2007-10-30_PERMIT FILE - C1982057 (2)

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table were agreed upon by representatives of CDRMS and SCC in conjunction with Permit Revision No. 2. Practice Factor: The practice factor (P) is based on current or future conservation practices in the watershed. The values used are presented in Attachment 13-5B, Table 4, Practice Factor. The values in this table were agreed upon by representatives of CDRMS and SCC in conjunction with Permit Revision No. 2. STORAGE CAPACITY Revised as-built SEDCAD results indicate the storm runoff from the 10-year, 24-hour precipitation event to be 1.9 acre-feet (ac-f t). The pond has capacity to store 5.9 ac-ft of sediment. There will be no discharge through the emergency spillway during the 10-year, 24-hour storm event. In addition, there will be adequate freeboard from the emergency spillway to the top of embankment during the 100-year, 24-hour storm event. The following table is a summary of the as-built storage capacity. _. ,- ,., ,; ~ As-Built'Storage Capacity Summary Description Elevation Stage Capacity (f t) (ft) (ac-f t) Bottom of Pond 6,857.0 0.0 0.0 Top of Sediment Storages 6,872.2 13.2 6.4 Principal Spillway Elevation 6,872.2 15.2 8.2 10-Year, 24-Hour Peak Stage 6,872.5 15.4 8.5 Emergency Spillway Invert 6,874.1 17.1 10.1 Elevation 25-Year, 24-Hour Peak Stage2 6,874.6 17.6 10.6 100-Year, 24-Hour Peak Stage2 6,874.9 17.9 10.9 Top of Embankment 6,879.6 22.6 16.8 Notes: 1) Top of sediment storage is onl applicable for 10-year, 24-hour storm event. The 25-year and 100-year, 24-hour storm event peak elevations and sediment storage elevations assume that the principal spillway is inoperable and, therefore, a conservative estimate. 2) Assumes that the principal spillway is inoperable. • The 25-year and 100-year, 24-hour SEDCAD demonstrations present conservative top of sediment elevations. Because these demonstrations assume the principal spillways are clogged, the sediment storage elevations are over estimated. TR-59 13-3C-6 Revised 08/07