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LOGE 1726: Phillips/Michael David NLS Addendum Page 8 September 20, 2017 • Table 4. Weighted Average Concentration Calculation Use Average Daily Estimated Waste Weighted Average Flow Water Quality Product Office Staff 278.6 gpd 85 mg/L-N 23,681 gpd-mg/L-N Restaurant Staff 234 gpd 85 mg/L-N 19,890 gpd-mg/L-N Restaurant Customers 1,350+642.8 gpd 35 mg/L-N 69,748 gpd-mg/L-N Tasting Room Staff 130 gpd 85 mg/L-N 11,050 gpd-mg/L-N Tasting Room Customers 668.6+288 gpd 85 mg/L-N 81,311 gpd-mg/L-N Overflow Tasting Room 11.1 gpd 85 mg/L-N 943.5 gpd-mg/L-N Staff Overflow Tasting Room 128.6 gpd 85 mg/L-N 10,931 gpd-mg/L-N Customers Winery Production Staff 464.3 gpd 85 mg/L-N 39,465.5 gpd-mg/L-N Potential Future Winery 464.3 gpd 85 mg/L-N 39,465.5 gpd-mg/L-N Production Staff Special Events Staff 16.0 gpd 85 mg/L-N 1,360 gpd-mg/L-N • Special Events Customers 102.7 gpd 85 mg/L-N 8,729.5 gpd-mg/L-N Totals 4,779 gpd 306,575 gpd-mg/L-N Weighted Average 306,575 gpd-mg/L-N/ 4,779 gpd= 64.2 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 wastewater and release nitrogen gas (Nz) 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 Plate 5.