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Soil Profile and Geologic Information <br /> The Site is depicted on the Preliminary geologic map of the Tracy quadrangle, San <br /> Joaquin County, California (Diblee, 1981). The Site is depicted within a map unit of <br /> Holocene alluvium (Plate 9). <br /> The surface and near surface soils located at the Site are reported by the USDA Web <br /> Soil Survey to be composed of Stomar clay loam and Zacharias clay loam (Plate 10) <br /> (USDA, 2019). The table below presents some selected properties of these soil units: <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 /> Stomar clay 0-17 Clay loam; CL <2 6.6-7.3 0.2-0.6 Severe: <br /> loam, 0-2% 17-47 Clay loam, clay; CL, CH <2 6.6-8.4 0.06-0.2 peres slowly <br /> slopes, 252 47-60 Clay loam, silty clay <2 7.4-8.4 0.2-0.6 <br /> loam; CL <br /> Zacharias 0-19 Clay loam; CL <2 6.1-7.3 0.2-0.6 Severe: <br /> clay loam, 19-53 Clay loam, loam; CL <2 6.6-7.8 0.2-0.6 peres slowly <br /> 0-2% 53-60 Gravelly clay loam, <2 6.6-8.4 0.2-0.6 <br /> slopes, gravelly loam; GC, CL <br /> 281 <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 June 15, 2020, Live Oak excavated a shallow soil boring on the Site for the purpose <br /> of conducting a percolation test. The boring was four inches in diameter, 3.28 feet <br /> deep, and was excavated by hand auger. The location of the boring is indicated on <br /> Plate 11. <br /> The soil in the boring was similar to that described by the Soil Survey. Silty clay was <br /> encountered to a depth of approximately two feet below ground surface, followed by <br /> silty clay with fine sand to the full depth of the hole. The soil log is presented on Plate <br /> 12. <br /> Discussion of Soil Lithology <br /> Based on the soil described, there appears to be some potential for percolation in the <br /> shallow soil zone. Sandy soils generally have a much greater potential for percolation <br /> than fine-grained or cemented soils. However, a percolation test is the only accepted <br /> method for determining the suitability of the soils for a septic disposal area. Percolation <br /> test results are discussed in the following section. <br /> LOGE 20-44 Page 4 <br />