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Round Butte Selective Withdrawl

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Deschutes River, OR

Round Butte Selective Withdrawl—Deschutes River, OR

Dix Corporation was awarded a contract for the Round Butte Selective Withdrawal project by Portland General Electric for the installation of five primary structures. These consisted of a 750-ton bottom structure that will be placed on the bottom of the lake 270 feet below the water surface, a 1500-ton floating top structure, built using large land and water based cranes and overland heavy haul equipment. A 40' diameter 120' long vertical conduit that the top structure rides on and a fish transfer facility and access structure. As the lake level varies 20' in elevation during the year the top structure is designed to move up and down on the conduit section.

Round Butte Selective Withdrawl—Deschutes River, OR

Construction in Progress

The pontoon barge shown in the center of this photo is constructed of 9’ diameter rolled and welded steel pipe and measures 160’ long x 132’ wide. The SWB unit under construction will weigh 1.5 million pounds when completed and will stand 75’ tall. This unit will be jacked down into 270’ of water when complete and secured to the bottom of the lake and an existing outlet structure that feeds water to the turbine at the powerhouse below the dam.

The structure you see at the left is a floating fish trap that will weigh 1,200 ton’s when complete. The concrete floats that support the structural steel are constructed of polystyrene and incased in concrete. Once the unit is completely erected and skinned with steel sheet it will be moved into the lake and positioned over a 40’ column that will rise from the SWB. When it is in its final position the top of the structure will only be 5’ out of the water at its lowest point.