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,1 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 />In ut East Ditch ~ West Ditcfi <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 />Out ut <br />Q (cfs) 10.5 cfs 1.0 cfs <br />Based on these discharges, the Dodson and Associates, Inc.'s computer <br />.J software was used to design the ditches based on Manning's equation <br />calculations. <br />11 <br />