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Soil Suitability and Nitrate Loading Evaluation Page 5 <br /> 25071 South Lammers Road <br /> Tracy, California <br /> June 16, 2023 NATS Job No. 22-355G <br /> 6.0 SPOIL PROFILE <br /> Published (USDA, Soil Survey of San Joaquin County, California) mapping <br /> (https://casoilresource.lawr.ucdavis.edu/gmap/) indicates soils at the site consist of <br /> "Capay Clay" described as clayey alluvium on basin floors derived from sedimentary rock <br /> sources, moderately well drained. Typical profile shown for this unit is clay from 0 to 60 <br /> inches. Shallow infiltration system rating for "Capay Clay" soils is indicated to be <br /> "severely limited" and septic tank absorption fields "very limited". Based on published <br /> regional geologic mapping by Wagner, E.J., Bortugno, E.J., and McJunkin, R.D. (CDMG <br /> Map Sheet 5A, 1991) the near surface geologic units underlying the site consist of <br /> Quaternary Alluvial Fan deposits consisting of gravel, sand, silt and clay. <br /> Soils encountered within the percolation test hole (P-1) are described as dark brown, <br /> dry, clay to cemented clay within the upper 2.5 ft and brown gravelly clay within the test <br /> interval from 2.5 ft to 3.5 ft. These soil materials are considered consistent with Alluvial <br /> Fan Deposits as shown on published mapping. <br /> 7.0 PERCOLATION TESTING <br /> Our subsurface investigation included conducting leach field soil suitability evaluations <br /> via percolation testing. The evaluation included the excavation and testing of one <br /> percolation test hole at the location shown on Figure-2. The percolation test (P-1) was <br /> conducted at the proposed leach field location at a depth of 42-inches. <br /> 4713 ENTERPRISE WAY * SUITE 4*MODESTO * CALIFORNIA * 95356* 209-545-1108 <br />