Monday, November 24, 2014

Alternate plan approved for demolition of old Ledbetter Bridge piers

A contractor for the Kentucky Transportation Cabinet (KyTC) has gained approval for an alternate demolition plan for the remaining in-water piers at the Old Ledbetter Bridge site.

The contractor plans to excavate the river bottom outside the navigation channel and knock over the top half of the piers so they will fall into the excavated areas, according to KyTC District 1 Chief Engineer Mike McGregor.

“The natural silting process along the river bottom will then cover the piers, leaving them below the river bottom,” McGregor said.

When the last truss section over the Tennessee River main navigation channel was detonated Oct. 1, the blast rocked over the piers that held it up. The contractor had planned to drill the piers, place explosives and bring them down with a controlled detonation. However, cracks left in the piers raised safety questions about the drilling process.

“We believe this new plan will provide appropriate safety for workers and accomplish our goal of removing the piers from the waterway,” McGregor said.

In a letter outlining the alternate plan, Mark Hutchins with C.J. Mahan Construction Company indicated excavations could be completed this week with plans to pull over one of the piers today, followed by the second pier on Tuesday. Wednesday is a backup date in case of an unexpected delay.

“With all of this work being in the back channels we will not impede navigation traffic,” Hutchins said. “Drilling of the lower sections will start after the Thanksgiving holiday.”

Hutchins noted that once the top of each pier is removed, a date will be set for using explosives to remove the bottom half.

KyTC engineers and the company worked closely with the U.S. Army Corps of Engineers and other agencies with jurisdiction over the project to gain approval for the alternate plan.

Meanwhile, the contractor has continued conventional demolition of the approach spans along the Livingston County end of the old Ledbetter Bridge and on the McCracken County shoreline.  All steel is down and the contractor is digging and pulling over the land-based piers.

The old Ledbetter Bridge went into service in 1931. In January 2012, it had to be restricted to a 3-ton load limit. Completion of the new U.S. 60 Tennessee River Bridge at Ledbetter was expedited and traffic flow moved to the new structure July 31, 2013. The old bridge was damaged by land slippage along the western shoreline of the Tennessee River in April prompting the demolition process to be expedited.