Wilson Lock Repair Schedule Remains In Progress

The Corps of Engineers has offered a ballpark cost estimate of $10 million to cover the repair of Wilson Lock and Dam, located at Tennessee River Mile 259.4 in Florence, Ala.

While funds are available to dewater the chamber to weld the cracked lower miter gates beginning in the next few days, the cost is an estimate to mobilize the Great Lakes and Ohio River Division’s Heavy Capacity Fleet a second time between January 20 and April 20 to dewater the chamber again and then jack up the gates to repair the pintle castings, said Brian Mangrum, chief of the Nashville Engineer District’s technical support branch.

The Nashville Engineer District has begun amending its formal request for funding, and Mangrum said he does not anticipate any issues as he has been assured that getting the main lock chamber back open is the highest priority in the district.

“They’re tracking the need,” he said of the Great Lakes and Ohio Rivers Division and Corps headquarters. “They are looking to identify the additional resources that are needed to cover those unanticipated fleet costs.”

Mangrum added that the regional maintenance team already met and approved the schedule change for the Heavy Capacity Fleet.

Wilson’s main navigational lock chamber closed September 25 after operators heard popping and cracking sounds, which were later determined to be cracks near the bottom of both lower miter gates. While the main chamber can typically pass a tow three barges wide and three deep, the auxiliary chamber can lift only one barge at a time. Mangrum said in a November 5 call with industry that, as of that morning, 24 vessels and more than 220 cuts of barges were waiting to transit the auxiliary chamber. That number is similar to the prior week.

The Corps of Engineers hopes to know by December 1 whether temporary welding of the cracks will permit at least some traffic to lock through the main chamber from December 20 to January 20, between the two planned dewaterings. The closure to replace the gates’ pintle components is scheduled to continue through April 20.

Mangrum said the project remains on schedule.

“We have completed repair of the lower caisson slot,” he said. “We’re going through some required cure time on the grout that we’ve pumped in to secure the steel plating.”

On November 2, the Tennessee Valley Authority (TVA) completed removal of excess sedimentation on the closure structure sill.

“That puts us in a good position for the slot and sill being on track and complete and ready for our diving crew to provide some final sweeping of debris and for the Heavy Capacity Fleet to set that caisson once they are mobilized on site,” Mangrum said.

The Heavy Capacity Fleet was expected to complete work at Smithland Locks and Dam on the Cumberland River on November 8, refuel, drop off some equipment so as to prevent excess congestion in the approach to Wilson Lock and then to begin work at Wilson.

Mangrum added that, concurrent with those tasks, the Corps is working on both the weld repair plan for the cracks, which must be confirmed in the initial days of the first dewatering inspection, and the gate-lifting plan for the second dewatering. The gate-lifting plan includes whether gates need to be strengthened, whether jacking pads must be added and the methods and materials needed to stabilize the gates while in the jacked position during that dewatering.

“One of the key tasks I mentioned for us was the final material determination for the forging of those pintle assemblies and the ordering of those raw materials by TVA’s Power Services Shop in Muscle Shoals,” Mangrum said. “Both of those tasks have now been completed.”

He anticipated giving the next update on those materials when they arrive in about four weeks.

The TVA Power Services Shop, which is forging the pintle castings since the original casting method was expected to have taken about a year, has been excellent to work with, Mangrum said.

“They’ve been printing 3D scale models to analyze each step of that fabrication and identifying what the potential challenges might be and how to work through those well in advance of receiving that material,” he said. “I have full confidence in them and their team to hit the ground running once those materials arrive.”

Risks to the schedule could include any delays receiving the pintle components, any unknown deficiencies with the gates discovered in the initial dewatering and any problems associated with weather or high-water periods.

Mangrum concluded, “Our key task for this week is continued coordination on the request for funding with [the Great Lakes and Rivers Division] through [Corps headquarters] and continued efforts on procurement of other miscellaneous materials and supplies to support this repair effort.”