Laserfiche WebLink
Since the number of people on-site vary throughout the year, a weighted average based upon <br /> wastewater flows during different times of the year is determined below to establish an Average <br /> Daily Flow(ADF): <br /> February - April= 89 days x 870 gals/day = 77,430 gals <br /> May - June = 61 days x 1020 gals/day= 62,220 gals <br /> July -August= 54 days (6 days/wk- 9 wks) x 795 gals/day=42,930 gals <br /> September - January = 110 (5 days/wk - 22 wks) days x 30 gals/day = 3,300 gals <br /> Total Gallons= 185,880 gals/yr-- 365 days/yr= 509 gals/day ADF <br /> The scientific literature cites nitrogen concentrations in residential septic effluent typically <br /> ranging from 17 mg NIL for basins, sinks, etc. to 140 mg N/L for toilet wastes. Therefore, <br /> considering a 70130 percent usage for toilet water volume and sink water volume, respectively, a <br /> value of 103 mg NIL of septic effluent will be used to calculate nitrate-nitrogen loading for this <br /> project. As illustrated on the Chart on Page 7, the loading projection is based on the maximum <br /> number of people who may potentially use the toilet/sink, etc. on a daily basis. <br /> HA NTZSCHEIFINNEMORE EQ UATION <br /> IN,,(1 - d)+R Nb <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 <br /> inches per yr <br /> Nw= Total nitrogen concentration of wastewater in mg NIL <br /> d = Fraction (%) of nitrate-nitrogen loss due to denitrification in the soil <br /> R — Average recharge rate of rainfall - inches per yr <br /> Nb= Background nitrate-nitrogen concentration of rainfall recharge, exclusive of wastewater <br /> influences (ppm NO3-N) <br /> Values and Assumptions <br /> I = 185,880 gals=total WW/yr=24,850 cu ft=0.623 in/yr <br /> 11.00 Ac x 43,560 sq ft/Ac x (1 ft/12 in) <br /> Nw= 103 mg NIL: 20% reduction from effluent filter+ 10%removal from biomat= 74 mg NIL <br /> d = Assume 30% due to high clay content soil <br /> R = I 1 in/yr. But 50% of total area covered w/roofs and asphalt :. 6 in/yr. <br /> Nb= Assumed to be 0.1 ppm NO3-N <br /> 0.623 in/yr (74 mg N/L)(1 - 0.30) + (6 in/yr x_0.1 mg/L1 <br /> Nr = (0.623 in/yr+ 6 in/yr) <br /> Nr = 4.96 ppm as nitrate-nitrogen(NO3-N) or 22.1 ppm as nitrate (NO3) <br /> 8 <br /> Vafley Ag Research <br />