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lrerraccin Soil Suitability / Nitrate Loading Study <br />Morada Produce — Ag Processing Building w Stockton, California <br />May 14, 2021 w Terracon Project No. NA217014 <br />Based on the results of the shallow soil borings, the proposed leach field is expected to be located <br />within silty sand. Based on depth to groundwater (Section 1.4.1) and the clayey soils anticipated <br />in the vadose zone (Section 1.5.3), a denitrification estimate of 30 percent was selected. <br />2.3.5 Nitrate Loading Scenario <br />A nitrate loading scenario was performed to determine the impact from the proposed project. The <br />scenario utilizes the variables discussed previously which represent the estimated conditions and <br />uses associated with this project. The following table presents a summary of the nitrate loading <br />calculation for the site. A copy of the nitrate loading calculation is included in Appendix F. <br />Table 11. <br />Summary of Nitrate Mass Balance Equation. <br />Septic System No. Result (Nc)* <br />(mg/L-N) <br />Acres <br />(A) <br />Average <br />Daily Flow <br />(Q) (gpd) <br />Effluent <br />Concentration <br />(NW) <br />(mg/L-N) <br />Leachfield <br />Denitrification <br />(d) <br />Net Rainfall <br />Recharge <br />(in/year) (R) <br />Existing Land Use <br />Septic Systems 1,2, <br />and 3 (Standard) <br />3.0 64.13 1,299 85 30% 7.79 <br />Existing Land Use <br />Septic Systems 1.2. <br />and 3 (Peak) <br />13.7 64.13 12,148 75 30% 7.79 <br />Existing Land Use + <br />Proposed Septic <br />System 4 (Standard) <br />3.2 64.13 1,462 85 30% 7.79 <br />Existing Land Use + <br />Proposed Septic <br />System 4 (Peak) <br />13.8 64.13 12,311 75 30% 7.79 <br />* Maximum contaminant level (MCL) for nitrate in drinking water is 10 mg/L-N <br />Peak Season - April to June and August to September <br />Standard Season, January to March, July, October to December <br />Based on the nitrate loading balance, nitrate levels for the existing land use (Septic Systems 1, <br />2, 3) is 3.0 milligrams per liter nitrogen (mg/L-N) per year during the standard season and 13.7 <br />mg/L-N during the peak season, slightly above the MCL of 10.0 mg/L-N. The proposed ag <br />processing building (Septic System 4) is anticipated to increase nitrate levels to 3.2 g/L-N during <br />the standard season and 13.8 mg/L-N during the peak season, which is also above the MCL. <br />The annual nitrate loading average for the existing land use is 8.35 mg/L-N and 8.5 nng/L-N for <br />the existing and proposed land use, which is below the MCL. <br />Responsive • Resourceful III Reliable 18