John L. Russell

Special to The Detroit News

Sault Ste. Marie — It's cold, complex and dangerous work.

But repairs to the Soo Locks are critical to ensuring ships can pass through the Great Lakes every year, despite challenges posed by frigid weather.

This season, the work began the day after the Locks closed for the season Jan. 15 and has kept up weekdays through the daylight hours.

Both the Poe and the MacArthur locks were emptied of water so $2.8 million in maintenance can be completed over 10 weeks prior to March 25, when the shipping season begins on the Great Lakes.

“We have a complex, accelerated work schedule in the winter,” said JoAnne Gray, chief of construction at the Army Corps' Soo Area Office. “It takes 10 hours to de-water a lock, then we put in stop logs and divers plug all leaks in the gates to ensure a dry environment to work.”

The two locks are massive, with the MacArthur Lock 80 feet wide and 800 feet long, the Poe Lock 110 feet wide and 1,200 feet long, allowing 1,000-foot freighters to transit 21 feet to and from Lake Superior and Lake Huron around the St. Mary’s River Rapids between Michigan and the Canadian province of Ontario.

Divers in suits filled with warm water that ensure survival enter the locks upon closure to open drains. Stop logs are placed in the gates and drains at the bottom of the locks are opened. More than 22 million gallons of water are flushed from each lock by five 300-horsepower pumps.

Oakum, a fiber rope used in building wooden ships, is used by the divers to plug small leaks in the huge four-foot-wide wood gates that rise 61 feet from the lock’s floor.

Huge barges with cranes and other equipment are placed in the lock and slowly lowered 61 feet to the bottom of the locks as the water is removed. And plastic covers are placed over the gates trapping pumped steam onto the gates, melting ice and snow so work can commence.

“We perform maintenance all year. In the winter, our work becomes more intense,” said LeighAnn Ryckeghem, chief of maintenance engineer with the U.S. Army Corps of Engineers.

A list of work to be completed by Monday included cylinder seal and embedded anchorage replacement as well as lock valve maintenance on the Poe Lock. Anchorage replacement, lock filling valve seal replacement and bevel gear replacement on the MacArthur Lock also were being done.

A crew of 120 employees keeps the locks maintained.

“We do most of the work ourselves,” engineer Kevin Sprague said. “We try to remain self-sufficient. We have our own dive team, a huge and extensive machine shop and our own hydro-electric plant for power and steam.”

More than 4,500 vessels carry up to 80 million tons of cargo through the locks annually, according to the U.S. Army Corps of Engineers, which oversees the operations of the locks.

Iron ore, coal, wheat, corn and fuel are some of the more common commodities that pass through the locks.

The locks are completely manual, with gates that close on one end allowing water to drain out the other end, raising or dropping a vessel to the correct level allowing them to continue to their destination.

To complete preparation for the lock’s return to service, all ice and snow is removed with powerful steam hoses, which melts the accumulated snow into water, which is drained from the bottom of the lock.

Snowfall in the Soo has been heavy this year and crews are busy placing hoses to remove all water. Ice and other debris could plug drainage if allowed to remain, so steam melts everything for removal.

“The Soo Locks are critical to the Great Lakes Navigation System,” said Lt. Col. Greg Turner, U.S. Army Corps of Engineers district engineer, in a statement. “We have a tremendous team that operates and maintains the locks throughout the year.”

John L. Russell is a writer and photojournalist from Traverse City.