Engineer: Proposed tunnel under Straits of Mackinac Could Explode Unless Design Changes

Apr. 28—TRAVERSE CITY — The proposed Line 5 tunnel beneath the Straits of Mackinac could explode if the current design is used, a tunnel engineer says.

Long a subject of public debate, the proposed 4.5-mile tunnel is designed to replace the 71-year-old pipeline that currently sits on the bottom of Lake Michigan.

Tunnel expert Brian O'Mara who spoke in Traverse City last week said the proposed tunnel is vulnerable to damage from a high-pressure explosion and fire, particularly from methane gas pockets and vapors from leaking crude.

"This is a recipe for disaster," O'Mara said. " Enbridge knows that there is methane in the groundwater along the tunnel path, but they don't know the extent of the gas and have denied its existence. You only need 5 percent methane in the air for an explosion.

"If there is an explosion, the tunnel will not contain the oil in the pipeline," he added. "It will leak into the soil under the water and then into Lake Michigan. Oil is lighter than water and will rise."

Even more concerning, he said, the current tunnel proposal uses an "open annulus" design that would allow other utilities, such as a high-voltage power line, to be run through the same space as the oil pipeline. Typically, such a tunnel would be backfilled with concrete instead, in what is called a "closed" or "sealed" annulus.

" Enbridge is trying to save money," O'Mara said. "What could possibly go wrong?"

O'Mara spoke Wednesday evening at a public seminar called "Tunnel Vision: A Masterclass in Rejecting the Line 5 Oil Tunnel." More than 150 people attended the standing-room-only event in the Alluvion performance space near downtown Traverse City. He holds a graduate degree in geological engineering from Michigan Technological University in Houghton. For more than 30 years, he's been working in environmental consulting, construction and remediation.

Growing concerns

Fears about Line 5 oil leaks into the Great Lakes have grown since July 2010 when a different Enbridge pipeline dumped more than 1 million gallons of tar sands crude oil into the Kalamazoo River, marking the largest inland oil spill in U.S. history. The cleanup effort that followed cost more than $1 billion.

Since then, citizen, tribal and environmental groups have joined forces to demand that Line 5 be shut down because of its alleged threats to the Great Lakes.

If the new tunnel is built using funds from Enbridge, it will be owned by the state's Mackinac Straits Corridor Authority.

MSCA also will oversee construction and operation of the tunnel, according to state officials.

At a total length 645 miles, Line 5 originates in Superior, Wis., and terminates in Sarnia, Ontario. Most of the pipeline consists of a 30-inch diameter metal tube. However, as it travels under the Straits of Mackinac, Line 5 splits into two 20-inch-diameter, parallel pipelines that are buried onshore and taper off deep underwater.

Currently, Line 5 carries about 432,000 barrels of crude oil and 108,000 barrels of natural gas liquids (including propane) per day. The vast majority of those liquids travel through Michigan and into Canada. The pipeline also provides propane to the Upper Peninsula and oil to some metro Detroit refineries, although in a much smaller quantity than shipments to Canada.

Enbridge currently operates about 90,000 miles of pipeline in various places around North America. However, only one mile of that distance is in a tunnel, officials said.

Tunnel disasters

Fatal tunnel explosions are not new, records show. Other tunnels in the Michigan have sustained catastrophic failures because of methane gas and petrochemical explosions.

In 1971, a gas-related blast in a water intake tunnel on Lake Huron killed 22 workers.

In 1999, a transport truck caught fire while traveling through the 7.2-mile Mt. Blanc tunnel between France and Italy. The subsequent violent combustion spread rapidly, killing 39 people who were trapped in the tunnel. Firefighters on the scene were unable to reach them.

Closer to home, the presence of methane gas in the Straits area is well-documented.

In April 2020, the U.S. Geological Survey released a report about the "Collingwood Shale Formation" in northern Michigan, spanning from the southern shore of the Upper Peninsula to the central Lower Peninsula.

It shows the extent and thickness of methane gas in that geographical area. O'Mara noted that the second-highest concentration of that explosive gas includes the Straits of Mackinac where the proposed Line 5 tunnel is to be located.

Poor rock quality

O'Mara said the proposed Line 5 tunnel, estimated to cost more than $500 million, may never be completed because of the low quality of soil beneath the lakebed.

"The soil there is not solid rock, but more like gravel," O'Mara said. "In fact, more than half the rock is rated poor to very poor for tunneling. Enbridge has almost no experience building tunnels."

In 2017, a state-commissioned study call the Dynamic Risk Report detailed several criteria for building a safe tunnel under the Straits. For example, the tunnel should be built through solid bedrock in an area with relatively low groundwater pressure and no methane or toxic gases.

"Before the tunnel is even designed, there should be core samples every 50-100 feet, not the 900 feet intervals that Enbridge used," O'Mara said. "And the tunnel should be filled with concrete, not open to allow other utilities to go through it.

"Building a tunnel under water is one of the most complex and dangerous challenges on Earth," he added. " Enbridge has no idea what it's doing. Their design fails at all the criteria outlined in the Dynamic Risk Report."

Enbridge responds

In response to O'Mara's statements, Enbridge spokesman Ryan Duffy said via e-mail, "Tunnels are used safely every day across the globe. The (Line 5) tunnel will conform to all approved tunnel specifications and will be subject to environmental reviews.

"We will continue to work with the Straits Corridor Authority (MSCA), which has oversight responsibility and with permitting agencies. We will continue to use industry leading expertise, and the tunnel will be built to stand the test of time. We are partnering with world-class firms on the project. The expertise of these firms has shaped the design and engineering process."

Following months of testimony and debate, the Michigan Public Service Commission gave qualified approval for the tunnel plan on Dec. 1, 2023.

"We believe that the MPSC carefully examined this complex issue and considered many viewpoints, questions, concerns, and ideas in reaching its decision to ... locate the tunnel," Duffy said.

However, a coalition of environmental groups announced Wednesday that they will file an appeal of the MPSC ruling on May 9 in yet another attempt to halt the tunnel's construction.

Leading the appeal effort is the Michigan Climate Action Network, a statewide coalition of about 50 organizations. Other members include Oil & Water Don't Mix, the Groundwork Center (formerly the Michigan Land Use Institute) and the Little Traverse Bay Bands of Odawa Indians.

"Tunnel opponents make it clear that they prefer to simply shut the line down," Duffy said. "We would hope that all who are concerned about the water would support the tunnel project being completed as quickly as possible to enhance safety at the Straits."

Enbridge is eager to get started on the massive construction effort, he said. "We are ready to begin work on this project as soon as we have all permits in hand."

Legal battles

Michigan Attorney General Dana Nessel has been opposing the tunnel project for years. She filed suit against Enbridge in May 2019 and has tried to have all Line 5-related cases moved back into state courts rather than federal courts.

Nessel's lead attorney on Line 5, Assistant Attorney General Dan Bock, was one of five panel members at Wednesday's event in Traverse City.

"We believe Line 5 violates the public trust principle in state law, especially concerning bottom lands on the Great Lakes," Bock told the overflow crowd. "The pipeline easement granted to Enbridge in 1953 for just $2,500 has been invalid since its conception."

The Line 5 debate also involves a complex web of laws, regulations and treaties.

One such treaty, called the 1977 Transit Pipelines Treaty, ensures that crude oil will flow between Canada and the United States "so long as the pipelines involved are compliant with various rules and regulations." Currently, more than 80 pipelines cross the U.S.- Canada border.

In November 2020, the Michigan Department of Natural Resources revoked the original pipeline easement and ordered Enbridge to shut down Line 5 by May 2021, stating that Enbridge was in violation of the public trust due to "compliance issues with the pipeline, including improper pipeline spans, improper pipeline coatings, the improper curvature of the pipeline, and unreasonable risks involving the operation of the pipeline."

Enbridge did not comply with that DNR order, pursuing legal remedies instead.

On October 4, 2021, Canada's government then invoked the Transit Pipelines Treaty to overrule that DNR action, claiming the treaty has supremacy over state law.

One month later, the White House chimed in on the issue. Through a spokesman, President Biden said he would not make a decision on the tunnel and new version of the pipeline until the U.S. Army Corps of Engineers completes an environmental review of the project, a process that generally takes two years.

However, in July 2023, the Army Corps of Engineers announced they will not include the entire scope of the Line 5 controversy, but only the Straits tunnel portion.

That decision has angered environmental activists who say the pipeline's entire 645-mile length must be considered, including a planned rerouting of a 12-mile section of Line 5 around the Bad River Band of Lake Superior Chippewa reservation in Wisconsin, according to a report by Michigan Advance.

Tribal input

Holly Bird, a tribal member and attorney who has been opposing Line 5 for years, said Wednesday that an oil leak near any reservation "would decimate our livelihood, culture and spirit in countless ways."

When Enbridge's easement to cross the Bad River Band reservation expired in 2013, " Enbridge ignored us," she said. "They basically said 'Come and sue us.'"

Tribal relations with oil companies have been fraught for decades, she added: "My people have been dying for a long time."

Financial impacts

Money is at the center of much of the Line 5 debate, said Sean McBrearty, operations director of Oil & Water Don't Mix.

Enbridge doesn't extract oil or refine it, he said. Rather, the company is the transportation "middle man" serving large oil companies in North America. It earns more than a $1 million a day in transport fees just from Line 5, he said.

In response, Duffy said that shutting down Line 5 could impact up to 10 refineries in Michigan and Ohio to Ontario and beyond.

"The closure of one of those refineries could result in the loss of $5.4 billion in annual economic output to Ohio and Southeast Michigan, and the loss of thousands of direct and contracted skilled trades jobs," he stated. "There are no viable options for replacing the volume of light crude delivered by Line 5. A rail line would provide less than 10 percent of that volume."

Gas prices in the region would also be impacted by the closure of Line 5, he said, as well as the cost of propane. Line 5 supplies 65 percent of propane demand in the Upper Peninsula, and 55 percent of Michigan's statewide propane needs.

For her part, MiCAN Director Denise Keele said her group's analysis shows that shutting down Line 5 would raise gas prices in the state 1 or 2 cents a gallon.

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