SEATTLE - The Hiram M. Chittenden Locks large chamber will close to vessel traffic from 7 a.m. to 5 p.m. January 24 and 25 to complete work on the emergency closure system, or ECS.
The small lock will continue operations during the closures. The large chamber closed December 12-14 for this work but the contractor could not finish the necessary work during that outage. The work includes replacing a wire rope, reconditioning a portion of the ECS and testing the system.
“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 contractor will test the system during this outage and place those gates, called stop logs.”
The aging 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 1920s-era 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 102-year-old Locks are the filling culvert valves. Funding for the valves was received June 2018 and the contract awarded for $10.5 million. Gate replacement is scheduled to start in 2019. Those closures are:
- 2019 – October 12 through November 30
- 2020 – February 12 through April 2
- October 12 through November 30
- 2021 – February 12 through April 2
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.
Release no. 19-003