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Bird Road Facility Page 11 of 13 <br /> Project Number: E07183A <br /> November 30, 2007 <br /> II.3.41 Denitr/Fcation Estimate <br /> _ Denitrification is an important process which occurs within the leach field whereby certain <br /> bacteria 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 <br /> 35 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 /> A denitrification factor of 25 percent was selected for the Site because of the fine grained <br /> nature of the soils. <br /> II.3.5 Nitrate Loading Scenario <br /> A nitrate loading scenario was performed to determine the impact from the proposed project. <br /> The scenario utilizes the variables discussed previously which represent the estimated <br /> conditions and uses associated with this project. The following table presents two scenarios; <br /> the first scenario uses 23.5 acres in the equation which is the proposed project area, and the <br /> second scenario uses the total property acreage of 42.39 acres. The following table presents a <br /> summary of the nitrate loading calculation for the site, as presented in Plate 10. <br /> Table S. <br /> S mmary of Nitrate Mass Balance Equation. <br /> r Result Average Effluent Leachfield Deep <br /> Parcel (Nc)* Acres(A) Daily Flow Concentration Denitrification Percolation <br /> (mg/L-N) (Q) (gpd) (Nw) (d) of Rainfall <br /> (mg/L-N) (R) (in) <br /> 1 6.0 23.5 678 51.60 25% 2.52 <br /> 1 4.0 42.39 678 51.60 25% 2.52 <br /> *Maximum contaminant level (MCL)for nitrate in drinking water is 10 mg/L-N. <br /> II.3.6 Impact of Nitrate Loading to Nearby Water Sources <br /> Since the Site is relatively flat, we do not foresee percolating effluent affecting any surface <br /> water resources. <br /> II.4 Discussion of Nitrate Loading Results <br /> II.4.1 Total Nitrate Impact <br /> Based on the method and assumptions described, the result of the nitrate loading balance <br /> indicates that the proposed development on the proposed parcels should not cause a build up <br /> of nitrates in the aquifer above 10 mg/L-N. <br /> �r 902 Industrial Way•Lodi,CA 95240•209.367.3701 •Fax 209.369.4228 02007 Neil O.Anderson&Associates,Inc <br />