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Nitrate Loading Study Irerracon <br /> Flag City#4 ■ Lodi, California <br /> September 20, 2018 ■Terracon Project No. NA187043 <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 (Nz) 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 loam soils <br /> anticipated on the site (Section 1.1), a denitrification factor of 15 percent would seem reasonable; <br /> however, given the hardpan present and the associated low permeability, a denitrification factor <br /> of 30 percent 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 /> Average Effluent Deep <br /> Result Leach Field <br /> Proposed Daily Concentration Percolation <br /> (mg/L-N) <br /> Use (Nc)" Acres (A) Effluent (NW) Denitrification of Rainfall <br /> (Q) (gpd) (mg/L-N) (R) (in) <br /> Truck 6.0 13.78 555 85 30 5.76 <br /> Terminal <br /> * EPA maximum contaminant level (MCL)for nitrate as N 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 6.0 mg/L-N which is below 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 United State Geological Survey Thornton (1978), Lodi North (1976), <br /> Terminous (1997), and Lodi South (1976) California Quadrangles topographic map (Appendix A), <br /> the site is located at approximately 15 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 adjacent south of the site. As the subject property is relatively flat, we do not foresee <br /> percolating effluent affecting the surface water resources. <br /> Responsive ■ Resourceful ■ Reliable 8 <br />