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( t <br /> Gcotechnical Engineering Report <br /> Proposed Ahn Warehouse <br /> May Il, ?001 <br /> CG File No. 1121 <br /> Page� <br /> We have included Schematic Cross-Section A-A' as Pigure 3. This cross section shows the <br /> thiclmess of fill encountered in our test pits, and the approximate contact with the underlying <br /> � native soils. <br /> Test Pits: All of our expbrations encountered a layer of fill. The upper 2 feet of fill encountered <br /> in Test Yits 1, 2, and 3 consisted of loose, fine sand with silt and trace gravel. f3elow this l�yer, <br /> the till generally consisted of a silty fine to a fine to coarse sand with gravel. Debris consisting of <br /> asphalt chunks and logs were encountered in the fill uniL "I'he fill encountered in Test Pits 4 and <br /> 5 consisted of loose, silty fine sand with gravel. The fill was 12.0, 13.5, and 3S feet in thidmess <br /> in Test Pits l, 2, and 4 (respectively). The fill was encountered to the full depths able to be <br /> explored by the reach of the backhoe in Test Pits 3 and 5, which extended to depths of 14.0 and <br /> 13A feet. <br /> Native soils consisting of loose[o medium dense, silty fine sand with roots to a fine sand with silt <br /> and trace gravel were encountered underlying the fill in Test Pits 1 and 2. Underlying the fill in <br /> Test Pit 4,a buned topsoil horizon, underlain by a weathered silty fine sand with gravel and hace <br /> cobbles was encountered to a depth of 7.5 feet. We have classified this weathered soil honzon as <br /> weathered glacial till. Underlying the weathered till, dense to very dense, silty fine sand, <br /> interpreted to be glacial till was encountered to the full depth explored of 12A feet in Test Pit 4. <br /> Hydrologic Couditions <br /> Minor ground water seepage was encountered in Test Pits 3, 4, and 5, at depths of 6A to 7.5 fcet <br /> below the ground surface and wet, saturated fill soils were encountered in Test Pits 1 and 2. The <br /> ground water is considered to be perched ground water. Perched water occury :vhen surface <br /> water infil[rates through less dense, more permeable zones and accumulates on [op of the <br /> underlying, less permeable soils. The more permeable zones consist of the loose fill, debns, sand <br /> zones, and the weathered till. The less permeable soils consist of the unweathered till. Perched <br /> water does not represent a regional ground water"table" within the upper soil horizons. It should <br /> be noted that the local volumes of perchecl ground water could vary depending upon the time of <br /> year and the upslope recharge conditions. <br /> �� a� <br /> Cornerstone Ge�technical, Inc. � <br />