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G~ ~~ T <br />fKJ10eePS a <br />p.o. box 121 <br />cowdrey, co 80434 <br />(970) 7234061 <br />CLIENT: City of 6reelry <br />PROJECT: gEv <br />PROJECT NO.: 02.08 <br />DATE: 1/22/2003 <br />BY: TEB <br />RATIONAL METHOD -RUNOFF CALCULATIONS <br />Reference: 1 Greeley -Storm Drainage Design Criteria, 10/1/97 <br />2 Urban Storm Drainage Criteria Manual UDFCD, Denver <br />3 Dillon -Storm Drainage Design Criteria, 9/82 <br />{Enter data only in boxes. All other values are calculated by program} <br />State: <br />Town: <br />Bnsin: <br />Sub-basin: <br />Design point: <br />Condition: <br />Design Storm: <br />------------------------------------------------------------------------------------------------------------------------- <br />Q=C~I'A <br />where : C =runoff coefficient <br />I =rainfall intensity (in/hr) <br />A =drainage basin area (acres) <br />Q =runoff in cfs <br />--------------------------------------------------------------------------------------------------------------------------- <br />Arta <br />Coefficicrrt, C <br />% Impervious <br />Land use: <br />Commercial <br />Street <br />Res (high) <br />Res (medium) <br />Res (low) <br />Park /Lawn <br />School <br />CMher native, sandy <br />Totd <br />Composite <br />USE: <br />Cnlwlate percent of impervious area <br />Calculate weighted nmoff coefficient "C <br /> <br />Area <br />acres) <br />Percent <br />Impervious Impervious <br />Area <br />(acres) 0 yr <br />Coefficient <br />°C 100 yr <br />Coefficient <br />"C <br /> 85% 0.00 0.75 0.90 <br /> 100% 0.00 0.88 0.93 <br /> 70% 0.00 0.60 0.80 <br /> 42% 0.00 0.40 0.65 <br /> 25% 0.00 0.30 0.60 ' <br /> 7% 0.00 0.10 0.45 <br /> 50% 0.00 0.45 0.70 <br />21.10 1% 0.21 0.20 <br />21.10 <br />1% 0.21 <br />0.00 <br />0.20 <br />0.40 <br />g38asinl.xls Page 1 <br />100 ~ <br />