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s <br /> Results of ground water sample analysis are included in Table 1. <br /> Results of soil sample analysis are included in Table 2 and shown <br /> in Figures 4 and 5 . Official laboratory reports and chain of <br /> custody documents are included in Appendix G. <br /> 5. 0 DISCUSSION OF RESULTS AND FINDINGS <br /> A brief description of site geology and hydrogeology based on the <br /> findings of field activities and laboratory analytical results of <br /> soil and ground water samples is discussed below. <br /> 5 . 1. Site Geology <br /> Based on this subsurface investigation, the stratigraphy across <br /> the site consists primarily of silty sand and poorly-graded sand. <br /> Silty sand was encountered from grade to approximately 15 fbg in <br /> Soil Borings SB-1, SB-2 , and MW-2 , and was underlain with <br /> interbedded silty sand, silty clay, and sandy clay units to the <br /> total drilling depth. A silty clay unit was encountered in MW-1 <br /> and MW-3 from the surface to approximately 8 fbg. A silty sand <br /> unit was encountered in MW-1 and MW-3 from approximately 8 to 15 <br /> fbg. Poorly-graded sand with interbedded silty sand, silty clay, <br /> and sandy clay units was encountered in all borings from <br /> approximately 15 fbg to the total drilling depths. <br /> 5 . 2 Site Hydrogeolgqy <br /> The average depth to ground water beneath the site is <br /> approximately 66 fbg, which corresponds to an elevation of <br /> 22 . 0 feet below mean sea level (msl) . Ground water elevations <br /> from MW-1, MW-2 , and MW--3 , as measured on April 6, 1992 , were <br /> used to develop the ground water elevation map shown in Figure 3 . <br /> Average ground water gradient onsite was estimated to be <br /> 0. 002 foot per foot to the west. <br /> 5 . 3 Results of Soil Analysis <br /> The results of soil sample analysis are discussed below. <br /> w TPH-G was detected in soil samples collected from <br /> SB-1 (120 parts per million, (ppm) ) , MW-2 (1 . 0 ppm) , <br /> and MW-3 (30 ppm) at 46 fbg. <br /> • Benzene was detected in soil samples collected from <br /> each boring at depths ranging from 35 fbg to the <br /> capillary fringe (66 fbg) . The highest concentrations <br /> of benzene (0. 69 ppm) , toluene (5. 2 ppm) , ethylbenzene <br /> (2 . 1 ppm) , and total xylene (13 ppm) were detected in <br /> SB-1 at 46 fbg. Concentrations of benzene, toluene, <br /> ethylbenzene, and total xylenes (BTEX) ranged from <br /> below the reported detection limit to less than 1 . 5 ppm. <br /> 4 <br />