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Soil Suitability/ Nitrate Loading Study Irerracon <br /> Vacant Commercial Property ■ Stockton, California <br /> December 7, 2018 ■ Terracon Project No. NA187056 <br /> that commercial use will have higher concentrations of total nitrogen when compared to residential <br /> use. It is estimated that the average concentration for total nitrogen in wastewater for the project <br /> is approximately 85 mg/L-N over the long term. <br /> 2.3.4.2 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. <br /> Based on the results of the soil borings, the leach field (<3.5 feet bgs) and deep seepage pits <br /> (<25 feet bgs) are anticipated to be located within silt and clay soil layers; therefore, a <br /> denitrification estimate of 35 percent is anticipated. <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 G. <br /> Table 10. <br /> Summary of Nitrate Mass Balance Equation Proposed Development. <br /> Result Average Effluent Leach Field Deep <br /> Parcels (Nc)" Acres(A) Daily Concentration Denitrification Percolation <br /> Effluent(Q) (Nw) of Rainfall <br /> (mg/L-N (gpd) (mg/L-N) (d) (R)(in) <br /> 2 33.6 4.18 6,000 85 35 12.78 <br /> 'Maximum contaminant level(MCL)for nitrate in drinking water is 16 mg/L-N. <br /> 2.3.6 Impact of Nitrate Loading to Nearby Water Sources <br /> Since the subject property is relatively flat, we do not foresee percolating effluent affecting surface <br /> water sources. <br /> Responsive■ Resourceful ■ Reliable 19 <br />