Power line underwater in Mackinac Straits leaks insulation oil
Repairs complicated by foul weather, ice
An underwater electric transmission line between upper Michigan and lower Michigan was damaged and began leaking oil into the Straits of Mackinac on Sunday.
The accident underscores the vulnerability of the Great Lakes as a shipping route for oil, natural gas and electricity and remains under investigation.
The four-mile-long transmission line is owned by Pewaukee-based American Transmission Co., or ATC, which operates in the Upper Midwest.
A spokeswoman said Tuesday the company believes slightly less than 600 gallons of an oil used for electrical insulation leaked into the straits a few miles west of the famed Mackinac bridge.
Spokeswoman Jackie Olson said that cleanup will start on Wednesday when crews pump oil from sleeves holding the electric cables. Poor weather conditions, including ice in the water, have complicated the response by the company and other parties, she said.
The mishap was discovered late Sunday afternoon and did not result in a loss of power in the Upper Peninsula, the company said. Olson said there were no reports of injuries.
The U.S. Coast Guard is overseeing the cleanup response while the work of pinpointing the cause of the rupture is being handled by the Pipeline and Hazardous Materials Safety Administration, a federal agency.
In addition to ATC’s transmission lines and other utility lines, the straits are home to the controversial Line 5 oil pipeline owned by Enbridge Energy and a natural gas transmission line owned by TransCanada.
Line 5, in particular, has raised worries that fast-moving currents could damage the pipeline and cause a catastrophic oil spill.
“The writing is on the wall that accidents happen,” said Liz Rosan Kirkwood, executive director of FLOW: For Love of Water, a Traverse City, Mich.-based organization that wants to see Michigan officials shut off Enbridge pipeline shipments through its underwater pipeline.
“Pipelines and other lines fail regardless of the technology and precautions that companies take. Human error and mechanical problems are the leading causes of pipeline failure.”
ATC’s Olson said that the company’s cables sit on the lake bed and lake currents are monitored. Based on a 2016 study, the cables have not moved significantly since 2008, she said.
Kirkwood said she was worried about the response to the transmission line accident.
ATC said that it discovered a problem about 5 p.m. Sunday and learned later Sunday or early Monday that the system was experiencing a leak.
“The information we were getting was that it was above ground,” Olson said, explaining that the company thought the leak was on land.
It wasn’t until late Monday afternoon that the Michigan Department of Environmental Quality was notified of an oil leak. But the Coast Guard said that the company did not know until then that oil was leaking into the water.
“From a policy perspective, that is a very critical issue and it’s important for people and policy-makers to understand what would happen if Line 5 ruptured,” Kirkwood said.
On Tuesday, the company determined that two of the six cables the company owns can’t be repaired and personnel are determining the conditions of the other cables.