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• Calculations for Sediment Storage 10-year, 24-hour (MUSLE) = 7457.35 tuns (see Table 5) 7457.35 tons x 2 (MUSLE) = 14914.70 tons 14914.70 tarts x 2000 lb/ton = 8.56 ac.-f t. 80 (lbs/f t3) x 43560 ft2/ac. Results 10-year, 24-hour Runoff Volume and Sediment Storage Volume All previously cited data was entered into a batch input data file which is presented in Table 4. The SEDIMOT II computer model was then run with this input file and the resultant output file is presented as Table 5. Results of the SEDIMOT II modeling show that the peak stage of the 10-year, 24-hour storm event will be 0.8 feet below the emergency spillway. This allows for 2.58 ac.-f t. (including the 1.0 ac.-f t. • needed for pit pumpage) before any flow would occur through the emergency spillway. The 6" CMP was considered the best practical size of pipe in order to increase detention time and still have enough storage above the peak stage for pit pumpage. Also the 6" diameter pipe should not freeze or plug up with the trash rack installed (see Exhibit 7-12). Peak discharge from the principal spillway will be 1.06 cfs with 100.0 percent basin trap efficiency (see Table 5). The pond can store up to 9.96 ac.-ft. of sediment or (2.33) 10-year, 24-hour (MUSLE) precipitation events with the principal spillway at the inlet elevation of 6945.2. Detention time from hydrograph centers is 15.29 hours. Therefore, the requirements for storage and treatment of the design storm have been met by Pond No. 004. Emergency Spillway The software from Dodson & Associates, Inc. was used to analyze the capacity of the emergency spillway. The emergency spillway is a • riprapped trapezoidal channel with 3H:1V side slopes and a width of 12 feet. From the routing of the 25-year, 24-hour storm event with the SEDIMOT II computer program, there is a peak inflow of 93.73 cfs at a 7-6c-5 Revised 8/27/86