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Cripple Creek and Victor <br />Phase 1 VLF <br />Lag Time Calculation Using Natural Resources Conservation Service TR -55 <br />Watershed Contribution Area 3 <br />Sheet Flow <br />Mannings n = 0.133 <br />Flow Length (ft, max 300 ft) = 300 <br />24 hr Rainfall, P2 (in) = 1.8 <br />Land Slope, s ( ft/ft) = 0.177 <br />Tt (hr) = 0.199 <br />Tt (min) = 11.9 <br />Shallow Concentrated Flow <br />Flow Length, L (ft) = 1389 <br />Watercourse Slope ( ft/ft) = 0.032 <br />Average Velocity, V (ft/sec, fig 3 -1) = 3 <br />Tt (hr) = 0.129 <br />Tt (min) = 7.7 <br />Channel Flow <br />Cross Sectional Flow Area, a (ft = 1 <br />Wetted Perimiter, p (ft) = 1 <br />Hydraulic Radius, r = a/p (ft) = 1.00 <br />Channel Slope, s (ft/ft) = 0.01 <br />Manning's n = 0.035 <br />V ( ft/sec) = 4.26 <br />Flow Length, L (ft) = 0 <br />Tt (hr) = <br />Tt (min) = <br />Watershed or subarea Tc = <br />Lag time (hr) _ <br />Lag time (min) = <br />0.328 <br />0.197 <br />11.80 <br />T 0.007 <br />= 0.8 <br />P 0.5 <br />2 <br />L <br />T t — <br />3 600 V <br />1 .49 r2t3 /2 <br />V = <br />n <br />L <br />T t — 3600 V <br />