Spillway. A concrete spillway with 14 gates, 380 metres long, capable of spilling up to 58,000 m3 per second, with an access channel dug upstream from the spillway. A channel lined with concrete will transmit the overflow from the spillway to the Paraná River approximately 1,500 metres downstream from the main dam.
Spillway. The spillway (Figure 4−8) will be used infrequently because the design flow capacity of the turbines is greater than the average flow of water into the reservoir. During spring runoff, turbine shut down for maintenance, or emergencies, the spillway will release water from the reservoir. The spillway will accommodate a probable maximum flood (PMF) of 20,800 m3/s. Located on the south bank, the spillway will have eight gated openings on a parabolic crest sloping down to a lined chute, a flip bucket, a large plunge pool and a short channel to the river. A cross−section of the spillway is shown in Figure 4−8. Figure 4-8 Cross-section of the Gull Island Spillway VOLUME IA, CHAPTER 4 PROJECT DESCRIPTION PAGE 4−9 ENVIRONMENTAL IMPACT STATEMENT I LOWER XXXXXXXXX HYDROELECTRIC GENERATION PROJECT The spillway will be equipped with eight, fixed−wheel vertical lift gates, each 13 m wide and 20 m high. The crest will discharge spillway flows at an elevation of 105.4 m into a 130 m wide, concrete−lined chute and flip bucket. The flip bucket allows the water to plunge into the unlined stilling basin (plunge pool) for the dissipation of its energy before passing into the discharge channel and the river. The elevation at the bottom of the 255 m long and 130 m wide plunge pool will be 14 m. The discharge channel will deliver water back to the river at less than 7 m/s.
Spillway. The spillway will be a reinforced concrete structure that will be located on the north side of the Burntwood River, northeast of Taskinigup Falls adjacent to the Non-overflow Gravity Dam. The purpose of the spillway will be to pass excess inflows and to be part of the system of flow regulation. The structure will be located within a connecting channel, referred to as the spillway channel, excavated in the bedrock which separates the upstream and downstream sections of the river. Operable steel vertical lift gates within the structure will be used to control the flow of water in the spillway channel. The spillway will be designed to pass the Probable Maximum Flood (PMF) safely. There will be a road on the upstream side of the structure to allow access across the structure.
Spillway. The spillway is a reinforced concrete channel located within the ridge about 900 feet from the right abutment of the dam. It has a xxxx length of about 82 feet and a capacity of 5,260 cfs. The estimated PMF has been updated during the planning study, indicated that the there is inadequate spillway capacity to prevent overtopping of the dams (main and auxiliary) during the PMF. The Staff Recommended Alternative includes raising the main and auxiliary dams to provide adequate freeboard during PMF loading.
