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en virus. <br /> Ground water samples contained TPH-G concentrations ranging from 23,000 parts per <br /> billion (ppb) to 150,000 ppb, TPH-D concentrations ranging from 1600 to 12,000 ppb, <br /> and benzene concentrations ranging from 970 ppb to 13,000 ppb <br /> 2.0 FIELD PROCEDURES <br /> 2.1 Exploratory Soil Borings <br /> Five exploratory soil borings (SB-1 through SB-5) were drilled and sampled on April 4, <br /> 1997 The borings were drilled using GeoProbe drilling equipment The locations and <br /> designations of each boring are shown on Plate 2 An Enviros geologist supervised the <br /> drilling and described encountered soils using the Unified Soil Classification System and <br /> Munsell Color chart Encountered lithology is described on the exploratory boring logs <br /> presented in Appendix A <br /> Soil samples were collected for lithologic description and chemical analysis from the <br /> borings at five-foot intervals Soil sample tubes selected for laboratory analysis were <br /> covered with Teflon tape, capped, labeled, entered onto a chain-of-custody record, and <br /> stored in a cooler with ice The samples were transported to Sequoia Analytical (Sequoia), <br /> a state-certified environmental laboratory located in Redwood City, California, for analysis <br /> The soil samples were analyzed for Total Purgeable Petroleum Hydrocarbons (TPPH) and <br /> Total Extractable Petroleum Hydrocarbons (TEPH) according to EPA Method 8015 <br /> (Modified), and benzene, toluene, ethylbenzene, xylenes (BTEX), and methyl-tertiary- <br /> butyl-ether(MTBE) according to EPA Method 8020 Samples collected from the vicinity <br /> of the former waste oil tank were also analyzed for Oil and Grease according to SM 5520 <br /> E&F, ICAP Metals according to EPA Method 6010, Volatile Organics (VOCs) according to <br /> EPA Method 8010, and Semi-Volatile Organics (SVOCs) according to EPA Method 8270 <br /> Two soil samples were analyzed for physical parameters including soil permeability, dry <br /> bulk density, porosity, water content, and fractional organic carbon content <br /> Decontamination Procedures <br /> Drilling and sampling equipment were decontaminated prior to beginning work and <br /> between activities performed at each boring Drilling equipment was inspected prior to <br /> drilling each bonng <br /> 2.2 Ground Water Sampling <br /> Ground water samples were collected from Borings SB-1 through SB-5, transferred to <br /> appropriate containers, labeled, logged onto a chain-of-custody record, and placed into a <br /> cooler with ice The ground water samples were transported to Sequoia for analysis for <br /> TPPH, TEPH, BTEX, and MTBE A confirmation analysis for MTBE, by EPA Method <br /> 8260, was performed on the sample for which the highest concentration of MTBE was <br /> detected by the EPA Method 8020 analysis Samples collected from Boring SB-2, located <br /> 407 2 <br />