The MacArthur lock was set to reopen in late April but replacing the almost 79-year-old tainter valve machinery, original to the lock built in 1943, caused the closure’s 59-day extension.

“The tainter valve machinery replacement contract was a very large task,” Soo Locks construction chief Nicholas Pettit said. “The original machinery had to be cut into pieces and removed by crane out through a small access tunnel. The new machinery had to be fabricated in sections, lowered by crane in through the small tunnel and installed inside of the lock.”

The installation took longer than scheduled, but this critical replacement means the MacArthur Lock will continue operating long into the future, according to Pettit.

The $7.2 million contract was awarded in August 2020 with the long lead time needed to manufacture the mechanical components.

The extended closure demonstrates how important the New Lock at the Soo project, currently under construction, and maintaining the current locks are to Great Lakes shipping. If the extended closure had happened to the larger Poe Lock it would have halted nearly all shipping.

The MacArthur Lock closed December 15, 2021, for seasonal maintenance, including the tainter valve machinery project. Every year, the Corps of Engineers uses the winter period to perform maintenance to keep the Soo Locks operating. The Sault Ste. Marie Project Office works long hours in extreme conditions to complete a significant amount of maintenance during this annual closure period. The work they perform is unique, especially given the harsh northern Michigan conditions they work in.

Corps of Engineers maintenance crews completed hydraulic steel structure inspections and repaired the MacArthur Lock’s miter gate 5 sill. In addition, crews also performed a wide range of other maintenance tasks from replacing fender timbers on the piers to electrical and mechanical systems inspections and preventive maintenance.

More than 4,500 vessels, carrying up to 80 million tons of cargo, maneuver through the locks annually. Iron ore, coal, wheat and limestone are the most frequently carried commodities.