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2222222 fFin stewater Flow Volume Projections total Average Daily Flow(ADF) volume of wastewater usage anticipated by CGS is illustrated Appendix G. As noted, a total of 8,143 gallons per day(gpd) is anticipated with a full occupancy 50 people. However, non-potable water use of 650 gpd has been removed from this figure for a total ADF of 7,493 gpd. It is anticipated CGS will have year-round occupancy. Consequently, the maximum yearly flow volume is estimated to be: 7,493 gpd x 365 days/year= 2,734,945 gallons of wastewater generated per year, which is used in the nitrate loading calculations below and will be used for the PTP design. Wastewater Characteristics The domestic wastewater generated from CGS will be composed primarily of blackwater from toilets and gray water from other sources, such as bathing,personal care, laundry, cooking, etc. Although a Total Nitrogen concentration of 35 mg/L is specified in the USEPA Design Manual- Wastewater Treatment and Disposal Systems (Office of Water/Office of Research and Development,EPA/625/R-00/008)for typical household nitrogen concentrations, a Total Nitrogen concentration of 42 mg/L is used in the calculations below accounting for an increase in blackwater flow volumes. Calculated Nitrate-Nitrogen Loading The calculated nitrate-nitrogen impact to the soil and potentially the groundwater, as illustrated below, is based on the CGS without wastewater treatment. These calculations demonstrate that wastewater treatment is warranted. From the results of the calculations using all applicable parameters, the nitrate loading is exceeded 61% over the MCL of 10 ppm. HANTZSCHEIFINNEMORE EQUATION IN,,,(1 -d)+R Nb Nr= (I+R) Where: Nr = Resultant average concentration of nitrate-nitrogen in recharge water-(ppm NO3-N). I = Volume rate of wastewater entering the soil averaged over the gross developed area. Nw = Total nitrogen concentration of wastewater in mg N/L. d = Fraction(%)of nitrate-nitrogen combined loss in the soil due to denitrification. R = Est. Annual Net Rainfall Recharge(NRR)from Precipitation and Eto Data Nb = Background nitrate-nitrogen concentration of rainfall recharge, exclusive of wastewater influence. Values and Assumptions: I = 2,270,379 gals/y=303,527 cu ft = 28.85 in/yr 2.9 Ac x 43,560 sq ft/Ac x(1 ft/12 in) Page -4- Chesney Engineering, Inc.