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Table 5. Weighted Average Concentration Calculation Use Average Daily Estimated Waste Weighted Average Flow Water Quality Product Existing Residence 480 gpd 45 mg/L-N 21,600 gpd-mg/L-N Potential Future 240 gpd 45 mg/L-N 10,800 gpd-mg/L-N Residence Winery Customers 28.6 gpd 85 mg/L-N 2,431 gpd-mg/L-N Winery Staff 14.8 gpd 85 mg/L-N 1,258 gpd-mg/L-N Special Event 1.4 gpd 85 mg/L-N 119 gpd-mg/L-N Customers Totals 764.8 gpd 36,208 gpd-mg/L-N Weighted Average 36,208 gpd-mg/L-N / 764.8 gpd = 47.3 mg/L-N Concentration: Denitrification Reductions Denitrification is a process that occurs in the septic system drain field whereby certain bacteria oxidize the nitrate (NO3) in the waste water and release nitrogen gas (N2) to the atmosphere. Due to the biologic processes in the shallow soils, nitrogen in the drain field will may undergo a reduction between 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 tend to denitrify at a lower rate of about 10 percent. A typical denitrification factor of 25 percent was selected for the Site because of the moderately fine-grained nature of the soils. Nitrate Loading Estimate A nitrate loading scenario was employed to determine the impact from the proposed project to ground water. 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 assumptions for the nitrate loading calculation for the Site, as presented in the attached sheet.