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18 September 2020 AdvancedGeo Project No. 20-6116 AnEmployee-Owned Company Page 14 of 16 RESIDENTIAL/COMMERCIAL: IresiaentiaI = Volume rate of wastewater entering the soil averaged over the gross developed area (acres) in inches per year. The total wastewater volume is 300 gpd (existing residential systems) x 365 days of proposed operation = 300 x 365 days = 7.48 gallons per cubic foot = 14,639 cubic feet of wastewater. Does not account for evapotranspiration likely to occur. (commercial = Volume rate of wastewater entering the soil averaged over the gross developed area (acres) in inches per year. The total wastewater volume is 220 gpd (existing commercial systems) x 260 days of proposed operation = 220 x 260 days _ 7.48 gallons per cubic foot = 7,647 cubic feet of wastewater. Does not account for evapotranspiration likely to occur. NW = Total nitrogen concentration of wastewater at 45 mg/L-N based on the average discharge. Accounting for the loss of mg/L-N in the septic tank at 15% = 45-15%= 38.25 and the loss from the biomat at 10% 38.25 - 10% = 34.425 mg/L-N. d = Fraction of nitrogen concentration removed from the wastewater due to denitrification within the soil (25 percent for loamy sandy soils). R = Estimated Deep percolation / average rainfall recharge rate per year: 3.00 inches. Nb = Background nitrate-nitrogen concentration of rainfall recharge: 1.0 mg/I. The Nb is an average value determined for San Joaquin County by the EHD. EXISTING RESIDENTIAL/COMMERCIAL CALCULATIONS: Nr = I x Nw (1-d)+ R x Nb = (I+R) Assumptions: I = 166,700 gallons = 22,286 cubic feet wastewater + [(20 acres x 43,560 feet2) _ 12 inches] = 22.286 - 72,600 = 0.31 inches/year NW = 34.425 mg/L-N d = 25 percent denitrification R = 3.00 inches/year Nb = 1.0 milligram per liter Nr = [0.31 inches/year x 34.425 mg/L-N (1-0.25)] + (3.00 inches/year x 1.0 milligram per liter) + (0.31 inches/year + 3.00 inches/year) Nr = 11.00 = 3.31 = 3.32 Nr = 3.32 ppm nitrogen (NO3_N)