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Calculated nitrate-nitrogen loading from the entire subject property: <br /> MG - d) + RN6 <br /> Nr= (I +R) <br /> Where: <br /> Nr = Resultant average concentration of nitrate-nitrogen in recharge water-(ppm NO3-N) <br /> I = Volume rate of wastewater entering the soil averaged over the gross developed area in inches per yr <br /> Nw = Total nitrogen concentration of wastewater in mg N/L <br /> d = Fraction(%)of nitrate-nitrogen loss due to deni tion in the soil <br /> R = Average recharge rate of rainfall- inches p yr NLS 3.2 <br /> Nb = Background nitrate-nitrogen concentration infall recharge, exclusive of wastewater influences <br /> (ppm NO3-N). <br /> Values and Assumptions: <br /> I=52,500 gals=total WW/yr=7,019 cu ft =0.75 in/yr <br /> 2.58 Ac x 43,560 sq ft/Ac x (I W12 in) <br /> Nw= 62 mg N/L <br /> d = Assume 25%due to high percentage of fine-grained clay soil and high CEC in upper soil profile. <br /> R = 13 in/yr. / <br /> Nb= Assumed to be 0.1 pm N0,-N INZ)�c C/1< acw' <br /> 7;, ,-s, 3�// <br /> 0.75 in/yr(62 mg N/L) 0 -0.25)+(13 in/yr x 0.f mg/L) <br /> Nr = (0.75 in/yr+ 13 in/yr) / 3 7j <br /> Nr = .63 m as nitrate-nitrogen (NO�11.8 ppm as nitrate (NO,) <br /> IV. SEPTIC SYSTEM DESIGN OF COMPONENTS AND OPERATIONAL PARAMETERS <br /> SSS . The following is a description and applicable calculations of the wastewater <br /> ma a ement system structures and operations. <br /> IV. SEPTIC SYSTEM DESIGN OF OPERATIONAL PARAMETERS AND COMPONENTS <br /> A. SEPTIC TANK CALCULATIONS <br /> Septic tanks store the accumulated sludge, scum and effluent(clear zone)volumes, which in tum <br /> affect treatment of nitrogen within septic tanks. <br /> Detention Time Calculation: <br /> Detention Time= 1,200 gal proposed tank capacity x 0.70 (30%volume lost to sludge/scum accumulation) <br /> 1.5 (Peaking factor)x 210 gals/day(total calculated ADF) <br /> Detention Time=2.7 days. The minimum acceptable detention time is 1.0 days. Therefore,a proposed tank <br /> size of 1,200 gallons is adequate for hydraulic residence time(HRT). <br /> 7 <br />