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A Spillway Rises


[construction sounds] [music] Brandt Demars: It’s been a multi-year project, and we’re in our third season. In 2011, the contractor began excavating and removing some of the existing structures, and over the past several years, we’ve continued to excavate and remove and actually form and place. [rushing water] So the project removes the existing extremely long spillway and replaces it with a shorter length of overflow spillway but, most importantly, a series of large gates whereby we can control the reservoir elevation of Lake Walcott. Eduardo Lopez-Owsley: Right now the major section that they’re building (are) the overflow spillways. We have two sections, a northern section and a southern section. They’re concentrating working on the north section. The North Overflow Spillway will be one of two components they will finalize by the end of summer. They’ll be the last major structural items of this project to be built. Brandt: In the summer of 2014, the contractor RSCI is actually placing concrete within spillway blocks. And these blocks, when put together assembled side by side on top of each other, actually form the spillway section. [machinery] It takes a lot of work to get the concrete placements, the blocks ready. They’ve got to clean the foundation or the previous placements, they’ve got to set up forms, install rebar, and then they have to soak the concrete below or rock, basalt foundation. Afterwards they start pumping the concrete in. [concrete placement] They’re putting in ten-plus hours. Sometimes just to get a placement ready, they’ll work ’til late or during concrete placements until all the concrete is placed. They have to keep up until it’s done, it’s topped off. So we’ve been here sometimes up until midnight placing concrete. [music] This new structure will not have any weirs. It will be full height to the Lake Walcott elevation of 4,245. If the reservoir for some reason overflows above 4,245, it will just over-top, overflow the new spillway. Brandt: One of the great benefits of the project is that it reduces the labor-intensive process of removing and replacing stoplogs for over 1,000 feet. Basically in order to control the elevation of Lake Walcott, Reclamation employees would actually have to go out and, using a long steel tool, reach in and pull out these heavy pieces of lumber. And they would have to do that over hundreds of bays. It’s labor-intensive, it’s inefficient, and this new spillway structure is really a modern, 21st century design. [music] Just several months ago we saw the South Gated Spillway in action, releasing thousands of CFS into the Snake River as part of routine reservoir and river operations. We see flows going into both canals. We see the South Gated Spillway in operation, the North Gated Spillway in operation, and we can really see how this is going to operate in the future. It’s been a great project for Reclamation, it’s been a great project for our stakeholders, and it’s been great to work with a local Idaho contractor, and I just see a win-win situation all around.

Glenn Chapman

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