Digging Line 5 Tunnel Could Cause Explosion, Activists Argue

(Source: MIRS.news, Published 08/26/20250) If Enbridge is given the green light to dig the Line 5 tunnel under the Mackinac Straits, crews could hit a methane pocket that could spark an explosion like the Lake Huron water tunnel explosion of 1971 that killed 22 workers, environmental activists argued Tuesday.

The Department of Environment, Great Lakes and Energy (EGLE) is collecting the last pieces of public comment Friday on whether permits should be reissued to allow Enbridge to dig a tunnel for the Line 5 pipeline. Environmental activists are urging the public to sound the alarm about the ground under the Straits.

“They're drilling on top of a shale formation that they know contains methane,” said Sean McBrearty, campaign coordinator for Oil and Water Don't Mix. “If they hit an unexpected methane pocket and there is an explosion, that could not only result in the death of anybody working inside that tunnel and the flooding of that tunnel behind them, it could also have surface impacts.”

There is no bedrock between the bottom of the Mackinac Straits and the tunnel, so a sudden shift from an explosion could impact the existing Line 5 tunnel, he said.

McBrearty and his Coalition are hoping EGLE declines to reissue 2021 permits. They claim the project will destroy a nearby wetland and close the nearby Dark Sky park because of the light pollution coming from the construction site.

In response, Mike Witkowski of the Michigan Manufacturers Association said more than 40,000 hours of survey work by top-level engineers went into this program. Nobody wants the type of catastrophe that McBrearty suggested.

“This has been completely vetted and researched by some of the best minds in the world,” Witkowski said.

The scientific experts who are working with Enbridge say the risk of an explosion in building the tunnel is the equivalent of one in every 169 million years.

The project has pit organized labor against environmentalists. The Laborers, for example, said they have 1,500 members trained and ready to work on the project, which Enbridge had originally estimated in 2018 would be finished in 2024.

“These are good union jobs, family-supportive jobs with health care and a pension,” said Paul Prebay, business manager for Laborers Local 1098. “We know from working on these projects for as many years as we've been doing this that this is the safest, most reliable means to transport these materials.”