Laserfiche WebLink
NitrateLoadingStudy 1�erracon <br /> Rowe Property s Lodi, CA <br /> November 6, 2017 ■ Terracon Project No. NA177059 <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 the USDA soil <br /> survey(Section 1.1), interviews with the owner, Tokay fine sandy loam soils known to exist at the <br /> site, depth to groundwater of 90 to 100 feet bgs, and the potential for interstrati ied finer grained <br /> soils to exist between the upper sandy loam and groundwater that are anticipated at the site; a <br /> denitrification factor of 25 percent was selected. <br /> 3.5.2 Nitrate Loading Scenario <br /> A nitrate loading scenario was performed to determine the impact from the estimated existing <br /> residential use and proposed future use. Additionally, a potential nitrate loading scenario was <br /> calculated for the existing three bedroom residence and future two bedroom residence as per <br /> EHD recommendations. The scenarios utilize the variables discussed previously which represent <br /> the estimated conditions and uses associated with the site. The following table presents a <br /> summary of the nitrate loading calculation for the existing and proposed site uses versus the <br /> potential site use. A copy of the nitrate loading calculations is included in Appendix B. <br /> Table 4. <br /> Summary of Nitrate Mass Balance Equation. <br /> Result Effluent Deep <br /> (Nc)` Average Concentration Leaccati 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 /> Existing 7.2 1.0 140 35 25% 5.76 <br /> residential use <br /> Existing <br /> residential + 11,0 1.0 280 35 25% 5.76 <br /> proposed <br /> future use <br /> Potential 13.5 1.0 420 35 25% 5.76 <br /> residential use <br /> Potential <br /> residential + 16.7 1.0 700 35 25% 5.76 <br /> proposed <br /> future use <br /> Maximum contaminant level (MCL)for nitrate in drinking water is 10 mg/L-N. <br /> Responsive ■ Resourceful ■ Reliable 8 <br />