Chittenden Locks large chamber closing up to 53 days October 12

Published Oct. 11, 2019

The Hiram M. Chittenden Locks large chamber will close to all vessel traffic 6:30 a.m. October 12, for the first of four scheduled extended closures to begin replacing the chamber’s filling culvert valves.


It will remain closed for up to 53 days, with a scheduled reopening December 3. That’s a month longer than the typical November annual maintenance closure two to three week timeframe. The small chamber will remain open during this time and vessels up to 28-feet wide by 123-feet long are able to use it.


A contract to replace the original large lock chamber’s 102-year-old filling culvert gates at the Hiram M. Chittenden Locks in Ballard was awarded by U.S. Army Corps of Engineers officials September 10, 2018.


Ferndale, Washington, headquartered IMCO received the contract award for their $10.5 million bid. The project will replace the original valves, called Stoney Gate Valves, designed and originally used during the Panama Canal construction.


“We know these closures don’t’ just affect the vessels that transit the locks, but the maritime industries that support them as well,” said Hofstra. "While this is a massive project and never before done, we’re extremely confident we’ll be back in operation by December 3.”

The Stoney Gate Valves are underwater during regular operations and seal off the 8-feet-6-inch wide by 14-feet tall filling culverts.


“The contractor will be jack hammering out old components that extend up nearly 30 feet in a space that is only about 3-feet wide,” said Project Manager Peter Gibson. “It was constructed more than 102-years ago and we really don’t know what they will encounter during the demolition portion.”


Once demolition is complete, forms will be erected to create the new valve component space and then concrete poured.


“It will take about a week for the concrete to fully cure,” Gibson said. “Then they can begin installing the new system.”


That installation will require drilling about 600 holes up to 1-inch in diameter and 20-inches deep into the concrete. According to Gibson, the contractor has a solid plan to meet their deadline and have prepared contingency plans if there are issues with construction to ensure a quality, well-built product.


During the first extended closure the contractor and Corps officials will meet regularly and look for ways to increase efficiencies to replace the remaining five Stone Gate Valves.


“We’ll be looking for ways we can shorten the closure duration to help reduce impacts to our Seattle maritime community and other stakeholders,” Hofstra said.


The current extended closure schedule is:

2019 –   October 12 through December 3

2020 –   February 12 through April 5

              October 12 through December 3

2021 –   February 12 through April 5


The regular annual lock maintenance closure is expected to return in fall 2021, currently set for November 9 through 24.


For more information about scheduled and projected Chittenden Lock closures visit For closures and other activities visit the Locks’ Web site at Also follow the Locks on Facebook and Twitter: and

Bill Dowell

Release no. 19-035