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Michigan Attorney General Bill Schuette is accusing Enbridge Energy, owner of a pair of underwater oil and natural gas pipelines beneath the Straits of Mackinac, of failing to meet safety standards to which the company previously agreed.

Schuette is questioning the number of anchor supports currently in place along what is known as Line 5. Easement agreements between Enbridge and the state of Michigan call for anchor supports to be a minimum of every 75 feet along the length of the line.

In a letter sent Wednesday to the Alberta, Canada-based energy company, the attorney general said the company is violating the standard.

“A few days ago, Enbridge submitted an application to the Michigan Department of Environmental Quality for a permit ... to install up to 19 additional pipe support anchors between August 15 and September 15...,” he wrote. “Enbridge’s pending permit application effectively acknowledges that it is currently in violation of the 75 foot span limit of the easement with respect to at least four locations.”

Enbridge officials said they were well aware of the support anchor issues since its June survey detected the new gaps. Ryan Duffy, Enbridge’s supervisor of regional communications, said the company alerted Michigan to the issues earlier this summer and has already set in motion steps to correct the situation.

Shifting conditions along the bottom of the Straits of Mackinac can create new gaps between pipeline sections, Duffy said – a dynamic environment that requires regular monitoring.

“Our biennial inspection program worked as designed; we found four sections of pipe that require additional support anchors to reinforce areas where erosion and span distances have increased since the last underwater inspection in 2014...,” Duffy said in a statement emailed last week to The Detroit News.

“In the four sections that are slightly longer than 75 feet, the safety or integrity of the Straits Crossing has never been compromised, which has been confirmed by engineering calculations showing that the allowable safe span length is 140 feet.

“We have contacted the State regarding the results of the inspection and our plans to restore the spans. At the same time, we will address another 15 spans before more erosion occurs as those sections have grown over the last two years, and are nearing 75 feet.”

Enbridge’s 63-year-old Line 5 has never experienced a major incident resulting in a release of oil or natural gas products into the Great Lakes.

But concern over pipelines running through the region has ratcheted up following the 2010 rupture of an underground line, also operated by Enbridge, near Marshall. The accident resulted in a release of over 800,000 gallons of crude oil -- much of which eventually reached the Kalamazoo River.

In July, the company agreed to a $177 million consent degree for what is considered the largest inland oil spill in U.S. history.

Duffy said Wednesday that additional anchor supports will be in place by mid-September.

JLynch@detroitnews.com

(313) 222-2034

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