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DRAINAGE CRITERIA MANUAL RUNOFF <br />' TABLE 3-1 (42) <br />COMMENDED <br />NOFF COEFFICIENTS AND PERCENT <br />R <br />R <br />IMPERYIOUS <br /> E <br />• <br />U <br /> <br />i LAND USE OR PERCENT FR EQUENCY <br /> SURFACE CHARACTERISTICS IMPERVIOUS 2 5 10 100 <br /> Business• <br />~ Commercial Areas 95 .87 .87 .88 .89 <br />' Neighborhood Areas 70 .60 .65 .70 .80 • <br /> <br />i Residential• <br />Single-Family * <br />.40 <br />.45 <br />.50 <br />.60 <br /> Multi-Unit (detached) 50 .45 .50 .60 .70 <br /> Multi-Unit (attached) 70 .60 .65 .70 .80 <br /> 1/2 Acre Lot or Larger * .30 .35 .40 .60 <br />' Apartments 70 .65 .70 .70 .80 <br /> Industrial: <br />' Light Areas 80 .71 .72 .76 .82 <br /> Heavy Acres 90 .80 .80 .85 .90 <br />' • Parks, Cemetaries: 7 .10 .18 .25 .45" <br />• Playgrounds: 13 .15 .20 .30 .50 <br /> Schools: 50 .45 .50 .60 70 <br />' Railroad Yard Areas 20 .20 .25 .35 . <br />.45 <br /> Undeveloped Areas: <br /> Historic Flow Analysis- 2 (See " Lawns") <br /> Greenbelts, Agricultural <br /> Offsite Flow Analysis 45 .4.3 .47 .55 .65 <br /> (when land use not defined) <br /> Streets: <br /> Paved 100 .87 .88 .90 .93 <br />' Gravel .(Packed) 40 .40 .45 .50 .60 <br />' Drive and Walks: 96 .87 .87 .88 .89 <br /> <br />' Roofs: 90 .80 .85 .90 .90 <br /> Lawns, Sandy Soil 0 .00 .O1 .OS .20 <br />', Lawns, Clayey Sail 0 .OS .10 .25 .50 <br /> <br />~ NOTE: These Rational Formula coefficien ts may not be valid for large basins. <br />' <br />Y . <br />t <br />i <br /> *See Figure 2-1 for percent impervious. <br />' 11-1-90 <br /> UP,BAtJ DRAINAGE A~JD FLOOD CONTROL DISTRIC T <br />