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LUCCA WINERY SOIL SUITABILITY & NITRATE LOADING STUDY MAY 2013 II. SOIL SUITABILITY STUDY FINDINGS A. Subject Property and Surrounding Study Area Information SSS§ 1.1. As noted on the San Joaquin County Parcel Viewer Maps, the current - surrounding land use is composed primarily of agricultural production land and very low density residential structures and ranchettes. Surrounding land has been in agricultural production for many decades. New development within the City of Ripon has occurred further to the west. The property is zoned AG-40 with no proposal for a zone reclassification. SSS§ 3.1, 3.2, 3.3, 3.4, 3.5, 3.6. Applications on file with EHD reveal that there have been twenty-three permits issued for repairs/additions to existing systems within a one- half mile surrounding the project site. A summary of the permit applications is provided in Appendix C. The project site has relatively level terrain; consequently, there will be no need to incorporate design considerations for slopes within the wastewater disposal area. B. Soil Physical Characteristics and Analytical Test Results SSS§ 5.2. The United States Department of Agriculture - Soil Conservation Service (USDA-NRCS) indicates the entirety of the on-site soils to consist of Delhi loamy sand (#142). As referenced by the NRCS, the surface layer is loamy sand about 26 inches thick. The remaining soil depth to 60 inches is also sand, which was also observed and confirmed by the percolation test results. NLS§ 1.1, 1.2. As noted on the A&L Western Agricultural Laboratory Soil Analysis Reports found in Appendix D, chemical analyses of the soil samples from the disposal area quantify the constituents that will influence nitrate loading from this project. The important parameters for nitrate loading assessment are the organic matter, pH, cation exchange capacity (CEC), and nitrate-nitrogen content. The nitrate-nitrogen concentrations are very low at both test depths of three feet and seven feet in comparison to normal agronomic concentrations. This suggests a low potential for future nitrate-nitrogen loading from indigenous nitrogen content within the soil. Further, based upon the reduction in the levels in nitrate-nitrogen from the shallow to deeper analysis would suggest denitrification within the soils through deep percolation. Since septic effluent is composed predominately of ammonium (NH4), the pH, along with the CEC, are significant influences on ammonium molecules. The pH of the soil is slightly acidic to balanced, which may promote 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 are low at both depths. This suggests a greater potential for denitrification. Page 13