Enbridge seeks to dismiss expert testimony warning of explosion risk for Line 5 tunnel

Federal agency letter hints at concern over recovery efforts in case of accident

By: - January 7, 2022 9:37 am

Mackinac Bridge | Susan J. Demas

While Attorney General Dana Nessel and Enbridge prepare to once again battle it out in court over the fate of the company’s controversial, nearly 69-year-old Line 5 oil pipeline, a regulatory fight is also heating up over Enbridge’s plan to eventually replace a portion of the pipeline and enclose it in an underwater tunnel.

That fight right now centers around whether the Michigan Public Service Commission (MPSC) should consider expert testimony that warns of a possible explosion under the Straits of Mackinac, which Enbridge is seeking to strike from the record.

The MPSC is one of three agencies charged with deciding Enbridge can build Line 5’s tunnel-encased replacement under the environmentally sensitive Straits. Since April 17, 2020, more than 950 documents have been filed in Enbridge’s contested case application before the three-member panel. An administrative law judge continues to rule on what will and will not be included in the final application.

Richard Kuprewicz is a chemical engineer with nearly 50 years in the oil and gas industry, whose background includes extensive work in emergency response and pipeline incident command. In his Dec. 14 expert testimony on behalf of the Bay Mills Indian Community (BMIC), Kuprewicz argues that the “inherent risks” associated with the tunnel project have been minimized by both Enbridge and the MPSC.

“From an engineering standpoint, there is a potential for a release into the Straits from the tunnel by way of a catastrophic explosion,” he says. “While a risk of release in this manner may be considered low, it is not negligible and, in my opinion, should not be downplayed in such a way by the [MPSC] Staff.

“A ‘low risk’ does not equate to ‘no risk’ or even a ‘negligible risk’ when transporting crude oil, and especially propane,” Kuprewicz writes.

He explains that propane and crude oil are highly hazardous and volatile substances which always present some risk of explosion when they are handled. Kuprewicz hits back at MPSC staff witness Travis Warner’s statements that the probability of a release of product from the tunnel is “virtually zero.”

Enbridge moved to strike portions of his testimony from the record on Dec. 21, claiming that it is “not proper rebuttal testimony” and its allowance would cause “undue prejudice.”

Enbridge sign, St. Ignace | Laina G. Stebbins

Enbridge spokesperson Ryan Duffy said Thursday that any testimony “outside the scope of the proceedings or irrelevant to the proceedings is not admissible and should not be allowed into the record, regardless of the party that offers it.”

“Based on Enbridge’s design and construction plans, the MPSC staff found that there are no concerns with the safety of the replacement segment of pipeline to be located within the tunnel,” Duffy said.

Christopher Clark, an attorney for the San Francisco-based Earthjustice who represents the BMIC in the contested case, told the Advance Tuesday that the notion that Kuprewicz’s testimony doesn’t belong in the case is “absurd.”

“As we were looking at the testimony that had come in, the tunnel was being presented as entirely risk-free,” Clark said. “That’s really problematic when you take that view of risk, when you say ‘this is failsafe.’ That, in fact, almost enhances or increases the likelihood of the risk, because you’ve become complacent.”

According to Kuprewicz, even Enbridge’s ventilation system cannot completely eliminate the risk of an explosion.

“… The difficulty in controlling the fuel air mixture within the tunnel … increases the possibility of multiple detonations/explosions within the tunnel. The ventilation system alone may help, but will not prevent, an explosion from occurring following the accumulation, or pocketing, of vapor in the tunnel,” he writes.

Kuprewicz adds that crude oil and propane in a confined space like a tunnel can generate a “tremendous amount of pressure, especially upon detonation.”

“A release in this unique environment carries the risk of both loss of human life and the release of crude oil and propane into the Great Lakes as an explosion in such a confined structure will most likely violate the tunnel’s secondary containment intent,” he said.

Clark said he also feels it is important to challenge Enbridge’s narrative that the tunnel “fixes all of the problems with Line 5.”

“It crosses, I believe, almost 300 waterways. And there has been a history of leaks across the entire length of the pipeline,” he said. “… Enbridge is trying to present its project of rerouting this pipeline into a tunnel as the fix. And it’s not.”

Clark also emphasized that the BMIC and surrounding tribes were never consulted in 1953 when the decision was made to run a pipeline through their treaty land and waters.

Brian O’Mara, a geological engineer and tunnel expert, says the fact that Enbridge detected methane in about 20% of its groundwater samples in the area should raise red flags.

“I’m convinced they’re going to find more,” O’Mara said. “… I’m irritated that Enbridge is not taking this seriously.”

O’Mara says that there are three possible scenarios which could cause a methane explosion/fire to happen, with the spark caused either by human or mechanical error:

  • While mining with the tunnel boring machine during construction, methane dissolved in the groundwater could enter the tunnel. If Enbridge contractors cannot mitigate that properly, there could be an explosion under the right conditions.
  • After construction, with so much pressure pushing on the tunnel from the Straits, groundwater with methane could still seep in if the tunnel isn’t sealed off properly. The right mix of oxygen and a spark could cause an explosion.
  • The Line 5 pipeline itself transports highly flammable substances. If the pipeline were to leak into its surrounding tunnel, an explosion could happen under the right conditions.

“I am just amazed that this thing has gotten so far with so little technical scrutiny,” O’Mara said, adding that the original design analyzed by the former Gov. Rick Snyder administration was markedly different from what it is now.

That design that Snyder commissioned a risk assessment for had envisioned that the space between the pipeline and inside wall would be sealed with concrete. That is no longer the case.

With space between the pipeline and the inner tunnel wall, the right conditions could converge and make the tunnel like “a barrel of a gun,” with no place for the energy to dissipate safely.

“I think Enbridge is just ignorant, they don’t know. They’re used to digging ditches, throwing a pipe in the ground and they’re done. I don’t mean to trivialize what a pipeline is, but that is a very different animal than trying to send a boring machine down 500 feet below ground under these high pressures. You’ve got completely different technology,” O’Mara said.

In a letter to the MPSC on Nov. 18, an official from the U.S. Pipeline and Hazardous Materials Safety Administration (PHMSA) acknowledged the unique “challenges” that are presented with the tunnel project’s distinct design.

“A pipeline situated inside the utility tunnel would require unique monitoring practices, as compared to buried or submerged pipelines,” wrote Alan Mayberry, associate administrator for pipeline safety.

PHMSA is Enbridge’s federal regulator, and the sole agency Enbridge argues has the legal right to decommission the pipeline.

“Enbridge eviction” celebration, Conkling Park, Mackinaw City | Laina G. Stebbins

“PHMSA will need to evaluate such O&M [operations and maintenance] plans to ensure that the operator has carefully considered the capabilities necessary to ensure ongoing compliance. These challenges may include the difficulty of performing routine maintenance deep within the tunnel or recovery efforts when a leak or incident occurs,” Mayberry continues.

The letter is the first hint of concern about Line 5 from PHMSA, the federal regulatory agency that often quietly greenlit Enbridge’s requests during former President Donald Trump’s administration.

A PHMSA spokesperson did not return a request for comment about whether PHMSA is concerned about the possibility of a methane explosion.

Duffy said that the letter does not state that PHMSA found compliance issues with the project, and does not see a mention of concerns.

“We will continue to work closely with PHMSA on the project going forward,” Duffy said.

Clark said that cross examination is set to begin on Jan. 13, and motions to strike are typically resolved before that process can occur.

For the tunnel project to go ahead, Enbridge needs permits from the MPSC, the U.S. Army Corps of Engineers (USACE) and the Department of Environment, Great Lakes and Energy (EGLE).

Of those, EGLE is the only one to grant permits so far.


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Laina G. Stebbins
Laina G. Stebbins

Laina G. Stebbins is a former Michigan Advance reporter. A lifelong Michigander, she is a graduate of Michigan State University’s School of Journalism, where she served as Founding Editor of The Tab Michigan State and as a reporter for the Capital News Service.