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Soil Profile and Geologic Information <br /> The Site is depicted on the Geologic map of the San Francisco-San Jose quadrangle, <br /> California (Wagner et. al, 1991). The Site is depicted within a map unit of the Modesto <br /> formation (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 Jacktone 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 pH (in/hr) fields <br /> Jacktone 0-22 Clay; CL, CH <2 6.6-8.4 0.06-0.2 Severe: <br /> clay, 0-2% 22-34 Clay loam, clay, silty <2 7.9-9.0 0.06-0.2 cemented <br /> slopes, clay; CL, CH pan, peres <br /> 180 34-37 Indurated --- --- --- slowly <br /> 37-46 Loam, clay loam; CL- <2 7.9-9.0 0.2-0.6 <br /> ML, CL <br /> 46-60 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 March 16, 2021, Live Oak excavated shallow and deep soil borings in the proposed <br /> septic disposal area of the Site for the purpose of conducting a percolation test. The <br /> borings were four inches in diameter, 3.28 and 4.82 feet deep, and were excavated by <br /> hand auger (Table 2). <br /> The location of the borings is indicated on Plate 10. <br /> The soil in the borings was similar to that described by the Soil Survey. Clay was <br /> encountered to approximately three feet below ground surface, followed by clayey silt <br /> with fine sand to the full depth of each 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 limited potential for <br /> percolation at the test location. Sandy soils generally have a much greater potential for <br /> percolation than fine-grained or cemented soils. However, a percolation test is the only <br /> accepted method for determining the suitability of the soils for a septic disposal area. <br /> Percolation test results are discussed in the following section. <br /> LOGE 2115 Page 5 <br />