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<br />i <br /> <br />i' <br />1 <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />1 <br />Based on the foregoing parameters, peak flow and peak time were established for each of the 75 <br />sub-basins fora 10 year-24 hour storm and a t00 year-24 hour storm. See Exhibits IX and X. <br />Exhibit XI show the hydrographs at the exit point of each of the l3 basins, using the Muskingum <br />Routing Method for the 100 year-24 hour storm. <br />Exhibit XII and XIII show the total flows and peak times of a 100 year-24 hour and a 10 year-24 <br />the anticipated peak flow at the area where the Tallahassee Creek exits into the Arkansas River. <br />hour storm, respectively, by routing and combining the hydrographs of the 13 basins to establish <br />CONCLUSION <br />1. Bridge Crossings <br />The following procedure is rued [o establish the clear opening required for the bridge crossings. <br />The 10 year-24 hour storm has been selected for the bridge design. <br />Q = 0.4A°" <br />Q =Peak Flow in cfs A =Area in square feet <br />Q = 847 cubic feet per second (cfs) <br />A°0=8.47/0.4=2117.5 A=2117.5''==312.15feet~ <br />The bridge openings will be designed to provide <br />a minimum square feet opening of 312 square feet <br />Velocity of Stream: V = Q/A = 847/312 = 2.71 feet per second (fps) <br />The flow velocity is below 5 fps which creates no disturbance in the stream channel per information <br />from Mr. Berhan Keffelew of the Department of Mines & Geology. The intent is to provide rip-rap <br />at both bridges regardless of the water velocity. Reference Bridge Crossing Drawings C-1 & C-2. <br />PAGE 11 <br />