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II. SOIL SUITABILITY STUDY FINDINGS A. SUBJECT PROPERTY AND SURROUNDING STUDY AREA INFORMATION SSS§ 1.1. Land use to the immediate north and east is industrial facilities an lie Stockton Metropolitan Airport. To t south is-predominately faunLand with ran and ranchettes. To the immediate west, i a stilling basin for the South Fork of Little Johns Creek his basin is less than six feet deep; therefore,t e leachfield setbac� is 1 ft. Further west is the town of French Camp. e i J SSS§3.1,3.2,3.3,3.4,3.5,3.6,3.7, 6.8. Applications for Permit in the EHD microfiche files were reviewed to determine life spans of surrounding septic systems. Since rural development is sparse in the surrounding areas, the town of French Camp was reviewed, specifically the French Camp School. From February 1961, up through June 1991 were there no repairs completed. Only one other repair was completed in the surrounding one mile radius from the subject property. Therefore, it appears that systems in this locale possess reasonable life spans. Copies of these Applications are found in Appendix F. 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§ The UC avis Soil Web esignates the soil as Ja nne( la 0 . Texture analysis - — by &L La s fin t e s t 20 below grade (b.g.)to be a hea clay, ut at the 42 depth, the soi is classified as loam(silt NLS§ 1.1, 1.2. The surface and subsurface soil investigation began on January 3,2019 with the drilling of one 40-inch deep perc test boring. Auger cuttings were sampled from the 20" depth and the 40" depth. As noted on the A&L Laboratory Soil Report in Appendix C, 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. In addition,the carbon:nitrogen(C:N) ratio was also determined. As noted, the organic matter is 2.4% at 20", but declines to 1.1%at 40" which translates to an Estimated Nitrogen Release(ENR) of 51 lbs. of N/acre. This is an insignificant concentration of nitrogen over a one acre area. The soil nitrate-nitrogen concentration is very low at 4 ppm at the 20" depth and declines to 1 ppm at 40", illustrating denitrification. 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 the ammonia formation. The CEC measures the ability of the soil to theoretically trap and hold ammonium molecules. The CEC at 20" is very high at 35.0 and lowers to a still significantly high 27.4 meq/100g. This indicates a high potential for the clay and silt soil to retain ammonium molecules within the soil environment. Page-2- Chesney Consulting