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Soil Profile and Geologic Information <br />The Site is depicted on the Preliminary geologic map showing Quaternary deposits of <br />the Lodi quadrangle, California (Marchand and Atwater, 1979). The Site is depicted <br />within a map unit of the Modesto formation upper member, described as "arkosic <br />alluvium forming Mokelumne River alluvial fan; chiefly sand, becoming finer-grained <br />toward fan toe; probably glacial outwash" (Plate 8). <br />The surface and near surface soils located at the Site are reported by the USDA Web <br />Soil Survey to be composed of Tokay fine sandy loam (Plate 9) (USDA, 2019). The <br />table below presents some selected properties of this soil: <br />Table 1. Selected Properties of On-Site Soils (USDA, 1992) <br />Soil Name <br />and Map <br />Symbol <br />Depth Unified Soil <br />(in) Classification <br />Soil Perme- Septic tank Salinity Reaction ability absorption mmhos/cm pH (in/hr) fields <br />Tokay fine 0-19 Fine sandy loam; SM <2 6.1-7.8 2.0-6.0 Slight <br />sandy loam, 19-45 Fine sandy loam, sandy <2 6.1-7.8 2.0-6.0 <br />0-2% loam; SM <br />slopes, 45-60 Fine sandy loam, sandy <2 6.1-8.4 2.0-6.0 <br />256 loam, coarse sandy <br />loam; SM <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 />Soil Borings <br />On February 28, 2019, Live Oak excavated a shallow soil boring adjacent to the existing <br />septic disposal area of the Site for the purpose of conducting a percolation test. The <br />boring was four inches in diameter, 3.06 feet deep, and was excavated by hand auger <br />(Table 2). <br />The location of the boring is indicated on Plate 10. <br />The soil in the boring was similar to that described by the Soil Survey. Sandy silt was <br />encountered to the full depth of the hole. The soil log is presented on Plate 11. <br />Discussion of Soil Lithology <br />Based on the soil observed in the borings, there appears to be good potential for <br />percolation in the shallow soil zone. Sandy soils generally have a much greater <br />potential for percolation than fine-grained or cemented soils. However, a percolation <br />test is the only accepted method for determining the suitability of the soils for a septic <br />disposal area. Percolation test results are discussed in the following section. <br />LOGE 1906 Page 5