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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 2 <br />Sheet Flow <br />Mannings n = 0.24 <br />Flow Length (ft, max 300 ft) = 300 <br />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) = 1509 <br />Watercourse Slope (ft/ft) = 0.292 <br />Average Velocity, V (ft/sec, fig 3 -1) = 8 <br />Tt (hr) = 0.052 <br />Tt (min) = 3.1 <br />Cross Sectional Flow Area, a (ft = 56 1 r2/3s1/2 <br />Wetted Perimiter, pw (ft) = 25.5 V = <br />Hydraulic Radius, r = a/p (ft) = 2.20 n <br />Channel Slope, s (ft/ft) = 0.005 <br />Manning's n = 0.035 7 , _ L <br />V (ft/sec) = 5.09 r <br />Flow Length, L (ft) = 280 3600 V <br />Tt (hr) = 0.015 <br />Tt (min) = 0.9 <br />Watershed or subarea Tc = <br />Lag time (hr) = <br />Lag time (min) = <br />Channel Flow <br />0.383 <br />0.230 <br />13.78 <br />7 , = 0.007 (nl) o.g <br />Tt P 0.5 S 0.4 <br />2 <br />L <br />T = <br />3 600 V <br />