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Soil Suitability / Nitrate Loading Study <br />Morada Produce — Ag Processing Building Stockton, California <br />May 14, 2021 rr Terracon Project No. NA217014 <br />lierracon <br />term effect (i.e., over years) on groundwater quality, and is not intended for prediction of seasonal <br />changes" (Hantzsche and Finnemore, 1992). <br />The method takes into account the development area, soil denitrification factor, rainfall volume, <br />rainfall nitrate concentration, waste effluent quantity, and waste effluent nitrate concentration. The <br />formula, assumptions and calculations used for the analysis are shown in Appendix F. The units <br />of nitrate used in the mass balance equation are nitrate-N, whose maximum drinking water <br />contaminant level (MCL) is 10.0 mg/L. <br />2.1 Chemical and Physical Properties of Soil <br />2.1.1 Chemical and Physical Soil Properties <br />Terracon reviewed the USDA NRCS Web Soil Survey and USDA Soil Survey of San Joaquin <br />County (1992) for information regarding Hollenbeck silty clay soils (Section 1.5). Selected <br />physical and chemical properties for the soil types are listed in the following table. <br />Table 8. <br />Physical and Chemical Properties* <br />Soil Name <br />/ Map <br />Symbol <br />Depth <br />(in) <br />USDA <br />Texture <br />Unified Soil <br />Classification <br />Clay <br />(%) <br />Permeability <br />(in/hour) <br />Soil <br />reaction <br />(pH) <br />Salinity <br />(mmhos/cm) <br />Septic tank <br />absorption <br />fields <br />Hollenbeck <br />silty clay <br />(173) <br />0-10 silty clay CH, CL 40-60 0.06-0.2 6.6-8.4 <2 <br />slowly <br />10-37 clay CH, CL 40-60 0.06-0.2 6.6-8.4 <2 <br />37-42 silty clay <br />loam CL 30-40 <br />Severe; percs <br />0.2-0.6 6.6-8.4 <2 <br />42-60 cemented --- --- --- --- <br />Selected USDA physical and chemical properties <br />2.1.2 Mass Transport Soil Properties <br />The longer the effluent remains near the surface, the more treatment is enhanced due to natural <br />processes within the soil. The percolation test has revealed that the onsite soils have a <br />moderately rapid percolation at deep depths (23 to 25 feet bgs); however, the shallow soils at 3 <br />feet bgs failed to percolate. <br />2.2 Groundwater Analysis <br />2.2.1 Regional Groundwater <br />A discussion of regional groundwater, including depth to groundwater is included in Section 1.4.1. <br />No significant seasonal trends were evident from the sources consulted. <br />Responsive • Resourceful • Reliable 14