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� <br />Table 1-5.6 SCS RunoffCurve Numbers <br />LAND USE DESCRIPTION CURVE NUMBERS BY <br />HYDROLOGIC SOIL GROUP <br />A B C D <br />Culfivated Land winter candition 86 91 94 95 <br />Mountain open area low growing brush 8c grasslands 74 82 89 92 <br />Madow or pacture 65 78 85 89 <br />Wood or forest land undisturbed 42 64 81 <br />young second growth or brush 55 72 81 86 <br />Orcherd with cover crop 81 88 9 94 <br />Open spaces (lawns, parks, <br />golfcourses,landscaping,etc.) <br />Good condition grass cover on >75% of area 68 80 86 90 <br />Fair condition grass cover on 50-75% of area 77 85 90 92 <br />Gravel roads and parking lots 76 85 89 91 <br />Dirt roeds end parlcing lots 72 82 89 <br />Impervious surfaces pavement, roofs, etc. 98 98 98 8 <br />Open water bodies lakes, wetlands, ponds, etc. (00 100 0 100 <br />Single family residential (1) <br />Dwelling UnidGross Acre % Impervious <br />1.0 15 Separate curve <br />1.5 20 • numbers must <br />2.0 25 be selected for <br />2.5 30 pervious and <br />3.0 34 irupervious <br />3.5 38 portions of the <br />4.0 42 site or basin <br />4.5 46 <br />5.0 48 <br />5.5 50 <br />6.0 52 <br />6.5 54 <br />7.0 56 <br />PRD's, multi-family, <br />commercial, industrial <br />(1) The % impervious values assumc that roof and driveway runoff is directed into the streeUstortn system <br />I-5-33 <br />