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• • a0aytori <br /> i <br /> Investigative methods employed in this study are described below. <br /> ` 2.3 SOIL BORINGS <br /> Clayton contracted with Environmental Control Associates, Inc. (ECA) located in Aptos, <br /> California to complete the subsurface investigation. ECA is a California licensed(C-57) <br /> drilling company. ECA utilized a truck-mounted direct push(Geoprobe) equipment to <br /> advance the boreholes. The soil borings were advanced to depths up to 16 feet below <br /> ground surface(bgs). During the drilling activities, soil cores were collected from each <br /> borehole for soil logging purposes. Soil cores were obtained using a 4-foot-long by <br /> 2-inch-diameter core barrel sampler. The core barrel contains a plastic liner that retains a <br /> relatively undisturbed soil core from which soil samples are collected. <br /> Each soil borehole was logged for lithological content using the Unified Soil <br /> Classification System(USCS) as a guide, and for relative moisture content, competency, <br /> and other observable characteristics (e.g., color changes, debris, rootlets, odor, etc.). <br /> Several soil samples were selected from each borehole and placed into a sealed plastic <br /> bag for field screening using an Organic Vapor Analyzer (OVA) to determine the <br /> presence of volatile organic compound(VOC)vapors. Field observations were entered <br /> on the boring logs. Soil boring logs are included as Appendix A. <br /> Clayton collected soil samples from each boring every four feet. Exact soil sampling <br /> depths were determined based on field observations and encountered depth to <br /> groundwater. The retrieved sample sleeves were sealed with Teflon tape and plastic end <br /> caps, labeled with identifying information, and stored in a pre-chilled ice-chest awaiting <br /> ' transportation to the laboratory. Selected soil samples were subsequently recorded onto a <br /> chain-of-custody document. At some depths of SB-7, soil samples were not recoverable <br /> due to the presence of unconsolidated pea gravel. <br /> 2.4 CHEMICAL ANALYTICAL METHODS <br /> All soil samples were submitted to McCampbell Analytical, Inc. located in Pacheco, <br /> California for analysis by approved United States Environmental Protection Agency <br /> (USEPA) methods. Selected soil samples were analyzed for the following analytical <br /> parameters: <br /> • Volatile Organic Compounds (VOCs), including benzene, toluene, ethylbenzene, and <br /> xylenes (BTEX),by Method 8260B. <br /> • Total Petroleum Hydrocarbons(TPH) quantified as gasoline, diesel, and motor oil <br /> range hydrocarbons(TPH-g, TPH-d, and TPH-mo)by Method 8015M using silica gel <br /> cleanup (SGCU). <br /> • Semi Volatile Organic Compounds (SVOCs)by Method 8270—soil samples <br /> !. collected from SB-2 and SB-5 only. <br /> 1 <br /> PLAES\PRWECT11100SUI%N RE Slit Company\Phac 11 ESA&c 3 <br />