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Project Name: Raverty Property Page 3 of 4 Our Project Number: LGS080551 Date: May 7, 2009 For the subject property, the total daily waste water quantity is 1,086 gallons per day. A 24/365 conversion was used to account for the banquet hall being open 24 days per year. A 2/7 conversion was used to account for the wine tasting facility being open two (2) days per week. The average total nitrogen concentration of domestic waste water is normally considered to be 20-85 mg/L-N with 35 to 45 mg/L-N being typical (Crites and Tchobanoglous, 1998). It is estimated that commercial use will have higher concentrations of total nitrogen when compared to residential use. It is estimated that the average concentration for total nitrogen in waste water for the commercial aspect of the project is approximately 85 mg/L-N over the long term. The adjusted nitrogen long term average using a weighted average is 53.55 mg/L-N. Below is the long term weighted average of nitrogen in the proposed development waste water. 840 gpd x 45 mg/L-N = 37,800 1 246 gpd x 85 mg/L-N = 20,910 58,710 / 1,086 gpd = 54.1 mg/L-N 2.3.4.2 Denitrification Estimate Denitrification is an important process which occurs within the leach field whereby certain bacteria utilize the oxygen in the nitrate (NO3) and release nitrogen gas (Nz) to the atmosphere. Denitrification is expressed as a percentage, and the normally accepted range is 10 percent to 35 percent. Soils with higher clay content, moist soil conditions, high pH, and organic material denitrify by about 35 percent, and soils with high sand content and fast percolation rates are estimated to denitrify at a lower rate, about 10 percent to 15 percent. A denitrification factor of 20 percent was selected for the Site because of the coarser-grained nature of the soils. 2.3.5 Nitrate Loading Scenario A nitrate loading scenario was performed to determine the impact from the proposed project. The scenario utilizes the variables discussed previously which represent the estimated conditions and uses associated with this project. The following table presents a summary of the nitrate loading calculation for the site, as presented in Plate 7. Table S. S mmary of Nitrate Mass Balance E uation. Result Average Effluent Leachfield Deep Parcel (Nc)* Acres(A) Daily Flow Concentration Denitrification Percolation (mg/L-N) (Q)(gpd) (Nw) ) (d) of)i n}II (mg/L-N 1 5.8 22.7 1,086 54.1 10% 5.76 * Maximum contaminant level (MCL)for nitrate in drinking water is 10 mg/L-N. I 902 industrial Way-Lodi,CA 95240-209.367.3701 -Fax 209.369.4228 02009 Neil 0.Anderson&Associates.Inc.