STARBUCK, Wash. – UPDATE #2 -- Work to replace the cracked gudgeon arm assembly on the top of Little Goose Dam’s navigation lock downstream south gate leaf remains on track to reopen for service by the end of April, according to U.S. Army Corps of Engineers’ Walla Walla District officials.
Work milestones completed to date include securing the gate leaf in place to keep it stabile during repairs; removing the old, cracked gudgeon arm assembly; and painting and installing the new gudgeon arm assembly.
The remainder of the work to be done relies heavily on the use of cranes and man baskets and includes adjusting diagonal tensioning on the gate leafs; preparing the hydraulic power unit for reattachment to the south gate leaf; removing work-related equipment from the site and final alignment testing prior to returning the navigation lock to service.
For safety, Little Goose Lock and Dam’s navigation lock will remain closed to all river traffic until repairs are completed.
“Many of the tasks involved with this repair have been and will be performed concurrently wherever we can to maximize efficiency and keep this lock outage as short as possible,” said Steve Hartman, Corps project manager. “The Corps is committed to meeting our obligations under the BiOp (Biological Opinion), and to providing safe commercial and recreational navigation services at our locks.”
BACKGROUND: The Corps awarded an emergency contract on April 1 to Knight Construction of Deer Park, Wash., to install a new gudgeon arm assembly -- the metal arm at the top of the downstream south gate leaf that hinges and holds the gate leaf to the navigation lock wall.
With the Little Goose lock out of service, the 2014 Federal Columbia River Power System Supplemental Biological Opinion (BiOp) fish transportation scheduled to begin sometime in late April may be delayed. Coordination of fish transportation operations and related research will be addressed through BiOp adaptive management processes.
Little Goose Dam’s navigation lock has a downstream miter gate resembling a giant set of French doors. One gate leaf is about 118 feet tall, 43 feet wide and weighs 334 tons -- from 1986 through 2013, the gate performed 35,713 lockages. A gate gudgeon assembly is a key component of this style of gate, holding the gate into position at the top while the gate pivots to open and close (a hinge-like assembly). The steel gudgeon assembly is an original component of the lock and has not been removed since installation in the late-1960s.
The Corps has notified commercial navigators, fish managers and other stakeholders, and will continue to provide updates as they become available. Public Notices and other navigation lock information are available on the Walla Walla District website at www.nww.usace.army.mil/Missions/Navigation.aspx.