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accurately estimating the quantity of recharge waters is 1.5 <br /> clearly evident,particularly in cases of higher nitrogen load- < <br /> w.,so a•va•riaw•wno••u <br /> ing and lower denitrification rates. <br /> In Figure 2,the critical minimum gross acreage per lot, m 2.0 <br /> A,is plotted against the annual rate of rainfall recharge,R, 0 <br /> for a selected range of values for nw and d,with nb= 1.0 .b <br /> mg/I as before.In this instance the long-term waste-water o * 3 . o <br /> (low,W,is assumed equal to 150 gal/day per DU,on the s = <br /> a <br /> basis of an average expected occupancy of three persons per "o o `� <br /> residence and 50 gal/person/day.The U.S.EPA(1980)cites = ► ` °°o <br /> 45 gal/day as the typical per capita flow for residential <br /> dwellings.The influence of climate and the water balance is <br /> seen to be significant,particularly for lower ranges of R,i.e., ° <br /> drier climates.Thus,in desert areas,very large lots may be <br /> 0 <br /> necessary. o a +a +s zo zs ao <br /> In typical new developments of single family resi- NATURAL RAINFALL RECHARGE,R,MIT, <br /> dences,practical lot size limits exist because of minimum Fig.2.Influence of effluent quality,denitrification,and rainfall <br /> space requirements for site development, disposal fields, recharge on critical lot size. <br /> roadways,open space,etc.These limits may be on the order <br /> of 0.25 to 1.0 gross acres per dwelling unit,depending on <br /> local codes and specific development plans. As seen in <br /> Figure 2, such practical or statutory limits may often be <br /> more stringent than the critical minimum gross acreage per <br /> lot,A,determined from equation(2).This is particularly =____ __ o <br /> true as R values increase. ------ <br />