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Existing Twin Lakes West-Prelim. Subdivision Type 1124-h� 100-y� Rainfall=5.90" <br />Prepared by RLK Incorporated Page 14 <br />HydroCAD� 7.00 s/n 000754 �O 1986-2003 Applied Microcomputer Systems 10/6/2006 <br />Tc Length Slope Velocity Capacity Description <br />( min) ( feeU ( ft/f� ( ft/sec� ( cfs) <br />21.3 300 0.0034 02 Sheet Flow, <br />Fallow n= 0.050 P2= 2.80" <br />4.0 414 0.0115 1.7 Shallow Concentrated Flow, <br />Unpaved Kv= 16.1 fps <br />0.6 128 0.0351 3.8 Shallow Concentrated Flow, <br />Paved Kv= 20.3 fps <br />2.9 261 0.0055 1.5 Shallow Concentrated Flow, <br />Paved Kv= 20.3 fps <br />1.9 493 0.0020 4.2 29.83 Circular Channel ( pipe) , <br />Diam= 36.0" Area= 7.1 sf Perim= 9.4' r- 0.75' n= 0.013 <br />30.7 1,596 Total <br />Subcatchment LL-1 ( Nh : Westem Portion to Langton Lake <br />Runoff = 29.71 cfs @ 12.27 hrs, Volume= 3.114 af, Depth= 4.86" <br />Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs <br />Type II 24-hr 100-yr Rainfa11=5.90" <br />Area ( ac� CN Description <br />0.150 61 >75% Grass cover, Good, HSG B <br />0.350 89 Gravel roads, HSG C <br />1.060 55 Woods, Good, HSG B <br />6.130 98 Paved parking & roofs <br />7.690 91 Weighted Average <br />Tc Length Slope Velocity Capacity Description <br />( min) ( fee� ( ft/f� ( fUsec) ( cfs) <br />5.0 300 0.0061 1.0 Sheet Flow, <br />Smooth surfaces n= 0.011 P2= 2.80" <br />1.8 127 0.0035 1.2 Shallow Concentrated Flow, <br />Paved Kv= 20.3 fps <br />0.6 57 0.0910 1.5 Shallow Conoentrated Flow, <br />Woodland Kv= 5.0 fps <br />23.3 70 0.0001 0.1 Shallow Concentrated Flow, <br />Woodland Kv= 5.0 fps <br />1.2 50 0.0001 0.7 2.26 Circular Channel ( pipe) , <br />Diam= 24.0" Area= 3.1 sf Perim= 6.3' r= 0.50' n= 0.013 <br />0.5 45 0.0900 1.5 Shallow Concentrated Flow, <br />Woodland Kv= 5.0 fps <br />32.4 649 Total <br />Subcatchment LL.: Area Surrounding Langton Lake ( South) <br />Runoff = 71.68 cfs @ 12.74 hrs, Volume= 12.863 af, Depth= 4.42" <br />Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs <br />Type II 24-hr 100-yr Rainfa11=5.90" <br />