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Enbridge Begins Recoating Gaps on Line 5

Wednesday, September 13, 2017

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Pipeline giant Enbridge Energy is reportedly working to repair coatings on its Line 5 under the Straits of Mackinac in Michigan after inspections over the summer turned up three small areas of bare metal on the pipeline, which has been subject to scrutiny this year by activists and government officials.

Line 5 map
Images: Enbridge Energy unless noted

Line 5, a dual pipeline that carries crude oil and natural gas liquids from Alberta to Sarnia, Ontario, via Michigan, runs under the Straits of Mackinac, between Michigan's Upper and Lower Peninsula.

The Petoskey News reported Sept. 7 that work was set to commence to repair the areas of coating loss on the underwater pipeline that were uncovered in August. Enbridge did not immediately respond to a request for an update on the status of the recoating project Tuesday (Sept. 12).

About Line 5

Line 5, a dual pipeline that carries crude oil and natural gas liquids from Alberta to Sarnia, Ontario, via Michigan, was built in 1953 and has never experienced a rupture, according to Enbridge. But environmentalists have expressed concerns over the potential for catastrophic damage if the aging steel pipeline were to fail.

Enbridge’s pipelines in Michigan have been scrutinized since the 2010 rupture of the company’s Line 6B in Kalamazoo, which released nearly 850,000 gallons of oil into the ground and the Kalamazoo River.

Mackinac Bridge
© / Dough4537

Environmentalists have expressed concerns over the potential for catastrophic damage if the aging steel pipeline under the Straits were to fail.

Earlier this year, activists clashed with Enbridge over reports from 2016 that seemed to indicate areas of coating loss on the underwater pipeline; the company said at the time that those reports referred to hypothetical situations, and did not describe the pipeline in its current state. In March, Enbridge said that there were 18 areas of delamination on the twin pipelines, but that it was only the outer coating that was affected, and that protective coatings and cathodic protection on the pipeline were “working as designed.”

The new areas of exposed metal on the line are not associated with the previously discussed delamination, Enbridge said in late August: “None of the areas involve where delamination of the outer wrap over the coating had been observed.”

Caused by Anchoring Work

A spokesperson for the company told that Enbridge believes the coating loss is associated with previously performed anchoring work. The company added four new screw anchors in 2016 to support areas where stretches of greater than 75 feet were unsupported due to erosion. It expects to add 18 more in the future. A report from MLive earlier this summer revealed that the pipeline operated for years in violation of easement stipulations regarding the maximum length of unsupported stretches of pipeline.

The company says there is “no visual evidence of any corrosion or impact on the integrity of the pipe” associated with the areas of coating failure. “Enbridge will repair these sections of coating immediately following the completion of all sampling and coating inspections, and after obtaining any necessary permits,” the firm added.

Government Response

While Enbridge says the catch and the subsequent repairs to the line show that its monitoring and maintenance programs are effective, several state agencies and other government figures have expressed concerns about the findings.

“The possibility this loss of coating occurred during the anchor installation process and was not immediately addressed is completely unacceptable," said Michigan Department of Environmental Quality director C. Heidi Grether.

Line 5 underwater

The company added four new screw anchors in 2016 to support areas where stretches of greater than 75 feet were unsupported due to erosion. (Photo from June 2016 underwater inspection does not depict the new anchors.)

“This recent finding raises concerns about the actions Enbridge is taking to protect the waters of the Great Lakes,” said Michigan Department of Natural Resources director Keith Creagh. “We need to ensure that all appropriate risk mitigation measures have been put in place by Enbridge. Until that happens, we as a state will not be satisfied.”

In June, Line 5 passed a series of pressure tests at 1,200 psi—eight times the normal operating pressure of the pipelines—and was declared “fit for service” by the company.

“While the hydrotest results give us confidence that the pipeline is not in imminent danger from these gaps, the fact that human error, not a mussel, created them is something that raises real concern,” said Valerie Brader, executive director of the Michigan Agency for Energy. “Human error was a major factor in Enbridge’s spill into the Kalamazoo River. These coating gaps point to other areas where human error, not the environment, are creating problems.”

And on Tuesday, U.S. Rep. Fred Upton, R-St. Joseph, sent a letter to Enbridge calling for more transparency on the company's part.

Legislative Action

In March, State Sen. Rick Jones, R-Grand Ledge, introduced legislation that would order new risk assessments for underwater pipelines like Line 5, and shut down the lines if they were determined to be at high risk. That bill is still in the Senate’s Committee on Natural Resources.


Tagged categories: Oil and Gas; Pipeline; Spot repair

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