Damaged Straits of Mackinac cables being replaced

Electric transmission cables that run along the bottom of the Straits of Mackinac are being replaced starting this week after an anchor strike incident three years ago severed two of the six cables.

Wisconsin-based American Transmission Co. said Monday it is doing the work following an April 2018 accident in which a 12,000-pound anchor damaged two transmission circuits, cut two cables and severely damaged a third.

ATC officials said the three undamaged cables were reconfigured to form a single transmission circuit, allowing workers to restore one electrical connection between the Upper Peninsula and lower Michigan.

The two operating circuits are needed to "manage and reinforce electric reliability within the region," ATC officials said.

In 2018, the Clyde S. VanEnkevort tug boat and the Erie Trader barge's anchor was dragged across the Straits bed, damaging three electric transmission cables and spilling more than 800 gallons of dielectric mineral oil. It also hit two other Consumers Energy retired lines and dented Line 5.

Enbridge and the tug company recently reached an undisclosed settlement in which an unspecified amount of money was wire-transferred from Van Enkevort to Enbridge. Van Enkevort Tug & Barge and MOM Erie Trader argued that Enbridge should be held at fault because it failed to locate its dual pipeline in an environment protected from anchor strikes.

ATC said it received permits from the U.S. Army Corps of Engineers and Michigan’s Department of Environment, Great Lakes and Energy to do its replacement work. ATC officials also said they have consulted with Michigan tribal nations to gather input and provide updates on the project since the April 2018 anchor accident.

"We are pleased to get started on this important electric infrastructure project for our customers and the state of Michigan," said Tom Finco, ATC vice president for external affairs. "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."

American Transmission Co. owns and operates 10,081 miles of electric transmission lines and 582 substations in portions of Wisconsin, Michigan, Minnesota and Illinois.

lfleming@detroitnews.com