PITTSBURGH – In carpentry, the saying goes, “measure twice, cut once,” but on a construction project involving steel gates weighing as much as 11 school buses, there never seems to be an end to measuring.
“It took us months and months of planning. We had a lot of meetings of just measuring, and measuring, and measuring to figure out how we can boom the gates down into place,” said Kevin McConnell, the maintenance mechanic supervisor for the U.S. Army Corps of Engineers Medium Capacity Fleet.
The fleet is currently at the New Cumberland Locks and Dams on the Ohio River to replace four miter gates for the lock’s auxiliary chamber. Each gate weighs at least 165 tons, measuring 61 feet wide and 30 feet tall on the upstream and 40 feet tall on the downstream side. Each gate weighs as much as three Army tanks. The crew will have to counterbalance a crane with water to prevent it from toppling over during the lift.
One wrong move could swing a gate out of control and destroy the fleet if it crashes upon it, McConnell said.
“It’s a lot more involved than just, ‘Hey, just pick it up and set it over there,’” McConnell said.
The lock’s auxiliary chamber has been out of commission since 2016, leaving only the main chamber to operate solo for six years.
“It’s something that had to be dealt with,” McConnell said. “You can’t rely on just one chamber. Eventually, the main chamber will need maintenance, and if that main chamber goes down, it shuts the entire river down here.”
Power plants and other industries rely on locks to transport commodities along the river year-round. More than 184 million tons of cargo, including coal, grain, steel, chemical, petroleum and construction materials, travel on the Ohio River yearly.
Six years ago, an inspection discovered the gates were severely worn and could not be repaired. Miter gates seal the lock chamber and control the water level inside it to act as an elevator. Except these 60-year-old gates were rotted and full of holes.
“They were so bad, you could put your hand through the thing,” said Chris Smidl, the onsite operations project engineer for the Pittsburgh District.
Normally, miter gates can last more than a century if inspected and maintained every 10 to 20 years, but due to a lack of funding in the region, the gates reached a point of irreparable damage.
“They were shot. We sent them to the scrap yard where they cut them up to recycle them. They may be your next refrigerator,” McConnell joked of the old hunks of steel.
Before installing the new gates, the fleet’s mechanics rehabilitated the anchorage assembly with new steel to hold the weight of the gates.
“It’s a careful process in which large steel parts have to be aligned within an eighth of an inch,” Smidl said.
If the anchorages are not perfectly aligned, the gates won’t swing open or seal shut properly.
“To get one of these anchorages out, you’re saw-cutting the concrete. You’re busting the concrete. You’re burning rivets off. Knocking rivets out. We’re talking about rivets that have been there since the late 50s and early 60s. We’re taking all this old steel and fitting brand new steel, welding it together,” McConnell said.
The fleet performs year-round repairs on the three major rivers around Pittsburgh. The crewmembers work 10-hour days, 12 days in a row, with only two days off. Yet, the shifts overlap, so there is never a pause in operation.
“Everybody on the fleet has a trade, but they all seem to master multiple skills,” Smidl said.
Due to their nonstop work ethic and all the pre-planning involved, Smidl estimates the fleet can accomplish work in two months that would typically take a year to finish. The chamber has been out of commission for six years due to a lack of funds, not willpower.
“That’s why they exist,” Smidl said of the Medium Capacity Fleet’s crew. “I’m always impressed with how quickly they can solve issues and come up with solutions. They have that steel-worker mentality. They’re just here to get the job done. No obstacle will get in their way.”
The fleet plans to hang and install the first two gates by then end of August 2022. For the next 12 months, the medium fleet has work scheduled at other locking facilities along the Ohio and Monongahela rivers. They will return to New Cumberland next year to drain the chamber and complete the final phase of construction. The corps expects the auxiliary chamber to be complete late of 2023.