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PHYSICAL SETTING <br /> Topography <br /> The elevation of the Site, according to a United States Geological Survey topographic <br /> map, is approximately nine to 10 feet above mean sea level (Plate 4). The Site is <br /> relatively flat. <br /> Geology <br /> The Site is mapped on the Preliminary geologic map showing Quaternary deposits of <br /> the Lodi quadrangle, California (Marchand and Atwater, 1979). It is depicted within a <br /> map unit of the Modesto formation lower member and two map units of the Modesto <br /> formation upper member. The units of the Modesto formation upper member are <br /> described as (Qm2) "arkosic alluvium forming Mokelumne River alluvial fan; chiefly <br /> sand, becoming finer-grained toward fan toe; probably glacial outwash" and (Qm2e) <br /> "arkosic alluvium forming low dunes on the Mokelumne River fan and in the Delta; <br /> probably eolian, although not well sorted." The Modesto formation lower member <br /> (Qm,°) is described as "Qm, (arkosic alluvium forming Mokelumne River alluvial fan,- <br /> chiefly <br /> an;chiefly sand; probably glacial outwash) and Qm,b (basin alluvium derived from the <br /> Mokelumne and Calaveras Rivers; includes arkosic alluvium, probably glacial outwash, <br /> and locally-derived materials; chiefly fine sand and silt) overlain by 0.5 to 2 m of Qm2 <br /> deposits" (Plate 5). <br /> Soil Analysis <br /> Chemical and Physical Properties of the Soil <br /> The surface and near surface soils located at the Site are reported by the Web Soil <br /> Survey (USDA, 2019) to be composed of Devries sandy loam, drained (Plate 6). The <br /> table below presents some selected properties of this soil type: <br /> Table 1. Selected Properties of On-Site Soils (USDA, 1992) <br /> Soil Name Depth Unified Soil Salinity Soil Perme- Septic tank <br /> and Map Reaction ability absorption <br /> Y <br /> S mbol (in) Classification mmhos/cm pH (in/hr) fields <br /> Devries 0-13 Sandy loam; SM <2 6.6-8.4 2.0-6.0 Severe: <br /> sandy loam, 13-28 Sandy loam, fine sandy <2 6.6-8.4 2.0-6.0 cemented <br /> drained, 0- loam; SM pan <br /> 2% slopes, 28-80 Indurated --- --- --- <br /> 149 <br /> Note: The table descriptions do not necessarily reflect site-specific soil properties. See description of the map unit for <br /> composition and behavior characteristics of the map unit. <br /> LOGE 1903 Page 3 <br />