Louisville, KY – The Markland Board of Investigation found improper alignment of the gate leaves, equipment failure and the need for additional procedures led the Markland lock chamber gate leaves to fail Sept. 27 on the Ohio River at Warsaw, Kentucky.
The U.S. Army Corps of Engineers report found the chamber gate leaves failed because a solenoid valve malfunctioned which caused continuous water flow into the lock chamber while the gates were closing. Solenoid valves are used in hydraulic systems to control valves. When the solenoid is active, the valve is open. When it is at rest, the valve is closed. The lock operator saw water disturbance in the chamber but attributed this to prop wash instead of additional water entering the chamber, and initiated the miter gates to close. The additional water and pressure caused the gates to close improperly. The combination of an incomplete gate seal and water pressure differential forced the gates past their designed closure position, leading to their failure.
“This is a unique situation in the history of our locks. We do not have any history of a solenoid valve failing in an open position, thus causing increased water flows and resulting damage to lock gate leaves,” said U.S. Army Corps of Engineers Louisville District Commander Col. Keith Landry.
The solenoid valves have been replaced in the 600-foot lock chamber at Markland and all valves have been inspected at the other Ohio River and tributary locks. The Corps continues its mission to keep the Ohio River open to navigation.
While the Markland gate failure is a unique and an isolated occurrence, it highlights the need for improved procedures to reduce the risk of this occurring in the future. The Army Corps of Engineers is undertaking a deliberate review of locking procedures and possible modes of failure along the entire Ohio River lock system. This review will result in establishing updated locking protocols and preventive maintenance checks that may include:
• Refined locking procedures with operator checklists, to include a second review of gages prior to closing the gate leaves
• Additional recurring training for lock masters and lock operators
• Better ergonomic and physical layouts of control indicator panels to facilitate lock operators' ability to view gages and indicators
• Preventive maintenance checks to be developed as a result of detailed failure mode analysis at each lock in the system
Structural and component repairs on the Markland 1,200-foot lock chamber gate leaves are expected to be complete by mid-January. Both gate leaves sustained some structural damages during the lock gate failure. These repairs are among several additional steps necessary to complete prior to the reopening of the 1,200 foot lock chamber.
“A lot of progress has been made, and commerce continues to move on the river,” said Gene Dowell, the U.S. Army locks and dam operations manager for the Corps of Engineers' Louisville District. “The entire team has been working really hard to ensure the auxiliary lock stays open and to repair the gate leaves.”
Welders and repair crews have been working two ten-hour shifts, 13 of 14 days with every other Sunday off at the Louisville Repair Station on Shippingport Island, adjacent to Louisville, Ky.
“The repairs we have been doing are intricate and time consuming work,” said Tracey Keel, assistant operations manager for locks and dams. The gates were slightly bent or warped but repairable. Keel said a significant amount of welding work has been done. “A critical aspect of the work is to ensure the repaired leaves and the pintle ball area at the bottom and gudgeon pin at the top line up perfectly straight and true.” Keel said the repair crew will use lasers to ensure the required precise alignment.
Previous to the mishap, new lock gates for Markland had already been under construction, and one set of miter gate leaves’ delivery has been expedited by nine months to arrive by mid-March 2010.
Current plans are to transport the repaired gate leaves up river after mid-January 2010 and re-hang the gates by the end of January, subject to river and weather conditions. Once the gate leaves are re-hung in the lock chamber, final additional repairs will be executed on the leaves. These final repairs will take three or four weeks to complete.
“Our repair plan is aggressive, but fully incorporates all safety requirements, and is dependent on low water river conditions,” said Col. Landry.