Engineers warn of Line 5 explosion risk

LANSING – Two engineers warned the Michigan Public Service Commission that Enbridge’s plans to dig a pipeline tunnel beneath the Straits of Mackinac could lead to an explosion and the release of oil that could devastate the freshwater, wildlife, and shorelines of Great Lakes. The testimony, submitted on behalf of the Bay Mills Indian Community, comes almost two years after Enbridge defied state orders to shut down the existing Line 5 dual pipelines due to the company’s “persistent and incurable” violations. Enbridge wants the Commission’s approval to replace that section with a never-been-done before hazardous liquids pipeline running underground in a tunnel beneath the lakebed of the Straits.

In documents submitted Friday, geologist and engineer Brian O’Mara and pipeline safety expert Richard Kuprewicz pointed to two sources of flammable gas that could set off an explosion under the Straits: the crude oil and natural gas liquids transported through Line 5, and methane that could leak into the tunnel through groundwater.

“I am very concerned about a methane explosion occurring in the proposed tunnel,” wrote engineering consultant Brian O’Mara in his testimony. “A methane explosion in a confined space like the tunnel project would be like a shotgun blast […] This kind of high-pressure event can cause loss of human life, damage to the tunnel lining and equipment, and cause a rupture of the pipeline itself—which in turn could then lead to an explosion and fire described.”

It was Kuprewicz who first flagged the serious risk of an explosion in the tunnel during a hearing before the Commission last year. In response, the Commission ordered Enbridge to provide more details about the tunnel’s safety features. Instead, Enbridge has submitted a probability analysis that attempts to dismiss the concerns as unlikely to occur.

Kuprewicz explains that downplaying the risks of an explosion in the tunnel project undermines federal pipeline safety regulations. “An operator who adopts this approach to the construction and operation of a pipeline will inevitably drive the line toward failure,” wrote Kuprewicz.

For members of the Bay Mills Indian Community, the immense cultural, spiritual, and economic significance of the Straits of Mackinac makes any risk of an oil spill unacceptable.

Bay Mills President Whitney Gravelle wrote in her testimony that Enbridge’s analysis “does not negate that fact that it could happen in year one of operation, or year two of operation, or year 99 of operation […] All it takes is one time and one spill to destroy my people and destroy all that we hold dear.”

“Far from assuring the public that this tunnel project is safe, Enbridge is making us even more worried,” said attorney Christopher Clarke of Earthjustice. “It’s clear that they would rather ignore and obfuscate the risks than address them.”

Earthjustice and the Native American Rights Fund are representing the Bay Mills Indian Community as an intervening party before the Michigan Public Service Commission. A hearing in this matter before an administrative law judge is scheduled for April 11-14.

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