Straits Project Map

American Transmission Co. to Replace Electric Cables in Straits of Mackinac

May 7, 2021
De-energized submarine cables will be removed, and new cables will be installed in 2021.

American Transmission Co. this week will continue removing six submarine electric transmission cables and begin installing new submarine cables on the lakebed of the Straits of Mackinac. The approximate seven-month process is a significant step in ATC’s Straits Cable Replacement Project.

In April 2018, ATC’s two transmission circuits were damaged when a ship anchor severed two of the six cables and severely damaged a third. The three undamaged cables were reconfigured to form a single transmission circuit, allowing ATC to restore one electrical connection between the Upper Peninsula and lower Michigan. Two operating circuits are needed to effectively manage and reinforce electric reliability within the region.

ATC received permits from the U.S. Army Corps of Engineers and Michigan’s Department of Environment, Great Lakes and Energy to conduct this work. ATC has collaborated with the Michigan tribal nations to gather input and provide updates on the project since the April 2018 anchor drag incident.

“We are pleased to get started on this important electric infrastructure project for our customers and the state of Michigan,” said ATC Vice President, External Affairs, Tom Finco. “From a design engineering and construction perspective, this is an extraordinary project. The cables we remove and the new, solid core cables we install will be located up to several hundred feet below the surface of the Straits. Together with our contractor partners, we’re committed to ensuring this project is completed safely and in an environmentally sensitive manner.”

ATC is partnering with LS Cable Systems America, Inc., a subsidiary of LS Cable & System Ltd of South Korea, to produce and install the replacement transmission cables. Durocher Marine, a division of Kokosing Industrial, Inc., will contract with LS Cable Systems America to remove the remaining submarine cables and replace both circuits with two, three-phase 138,000-V cables containing solid dielectric insulation. Following necessary upgrades at the Point La Barbe Substation in St. Ignace and the McGulpin Riser Station in Mackinaw City, the $105 million project will be complete by December 2021. 

For more information, view the YouTube video below. 

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