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The project site has level terrain; consequently, there is no need to incorporate design considerations for slopes within the effluent disposal area. B. SOIL PHYSICAL CHARACTERISTICS AND ANALYTICAL TEST RESULTS SSS§ 5.2. The UC Davis Soil Web designates the soil as a Vernalis Clay (#268), with loamy sand at 125 cm below grade. Texture analysis by A&L Labs show the soils at 42" below grade in the proposed filter bed area to be a sandy loam (silty sand). NLS§ 1.1, 1.2. The surface and subsurface soil investigation began on September 29, 2019 with the drilling of one 42-inch deep perc test boring. Auger cuttings were sampled from the 42" depth. Five soil samples were also retrieved in the adjacent almond orchard from a 12" depth and composited for comparison purposes. As noted on the A&L Laboratory Soil Report in Appendix B, chemical analysis of the soil samples quantifies a number of constituents that influence nitrate loading for this project. The important parameters for nitrate loading assessment are the organic matter, pH, cation exchange capacity (CEC), and the nitrate-nitrogen content of the soil. The soil nitrate-nitrogen concentration is a medium concentration under the proposed filter bed location at 18 ppm at the 42" depth. The orchard soils have a very low nitrate-nitrogen concentration of 2 ppm. Because septic effluent is composed predominately of ammonium (NH4), the pH, along with the CEC, are significant influences on the ammonium molecules. The pH of the soil profile is alkaline at over 8. At this pH, ammonium will have a propensity to convert to ammonia. The CEC measures the ability of the soil to theoretically trap and hold ammonium molecules. The CEC at 42" is low at 7.8 meq/100g. NLS§ 3.3, SSS§ 5.3, 5.4. Table 1 below summarizes the soil physical and chemical characteristics for the proposed filter bed soil and almond orchard soil: TABLE 1 SOIL PROFILE CHARACTERISTICS AND ANALYTICAL TEST RESULTS SAMPLE DEPTH AND (SAMPLE NUMBER ON TEST RESULT FORM) SOIL CLASSIFICATION SOIL NITRATE- NITROGEN CONTENT pli , CATION EXCHANGE CAPACITY FILTER BED 42" DEPTH (FB42") Sandy Loam 18 ppm NO R -N 7.8 18.5 meq/ 1 00g CROPLAND (ALMOND ORCHARD) 12" DEPTH (CL12") Sandy Clay Loam 2 ppm NO,-N 7.2 9.8 meq/100g Page -2- Chesney Consulting