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Nitrate Loading Study Irerracon <br /> Cho Property ■ Ripon,California <br /> September 6, 2018 0 Terracon Project No. NA187038 <br /> concentration for total nitrogen in wastewater for the project is approximately 35 mg/L-N over the <br /> long term. <br /> 3.5.1 Denitrification Estimate <br /> Denitrification is an important process which occurs within the leach field whereby certain bacteria <br /> utilize the oxygen in the nitrate (NO3) and release nitrogen gas (N2) to the atmosphere. <br /> Denitrification is expressed as a percentage, and the normally accepted range is 10 percent to 35 <br /> percent. Soils with higher clay content, moist soil conditions, high pH, and organic material <br /> denitrify by about 35 percent, and soils with high sand content and fast percolation rates are <br /> estimated to denitrify at a lower rate, about 10 to 15 percent_ Based on the sandy soils and <br /> relatively low clay content anticipated on the site(Section 1.1), a denitrification factor of 10 percent <br /> was selected. <br /> 3.5.2 Nitrate Loading Scenario <br /> The following table presents a summary of the nitrate loading calculation for the proposed site <br /> use. A copy of the nitrate loading calculation is included in Appendix B_ <br /> Table 4. <br /> Summary of Nitrate Mass Balance Equation. <br /> Result Average Effluent Leachfield Deep <br /> Land Use (Nc)* Acres(A) Daily Flow Concentration Denitrification Percolation <br /> (mg/L- (Q)(gpd) (Nw) (d) of Rainfall <br /> N) (mg/L-N) (R)(in) <br /> Proposed 31.3 1.5 560 35 10% 2.54 <br /> residential use <br /> *EPA maximum contaminant level (MCL)for nitrate as N in drinking water is 10 mg/1.-N. <br /> Based on the nitrate loading balance calculation (Table 4), nitrate levels for the proposed future <br /> use is anticipated to be 21.3 mg/L-N which is above the MCL of 10.0 mg/L-N_ <br /> 3.5.3 Impact of Nitrate Loading to Nearby Water Sources <br /> Based on a review of the USES Avena (1994) California Quadrangle topographic map(Appendix <br /> A), the site is located at approximately 80 feet above mean sea level with a topographic gradient <br /> toward the west. The nearest surface water source to the site is an unidentified irrigation canal <br /> located approximately 1,000 feet southwest of the site. As the subject property is relatively flat, <br /> we do not foresee percolating effluent affecting the surface water resources. <br /> Responsive ■ Resourceful ■ Reliable 8 <br />