Unified Command approves plan to cap, seal severed utility cables in Straits of Mackinac

A remotely operated vehicle (ROV) was deployed in the Straits of Mackinac to assess damage to the American Transmission Company’s cable 6 (Photo courtesy of the American Transmission Company)

MACKINAW CITY, Mich. — The Unified Command approved a plan developed by American Transmission Company, contracting with Durocher Marine and T&T Subsea, to cap and seal the two severed utility cables in the Straits of Mackinac, Wednesday.

Thursday, a tug, barge, and remotely operating underwater vehicle commenced operations to cap the ends of the two severed ATC utility cables.

One by one, the ends of severed cables will be lifted to the surface of the water, to solder and affix a permanent cap. The caps will be wrapped with the existing outer steel armor wires of the cables and banded with steel clamps. Once the ends of the cables are soldered, capped, and sealed, they will be laid on the bottom of the Straits in their original position. Afterwards, concrete mats will be placed over the ends of the two cables to prevent them from moving.

During the course of the operation, a back pressure will be applied to the shore side ends of the cables to prevent any additional spillage of mineral oil into the Straits of Mackinac.

To date, 612 gallons of mineral oil have been extracted from the two severed cables and the effort is ongoing. Together, the two cables hold a maximum of 800 gallons of mineral oil.

Additionally, during the ROV assessment of the ATC cables, deenergized and retired 46kV cables owned by Consumers Energy were also found to be damaged. The cables were installed in 1956 and, deenergized and retired in 1990.

Consumers Energy reported to the Unified Command that there is no free flowing fluid within their retired cables.

Chemical testing of the material in the cable will be completed to gauge any risk to the environment due to the damage. A representative from Consumers Energy has joined the Unified Command in Mackinaw City, to coordinate a plan to respond to their damaged cables. Emergency managers from Mackinaw, Charlevoix, Cheboygan, and Emmet counties have been notified of the discovered damage to the Consumers Energy cables.

The Unified Command continues to communicate with other utility companies in the Straits to ensure that all steps are taken to assess and mitigate any further damage to active and retired infrastructure.

Wildlife biologists from the United States Department of Agriculture’s Animal and Plant Health Inspection Service Wildlife Services program, personnel from the Michigan Department of Environmental Quality, and Coast Guard Marine Science Technicians continue to survey the area, on the water, from shore and from the air, to look for any signs of pollution or impacted fish and wildlife.

No impacts to the environment or wildlife have been identified.

The Coast Guard marine casualty investigation into vessel activity that may have caused the damage to the ATC cables is ongoing.

To report affected wildlife or animals acting abnormally please call the USDA at (517)-336-1928.

To report any oil sheen or pollution, please call the National Response Center at 1-800-424-8802.

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