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r2 B. SOIL INFORMATION I NLS§ 1.1. The UC Davis Soil Web Map indicates the Map Unit Name to be a Delhi loamy sand, 0 to 2 percent slopes (#142). As referenced, a soil sample was retrieved from the 36-inch depth and 10 ft backhoe test pit depth for physical and chemical analyses. The attached soil texture analysis reveals the on-site soils at the 36-inch depth consists of a loamy sand, with sand, silt and clay percentages of 88%, 4% and 8%respectively. Although the clay content of the on-site soils can be considered comparatively low, denitrification potential still exists as evidenced by the decrease in nitrate-nitrogen concentration from 3 ppm at the 3 ft depth to 2 ppm at the 10 ft depth, a 33% decrease. NLS§ 1.2. As noted on the attached Soil Analysis Report, the chemical analyses conducted quantifies several constituents that influence nitrate loading for this project. The important parameters for nitrate loading assessment are the organic matter and estimated nitrogen release (ENR), clay content, pH, cation exchange capacity (CEC), and the nitrate-nitrogen content of the soil. SSS§ 2.1. The organic matter is low at 0.3% and the ENR is low at 37 lbs/ac. This OM and ENR concentrations suggest there is a low potential for future nitrate forming from organic matter. Since septic effluent is composed predominately of ammonium(NH4),the pH,along with the CEC, have significant influence on ammonium molecules. The pH of the soil is nearly neutral at the proposed filter bed depth, which may stabilize the ammonium fraction of the effluent. The CEC measures the ability of the soil to theoretically trap and hold ammonium molecules and was measured at 3.1 meq/100 g, which is a low value. This suggests a low potential for the retention of ammonium molecules that may form for microbial assimilation within the soil, but will allow for immediate uptake by grass root structures. NLS§3.3. Table 1 below summarizes the analyzed soil physical and chemical characteristics from the retrieved soil sample. i TABLE 1 SOIL PROFILE CHARACTERISTICS AND ANALYTICAL TEST RESULTS SAMPLE DEPTH SOIL.TEXTURE SOIL NITRATE- pH AND CLASSIFICATION NITROGEN CONTENT CATION EXCHANGE CAPACITY In meq/100g 3 FT Depth Loamy Sand 3 ppm NO,-N 6.9 3.1 meq/100g 10 FT Depth Sand 2 pprn NO,-N 7.0 2.9 me /100 i i Page -3- Chesney Consulting