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Spokane River

What’s with the crane? Rock removal at Monroe Street Dam started this week   

Tags: Avista Utilities, Electricity, Hydro power, Spokane River

 This week, we started removing accumulated rock and gravel from the forebay, (the area that pools behind the dam) at Monroe Street and are relocating the materials back into the river below the dam.

Post by Brandi Smith
If you happened to be in downtown Spokane over the weekend taking part in the festivities that go along with Pig Out in the Park, you may have noticed the large crane sitting near the Monroe Street dam as well as other projects taking place in and around the Spokane River. 

Removing accumulated rock and gravel from the forebay
Removing accumulated rock and gravel from
Monroe Street Dam forebay. Enlarge photo.
The work is part of Avista’s 50-year Federal Energy Regulatory Commission (FERC) license to operate our five hydroelectric dams on the river and will help protect the resources and operations of our dams in order to generate clean, reliable and cost-effective hydropower for our customers.

This week, we started removing accumulated rock and gravel from the forebay, (the area that pools behind the dam) at Monroe Street and are relocating the materials back into the river below the dam. This is being done because the high river flows from this spring caused large amounts of rock, gravel and other materials to accumulate at the dam. The accumulated rock can damage the intake structure where water enters the turbine, thus interrupting clean and efficient power generation.

Before we were able to begin the project, we performed a bathymetry survey which illustrates the terrain under water so we know where the material has accumulated. We also sampled and tested the materials for contaminants to determine whether or not the rock and gravel could safely be placed back into the river below the dam. The testing and analysis of the sample materials was conducted by a third-party that determined the material was safe to relocate downstream. Once the rock removal is complete, we will perform a second bathymetry survey in order to calculate the total amount of material removed from the forebay.

Other projects that are highly visible to downtown visitors include the construction of a new viewing platform at Upper Falls and the Aesthetic Flows Project in the Upper Falls’ north and south channels.  Look for more information about these projects here on the blog as they continue to progress. In the meantime, if you would like additional information about Avista’s hydroelectric projects, please contact Speed Fitzhugh, Spokane River License Manager for Avista at, 509-495-4998.
River video
Last year we did this video that showed the relocation of rock and gravel in action. Taken Aug. 2010.
Posted by  System Account  on  9/8/2011
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