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<br />TABLE 111-4 <br /> <br />RU"lOFF CURVE NUMBERS FOR SELECTED <br />AGRICULTURAL, SUBURBAN & URBAN LAND USE - <br />SCS !:'ormula <br /> <br />91 <br /> <br />- <br />;:..; <br />~ <br />~: <br /> <br />b <br /> <br />~ <br />!: <br />~I <br /> <br />HYDROLOGIC SOIL GROUP <br />ABC D <br /> <br />LAND USE DESCRIPTION <br /> <br />Cultivated landl: without conservation <br />treatment <br />with conservation <br />treatment <br /> <br />72 <br /> <br />62 <br /> <br />Pasture or range land: poor condition <br />good condition <br /> <br />68 <br />39 <br /> <br />Meadow: good condition <br /> <br />30 <br /> <br />l~ood or forest land: thin stand, Door <br />cover, no mulch <br />good cover 2 <br /> <br />45 <br /> <br />25 <br /> <br />Open spaces, lawns, parks, golf courses, <br />cemeteries, etc.: good condition, 39 <br />grass cover on 75% or more of the area <br />fair condition: grass cover on 50% to <br />75% of the area 49 <br /> <br />Commercial and business areas <br />(85% impervious) 89 <br /> <br />Industrial districts (72% impervious) <br /> <br />81 <br /> <br />81 <br /> <br />71 <br /> <br />79 <br />61 <br /> <br />58 <br /> <br />66 <br /> <br />55 <br /> <br />61 <br /> <br />fi9 <br /> <br />92 <br /> <br />88 <br /> <br />88 <br /> <br />78 <br /> <br />86 <br />74 <br /> <br />71 <br /> <br />77 <br /> <br />70 <br /> <br />74 <br /> <br />79 <br /> <br />94 <br /> <br />91 <br /> <br />81 <br /> <br />89 <br />80 <br /> <br />78 <br /> <br /> <br />83 <br /> <br />77 <br /> <br />80 <br /> <br />~ <br />I: <br /> <br />84 <br /> <br />t'j <br /> <br />95 <br /> <br />93 <br /> <br />. d . 13 Averaqe Lot Aver';iqe%4 <br />Res~ ent~a : <br /> Size Imperv~ous <br /> 1/8 acre or less 65 77 85 90 92 <br /> 1/4 acre 38 61 75 83 87 L <br /> 1/3 acre 30 --5'7- 72 l:H i <br /> 1/2 acre 25 54 70 80 85 <br /> 1 acre 20 51 68 79 84 <br />Paved parking lots, roofs, driveways, <br />etc. 98 98 98 98 -, <br />Street and roads: paved w/curb & storm <br /> sewers 98 98 98 98 - <br /> gravel 76 85 89 91 <br /> C!irt-~-~ 72 82 87 89 <br /> <br /> <br />---------- <br />lpor a more detailed description of agricultural rand--~curve <br />2numbers, refer to NEH, Sec 4, Hydrology, Chap. 9, August 197'20 <br />3Good cover is rrotected from grazing & litter & brush cover soil. <br />Curve numbers are computed assuming the runoff from the house and <br />driveway is directed towards the street with a minimum of roof <br />4water directed to lawns where additional infiltration could occur. <br />The remaining pervious areas (lawn) are considered to be in good <br />pasture condition for these curve numbers. <br /> <br />26 <br /> <br />.'1 <br />ii.I <br />