Officials with the U.S. Coast Guard are investigating whether vessel activity may have caused 600 gallons of mineral oil to spill from transmission lines underneath the Straits of Mackinac, which connect Lake Michigan and Lake Huron.
Wisconsin-based American Transmission Company spokeswoman Jackie Olson said their system initially alerted them Sunday evening that problems may exist with facilities on the land. Crews were dispatched to investigate, but no damage was discovered. Company officials determined Monday morning there was a leak and reduced pressure in the lines.
“It was determined after quite a bit of investigation that the leak was probably occurring in the lake, and we made the decision to shut off the flow of the mineral oil to the two cables that were determined to be leaking on Tuesday morning,” she said.
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Olson said the lines are now out of service, and they’re currently bringing power to the Upper Peninsula through the Presque Isle Power Plant in Marquette and the transmission system in northeastern Wisconsin. The company notified several state and federal agencies, including the U.S. Coast Guard, which has been leading the spill response.
Coast Guard Public Information Officer Pamela Manns said Friday that vessel activity may have caused the leak.
“The Coast Guard is doing an investigation of vessel activity in that area,” she said, noting no further details would be released at this time. No visible signs of streaming or pollution have been seen from the spill, Manns said. The mineral oil that was released from the cables is an insulating fluid used as a coolant. She said that fluid contains a benzene compound.
“We took samples to the laboratory for further analysis, but, given the dilution of the product and the mobility of fish, we really think there’s a low risk to fisheries and wildlife at this point,” she said.
Petty Officer 2nd Class Brandon McCarty, a marine science technician assigned to Coast Guard Sector Sault Sainte Marie, Mich., conducts a waterside investigation of a mineral oil spill while Matt Kleitch, an environmental quality analyst for the state of Michigan’s Department of Environmental Quality, looks for possible impacted wildlife on the Straits of Mackinac, Thursday, April 5, 2018. Photo courtesy of the U.S. Coast Guard
ATC has been conducting cleanup according to its oil spill response plan, which must be re-certified every five years to meet federal requirements. The company has been using a vacuum truck to remove around 400 gallons of oil from each of the lines.
The initial response to the spill drew concerns from groups like the National Wildlife Federation, which has voiced concerns over the region’s vulnerability to a spill from utility lines running under the Straits of Mackinac. Response and inspection of the cables has been hampered by weather conditions and icing in the area, said Beth Wallace, NWF’s conservation partnership manager.
“This is a location that has extremely sensitive ecosystem, as well as there’s a lot of freshwater intakes for communities right in the area,” she said. “If we are not prepared to fully address an incident when it happens immediately, then we have to evaluate whether this is a location for those types of materials.”
Wallace highlighted concerns over the age of infrastructure underneath the Straits of Mackinac, including Enbridge’s Line 5.
ATC’s Olson said the company’s cables have not experienced any prior damage to her knowledge. The company has two power lines that connect the Upper Peninsula to lower Michigan, which are composed of six separate cables lying on the lake bed. Olson said one power line has been in service since 1975, while the other was installed in 1990. ATC assumed ownership of the lines in 2001.
“I do know that the cables were tested in 2017 and were operating normally,” she said. “No issues were found.”
Petty Officer 2nd Class Brandon McCarty, a marine science technician assigned to Coast Guard Sector Sault Sainte Marie, Michigan, and Matt Kleitch, an environmental quality analyst for the state of Michigan’s Department of Environmental Quality, survey the Straits of Mackinac, Thursday, April 5, 2018. Photo courtesy of the U.S. Coast Guard
The company conducts inspections of its lines and reports any issues to the appropriate state or federal agencies, Olson said. She added the company works closely with regulators to meet standards with the operation of its system, including the Wisconsin and Michigan public service commissions, as well as the Federal Energy Regulatory Commission (FERC).
Officials with FERC and the Pipeline and Hazardous Materials Safety Administration said their agencies have no jurisdiction over the incident. The U.S. Coast Guard’s Manns said they’re continuing to monitor the spill response and cleanup.
Editor’s Note: American Transmission Company is an underwriter of Wisconsin Public Radio.
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