2017-08-26 / News

Enbridge Begins Underwater Inspections

By Erich T. Doerr

Enbridge Energy began an underwater inspection of its Line 5 oil and natural gas pipeline under the Straits of Mackinac last week. Divers will inspect the outer coating and test anchor strike-focused leak detection equipment. A barge above them is serving as their base.

“This is all part of our rigorous maintenance program,” Enbridge Communications Strategist Ryan Duffy told The St. Ignace News. “This will help assure this line remains in top working condition.”

The two pipes making up the Line 5 pipeline under the Straits of Mackinac are protected from the water by a fiber-reinforced enamel coating. The inspection of this coating is focused on seeing if aquatic organisms like mussels are having any impact on it. The divers will carry out a visual inspection of the line and take both samples and pictures that Enbridge will then analyze. Mr. Duffy said the company does not expect to find any issues with the line; a prior inspection in 2014 showed the coating was intact with no issues related to any organisms. The interior of the Line 5 pipeline is inspected regularly, but that process is not connected with these operations.

Fiber-reinforced enamel is the standard for oil industry pipeline coatings, he said. The one on Line 5 was specifically designed to allow the long-term operation of the pipeline in the Straits, as it can easily withstand all kinds of temperature changes. Line 5 has never had a serious issue throughout its decades of operation.

“After more than 60 years and through our effective maintenance programs, the twin pipelines remain in outstanding operating condition, and we intend to keep them that way,” Mr. Duffy said. “The twin pipelines were designed and constructed specifically to meet the environmental conditions of the Straits, and they still exceed today’s standards for pipeline construction.”

If an issue is found during this inspection, Enbridge will develop a repair plan to resolve it. Mr. Duffy noted there are several ways to restore the coating on an underwater pipeline and the process is routine, having been developed for offshore lines.

The new leak detection technology the divers will test is an acoustic system that is designed to hear a possible strike on the line if a boat were to drop anchor and hit it. The system will listen to the pipeline during its operations and detect if there are any issues. Enbridge will evaluate and report on the system’s performance once the tests are completed.

There has never been an anchor strike on Line 5 throughout its 65 years of operation. The pipeline’s two pipes, and several other pipes and submerged cables running beneath the Straits in the same area, are in an area specifically identified and marked for all vessels as a no-anchor zone.

The barge Enbridge has out in the Straits this week is serving both its divers and other crewmembers, allowing them to monitor the underwater operations. The company will also use the barge to transport more underwater anchor supports to the line. Mr. Duffy said Enbridge hopes to install the supports in September, if the state approves the required permits by then.

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