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3.0 FINDINGS <br /> 3.1 Subsurface Conditions <br /> _ The site is underlain primarily by silts and clays with sand interbeds to the maximum <br /> depth explored of 27 feet. Surficial sands were observed in the locations of U-A, U-B, <br /> U-C, and U-4, at an approximate thickness of 5 to 8 feet (Figures 2, 3, 4). These <br /> surficial sands are gray to medium brown, and contain from 5 to 45 percent low <br /> plasticity silt, with lesser amounts of coarse sand and fine gravel (Appendix A). An <br /> orange-brown to dark-brown silty sand was encountered at a depth of 6 to 8-1/2 feet in <br /> Borings U-B and U-6. This sand is fine grained in the location of U-6 with a minimum <br /> thickness of 1 foot. In the vicinity of U-B, this sand has a maximum thickness of 1 foot, <br /> and contains coarse sand and fine gravel. A lower sand horizon occurs in the vicinity of <br /> U-C, U-1, U-2, U-3, and U4, at a depth ranging from apprwdmateiv 16-1/2 to 20 feet <br /> �- below grade. This horizon varies from fine silty sand in the vicinity of U-C and U-1, to <br /> well graded water-bearing sand and fine gravel in the locations of U-2, U-3 and U-4, <br /> and has a thickness ranging from 1-1/2 to at least 5 feet. These subsurface sands <br /> appear to trend northwest-southeast, and cross the western portion of the site. <br /> Static groundwater occurred at a depth of approximately 8 feet during the <br /> May 23, 1991,`sampling event, with a northerly flow direction at a a adient.of 0.006 <br /> (Figure 5). A north-no-rtliwesterly flow direction was calculated for the vicinity of <br /> Monitoring Wells U-1 through U-3, which is consistent %pith that observed for those <br /> wells in pre.vious.sampling events. 'Lha newly available data from Wells U-4 through <br /> U-6 indicates that a oundwater flow on the broader scale of the site is toward the north. <br /> 3.2 Soil Analytical Results <br /> c Selected soil samples collected during the Nfav 9, 1991, drilling activities were <br /> submitted to a_State-certified_analv-tical-laboratory,_and_analyzed- for-TPH-gasoline,___ <br /> r � TPH-diesel, and B EX compounds (Table 2). '1-PH-gasoline concentrations ranged <br /> from none-detected to a maximum of 1,700 ppm, in the 5 to 6-1/2 foot depth sample <br /> from Boring U-C. TPH-gasoline was also observed in Borings U-A. U-C, and U-5, at <br /> 420 ppm to 1,700 ppm. The maximum TPH-diesel concentration. 4,900 ppm, also <br /> JI 3100101/R£PORI-2 4 5epicmber 30,1091 <br /> fr <br />