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Nitrate Loading Study 1 rerracon <br /> Landavazo Property Tracy, CA <br /> December 15, 2017 Terracon Project No. NA177067 <br /> Based on a review of Table 2, the estimated potential sewage Flow rate for the proposed three <br /> bedroom residence is 420-gallons per day. <br /> The average total nitrogen concentration of domestic wastewater is normally considered to be 20 <br /> to 85 mg/L-N with 35 to 45 mg/L-N being typical(Crites and Tchobanoglous, 1998). It is estimated <br /> that commercial use will have higher concentrations of total nitrogen when compared to residential <br /> use. For the purposes of the nitrate loading estimate, it is estimated that the average <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 percent to 15 percent. Based on clay soil present <br /> at the site per the USDA soil survey (Section 1.1), a denitrification factor of 35 percent was <br /> 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 Effluent Deep <br /> (Nc)` Average Concentration Leitchfield percolation <br /> Land Use Acres(A) Daily Flow Denitrification <br /> (mg/L- (Q) (gpd) (Nw) (d) of Rainfall <br /> N) (mg/L-N) (R) (in) <br /> Proposed 17.6 0.78 420 35 35% 2.27 <br /> residential use <br /> Maximum contaminant level (MCL)for nitrate in drinking water is 10 mg/L-N. <br /> Based on the nitrate loading balance calculation (Table 4), nitrate levels for the proposed future <br /> use is anticipated to be 17.60 mg/L-N which is above the MCL of 10.0 mg/L-N. <br /> Responsive■ Resourceful ■ Reliable 7 <br />