Chittenden Locks large chamber to close for maintenance

Published July 10, 2018

SEATTLE – The Hiram M. Chittenden Locks large chamber will close to vessel traffic from 7 a.m. to 5 p.m. July 17, 18 and 19, for work on the emergency closure system, or ECS.

The large chamber will also close the same times August 6-8 as part of the work. The small lock will continue operations during both closures. A contractor will replace a wire rope and recondition a portion of the ECS.

“In the unlikely event of a large lock gate failure and uncontrolled flow through the chamber, this system lowers a series of gates into the flow to stop it,” said Operations Project Manager Jon Hofstra.

The aging emergency closure system was identified as one potential issue when the Lake Washington Ship Canal, which includes the locks and Montlake and Fremont Cuts, received a revised dam safety action classification in 2011. Corps officials use the classification system nationwide to prioritize dam safety decisions and allocate funding. Experts try to plan for every possible scenario that could take place, analyze the potential risks and come up with solutions long before they become reality.

A large crane on the east end of the large chamber is also part of the ECS and a contract to replace the crane was awarded in 2017. Work is not yet scheduled for installation.

“The dam safety program is critical to addressing the nation’s aging infrastructure and ensuring dams are safe and present minimal public risk,” said Hofstra. “We’ve completed repairs and studies that address several primary concerns and are aggressively working our long-term solutions along with prioritizing other aging systems at the facility.”

Another major component being replaced at the 100-year-old Locks are the filling culvert valves. Funding for the valves was received in June and officials are currently working to get a contract awarded for the work. In addition to dam safety the new valves will help with the U.S. Army Corps of Engineers’ environmental stewardship of salmon migrating through the Locks. The replacement will cause extended large chamber closures beginning in 2019.

Corps officials are hosting a public meeting 8:30 a.m. July 17 at the Locks Visitor Center to review 2018 pump-out dates of October 29 through November 21, plus plans to repair or replace aging equipment that could result in additional closures. The meeting is expected to last less than an hour and anyone with interest is welcome to attend.

Bill Dowell

Release no. 18-052