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3.2.3 Chemical Analyses <br /> Soil samples were analyzed for Total Petroleum Hydrocarbons (TPH) as gasoline, <br /> for benzene, toluene, ethylbenzene and xylenes and TPH as diesel by EPA Methods 5030, <br /> 8020 and the DHS extraction method respectively. Laboratory results are enclosed as <br /> Appendix D. <br /> 3.2.4 Disposal <br /> Soil cuttings accumulated during the drilling process are stored in appropriately labeled drums <br /> on site. Because all soil samples revealed no detectable levels of petroleum hydrocarbons <br /> (Section 4.3), the drum contents will be combined with soil stockpiles generated during future <br /> construction activities, for a one time disposal effort. A suitable disposal facility will be <br /> selected contingent upon the concentration of petroleum hydrocarbons encountered. <br /> 4.0 Results <br /> 4.1 Site Geology _ <br /> Review of the boring logs (Appendix B) indicates that the shallow subsurface beneath the site <br /> consists mainly of coarse grained materials, sands and gravels, with varying concentrations of <br /> fines. The site is situated at approximately 20 feet above Mean Sea Level (USGS Stockton <br /> West, Califomia 7.5' topographic sheet). <br /> 4.2 Site Hydrogeology <br /> Groundwater was not encountered in the soil borings. San Joaquin County maps (Flood <br /> Control and Water Conservation District, Spring 1990 and Fall 1990) indicate that <br /> groundwater beneath the site rises to 50 feet (below ground surface) in the spring and falls to <br /> 78 feet in the fall. Groundwater flows from south-southeast to east, varying seasonally (same <br /> source). Both depth to groundwater and groundwater flow directions are strongly influenced <br /> by groundwater withdrawal in the region. <br /> 4.3 Soil Quality Data <br /> Analysis of soil samples collected on June 17, 1991, revealed no detectable levels of <br /> petroleum hydrocarbons (Table 1). Although no detectable hydrocarbons mere encountered <br /> during the preconstruction assessment, it is possible that due to the nature of the site's coarse <br /> '� MA/8-12-91/ENG/9284MER 4 <br />