Enbridge says contractor vessels may have damaged pipeline

TRAVERSE CITY, Mich. (AP) — Recent damage that prompted the temporary shutdown of an Enbridge oil pipeline in a channel linking two of the Great Lakes may have been done by vessels working for the company, according to an in-house report provided Thursday to The Associated Press.

Enbridge this week submitted to government agencies the results of its investigation into “disturbances” that were discovered during inspections of dual pipelines that run across Michigan's Straits of Mackinac. The two pipelines are part of Line 5, which carries oil and liquids used in propane between Superior, Wisconsin, and Sarnia, Ontario.

The Canadian company said it had narrowed down a list of vessels known to have been operating in the area that might have dragged a mooring cable across the pipelines, bending a support structure and scraping protective outer coating.

Four of the five likeliest suspects were Enbridge contractors doing maintenance or geotechnical work related to the company's plan to build a tunnel for a replacement pipeline beneath the straits, the report said.

The other was a dredging craft, it said, adding that efforts were continuing to determine what was responsible.

The damage was minor and didn't endanger either pipeline's structural integrity, the report said.

“Our investigators determined conclusively there was no internal or external metal loss, no dents and no safety issues with either the east or west segments and the pipelines are safe to operate,” spokesman Ryan Duffy said.

Enbridge sent its findings to the U.S. Pipeline and Hazardous Materials Safety Administration, the Michigan attorney general's office and the state Department of Environment, Great Lakes and Energy. The state agencies said they were studying the document and had no immediate...