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i <br /> I <br />' 4 SUBSURFACE CONDITIONS <br />' The following sections describe the subsurface conditions encountered <br /> during field activities. <br /> 4.1 Soil <br />' Shallow soils to depths of 91.5 feet in the vicinity of the former tank <br /> complex consist primarily of sands, silty sands, and clayey sands, with <br /> interbedded lenses of silt and clay. The exploratory boring logs in <br /> Appendix C present detailed descriptions of the soils encountered during <br /> drilling. <br />' 4.2 Ground Water <br />' Ground water was first encountered during drilling at a depth of 85 feet <br /> below the ground surface. After installation of the wells, the static water <br /> level was reported to be approximately 80.5 to 80 feet below the ground <br /> surface, a rise of approximately 4.5 to 5 feet, indicating that ground water <br /> at the site is partially confined. <br /> Drawing 2 is a ground-water contour map based on top-of-casing elevations <br />' and depths to water measured in the wells on August 24, 1992. Ground <br /> water at the site flows toward the southeast, and the ground-water gradient <br />' is 0.003 foot per foot. This direction of ground-water flow is contrary to the <br /> ground-water flow direction (northwest) reported by Elder Engineering, Inc., <br /> for the time period from March 29, 1990, to June 10, 1991. <br /> 1 <br /> pj010f9010f900020.1 ag 4 - 1 Rev. 0 December 15, 1992 <br />