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ATC to begin soil boring testing in Straits of Mackinac for upcoming cable replacement project

Michigan Department of Environment, Great Lakes and Energy, U.S. Army Corp of Engineers issued permit; work will include shoreline and submarine soil borings

PEWAUKEE, Wis. — American Transmission Co. will begin soil boring testing the week of May 13 in preparation for the planned replacement of ATC’s 138,000-volt submarine electric cables crossing the Straits of Mackinac that were damaged last year when an anchor struck them. The soil borings will begin along the Upper and Lower Michigan shorelines, near the McGulpin and Point La Barbe Riser Stations, and will continue along the lakebed of the Straits through June. The Michigan Department of Environment, Great Lakes and Energy and U.S. Army Corps of Engineers in mid-March issued a permit authorizing the work.

“Our goal is to fully assess the soil where we anticipate the new cables will be located, while minimizing shoreline and lakebed disturbance,” said ATC Project Manager Dustin Johanek.

Following the soil boring work, ATC will apply for additional regulatory and environmental permits from the U.S. Army Corp of Engineers and Michigan’s EGLE by the end of 2019. Beginning in the second quarter of 2021, ATC plans to remove the existing submarine cables and replace them with cables containing solid dielectric insulation to re-establish the two, approximately 4-mile, 138-kv circuits in the Straits. The in-service date is anticipated to be December 2021. ATC continues to work with tribal nations, regulators and nearby landowners to gather input on the cable replacement project.

Note to editors: In its December 2018 Transmission Expansion Plan, the Midcontinent Independent System Operator recommended the replacement of ATC’s two electric circuits in the Straits as soon as practical to ensure the continued reliable service to the Upper Peninsula. More information about ATC’s Straits Cable Replacement Project can be found on the project page. Details regarding the April 2018 anchor strike to ATC’s cables and the subsequent restoration can be found here.

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ATC is a Wisconsin-based company that moves energy along the regional electric grid in parts of Wisconsin, Michigan, Minnesota and Illinois, serving more than 5 million electric consumers. We are experts at what we do: planning, maintaining, operating and protecting the grid. As the electric industry moves toward renewable generation sources, we are transforming our system to continue delivering energy reliably and safely. We proudly support STEM education programs that empower youth with the skills needed to succeed in tomorrow’s energy workforce. For more information, visit and follow us on LinkedIn and X (Twitter).