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In summary, the soils testing and investigation has found the indigenous soils at the proposed soil - effluent interface depth to serve the proposed ADU, to contain a predominately fine-grained sandy loam material that possesses a relatively rapid percolation rate. The nitrate loading criteria were found to be acceptable (Under the Maximum Contaminant Level MCL). II. SOIL SUITABILITY STUDY FINDINGS A. SUBJECT PROPERTY AND SURROUNDING STUDY AREA INFORMATION SSS§ 1.1. Surrounding land use to the north is, and has been, in agricultural production and rural residential for many decades. To the west is the City of Mountain House and to the east is rural residential (The Santos Ranch Subdivision). To the southeast is the City of Tracy. The property is zoned AG -40. SSS§ 3.1, 3.2, 3.3, 3.4, 3.5, 3.6. Applications on file with the EHD reveal that there have been three permits issued for repairs/replacements/additions to existing systems within the one-half mile study area on Von Sosten Road. These applications in addition to all applications made for the subject property are found in Appendix G. The project site has level terrain; consequently, there will be 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 United States Department of Agriculture - Soil Conservation Service (USDA -SCS) and the UC Davis Soil Web indicates the onsite surface soils to consist of Capay clay (#118) and low percentages of Stomar, Vernalis and Willows clay soils. The deeper soils from the bottom of the percolation test boring (34"-38") were determined by particle size analysis to be a sandy loam. NLS§ 1.1, 1.2. As the noted on the A&L Laboratory Soil Analysis Report in Appendix B, the chemical analyses of the retrieved soil sample quantify several constituents that influence nitrate loading from this project. The important parameters for loading assessment are the organic matter, pH, cation exchange capacity (CEC), clay content percentage, along with the nitrate -nitrogen content of the soil. As noted, the organic matter is low which is to be expected since it has not been farmed for many years. The nitrate -nitrogen concentration is at 9 ppm, indicative of organic matter decomposition and animal waste. Because 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 alkaline which retards ammonium formation and stability. The CEC measures the ability of the soil to theoretically trap and hold ammonium molecules and was measured at 13.3; indicative of the sand content at 73%. The clay content percentage of 17% indicates a higher potential for the retention of ammonium molecules for microbial uptake, and suppression of nitrification and promotion of denitrification. 2 Chesney Consulting