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Bail Bond Business Page 11 of 13 <br /> our Project Number: LGS080549 <br /> January 13,2009 <br /> 4.2Denitrification Estimate <br /> Denitrificatio is an important process which occurs within the leach field whereby certain <br /> bacteria utilitie 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 <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 ont t and fast percolation rates are <br /> estimated to denitrify at a I wer rate, about 10 percent to 15 percent. <br /> A denitrification factor of 10 per ent was selected for the Site because of the coarser-grained <br /> nature of the soils. <br /> 2.3.5 Nitrate Loading Scenario <br /> A nitrate loading scenari&was performed to determine the impact from the proposed project. <br /> The scenario utilizes the variables discussed previousl which represent the estimated <br /> conditions and uses associated with this project. The followin table presents a summary of the <br /> nitrate loading calculation for the site, as presented in Plate 7. <br /> Table 5� <br /> S rnmary of Nitrate Mass Balance Equation. <br /> 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 42.8 0.11 36 85 10% 3.54 <br /> * Maximum contaminant level(MCL)for nitrate in drinking water js o m /L-N. <br /> 2.3.6 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 /> 2.4 Discussion of Nitrate Loading Results <br /> 2.4.1 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 parcel may cause a build up of, <br /> nitrates in the aquifer abo10 mg/L-N. <br /> 2.4.2 Methods of Mitigation <br /> An engineered septic system designed to mitigate high nitrate levels .will be required by the <br /> EHD. Our office has been contracted by the client to design the system. The plans for the <br /> system are forthcoming. <br /> 902 Industrial Way•Lodi,CA 95240.209.367.3701 •Fax 209.369.4228 02008 Neil O.Anderson&Associates,Inc <br />