Global was contracted by Kiewit to provide diving services to assist with the installation of a wall between Bays 8 and 9 of The Dalles Dam on the Columbia River. The wall is intended to redirect the salmonids that are migrating downstream and increase their survival rate.

The wall is 10 feet wide and over 800 feet long, the last 150 feet of which is at an angle to direct the water flow into a deeper portion of the river. It is constructed of precast concrete segments that were installed in the spillway and onto a leveling slab built on the river bottom. The segments were set in place and leveled using jacking rods. Once level and in place, the next segment was brought in and the process repeated. After several of them were in place, divers tied the segments together with rebar dowels. Forms were then installed on the joints between and around the bottoms. Concrete was then tremied into the segments. This process was repeated across the stilling basin.

Where the wall extended beyond the stilling basin, a 15-foot-wide leveling slab was installed. The river bottom was cleaned of loose debris. An area that ran across the path of the wall was excavated, because the underlying rock was fractured and non-competent. Form work was lowered from the surface and fit to the bottom contour. Rebar doweling was drilled and epoxied into the river bottom where needed. Rebar mats were installed inside the form work. Concrete was again tremied in place. The wall was carried over onto the leveling slab in the same manner as on the stilling basin.

News

7/1/10: Fish Passage: The Dalles Dam – a safer place for salmon (Hydroworld)
1/1/10: Computational Fluid Dynamics Modeling of The Dalles Project (US Dept. of Energy)
6/10/09: Army Corp tackles $46M Dalles spillwall project (DJC Oregon)
12/9/08: $45M wall at Dalles Dam to protect fish (Daily Journal of Commerce)