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STORMWATER MANAGEMENT MANUAL <br />RUNOFF CURVE NUMBERS <br />NOTE: <br />ESTIMATE IMPERVIOUS FROM FIGURES 703, 704, 705. THEN COMPUTE CURVE NUMBER. CN, FROM <br />EQUATION 708, BASED ON MRCS SOILS TYPE. USE OF THIS TABLE IS LIMITED TO EVALUATION OF <br />IMPERVIOUSNESS FOR FUTURE DEVELOPMENT PROJECTIONS WITHIN REGIONAL WATERSHED MASTER <br />PLANS, OR IN CONCEPTUAL DRAINAGE PLANS. <br />050 <br />Ic ! SCS TECHNICAL RELEASE NO. 55 (1886) 1 TABLE 704 <br />Average <br />Runoff Curve Number <br />Land Use or Surface Characteristic <br />lmperv. <br />Soil Co m lex <br />( %} <br />A <br />B <br />C <br />17 <br />Business <br />Commercial Areas <br />85 <br />89 <br />92 <br />94 <br />95 <br />Neighborhood Arc,as <br />70 <br />80 <br />87 <br />91 <br />93 <br />Residential <br />Single Family (note 1) <br />(note 1) <br />Multi -unit (detached) <br />60 <br />74 <br />K3 <br />88 <br />91 <br />Multi -unit (attached) <br />75 <br />83 <br />89 <br />92 <br />94 <br />Apartments <br />RO <br />86 <br />91 <br />93 <br />94 <br />Industrial <br />Light <br />80 <br />86 <br />91 <br />93 <br />94 <br />Heavy <br />90 <br />92 <br />94 <br />96 <br />Parks, cemeteries <br />5 <br />42 <br />63 <br />75 <br />_96 <br />81 <br />Playgrounds <br />10 <br />45 <br />65 <br />761 <br />82 <br />Schools <br />50 <br />69 <br />80 <br />86 <br />89 <br />Railroad yards <br />15 <br />48 <br />67 <br />78 <br />83 <br />Irrigated Areas <br />t <br />Lawns, parks, golf course <br />0 <br />39 <br />61 <br />74 <br />80 <br />Agriculture <br />0 <br />39 <br />61 <br />74 <br />80 <br />Undeveloped Areas <br />Pre - development conditions ---> <br />2 <br />40 <br />62 ! <br />74 <br />80 <br />Greenbcits, agriculture <br />2 <br />40 <br />62 <br />74 <br />80 <br />Off -site analysis when land use --3 <br />45 <br />66 <br />78 <br />85 <br />88 <br />Unknown <br />Outcrops <br />70 <br />80 <br />87 <br />94 <br />StreeWRoads <br />Paved <br />100 <br />98 <br />98 <br />98 <br />98 <br />Gravel <br />40 <br />63 <br />76 <br />84 <br />87 <br />Drives/ Walks <br />90 <br />92 <br />94 <br />96 <br />96 <br />Roofs <br />90 <br />92i <br />- 94 <br />96 <br />96 <br />NOTE: <br />ESTIMATE IMPERVIOUS FROM FIGURES 703, 704, 705. THEN COMPUTE CURVE NUMBER. CN, FROM <br />EQUATION 708, BASED ON MRCS SOILS TYPE. USE OF THIS TABLE IS LIMITED TO EVALUATION OF <br />IMPERVIOUSNESS FOR FUTURE DEVELOPMENT PROJECTIONS WITHIN REGIONAL WATERSHED MASTER <br />PLANS, OR IN CONCEPTUAL DRAINAGE PLANS. <br />050 <br />Ic ! SCS TECHNICAL RELEASE NO. 55 (1886) 1 TABLE 704 <br />