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30 August 2019 AdvancedGeo AGE Project No. 19-4819 Environmental Page 13 of 15 I = Volume rate of wastewater entering the soil averaged over the gross developed area (acres) in inches per year. The total wastewater volume for proposed project will be 600 gpd (existing system) + 300 gpd (proposed system) x 365 days of proposed operation _ (600 + 300) x 365 days - 7.48 gallons per cubic foot = 43,917 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 (30 percent for clay type soils). R = Average rainfall rate per year: 12.03 inches. Nb = Background nitrate-nitrogen concentration of rainfall recharge, from wastewater influences. EXISTING HOME AND PROPOSED HOME CALCULATIONS (COMBINED): Nr = I x Nw (1-d)+ R x Nb _ (I+R) Assumptions: = 328,500 gallons = 43,917 cubic feet wastewater - [(1.67 acres x 43,560 feetz) _ 12 inches] = 7.24 inches/year NW = 34.425 mg/L-N d = 25 percent denitrification R = 12.03 inches/year Nb = 0.1 milligram per liter Nr = [7.24 inches/year x 34.425 mg/L-N (1-0.25)] + (12.03 inches/year x 0.1 milligram per liter) _ (7.24 inches/year + 12.03 inches/year) Nr = 188.13 = 19.27 = 9.76 Nr = 9.76 ppm nitrogen (NO3_N) 9.7. IMPACT OF NITROGEN LOADING FROM SITE PROJECT TO DOWNGRADIENT WATER SOURCES The recharging of groundwater is the most likely potential feature that could impact future nitrogen loading. Since the subject property is flat, AGE does not anticipate percolating effluent will affect any nearby water sources. Based on the volume of wastewater to be generated, the potential vertical migration would not likely degrade the local groundwater.