20-052 Floating Guidewall Cable replaced at Lower Monumental, restrictions still in place

Published Sept. 28, 2020

Kahlotus, Wash. – On June 13, an operator at Lower Monumental Lock and Dam noticed that the floating guidewall had drifted out of alignment. A service cable inspection and repair dive were conducted and discovered, on July 28, that the anchor cable had broken, allowing the guidewall to swing towards the dam until broken cables snagged in the mud. To prevent further movement, and to allow grain to continue moving down river, Corps officials brought in a tugboat to hold the guidewall in place. The tugboat held the guidewall in place from Aug. 1 until Sep. 22.

Corps officials brought a contractor in to dredge the area and replace the cables. The area around the anchor cable had filled with rock and hard clay, which had rubbed against the cable, causing it to fray and eventually break. The contractor worked 12 hours a day, seven days a week, to allow shippers time through the locks each evening. Fires, dust storm and high winds made work more difficult, but repairs were ultimately finished on Sept. 25, and the lock was reopened.

The anchor cable was replaced with an anchor chain. The chain is not nearly as susceptible to abrasion damage as the original cable and will be able to last for many decades. The Walla Walla District, Northwestern Division and the U.S. Army Corps of Engineers headquarters coordinated to secure funding for this project in order to complete the work in a timely manner.

Until further notice, vessels transiting the Ice Harbor, Lower Monumental, and Little Goose navigation locks must use caution when near the upstream floating guide walls.

At these projects, vessels may not tie up to the floating guide wall or rub against the floating guide wall when approaching or leaving the lock. The guide wall should also not be used as a pivot point for entering the lock. These restrictions will remain in place until inspections and repairs can be performed on all floating guidewall cables and other related assets.

For more information, contact the NWW Operations Division at (509) 527-7364.


Release no. 20-123