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I I I I I I I I I I I I I I I I I I I The outlet conduit will have a sand filter near the dam toe to prevent the migration of fines along the pipe. The Inlet will be a box type structure containing the Inlet screen and the outlet control gates. The outlet structure will be designed to contain the flows and will Include an energy dissipater to eliminate the downstream erosion. The outlet structure will be divided such that the releases from the two conduits can be separated. The outlet structure would also be configured to allow the 24-lncl1 conduit to be valved on the downstream end and extended Into an Intake or pump structure for deliveries to users that can not be served by gravity flow. The main control gate operators will be manual, hand crank type, enclosed gear pedestal as manufactured by Hydro Gate or Waterman Industries. The gate stem will be a non-rising type stem since tile gate will be Inclined and the operator will be mounted on an Incline. The stem will be supported by a concrete grade beam and will be protected by being Ingerted Into a schedule 80 galvanized steel pipe attached to the concrete grade beam. The gate operator will be protected by a building enclosure located on the crest of the dam. An alternative to the arrangement described above will be to Include an overflow type service spillway In conjunction with the outlet works. This structure will Include a screened Intake approximately 4-foot square that will empty Into a 4- foot square concrete tower that empties Into the outlet conduit. This structure will not be gated and will be designed to act as a service spillway to handle nuisance flows. The overflow lip will be set at Gage height 36 feet to limit the normal water to that elevation. 6. Spillway. Two types of emergency spillways were proposed at two different locations. The plan view on Figures V-2 and V-3 and the alternatives shown on Figure V-6 In this chapter show the two proposed locations and the two types of spillways considered. Emergency Spillway Alternative No. I. Alternative No. 1 Is a spillway excavated Into the west (right) abutmeI1t area. This spillway will be excavated Into natural solis In the abutment and consists of a grass lined channel, training dikes, and a concrete control wall with rip rap protection. Emergency Spillway Alternative No.2. The second alternative Is located between the two dams at Station 18+60 to Station 22+00. At this location a roller compacted concrete (RCC) spillway was considered due to the need for a reinforced spillway section at this location. At this location, we would not recommend a grass lined spillway wlttl a control wall as used In the first alternative. The location of the splllwtly and the potential for erosion Into the main dam makes this location undesirable for a rip rap and earth type spillway. Both spillways flow Into the same watercourse near the outlet channel. Both spillway flows would Inundate State Jlighway #1 after filling up the outlet channel. No other alternative Is available, however, to be able to pass the Probable Maximum Flood (PMF) without flowing across the highway. PAG! 12 Cliapler V - No. 6 Peulblllty