Top Projects of 2002 -- Seattle DJC.COM

#22. Keechelus Dam modification

Original contract amount: $15,309,150

New embankments at Keechelus Dam will be constructed out of materials recycled from the old dam.
Photo courtesy US Bureau of Reclamation

Project address:
On the Yakima River, 10 miles northeast of Easton

Start of construction:
May 28, 2002

Expected completion date:
Late November 2003

Owner:
Pacific Northwest Region, U.S. Bureau of Reclamation

Description In 1998, inspectors discovered large hollows within the Keechelus Dam that were caused by rotting timbers left in the earthen structure when the dam was built in 1917. Engineers determined that these voids, if uncorrected, would result in the eventual failure of the dam, interruption of water service to farmers and possible damage to downstream inhabitants.

Addressing these public safety concerns, the water level in the dam was lowered by seven feet, drastically affecting the storage volume of the reservoir.

To repair the dam, a new dam will essentially be built in the place of the old dam. The new dam will use the same spillway structure, and will recycle the earth and stone materials already at the site to construct new embankments.

In addition, the project also involves constructing a bentonite slurry trench wall, downstream drains, monitoring equipment and systems, and replacing a section of outlet conduit. Upon completion, the storage volume of the dam will return to its pre-1996 levels.

The project is planned to take place over two years, to ensure that irrigation water will be available during farming seasons. Excavations are timed to coordinate with the receding water levels, as water is used during the irrigation seasons.

PROJECT PARTICIPANTS

Contractor:
Kiewit Pacific, P.O. Box 1769, Vancouver, WA 98861, (360) 693-1478

Other Participants

Concord Construction

Ellensburg Concrete Products

Geocon

Granite Precast

HD Fowler

Jensen Drilling

Landel Corp.

MRM Construction

Slead Well Drilling

SureSpan Contracting

Valley Electric