COLUMBIA & SNAKE RIVERS, Ore. & Wash. – The U.S. Army Corps of Engineers Walla Walla District reopened navigation locks on the Columbia and Snake rivers on March 29 after an eleven-week outage. This extended outage allowed the district to perform routine maintenance and to replace aged equipment to reduce the risk of asset failure.
The navigation locks included in the extended outage are McNary Dam, located at river mile 292 of the Columbia River, and Lower Monumental Dam, Little Goose Dam and Lower Granite Dam, located on the Snake River at river miles 41, 70 and 107 respectively. These locks were closed on Jan. 14. The Ice Harbor Navigation Lock, located at river mile 10, was closed Feb. 26 and returned to service by March 22, at 11:59 p.m.. Work at Ice Harbor consisted of routine maintenance.
During the outage, the Walla Walla District completed multiple projects to replace and repair equipment within the navigation locks. In addition to the routine maintenance, there were six major projects.
At McNary, the four gudgeon anchors for the downstream gate of the McNary Navigation Lock were replaced during the outage. These gudgeon anchors hold the top of the 400-ton miter gate leaves in place and have been in service since 1954. The district identified the gudgeon anchors as the primary risk driver for failure of the downstream gate. The new anchors use a new design that makes the anchors easier to inspect and maintain. This project was partially funded through the Bipartisan Infrastructure Law.
Work also began to replace the power and control systems for the McNary Navigation Lock. These controls are more than 69 years old, exceeding the typical life expectancy for this industry. Work during the outage replaced all asbestos cable trays and installed new conduits. The lock control stands, bascule bridge electrical and control components, lock electrical transformers, and lock switchgear will be replaced after the outage, for commissioning in 2025. This project was partially funded through the Bipartisan Infrastructure Law.
All the electric power distribution equipment in the Lower Monumental Navigation Lock was original equipment and was over 55 years old. Work during the outage included replacement of all navigation lock feeder cables from the powerhouse, upstream electrical switching gear and transformers, and all cable trays. Downstream electrical switchgear will be replaced in the coming months. This project was funded through the Bipartisan Infrastructure Law.
The floating guide wall at Lower Granite originally used timbers for protection from barge impacts. During the outage, these timbers were replaced with high-density polyethylene walers to improve river conditions for Endangered Species Act listed fish. The original timbers had been in service since 1974 and had decayed due to water, weather and bacteria. Additionally, the original timbers were soaked in creosote, which presented environmental issues. This project was funded through the Bipartisan Infrastructure Law.
Within the McNary and Little Goose navigation locks, numerous areas of damaged, cracked, and spalled concrete, exposed rebar, and cavitation damage were repaired. Four repair sites were identified at McNary and eight sites were identified at Little Goose. The damages were repaired using both new concrete and fiber reinforced polymer.
More information about work performed during the extended navigation lock outage can be found at https://www.nww.usace.army.mil/missions/navigation/2024-extended-navigation-lock-outage/.
To maintain safe and reliable passage through this valuable navigation system, USACE coordinates the annual lock closures with inland shippers and cruise lines to minimize impacts to lock users. For Walla Walla District navigation lock information and public notices, visit www.nww.usace.army.mil/Missions/Navigation.
Together, the USACE Walla Walla and Portland districts maintain 465 miles of commercial waterway from the Pacific Ocean to Lewiston, Idaho. The Columbia-Snake inland navigation system provides important benefits to business and the public. Approximately 9 million tons of cargo valued at over $3 billion is barged on the Columbia-Snake River System annually. The navigation system contributes jobs, facilitates import and export trade, and benefits the economy, environment and quality of life in the Pacific Northwest.