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TABLE 7 (Cont. ) <br /> Manning Coef. 0.025 <br /> Inlet Elevation. . 5701.0 <br /> 25-year, 24-hour Peak <br /> Stage. . . . . . . . . 5700.06 <br /> The entrance to the emergency spillway is located more than one foot <br /> above the principal spillway. There will be no flow through the <br /> emergency spillway inlet as a result of the runoff from a 10-year, <br /> 24-hour precipitation event or less. <br /> Pond No. 005 - East Ditch and' West Ditch <br /> In order to maximize coal recovery and to contain runoff from the <br /> proposed disturbance areas, two contour ditches are required along the <br /> disturbance areas east and west of Pond No. 005, flowing into Pond No. <br /> 005 (see Exhibit 13-4). <br /> For design of these two ditches, the SEDIMOT II model was used to <br /> predict runoff from the watershed (see Addendum D and E for the batch <br /> input and output, respectively). A 10-year, 24-hour precipitation event <br /> was used in the design, which is a conservative approach to a temporary <br /> ditch. <br /> Following is a list of the main input factors which were derived in the <br /> same manner to the factors of Pond No. 005: <br /> Input East Ditch West Ditch <br /> Precipitation 1.60 in. 1.60 in. <br /> Drainage Area 23.5 ac 2.4 ac. <br /> CN 84 81 <br /> L 0.49 miles 0.08 mile <br /> H 121 ft. 53 ft. <br /> tc 0.18 hour 0.03 hour <br /> Output <br /> Q (cfs) 10.5 cfs 1.0 cfs <br /> Based on these discharges, the Dodson and Associates, Inc. 's computer <br /> software was used to design the ditches based on Manning's equation <br /> calculations. <br /> 11 <br />