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33503 S Koster Road Project No. 2021-00073 P a g e | 3 <br />3.0 GEOLOGIC AND SOIL PROFILE INFORMATION <br />3.1 Chemical and Physical Soil Properties <br />The Site is depicted on the Geologic Map of the San Francisco-San Jose Quadrangle4 and falls <br />within the alluvial fan deposits (Qf) of the Holocene. Qf is a unit of unconsolidated to locally <br />cemented, undissected deposits of gravel and sand that form active parts of alluvial fans <br />(Plate 3, Appendix A). <br />The surface and near surface soils located at the site are reported by the San Joaquin County <br />Soil Survey5 to be composed of the El Solyo clay, and Capay clay, 0-2 percent slopes (Plate 4, <br />Appendix A). The table below presents some selected properties of these soils: <br />Table 1. <br />San Joaquin County Soil Survey <br />Elected Soil Properties of On-Site Soils <br />Soil Name <br />and Map <br />Symbol <br />Depth <br />(in)Unified Soil Classification <br />Salinity <br />mmhos <br />/cm <br />Soil <br />Reaction <br />pH <br />Perme- <br />ability <br />(in/hr) <br />Septic tank <br />absorption <br />fields <br />Capay clay, <br />118 <br />0-20: <br />20-44: <br />Clay; CL, CH <br />Clay, Silty clay; CL, CH <br /><2 <br /><2 <br />6.6 – 8.4 <br />6.6 – 8.4 <br />0.06 – 0.2 <br />0.06 – 0.2 <br />Severe: <br />percs <br />slowly. <br />El Solyo <br />Clay loam <br />156 <br />0-10: <br />10-60: <br />Clay; ML, CL <br />Silty clay loam, silty clay; <br />ML, CL, CH <br /><2 <br /><2 <br />6.6 – 7.8 <br />7.4 – 8.4 <br />0.2 – 0.6 <br />0.06 – 0.2 <br />Severe: <br />percs <br />slowly. <br />Note: The table descriptions do not necessarily reflect site-specific soil properties. <br />* See description of the map unit for composition and behavior characteristics of the map unit <br />3.2 Mass Transport Soil Properties <br />The clay and silty clay loam soil such as the layers reported for the San Joaquin soil at the site <br />typically provide a high degree of protection between percolating effluent at the surface and <br />4 Wagner, D.L., Bortugno, E.J., and McJunkin, R.D, 1991. Geologic Map of the San Francisco Quadrangle, California, California Division of <br />Mines and Geology Map 5A. 1: 250,000 <br />5 United States Department of Agriculture. Soil Survey of San Joaquin County, California. October 1992.