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Soil Suitability / Nitrate Loading Study <br /> 11065 North Alpine Road I Stockton, California r rerracon <br /> June 30, 2026 1 Terracon Project No. NA267068 <br /> The Hantzsche and Finnemore approach is "...a conservative (worst case) first <br /> approximation of groundwater nitrate-nitrogen concentration resulting from the <br /> combined effect of on-site sewage disposal systems and precipitation. This (the equation <br /> and approach) is for estimation of long-term effect (i.e., over years) on groundwater <br /> quality, and is not intended for prediction of seasonal changes" (Hantzsche and <br /> Finnemore, 1992). <br /> The method takes into account the development area, soil denitrification factor, rainfall <br /> volume, rainfall nitrate concentration, waste effluent quantity, and waste effluent nitrate <br /> concentration. The formula, assumptions and calculations used for the analysis are <br /> shown in Appendix F. The units of nitrate used in the mass balance equation are nitrate- <br /> N, whose maximum drinking water contaminant level (MCL) is 10.0 mg/L. <br /> 2.1. Chemical and Physical Properties of S4 <br /> 2.1.1. Chemical and Physical Soil Properties <br /> Terracon reviewed the USDA NRCS Web Soil Survey and USDA Soil Survey of San <br /> Joaquin County (1992) for information regarding Hollenbeck silty clay (Section 1.5). <br /> Selected physical and chemical properties for the soil type are listed in the following <br /> table. <br /> Table 8 <br /> Physical and Chemical Properties <br /> Soil Name Depth Clay Permeability Soil Salinity Septic <br /> / Map USDA Unified Soil reaction tank <br /> Symbol (in) Texture Classification (o/o) (in/hour) (PH) (mmhos/cm) abf a dson <br /> 0-10 Silty Clay CL 40-60 0.06-0.2 6.6-8.4 <2 <br /> Hollenbeck 10-37 Clay CL 40-60 0.06-0.2 6.6-8.4 <2 <br /> Severe <br /> (173) 37-42 Silty Clay ML 30-40 0.2-0.6 6.6-8.4 <2 <br /> Loam <br /> 42-60 Cemented --- --- --- --- --- <br /> 0-25 Clay CL 40-60 0.06 - 0.2 6.6-7.3 <2 <br /> Galt <br /> 25-34 Clay CL 40-60 0.06 - 0.2 6.6-8.4 <2 Severe <br /> (160) <br /> 34-60 Cemented --- --- --- --- <2 <br /> Note: U.S. Department of Agriculture, Soil Conservation Service, 1992, Soil Survey of San Joaquin <br /> County, California. Selected USDA physical and chemical properties <br /> millimhos per centimeter (mmhos/cm) <br /> Facilities I Environmental I Geotechnical I Materials 15 <br />