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City Light starts gate rehab at Boundary Dam

August 13, 2010

Seattle City Light is preparing for a $1.2 million maintenance project at Boundary Dam on the Pend Oreille River in northeast Washington. The yearlong project will rehabilitate a 312-ton gate used to maintain the dam's seven sluice gates.

The maintenance gate sits under 200 feet of water and is slid into place in front of a sluice gate to seal it off so that crews can work on the sluice gate. City Light recently finished maintenance work on all seven sluice gates.

“Boundary Dam is a vital resource for Seattle City Light, providing about half of the electricity we produce for our customers, and a significant contributor to the economy of Pend Oreille County,” City Light superintendent Jorge Carrasco said in a statement. “Completing this maintenance work is an important part of ensuring its operation for years to come.”

City Light on Sept. 1 will start drawing down the reservoir so that crews can better access the gate. That operation will drop the reservoir level down 40 feet and could last up to 11 days.

During the drawdown, the gate will be detached from the dam and floated to the nearby recreation area where it will be removed from the water. It will be placed on a concrete pad and housed for a year in a temporary building for the retrofit. Once the retrofit is completed in the fall of 2011, the reservoir will be drawn down again for reinstallation.

City Light crews will rehabilitate the gate, which is 72 feet tall and 32 feet wide. Workers will clean the inside and outside of the gate, and patch any holes or thin spots they might find. The gate was last hauled out for maintenance 27 years ago.

McClure & Sons of Mill Creek will move the gate from the water to the new concrete pad, which is being built by Centennial Contractors of Fife. The temporary building will be pre-engineered with a steel frame. City Light expects to seek bids for the building in the coming weeks.

Others working on the project include: Dawson Construction of Ione, excavation and concrete supplier; Wm. Winkler Co. of Spokane, concrete placement and finishing; and GeoEngineers of Spokane, geotechnical, special inspection and material testing.

A City Light spokesman said the building will be moved elsewhere for another use after the gate work is done. He said the concrete slab will be left in place for future maintenance work and maybe other uses.

Several area recreation facilities will be closed during the reservoir drawdown and City Light officials will work closely with other dam operators on the river. Metaline Falls will reappear along portions of the reservoir during the drawdown. The falls have not been seen since 1982, according to City Light.

Journal Staff of Daily Journal of Commerce

http://www.djc.com/news/co/12020695.html