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3 . Red brown, silty, clayey sand from below the clay layer <br /> . to the base of the borings. Over most of the site, this <br /> sand is very fine grained; in some locations it grades <br /> to a coarser gray brown sand at the 15 foot level. <br /> While in other areas, it grades into almost a clayey <br /> silt. <br /> Ground water was first observed in the borings from 14 to 18 feet <br /> below the surface. After time, the water rose to approximately to <br /> feet below the surface. This indicates that the clay layer (number <br /> 2 above) forms a confining layer at the site. <br /> RESULTS SOIL SAMPLES <br /> Soil samples were chosen for analysis where elevated PID readings <br /> were encountered or at least at the 15 foot below surface level. <br /> Of the soil samples analyzed, only those from SBA contained <br /> detectable amounts of hydrocarbons. The highest level encountered <br /> was in the 20 foot depth sample (see Table 1, Figure 4) . <br /> RESULTS WATER SAMPLES <br /> During drilling, a water sample was collected from each of the soil <br /> borings. All of these samples were analyzed for TPHg and BTEX. Of <br /> these samples, hydrocarbons were detected in SBA, (see Table 1 and <br />. Figure 5) . The highest level was detected in SBA which contained <br /> 26, 000 ppb TPHg. <br /> CONCLUSIONS <br /> The presence of soil and water hydrocarbon contamination in SBA, <br /> and the lack of soil contamination and the much lower level of <br /> water contamination in SB4, indicate that the contamination found <br /> in SBA most probably results from the former gasoline storage tank. <br /> These borings further defined the general hydrogeology of the site, <br /> of a confined silty, clayey, sand aquifer, overlain by a silty <br /> clay. This aquifer contains a large amount of clay and fine <br /> grained particles and therefore has a low hydraulic conductivity <br /> which probably has slowed the migration of the contamination. <br /> The confined nature of the aquifer and the presence of the gasoline <br /> under the confining clay as evidenced by the SBA at 15 foot sample <br /> makes remediation of the contamination difficult. The lack of <br /> vertical permeability, confining clay layer, and the trapping of <br /> the gasoline beneath the clay present a number of problems: <br /> 1. The lack of vertical permeability, greatly slows the <br /> rate of vertical gas exchange effecting a number of <br />• factors: <br /> 4 <br />