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State AG: Parts of pipelines under Mackinac Straits not properly supported

Aug 3, 2016

UPDATED at 9:34 pm on 8/3/16

Some of the supports for Enbridge Energy’s Line 5 pipelines under the Straits of Mackinac are not as close together as they should be, according to State Attorney General Bill Schuette.

That’s gotten the company into some hot water with the state of Michigan.

Supports help keep the pipeline stable as it is buffeted by the powerful currents of the Straits. 

Enbridge told the state in 2014 the pipeline has supports every 75 feet, as required by the state's 1953 easement.

But a permit application submitted by Enbridge a few days ago shows that's no longer true. At least four places in the pipeline stretch further than 75 feet without a support. 

State Attorney General Bill Schuette sent a letter to Enbridge asking the company to explain why the supports are not in place, despite a “predictive maintenance model” that suggested an inspection of the span every two years was sufficient.

The letter also requires Enbridge to develop a new span monitoring and preventive maintenance plan to ensure future compliance with the support requirement.

Ryan Duffy, a spokesman for Enbridge, says the company believes it remains in compliance with the easement terms, and the situation is not a safety concern.  The company's statement:

In June, as part of Enbridge’s ongoing inspection process of Line 5 in the Straits, we conducted underwater inspections of the twin pipelines using remote operated vehicle (ROV) and an autonomous underwater vehicle (AUV). The intent of the inspections is to provide a visual, external inspection of the pipelines to identify potential areas of concern that need additional examination.

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. Although the easement agreement with the State of Michigan requires a span distance of 75-feet or less, the average distance between underwater supports along the portion of Line 5 through the Straits is approximately 50 feet.

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.

The Great Lakes is a dynamic environment and we anticipated that at times there can be changes to the lake bottom. In fact when Line 5 was built in 1953, its state-of-the-art engineering design included supports on the lake bed and regular measurements to understand the impact of currents and resulting erosion. In 2014, we installed 40 new support anchors; after that work was completed, there were no spans greater than 75-feet in length. Our robust integrity and inspection programs allow us to identify any areas that require attention, including at the lake bed.

We expect to begin installation of the support anchors in August, pending receipt of the necessary permits from the state.

Meanwhile, the state has hired two independent contractors to assess the risk of a pipeline rupture and the effect it would have on the environment, as well as alternatives to keeping the pipelines open.

The National Wildlife Federation has filed a lawsuit alleging the pipeline is being allowed to remain in operation despite federal agencies failing to comply with environmental laws, including the National Environmental Policy Act and the Endangered Species Act.

Other groups are demanding the immediate shutdown of the pipelines. Earth First members last month staged a protest in front of the home of State Attorney General Bill Schuette.

UPDATE: An earlier version of this story indicated the anchor supports for the pipeline were shifting. Enbridge says the supports themselves are not shifting, but the lake bed is shifting due to erosion.

In full disclosure, Enbridge Energy is a financial supporter of Michigan Radio.