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, <br /> IM <br /> Hardirig LOWSon AsataEot@g <br /> V SURFACE AND SUBSURFACE CONDITIONS <br /> The 7-Eleven convenience store at 455 Wcst Grant Line Road consists of a <br /> FAA <br /> store, a gasoline station, asphalt-covered parking and driveway areas, and <br /> landscaped areas at the corners of the prapertY. The site is bounded by paved <br /> i <br /> 1i streets on the east and south, and by vacant lots on the north and west. <br /> The seven shallow borings and two of the three monitoring wells were <br /> drilled through either asphalt or landscaped areas. The shallow subsurface is <br /> Primarily composed of fine-grained silts, silty clays, and clays. A coarse- <br /> _ r• <br /> grained stratum was encountered at various depths across the site and may be <br /> Coarse-grained m <br /> oarse-. <br /> as thick as 12 feetCaterials are silt <br /> g <br /> - Y:.clayey, or gravelly <br /> < sands in the upper 20 feet of soil. As shown on the <br /> Fn Pp neralized geologic <br /> cross-section for the site, Plate 12, the coarse-grained stratum may be <br /> i� discontinuous across the site. <br /> MW-7, adjacent to the tanks' g Y was drilled <br /> through the clayey Y sand backfill <br /> surrounding them. This backfill extended to a depth of approximately 12 feet. <br /> Silty clays were encountered from 12 feet to the bottom <br /> of the boring at" 13.5 <br /> feet. <br /> The elevation of each of the monitoring wells was determined b ;-i <br /> y a licensed <br /> land surveyor. Table d presents these elevations, the measured depth to water <br /> r ,' 1 <br /> and the potentiometric levels collected to date. <br /> The tank backfill is probably in hydraulic. connection. with the shallow <br /> sand stratum beneath the site. Such a connection is indicated on Pate 12 and <br /> is further suggested by similar water levels in the shallow sand stratum and <br /> }° in the tank backfill. <br /> �a 9 <br />