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Discussion on the Alkalinity Requirement for Nitrification The nitrate-nitrogen loading calculation are contingent upon the environmental factors required for nitrification to occur. These conditions include soil pore-space oxygen content, soil temperature, pH, electrical conductivity, organic matter, cation exchange capacity, and alkalinity. Alkalinity in wastewater effluent is derived from well water, in addition to the introduction of wastes. Nitrification consumes approximately 7.1 mg of alkalinity for every mg of ammonia-nitrogen (NI-14 - N) oxidized. Nitrification of the average Total Nitrogen (TN) concentration of 62 mg/L, as determined below, would require: 62 mg/L NH4-N x 7.1 mg CaCO3 = 440 mg/L alkalinity. The alkalinity in the city water is typically around 106 mg/L. Therefore, soil alkalinity and alkalinity from wastes must provide a significant alkalinity concentration for nitrification to occur. D. SURFACE WATER INFORMATION Climatic Data. NLS§ 3.2. Hantzsche Rainfall Mass Balance Approach Available Rainfall = 17.85" (1.49 ft) Net Rainfall Recharge = 8.82" (0.735 ft) Pervious areas = (5,800 sf) = 0.133 ac x 325,851 gals/ac-ft x 0.735 ft = 31,889 gals (R1) Buildings/paved areas = 4,219 sf = 0.0969 ac 0.735 fix 325,851 gals/ac-ft = 239,501 gals/ac x 0.0969 ac = 23,207 gals runoff from house/paved areas onto pervious areas of property including leachfield area. Thus, Net Rainfall Recharge was used. (b) City stormwater management, no Retention Basin area (c) (e) = 23,207 gals (b) + 0 gals (c) = 23,207 gals (R2) R1 + R2 = R = 31,889 gals + 23,207 gals = 55,096 gals = 0.169 ac-ft III. NITRATE LOADING STUDY FINDINGS WASTEWATER FLOW VOLUME PROJECTIONS AND CHARACTERISTICS A. Wastewater Flow Volume Projections To determine nitrate-nitrogen loading from any project, wastewater flow volumes must be determined as accurately as possible. Domestic flow volume projections have been approximated from the USEPA Onsite Wastewater Treatment Systems Manual, Pg. 3-4. Residential (domestic) flow volumes average approximately 69 gallons/person/day. The EHD specifies that each bedroom has the potential for two people, therefore an ADF/bedroom of -140 gpd, 365 dpy. As referenced, the proposed house will have two bedrooms. Therefore, total flow volume projection = 2 bedrooms x 140 gpd/bedroom = 280 gallons wastewater /day x 365 dpy = 102,200 gals/yr = 0.314 ac ft/yr Page -4- Chesney Consulting