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F7= Resultant <br /> average concentration of nitrate-nitrogen in recharge water- (ppm N0,-N) <br /> te of wastewater entering the soil averaged over the gross developed area in inches per yr <br /> gen concentration of wastewater in mg N/L <br /> d = Fraction(%)of nitrate-nitrogen loss due to denitrification in the soil <br /> R = Average recharge rate of rainfall - inches per yr NLS§3.2 <br /> Nb= Background nitrate-nitrogen concentration of rainfall recharge, exclusive of wastewater influences <br /> (ppm NO3-N) <br /> Values and Assumptions <br /> 1= 360 and x 306 work d/yr= 110,160 gals=total W W/yr= 14,727 cu ft = 1.00 in. <br /> 4.08 Ac x 43,560 sq ft/Ac x(1 ft/12 in.) <br /> Nw = 103 mg N/L: 20% reduction from the septic tanks =(1-0.2)103 =82 mg N/L <br /> d = Assume 20% due to the fine-grained soil at the potential soil-effluent interface as observed in the <br /> soil chemistry results. <br /> R = 12 in/yr. <br /> Nb= Assumed to be 0.1 ppm NO3 N <br /> 1.00 in/yr(82.4 me N/L) (1 - 0.20)+(12 in/yr x 0.1 me/L) <br /> Nr = (1.00 in/yr+ 12 in/yr) <br /> Nr = 5.1 ppm as nitrate-nitrogen(NO3 N)or 23 ppm as nitrate(NOD <br /> IV. WASTEWATER DISPOSAL SYSTEM <br /> OPERATIONAL PARAMETERS <br /> The ADF of 360 gpd is based on a Men's and Women's restrooms with low-flow toilets, one urinal <br /> in the Men's and lavatories in each restroom. A filter bed effluent disposal structure has been <br /> installed and is operational. A filter bed was installed instead of conventional leachlines to reduce <br /> the disposal area footprint. <br /> Lift Station and Septic Tanks <br /> Influent from the future Office Building is currently proposed to gravity flow into a lift station per <br /> the Burns & McDonnell plans. Chesney Consulting is recommending that a 1,200 gallon septic <br /> tank be installed in front of this lift station to trap all solids,trash, etc. Therefore, the lift station <br /> will only be pumping clarified influent/effluent to the existing 2,000 gallon septic tank. <br /> Lc= <br /> natively, the second compartment of the 1,200 gallon tank can be the pump chamber/lift <br /> n, foregoing the need for a separate lift station. Effluent from the 2,000 gallon tank will <br /> ty flow to the existing filter bed as illustrated on the Site Plans. The lift station(if separate) <br /> e off-the-shelf and must have a duplex pump system. <br /> 7 <br /> Chesney Consulting <br />