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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, 2020). 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 />Depth <br />Unified Soil <br />Salinity <br />Soil <br />Perme- <br />Septic tank <br />and Map <br />(in) <br />Classification <br />mmhos/cm <br />Reaction <br />ability <br />absorption <br />Symbol <br />y <br />pH <br />(in/hr) <br />fields <br />Tokay fine <br />0-19 <br />Fine sandy loam; SM <br /><2 <br />6.1-7.8 <br />2.0-6.0 <br />Slight <br />sandy loam, <br />19-45 <br />Fine sandy loam, sandy <br /><2 <br />6.1-7.8 <br />2.0-6.0 <br />0-2% <br />loam, SM <br />slopes, <br />45-60 <br />Fine sandy loam, sandy <br /><2 <br />6.1-8.4 <br />2.0-6.0 <br />256 <br />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 September 2, 2021, Live Oak excavated a shallow soil boring near the proposed <br />septic disposal area of the Site for the purpose of conducting a percolation test. The <br />boring was four inches in diameter, 2.30 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; some gravel was present in the first six inches. <br />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 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 2145 Page 5 <br />