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�� .. <br /> 17 <br /> 1 - - <br /> Page 4 <br /> Mr. yleleyco <br /> f <br /> March 19, 1997 <br /> calculations and assumptions an as follows: <br /> SN-, = Aw xN. I1_0) +(Nb)r <br /> AW+ r <br /> Where: <br /> N,= cZlculated nitrate concentrvioc in groundwater resulting from domestic sources and <br /> precipitation - mg/l, as N <br /> , <br /> A = number of dwelling units per acres on septic tanks (wiit/acre) <br /> W = annual wastewater loading per dwelling unit ger acre (inelks) =2.0 inches (based on 150 <br /> gpd/residence) <br /> I <br /> N.,, = nitrate concentration of nitrified leachtield effluent (mg;1)=40Mgil to 60 rrigi1. ss N <br /> i D = percent denitrification of leachfieid effluent =0.25 to 0.i0 <br /> r = annual deep perotation of Precipitation (inches) = 3-0 inches (based an 13.5 inches <br /> precipitation, 2 inches runoff and 8.5 inches ET) <br /> Nb = background nitrate concentration of the deep percolatirg precipitation - m9A =2.2 mg/l, <br /> as N(per Keinfelder) <br /> Low Estimate: <br /> N,; = 1.0 (2-0) (.40 mg/1)( i -0. 5 +f3.0 2.2 I <br /> (1.0)(2-0) +3.0 <br /> 4 <br /> N; = 60+6.6 = 666 13.3 mg/I nitrate, as N <br /> + 2f3 5 <br /> High Estimate. <br /> t <br /> N, = .01 2.0 60m lyft - 0.101+Q.0 2.2m m <br /> 1 <br /> (1.0) (2.0) + 3.0 <br /> a <br />