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Soil Suitability/ Nitrate Loading Study Irerracon <br /> Proposed Commercial Truck Yard ■ Stockton, CA <br /> August 16, 2019 ■ Terracon Project No. NA197053 <br /> concentration for total nitrogen in wastewater for the proposed office is approximately 85 mg/L-N <br /> for the agricultural building. <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 soils encountered during our borings and anticipated hardpan and sandy clay layers <br /> between 14 and 28 feet bgs , a denitrification estimate of 35 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 /> Result Average Effluent Leachfield Deep <br /> Acres Concentration Percolation <br /> Land Use (Nc)* Daily Flow Denitrification <br /> (mg/L-N) (A) (Q)(gpd) (Nw) (d) of Rainfall <br /> (mg/L-N) (R)(in) <br /> Office 9.5 4.11 100 85 35% 1.77 <br /> Nitrate as N Total 9.5 <br /> Maximum contaminant level(MCL)for nitrate in drinking water is 10 mg/L-N. <br /> Based on the nitrate loading balance, the proposed development is anticipated add 9.5 mg/L-N <br /> below the MCL of 10.0 mg/L-N. <br /> 2.3.6 Impact of Nitrate Loading to Nearby Water Sources <br /> Based on a review of the topographic map (Section 1.1), a slough is located approximately 2,000 <br /> feet north of the site.As the subject property is relatively flat,we do not foresee percolating effluent <br /> affecting surface water resources. <br /> Responsive■ Resourceful ■ Reliable 16 <br />