Two geologists said they found numerous shortcomings with the Canadian company's proposals to the Michigan
“What Enbridge has submitted to the state of
The analysis was requested by Oil & Water Don't Mix, a coalition of environmental, business and tribal organizations. They are fighting to shut down Line 5, an
“Jay Dee and Obayashi have a collective track record of constructing more than 400 pressurized-face tunnels consisting of more than 2.4 million feet (732,000 meters) of tunnelway,” Duffy said. “A number of those projects involved high pressure and ground condition parameters similar to those that will exist in the Straits of Mackinac.”
The company contends the 67-year-old Line 5 that runs between
During an online news conference, O'Mara said the tunnel plans had changed considerably since a 2017 assessment, which described the project as feasible and low-risk. That analysis by a Canadian firm was based on assumptions that have proven incorrect, he said.
It presumed the tunnel would be located entirely in solid bedrock, yet
Limestone and dolomite formations beneath the waterway connecting
For that reason, tunnel designers usually extract samples every 50 to 200 feet (15 to 61 meters), he said. Yet, Enbridge’s contractor took them once every 950 feet (290 meters).
“They have done just a fraction of what you would expect on a project of this size and magnitude," O'Mara said.
O'Mara said the risk analysis also presumed that the tunnel interior around the pipeline would be filled completely with cement to prevent leaks and collapse, but that feature is absent from the current plan.
“This single design change represents the greatest risk and would make a catastrophic disaster much more likely to occur,” O'Mara said.
The
O'Mara said the proposed tunnel's V-shaped design configuration would endanger workers by putting the deepest point in the middle of the straits.
Another threat is posed by a slurry that would be injected during construction to keep the tunnel stable and lubricated, said
Plans call for piping the mud to the surface, removing the clay and discharging up to 5 million gallons (18.9 million liters) of treated wastewater back to the straits, he said, but the permit application doesn't show how the lakes would be protected from accidental releases.
A bentonite spill could be more environmentally damaging than oil, which floats on the surface and can be recovered, Wilczynki said.
“Bentonite can stick to everything it touches and forms an impermeable barrier" that can smother fish and bottom-dwelling invertebrates that are essential for food chains, he said.
Duffy said slurry and water would be piped to settling ponds for treatment and water would be cleansed to meet state standards before discharged back into the straits.
The state environment department is scheduled to conduct the first of several public hearings Tuesday on wastewater treatment and wetlands permits that
Environmentalists urged state regulators to demand answers about issues raised by the outside review before green-lighting the project.
“Failure to do so could result in tragedy for the
Spokesman
“The state also has retained tunneling experts as consultants and will explore if others are needed to help evaluate technical information that is part of the public record," Assendelft said.
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