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II. SOIL SUITABILITY STUDY FINDINGS A. SUBJECT PROPERTY AND SURROUNDING STUDY AREA INFORMATION SSS 1. Land use to the immediate north, south and east of the project is rural residential, co rcial, industrial, educational, and farmland. To the south is Durham Ferry Road and to the west is State Route 33, and the Union Pacific Railroad. �%SSS§3.1,3.2,3.3,3.4,3.5,3.6,3.' , 6.8. Applications on microfiche files with the EHD reveal that there have been seven permits issued for repairs/replacements/additions to existing systems within the one-half mile radius study area, including an addition of90 ft of leachline on the subject property. This can be considered a high number of permits for the study area but considering the length of time these structures have been in existence, septic system failures were bound to occur. The project site has level terrain; consequently, there will be no need to incorporate design considerations for slopes within the future disposal area. -- B. SOIL PHYSICAL CHARACTERISTICS AND ANALYTICAL TEST RESULTS SSS 5.2. The United States Department of Agriculture -Natural Resource Conservation Service (U -NRCS) indicates the property soils are Capay clay(#121). The surface and subsurface soil investigation began on March 12, 2015 with the drilling of three shallow perc test borings. Test borings were drilled in the future disposal field as illustrated on the Site Plans found in Appendix C. The first test drilled was 24 inches deep and tested percolation from the soil surface down to 2 ft in depth, representing permeability occurring on the sides of the future filter bed. The second test measured percolation at the proposed floor of the filter bed at the 36-inch depth and the final 48- inch depth test depth measured percolation under the floor of the future filter bed. NLS§ 1(�. 1.2. uger cuttings were sampled from the 4 ft test boring, and were retrieved from the 2 ft and 4�de the for chemical analysis. No standing water, or saturated soil was observed at the P Y g _ bottom of the 4 ft boring. As the noted on the A&L Laboratory Soil Analysis Reports i Append B, chemical analyses of the two soil samples quantify several 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. As noted,the organic matter in the surface soils is low and decreases with depth. The nitrate- nitrogen concentration is very low in the surface soils at 3 ppm and decreases to 1 ppm illustrating that denitrification(66%) is occurring in these high clay content soils. 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 is somewhat alkaline throughout the soil profile which may have a negative effect on ammonium formation and stability. The CEC measures the ability of the soil to theoretically trap and hold ammonium molecules. Cation Exchange Capacities of the soil samples illustrate a high potential for the clay soil to retain the ammonium molecules for microbial and plant root uptake. Nitrification is also hindered due to the anaerobic micro-sites within the clay soil. Page -2-