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Soil Profile and Geologic Information <br /> The Site is depicted on the Preliminary geologic map of Cenozoic deposits of the <br /> Bellota Quadrangle, California (Marchand and Bartow, 1979). The Site is depicted <br /> within a map unit of the Modesto formation lower member described as "basin alluvium <br /> from both the Mokelumne and Calaveras Rivers; includes arkosic alluvium, probably <br /> glacial outwash, and locally-derived materials; chiefly fine sand and silt" (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 Stockton clay (Plate 9) (USDA, 2020). The table below <br /> presents some selected properties of this soil: <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 /> Symbol (in) Classification mmhos/cm <br /> y pH (in/hr) fields <br /> Stockton 0-29: Clay; CL, CH <2 7.4-8.4 0.14-0.16 Severe: <br /> clay, 0-2% 29-37: Clay, silty clay, CL, CH <2 7.4-8.4 0.14-0.16 peres slowly <br /> slopes, 250. 37-42: Clay loam, silty clay <2 7.4-8.4 0.14-0.17 <br /> loam; CL <br /> 42-60: Cemented --- --- --- <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 October 2, 2020, Live Oak excavated a shallow soil boring near the proposed septic <br /> disposal area of the Site for the purpose of conducting a percolation test. The boring <br /> was four inches in diameter, 3.40 feet deep, and was excavated by hand auger (Table <br /> 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. Clay 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 boring, there appears to be limited 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 20-49 Page 5 <br />