EPA <br /> method 8260 and one soil sample was analyzed for total petroleum hydrocarbons as diesel <br /> (TPHd)by EPA method 8015 modified. <br /> 3.0 SUBSURFACE CONDITIONS <br /> The soil in borings SBI through SB5 consisted of a mixture of sandy silt, poorly graded sand, and <br /> poorly graded sand with silt from the surface to 16 to 19.5 feet bgs. Soil from borings SB 1, SB2, <br /> and SB3 consisted of silt from depths between 16 to 19.5 feet bgs and 36 feet bgs, the maximum <br /> depth explored, although sand with silt was encountered in boring SB3 at a depth between 20.5 to <br /> 24.5 feet bgs and 26 feet bgs. Soil boring logs with a detailed description of soil types are <br /> contained in Appendix A. <br /> i. 4.0 ANALYTICAL RESULTS <br /> Soil samples collected from borings S132, SB4, and SB5 contained no detectable concentrations <br /> of petroleum hydrocarbons. The soil sample collected from boring SB 1 at a depth of thirty-five <br /> feet bgs contained total xylenes at 0.0095 parts per million (ppm). The soil sample collected from <br /> SB3 at a depth of 15 bgs contained low levels of BTEX and TPHg. The soil sample collected <br /> wA149841reports�sumAm 2 <br />