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Introduction <br /> The design of the reclaimed drainage channel in the Nucla East permit area was based on <br /> 04LRD regulations for conveyance of overland flow of watersheds less than one square mile. <br /> The reclaimed channel is shown on Exhibit 20-10 between points AA to BB. The premine <br /> drainage channel slope is 3.0 percent and the postmining drainage channel will be 3.2 <br /> percent. <br /> Design <br /> For the design of this reclaimed channel, the SEDIMOT II model was used to predict runoff <br /> from the watershed (see Attachment A, Tab 13). A 10-year, 24-hour precipitation event was <br /> used in the design. The peak flow was determined at the downstream end of the drainage <br /> channel. Following is a list of main input factors which were derived in a similar manner <br /> to the factors for Pond No. 007 (see Attachment G, Tab 13). <br /> Input Channel AA-BB <br /> Precipitation 1.60 in <br /> Drainage Area 217.8 ac <br /> CN 81 <br /> L 6650 ft <br /> Y 4.65 % <br /> tc 1.08 hr <br /> Output <br /> Q 33.2 cfs <br /> Based on this discharge, the Dodson and Associates, Inc.'s computer software (see <br /> Attachment J, Tab 13) was used to design the reclaimed drainage channel bottom width based <br /> on Manning's equation calculation. The shape of the channel was assumed to be trapezoidal <br /> with 5h:ly side slopes. The channel bottom width was increased to insure that the peak <br /> velocity was below the limiting velocity of 5.0 fps. Below is a summary of the input <br /> factors and the results determined by the computer program. <br />