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I I I I I I I I I I I I I I I I I I I total, the spillways will be capable of passing about 5480 cfs. The fuse plug location is shown on Figure 6-1. The rehabilitation of the existing spillway will be addressed specifically during Phase 2 of this alternative, after the PMP estimates have been revised and the moratorium lifted. Alternative 2 - Low-Level Outlet Only This alternative includes a 36-inch-diameter steel pipe as the low-level outlet. This is similar to Alternative I, except there would not be the ability to pass the 100-year event. There would be a hydraulically operated gate to pass inflow but the gate would have to be manually operated during a flood. The low-level outlet could pass approximately 240 cfs if fully opened. The emergency spillway would remain the same and would have the ability to pass 4,560 cfs before overtopping the dam. Alternative 3 - No Action This alternative involved not repairing the breach in the reservoir. This alternative would not have any additional construction cost. 7.3 REHABILITATION ALTERNATIVES Two alternatives were considered to reconstruct the breach dam. These two alternatives were compared to the existing condition. The first alternative would involve reconstructing the lower level and providing a 100-year level of flood protection through the principal spillway. This alternative would add to the ability of the dam to pass the PMF. The second alternative would only involve reconstructing the lower level outlet and would not provide any additional flood protection. The dam before breach construction was not capable of passing the 50 percent PMF before the CDWR moratorium on spillway protection. Alternative I provides additional capabilities for passing less frequent events without overtopping the dam; therefore, the plan will require less modification to pass the PMF once the new CDWR guidelines are approved. 242161R1.DOC 01.12-97(H8PM)/RPT 7-2