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N <br />� <br />� <br />,� <br />� <br />� <br />� <br />� <br />.'� %��` <br />JAVID L. NELSON AND ASSOCIATES, INC. <br />Consuiting Engineering Geology <br />October 27, 1988 <br />Project No. 13288 <br />Pa9e 3 <br />are generally overlain by 0.5 to 1.5 feet of brarn loose silty sand with roots <br />and 0.5 feet of organic topsoil. Within the suspected artificial fill or <br />surficially modified ground areas, the dense Dasa1 soils were `ound at greater <br />depths, and are overlain by variable materials. As shavn 1n TP-5, TP-6. TP-7, <br />TP-9 and TP-10, artificial fill occurs overlying Lhe native naterials. During <br />our exploration, we found that past grading probably has occurred in the area, <br />creating the present surface conditions. It appears that an old drainage <br />swale may have occurred within the area, located approximately as shavn on the <br />location map. As shown on the test pit logs, the dense basal soils are <br />overlain within the suspected deeper old swate area Dy about 2 feet of brown, <br />medium dense, poorly sorted gravelty silty sand (nat:ral) in a wet condition, <br />which is directly overlain by of variable and non-uniform artificial fi11. <br />The artificial fill was found to vary from black/brown, loose, organic silty <br />sand, organic debris, wood, logs, etc., to grey and brown, loose mixed <br />gravelty silty sand with scattered organics. The fill appears to thin toward <br />the west, south and east, creating the indication of an old (filled) drainage <br />swale, and of grading and filling along the easterly portion of the site. The <br />artificial fill, where encountered, appears to vary from about 2 to 6 feet <br />thick, but could be thicker within the area of the main old drainage swale. A <br />thin (about 1 foot thick) strata of arrtificial fill was encountered along the <br />top-of-slope area (see TP-2, TP-3 and TP-4), probably derived from past <br />clearing and grading operations within the area. <br />Hydrologic Conditions <br />� The true ground water table was not encountered in any of the test pits <br />performed around the site area. Wet to very wet conditions v+ere observed <br />� ►vithin the fill areas, and particularly Nithin the old drainage swale area. <br />These conditions are considered perched water, a conditian created by the <br />occurrence of the relatively impernieable basal soils, where surface waters <br />� cannot readily penetrate. Accumula4ed surface waters within the site flow <br />along the interface of the dense basal soils/overlying soils (or fi11), and <br />� <br />� <br />