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area have been reclaimed, the selection here of the 100 year design basis and the need for erosion <br />protection is consistent with those analyses. <br />The Trib. G ditch, which has the largest drainage area and largest resultant peak flow has been <br />used as the representative example for design of all of the secondary ditches. Although <br />dimensions for all secondary ditches are presented in attached Table 1, the flow results are only <br />provided for Trib. G Ditch. Flows in the other ditches would be proportionately less. <br />The following SEDCAD4 run for Trib. G Ditch is provided for this long term case where the 100 <br />year, 24 hour design storm is used and the entire drainage area is assumed to be both <br />contributory and recently reclaimed (Curve Number 74). The resultant peak flow generated was <br />32.2 cfs, and requires a riprap size with D50 of 12 inches in its lowermost (steepest) reach. For <br />design simplicity and as an added conservative measure, a D50 of 12 inches has been selected <br />for all of the secondary ditches. As such, all of the secondary channels will be constructed as <br />trapezoidal ditches with a 12.0 foot bottom width, 211:1 V side slopes, and a minimum D50 riprap <br />diameter of at least 12 inches. <br />Exh. 7-20E-3 Revision Date: 07/20/15 <br />Revision No.: TR -105 <br />