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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 1 <br />Sheet Flow <br />Mannings n = 0.24 <br />Flow Length (ft, max 300 ft) = 300 <br />2 -year 24 hr Rainfall, P2 (in) = 1.8 <br />Land Slope, s (ft/ft) = 0.183 <br />Tt (hr) = 0.315 <br />Tt (min) = 18.9 <br />Shallow Concentrated Flow <br />Flow Length, L (ft) = 551 <br />Watercourse Slope (ft/ft) = 0.240 <br />Average Velocity, V ( ft/sec, fig 3 -1) = 8 <br />Tt (hr) = 0.019 <br />Tt (min) = 1.1 <br />Channel Flow <br />Cross Sectional Flow Area, a (ft = 56 <br />Wetted Perimiter, p„, (ft) = 25.5 <br />Hydraulic Radius, r = a/p (ft) = 2.20 <br />Channel Slope, s (ft/ft) = 0.005 <br />Manning's n = 0.035 <br />V (ft/sec) = 5.09 <br />Flow Length, L (ft) = 1040 <br />Tt (hr) = 0.057 <br />Tt (min) = 3.4 <br />Watershed or subarea Tc = <br />Lag time (hr) = <br />Lag time (min) = <br />0.391 <br />0.235 <br />14.07 <br />T = 0.007 (nl) o.g <br />t P 0.5 S 0.4 <br />2 <br />_ L <br />Tt 3 600 V <br />V = 1.49 r 2i3s1/2 <br />T <br />n <br />L <br />— 3600 V <br />