Images | Contractors repair dam concrete ahead of $2.1bn reconstruction programme

The Pittsburgh District is repairing concrete on all 11 dam piers at the Montgomery facility in Monaco, Pennsylvania, in a process expected to take about a year to complete.

The dam is nearly 90 years old and the piers require repairs and resurfacing every few years to keep them structurally sound.

The pier work also prepares the dam for a major construction project in the coming years, according to USACE.

Image: U.S. Army Corps of Engineers Pittsburgh District/Michel Sauret)

Under the $2.1 billion Upper Ohio Navigation Project, the auxiliary chamber at the Montgomery facility, measuring 56 feet wide by 360 feet long, will be replaced with a new lock measuring 110 feet wide by 600 feet long.

Chambers at the Emsworth and Dashields locks and dams will also be replaced under the project.

Jim Carr, quality control manager on the repair work to the Montgomery facility’s concrete piers, said, “This work will help extend the lift of this dam by 50 years or more.”

When it comes to analysing concrete, contractors eschew laser or scanning systems, instead preferring to rely on a hammer and their ears.

“We ‘sound’ the concrete by taking a hammer and tapping on it. If the concrete is good, it has a higher pitch sound. If it’s bad concrete, it has a hollow, dead sound,” said Tim Rescinti, a project engineer for the Pittsburgh District overseeing the Montgomery Dam pier-repair project.

“We remove it and install new concrete that is structurally adherent to the old piers. We embed dowels into existing sound concrete, bonding them with an adhesive. The bond between the new concrete and the old, in addition to reinforcement, transfers the load between new and old.”

The repairs include various forms to restore each pier’s original shape. Some forms are made of wood, while others are metal, shaped to fit the full-rounded nose of each pier. Workers load the concrete into a bucket, raised by a crane, and pour it into the forms.

Contractors also built customized platforms that conform to the piers’ base to work as close to the water’s surface as possible.

“Our repair area starts at about a foot above the waterline, so we came up with a platform solution on site to fit our needs,” Resciniti said.

The Montgomery Locks and Dam were built in 1936 and hold back a pool of water on the Ohio River, ensuring the river is deep enough for commercial barges to navigate it. The locks, built alongside the dam, create chambers for towboats and barges to pass through.

Image: U.S. Army Corps of Engineers Pittsburgh District/Michel Sauret)

According to the schedule, contractors will finish the project by July 2025, with a pause in January and February due to expected winter weather.

The district resurfaces different portions of the piers every few years to keep them structurally sound for the long term. The last time USACE completed resurfacing work at Montgomery was in 2022.

Image: U.S. Army Corps of Engineers Pittsburgh District/Michel Sauret)