Photo By Michel Sauret | U.S. Army Corps of Engineers Pittsburgh District contractors use a...... read more read more
PITTSBURGH – With the Ohio River's navigation system at stake, the U.S. Army Corps of Engineers Pittsburgh District is restoring the aging Montgomery Dam piers, which are vital for supporting commercial barge traffic.
The Pittsburgh District has been chipping away at the nearly 90-year-old concrete from the dam piers to restore them to new life.
The work is not a superficial facelift but an effective method to strengthen the piers to last decades into the future.
“This work will help extend the life of this dam by 50 years or more,” said Jim Carr, the contract’s project quality control manager.
The Pittsburgh District constructed the Montgomery Locks and Dam in 1936. The dam holds back a pool of water on the Ohio River, ensuring the river is deep enough for commercial barges to navigate without scraping the bottom. The locks, built alongside the dam, create chambers for towboats and barges to pass through.
“This project supports the consumers who use the river, such as the coal that comes up and down the river, which powers people’s houses and is still one of our main sources of energy,” Carr said. “If the river shuts down, there’s no power for plants, so absolutely this is important.”
Transporting commodities on the waterways is four times less expensive than by truck and 33 percent cheaper than by rail. Between 15 million and 20 million tons of cargo travel on the upper Ohio River each year, including mainly coal, but also coke, petroleum products, raw and finished steel, and aggregates.
Like most locks and dams nationwide, the facility was designed to last about 50 years before requiring major maintenance and repairs. The concrete surfaces deteriorate over time. Now, nine decades into its use, the lock chambers and dam need ongoing attention to continue supporting the navigation industry.
“We identify concrete that needs to be removed — the unsound, old, bad concrete — and we remove it and install new concrete that is structurally adherent to the old piers,” said Tim Resciniti, a project engineer for the Pittsburgh District overseeing the Montgomery Dam pier-repair project.
The district is working to repair the concrete on all 11 dam piers at the Montgomery facility, a process that will take about a year to complete. 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.
When it comes to analyzing concrete, tried-and-true methods are the most effective. Instead of complicated laser or scanning systems, contractors use simpler means, relying on a hammer and their ears.
“We ‘sound’ the concrete by taking a hammer and tapping on it,” Resciniti said. “If the concrete is good, it has a higher pitch sound. If it’s bad concrete, it has a hollow, dead sound.”
“The difference is generally night and day. It’s pretty easy to identify,” he said.
After sounding the concrete, contractors label and mark areas with spray paint and jack hammer the marked concrete, removing up to 12 inches away from the surface. Workers then drill holes to install rebar, attach custom-shaped forms to the piers, and pour new concrete into the exposed areas.
“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,” Resciniti said.
The crew mixes the concrete on site using cement with a special bonding agent and aggregate that will adhere to the old surface. They mix roughly one cubic yard of concrete at a time to place in areas of need.
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.
As the dam pier-repair project continues, it also prepares the dam for a major construction project in the coming years. The project will replace the auxiliary chamber, measuring 56 feet wide by 360 feet long, with a new lock measuring 110 feet wide by 600 feet long. The new lock construction is part of the multibillion-dollar Upper Ohio Navigation Project, replacing chambers at the Emsworth and Dashields locks and dams.
“Our goal is to maintain our aging infrastructure,” Resciniti said. “We have dam piers approaching 100 years soon. If we didn’t do anything, the concrete would continue to deteriorate. This project extends the life of the dam for industry to use our rivers well into the future.”
| Date Taken: | 09.23.2024 |
| Date Posted: | 09.23.2024 14:05 |
| Story ID: | 481536 |
| Location: | PITTSBURGH, PENNSYLVANIA, US |
| Web Views: | 122 |
| Downloads: | 0 |
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