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7HfANT7ZSCH:E1jF1A <br /> M NUMBER OF PEOPLE 190-230-08 (1.39 Acres) CAN SUPPORT= <br /> NEMORE EQUATION <br /> M(I - d) +RNb <br /> Nr= (I +R) <br /> Values and Assumptions: <br /> I = 12 people x 15 gals/person/d x 260 work d/y,=46,800 pals=total W W/vr=6,257 cu ft= 1.24 in/yr <br /> 1.39 Ac x 43,560 sq ft/Ac x (1 ft/12 in) <br /> Nw= 103 mg N/L <br /> d = Assume 20% due to fine-grained soil <br /> R = 11 in/yr. <br /> Nb= Assumed to be 0.1 ppm NO3-N <br /> lay.7 x . 0 4 1. 1 <br /> 1.24 in/yr(103 me N/L) (I - 0.20) + (11 in/yr x 0.1 mg/L) j Y <br /> Nr = (1.24 in/yr+ l l in/yr) ? y <br /> Nr = 9.0 ppm as nitrate-nitrogen(NO3-N) or 40 ppm as nitrate(NO3) <br /> 12 people for 190-230-08 (1.39 Acres). Area constraints caused by building footprints, <br /> stormwater retention, parking, well site location, septic system location and 100%replacement <br /> area may decrease the number of on-site people significantly. Due to these area constraints, it is <br /> most likely that a filter bed disposal field will have to be installed. <br /> Landscape plants may be used to absorb a percentage of the nitrogen in the effluent pumped to a <br /> filter bed or shallow leachfield. Most plants utilize only two forms of nitrogen- nitrate and <br /> ammonium (NH4). Approximately 75% of conventionally treated septic effluent is ammonium. <br /> The on-site septic systems must discharge under the MCL for nitrate at 10 ppm nitrate-nitrogen or <br /> 45 ppm nitrate. Therefore, percentages of the maximum nitrate concentration in the effluent will <br /> be correlated with the amount estimated to be synthesized by landscape plants: For six months <br /> out of each year(April-September), it is theorized the plants will use 50% of available ammonium <br /> and nitrate molecules emanating from the septic effluent(the remaining 50% is lost to <br /> denitrification, immobilization and leaching). During the colder months of the year, the plants <br /> may synthesize 20%of available ammonium and nitrate. Theoretically, an additional 35% (50% <br /> + 20%= 2 = 35%)reduction in nitrate concentrations may occur: 10 ppm nitrate-nitrogen max <br /> minus 35% reduction due to landscape plants =6.5 ppm NO3-N(29 ppm NO3) potentially <br /> entering the water table. <br /> 11 <br /> Chesney Consu((ing <br />