Army Corps Fixes Bonneville Dam Early,
by Thomas Clouse
Grain barges are again flowing on the Columbia River after the U.S. Army Corps of Engineers fixed a broken lock on the Bonneville Dam sooner than expected.
The Corps shut down the Bonneville Dam in early September when crews found a crack on the sill of one of its massive locks, which allow barges to navigate the Columbia River. About $2 billion worth of grain, logs and freight gets shipped through the dam, which is about 40 miles upstream from Portland. About 60% to 65% of Washington wheat is sent downstream on barges.
As a result of the lock problem, farmers from Washington, Idaho and Oregon had to wait to ship their wheat. Corps officials expected to fix the lock by Sept. 30 but finished the project early.
Locks work by allowing a boat to enter a chamber that is sealed -- essentially like a giant concrete bathtub -- before the water level is lowered or raised to match the level of the river on the other side of the dam. Then the lock opens on the other side and the boat exits.
The concrete sill that cracked on the lock in the Bonneville Dam is similar to a rubber threshold on the bottom of a door. Just as that rubber strip creates a seal to keep cold air and moisture from leaking in under the door, the concrete sill creates a seal to keep water in the lock. The cracked concrete is like having a crack in a full bathtub, Army Corps spokesman Chris Gaylord said last month.
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