LoMo navigation lock inspections, repairs to temporarily affect navigators, cross-dam drivers
– NavLock to temporarily close Sept. 9-10 for valve inspections
– Recreational vessel lock schedule limited to minimize single-valve fill operations
– Public vehicle crossings suspended during repair of lock valve 4
KAHLOTUS, Wash. – Lower Monumental Dam’s navigation lock will be temporarily out of service Sept. 9-10 to allow inspection of the lock’s tainter fill valves, according to U.S. Army Corps of Engineers navigation officials at the Walla Walla District.
Inspections conducted Aug. 19 of tainter valve 4, one of two valves used to fill the lock, revealed cracks developed in its lifting-eye mechanism, causing it to malfunction. While this does not prevent the lock from being used, it does take twice as long to operate the lock having only one functioning valve with which to fill, explained Navigation Business Line Manager Jeanette Wilson.
“Tainter valve 3 is now demonstrating similar symptoms that valve 4 displayed prior to its failure -- excessive noise and vibration during operations. Modified operations of the valve have mitigated risk of imminent failure. We must get into the valve shaft to inspect it.” Wilson noted.
The two-day temporary outage will allow Corps inspectors to evaluate valve 3 while contractors work on repairing valve 4. To inspect valve 3, the lock must be out of service and the valve shaft dewatered before engineers can enter the shaft. The inspection results will determine if any additional operational changes or repairs are required. If valve 3 requires repairs, the district is aligning resources so that the contractor can move there once valve 4 is operational.
The district is working aggressively to repair valve 4. The contractor is expected to begin work no later than Sept. 8 and should be able to complete repairs by early October. Repairs will include installing new tainter valve lifting eyes, replacing various pins and bushings throughout the tainter valve operating assembly and concrete spalling repairs. It is anticipated that the lock could be in service while the contractor makes these repairs.
To minimize strain on valve 3 while valve 4 is being repaired, the recreational vessel lockage schedule will be limited to twice a day -- 9 a.m. and 6 p.m. for upstream-traveling vessels, and 9:30 a.m. and 6:30 p.m. for downstream-traveling vessels.
Public vehicle crossings at the dam will be suspended during the valve 4 work period to accommodate contractor work activities requiring use of the dam’s top deck. Travelers are strongly encouraged to check the dam-crossing information line for crossing updates 1-888-DAM-INFO (1-888-326-4636).
The valve 4 repair is estimated for completion in early October. The schedule duration is being driven by lead time to fabricate the pins and bushings in addition to the confined space environment in which the repairs will be completed. To reduce the duration of valve 4 outage, the contractor will begin working on site while these parts are fabricated.
The Corps has notified commercial navigators and other stakeholders of the situation. An update will be provided once valve 3 inspection results have been evaluated. Any necessary repairs identified during inspection of valve 3 will be scheduled in a timely manner, having the least impact to navigators.
The Corps coordinates navigation maintenance with inland shippers and cruise lines to achieve minimal impact to the various industries that use the locks. Public Notices and other navigation lock information are available on the Walla Walla District website at http://www.nww.usace.army.mil/Missions/Navigation.aspx.
Release no. 15-059