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ATi: <br /> r i A S S O C I A T E S ! N C <br /> 3.0 SUBSURFACE CONDITIONS <br /> F <br /> 331 Geology <br /> Soil in borings SB 1 and SB2 consisted primarily of silty sand (SM) to a depth of approximately <br /> 5 to 6 feet bgs. Under lying the silty sand, soil properties exhibited an increasing amount of fine <br /> ` particles consisting of silt (ML) and clay (CL) to a depth of approximately 24 feet to 29 feet bgs. <br /> These fine soils were underlain by well graded sand with silt (SW-SM) to a depth of <br /> approximately 31 feet bgs, the maximum depth explor d during this investigation. <br /> 3.2 Hydrogcology <br /> Groundwater was not encountered during field activities performed for this investigation. Based <br /> on the San Joaquin County Flood Control and Water Conservation District Spring 1997 <br /> k Groundwater Report, groundwater is approximately 30 feet bgs at the site and flows in an <br /> easterly direction. <br /> 4.0 ANALYTICAL RESULTS <br /> �} 4.1 Soil Analytical Results <br /> The laboratory reported that none of the soil samples collected in the vicinity of the former diesel <br /> UST contained aromatic petroleum hydrocarbon constituents (BTEX) above laboratory detection <br /> limits. <br /> FSoil samples collected from borings SB 1 and SB2 did contain detectable concentrations of <br /> TPHd. SB 1 and SB2 contained concentrations of TPIld ranging from <1.0 to 7.9 ppm, however <br /> Fthe chromatogram pattern indicated the presence of an unidentified hydrocarbon (C9-C24) and/or <br /> discrete peaks (@C24). These TPHd concentrations appear to attenuate relative to depth. <br /> According to Mr. Kayvon Kimyai, Project Manager of Sequoia Analytical, these chromatograms <br /> do not match that of a fresh diesel standard and the discrete peaks observed may or may not be <br /> F naturally occurring organic in the soil. Mr. Kimyai stated that additional analyses would be <br /> required to perform further quantification. <br /> Analytical results of soil samples are summarized in able 1. Laboratory data sheets, chain-of- <br /> F custody documentation, and copies of chromatogram atterns are included in Appendix B. <br /> li <br /> w:1172921repomt sumwel.doc 3 <br /> F <br />