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5 SITE CONDITIONS <br />' 5.1 Site Geology <br /> The subsurface materials encountered beneath the site consist predominantly of silt and <br /> lenses of silty sand to sand The silty sand to sand lenses vary in thickness from <br /> approximately 5 to 30 feet Graphic interpretations of the soil stratigraphy encountered ui <br /> the borings from previous investigations are shown in geologic cross sections A-A' and <br /> B-B' presented on Figures 3 and 4, respectively The trace of the cross sections are shown <br /> on Figure 2 <br /> 5.2 Site Hydrogeology <br /> Quarterly evaluations of groundwater flow direction were initiated in March 1994 The <br /> elevations of groundwater in each well (see Table 5) were used to evaluate the <br /> groundwater gradient and direction of groundwater flow and to construct groundwater <br /> contour maps Groundwater has generally fluctuated between 56 and 65 feet bgs in the <br /> wells (EMCON, August 5, 1996) Groundwater occurs in a fine-to coarse-grained sand <br /> under unconfined conditions The direction of groundwater flow has been consistently to <br /> the south to southwest, except during the second quarter 1994 sampling event when the <br /> groundwater flow direction was toward the northeast The groundwater gradient has <br /> ranged from 0 001 to 0 004 Groundwater contour maps from previous sampling events <br /> are presented in Appendix D <br /> 5.3 Residual Petroleum Hydrocarbons in Soil <br /> The results of subjective and laboratory analyses of soil samples collected during the <br /> investigations were used to evaluate the lateral and vertical extent of residual petroleum <br />' hydrocarbons in soil The vertical distribution of petroleum hydrocarbons are shown on <br /> Figure 3 and Figure 4 The lateral extent of residual petroleum hydrocarbons in soil <br /> between 0 and 29 feet bgs and between 30 and 61 5 feet bgs are shown on Figures 5 <br />' through 10 Tables 6 through 9 sumirianze the analytical results of soil samples collected <br /> from the tank cavities and pipeline trench The investigations detected residual gasoline <br /> petroleum hydrocarbons in the soil beneath and near the former tanks, beneath the product <br /> delivery lines, and in the area of the former waste-oil tanks <br /> SA(\N V'iM80%8051420 4BS-97\prz i Rev 0 3112197 <br /> 20805 142 004 5-1 <br />