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be required to remove this contaminant should it occur in drinking water. The Maximum Contaminant Level Goal (MCLG) for DBCP is zero. Soil Profile and Geologic Information The Site is depicted on the Preliminary Geologic Map showing Quaternary deposits of the Lodi Quadrangle, California (Marchand and Atwater, 1979). The Site is depicted within a map unit of the Riverbank formation upper unit (Plate 10), described as "arkosic alluvium forming Mokelumne River alluvial fan; chiefly sand; probably glacial outwash." The surface and near surface soils located at the Site are reported by the USDA Web Soil Survey to be composed of San Joaquin loam (Plate 11) (USDA, 2022). The table below presents some selected properties of this soil: Table 1. Selected Properties of On-Site Soils (USDA, 1992) Soil Name and Depth Unified Soil Salinity Soil Perme Septic tank Map Symbol (in) Classification mmhos/cm Reaction -ability absorption pH (in/hr) fields San Joaquin loam, 0-16 Loam; CL-ML, ML <2 5.6-6.5 0.6-2.0 Severe: 0-2% slopes, 16-26 Clay loam, clay; CL <2 6.1-7.8 <0.06 cemented pan, 238 26-60 Indurated --- --- --- peres slowly San Joaquin loam, 0-16 Loam; CL-ML, ML <2 5.6-6.5 0.6-2.0 Severe: 2-8% slopes, 16-26 Clay loam, clay; CL <2 6.1-7.8 <0.06 cemented pan, eroded, 239 26-60 Indurated --- --- --- peres slowly Note:The table descriptions do not necessarily reflect site-specific soil properties. See description of the map unit for composition and behavior characteristics of the map unit. Soil Borings On April 26, 2023, Live Oak excavated a shallow soil boring near the proposed septic disposal area for the new ADU on the Site. The boring was 4 inches in diameter, 1.81 feet deep, and was excavated by hand auger (Table 2). The location of the boring is indicated on Plate 12. The soil in the boring was similar to that described by the Soil Survey. Silty clay with fine sand was encountered to the full depth of the hole. The soil log is presented on Plate 13. Discussion of Soil Lithology Based on the soil observed in the boring, there appears to be limited potential for percolation in the shallow soil zone. Sandy soils generally have a much greater potential for percolation than fine-grained or cemented soils. However, a percolation test is the only accepted method for determining the suitability of the soils for a septic disposal area. Percolation test results are discussed in the following section. LOGE 2312 Page 5