Enbridge Reduces Line 5 Maximum Pressure

TUESDAY, MAY 1, 2018

After the discovery last month of marring on the twin liquid pipelines of Enbridge Energy's Line 5 under the Straits of Mackinac, the company announced last week that it reduced the maximum operating pressure of the lines, a move it says was precautionary but which came at the request of the Pipeline and Hazardous Materials Safety Administration.

Earlier in April, Line 5 and a nearby electric cable housing under the Straits of Mackinac sustained damage, allegedly from a vessel, operated by VanEnkevort Tug and Barge, dropping anchor over the area.

Pipeline Pressure

According to 9 & 10 News, the tug Clyde S. VanEnkevort stands accused of dropping anchor in the Straits, causing irreparable harm to two of American Transmission Company's cables and releasing 600 gallons of dielectric fluid into the water. The oil has reportedly not harmed any animals or the environment.

Line 5, the 65-year-old liquids pipeline running under the Straits of Mackinac, was shut down temporarily after the leak from the nearby submerged electric line was found April 1, raising concerns that a ship anchor or other object may have damaged the cable’s housing. Anchor drops are prohibited in the area of the Straits where the lines are.

While the pipeline was restarted by April 4, it was revealed that Enbridge found damage to the pipeline, likely linked with the same incident. The company reportedly uncovered three small dents; officials say the dents do not compromise the line’s integrity.

According to a statement released by Enbridge on Friday (April 27), “Enbridge placed additional operating pressure restrictions on the pipelines across the Straits of Mackinac as a precautionary and prudent measure.”

The company went on to note that diver inspections are still ongoing.

U.S. Coast Guard

Earlier in April, Enbridge Energy's Line 5 pipeline and a nearby electric cable housing under the Straits of Mackinac allegedly sustained damage from a vessel, operated by VanEnkevort Tug and Barge, dropping anchor over the area.

“Plans to reinforce the pipes continue to be developed and will be finalized in close coordination with PHMSA and the State of Michigan.”

The pipes remain structurally sound, and operations continue at a reduced pressure limit. In a separate statement, Enbridge spokesperson Ryan Duffy said that Line 5 was tested at 1,200 psi, with the maximum pressure allowed set at psi 600. Day-to-day operations range from 150-200 psi. “The only change now is the reduction in max pressure is lower. So instead of 600, it's less,” Duffy said.

Mike Shriberg, Great Lakes executive director for the National Wildlife Federation and a member of Michigan's Pipeline Safety Advisory Board, is calling for a complete shutdown to protect the Great Lakes from a pipeline rupture. Michigan Gov. Rick Snyder rejected the idea of an immediate shutdown late last year; he reached an agreement with Enbridge to work on identifying alternatives in the event of the eventual closing of the line.


Tagged categories: Infrastructure; NA; North America; Oil and Gas; Pipelines; Program/Project Management

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