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<br />( <br />- <br /> <br />e <br /> <br />e <br /> <br />DRAINAGE CRITERIA MANUAL <br /> <br />TABLE 3-1 (42) <br />RECOMMENDED.RUNOFF COEFFICIENTS AND PERCENT IMPERVIOUS <br /> <br />LAND USE OR <br />SURFACE CHARACTERISTICS <br />Business: <br />Commercial Areas <br />Neighborhood Areas <br />Residential: <br />Single-Family <br />Multi-Unit (detached) <br />Multi-Unit (attached) <br />1/2 Acre Lot or Larger <br />Apa rtments <br />Industrial: <br />Light Areas <br />Heavy Acres <br />Parks, Cemetaries: <br />Playgrounds: <br />Schools: <br />Railroad Yard Areas <br />Undeveloped Areas: <br />Historic Flow Analysis- <br /> <br />PERCENT <br />IMPERVIOUS <br /> <br />95 <br />70 <br /> <br />* <br /> <br />50 <br />70 <br /> <br />* <br /> <br />70 <br /> <br />80 <br />90 <br />7 <br />13 <br />50 <br />20 <br /> <br />2 <br /> <br />Greenbelts, Agricultural <br /> <br />Offsite Flow Analysis 45 <br />(when land use not defined) <br /> <br />Streets: <br /> <br />Paved <br /> <br />Gravel (Packed) <br /> <br />Drive and Walks: <br /> <br />Roofs: <br /> <br />Lawns, Sandy Soil <br />Lawns. Clayey Soil <br /> <br />100 <br />40 <br />96 <br />90 <br />o <br />o <br /> <br />2 <br /> <br />.87 <br />.60 <br /> <br />.40 <br />.45 <br />.60 <br />.30 <br />.65 <br /> <br />FREQUENCY <br />5 10 <br /> <br />.87 <br />.65 <br /> <br />.88 <br />.70 <br /> <br />.45 <br />.50 <br />.65 <br />.35 <br />.70 <br /> <br />.50 <br />.60 <br />.70 <br />.40 <br />.70 <br /> <br />RUNOFF <br /> <br />100 <br /> <br />.89 <br />.80 <br /> <br />.60 <br />.70 <br />.80 <br />.60 <br />.80 <br /> <br />.82 <br />.90 <br />.45 <br />.50 <br />.70 <br />.45 <br /> <br />.65 <br /> <br />.93 <br />.60 <br />.89 <br />.90 <br />.20 <br />.50 <br /> <br />NOTE: These Rational Fonnula coefficients may not be valid for large basins. <br /> <br />.71 .72 <br />.80 .80 <br />.10 .18 <br />.15 .20 <br />.45 .50 <br />.20 .25 <br /> <br />.76 <br />.85 <br />.25 <br />.30 <br />.60 <br />.35 <br /> <br />(See "Lawns") <br /> <br />.43 <br /> <br />.87 <br />.40 <br />.87 <br />.80 <br />.00 <br />.05 <br /> <br />*See Fi9ure 2-1 for percent impervious. <br /> <br />11-1-90 <br />URBAN DRAINAGE AND FLOOD CONTROL DISTRICT <br /> <br />.47 <br /> <br />.55 <br /> <br />.88 <br />.45 <br />.87 <br />.85 <br />.01 <br />.15 <br /> <br />.90 <br />.50 <br />.88 <br />.90 <br />.05 <br />.25 <br />