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Mackinac Pipeline Assessment Released

Friday, July 7, 2017

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A series of public meetings will allow debate over Enbridge Energy’s Line 5 liquid pipeline in the wake of a new assessment of the line’s future, released by the Michigan Pipeline Safety Advisory Board.

The report, released last week and prepared by Dynamic Risk Assessments Inc., looks at the risks related to keeping the current pipeline—which was built in the 1950s and crosses under the Straits of Mackinac—as well as alternatives, including new lines in or around the straits, a new pipeline elsewhere or a complete abandonment of the line.

Straits of Mackinac
© iStock.com / Dough4537

A new report prepared by Dynamic Risk Assessments Inc., looks at the risks related to keeping the Line 5 pipeline, which was built in the 1950s and crosses under the Straits of Mackinac, or replacing it with another pipeline or an alternative mode of transport.

According to Dynamic Risk, the biggest threats to the existing pipeline are anchor hooking, incorrect operations, vortex-induced vibration and spanning stress. A spill in the straits, the firm contends, would likely incur $100-200 million in costs, about 60 percent of that covering environmental cleanup. Those figures account for what Dynamic Risk calls “objective assessments of credible risks,” and not a worst-case scenario.

Line 5 moves crude oil and natural gas liquids from Alberta to Sarnia, Ontario, via Michigan. According to Enbridge, while much of the crude coming from Alberta goes to refineries in Sarnia, some is also refined in Michigan and Ohio. And it’s not all Canadian oil moving through the pipeline: At points, sweet crude produced in Michigan is pumped into Line 5 to make its way to refineries as well.

Coating Concerns Quelled

The report examines corrosion protection and pipeline coatings, relying largely on information from previous investigations and assessments performed by Enbridge. Dynamic Risk largely discounts concerns raised earlier this year over potential coatings holidays on the pipeline; the firm cites a recently performed cathodic protection current mapping that showed no anomalies in current density.

“The fact that the tool reported no current density anomalies supports the contention of an intact coating,” the report says.

Line 5 underwater
Enbridge Energy

Dynamic Risk largely discounts concerns raised earlier this year over potential coatings holidays on the pipeline; the firm cites a recently performed cathodic protection current mapping that showed no anomalies in current density.

Enbridge previously admitted that some sections of the outer layer of the coal tar enamel coatings on the pipeline have come off, but that there is no risk because the underlying layers are intact. Dynamic Risk agrees that “in the project team’s experience, it is not unusual for the outer layer of CTE coatings to separate from the underlying corrosion coating, with no apparent compromise made to the corrosion protection performance of the coating.”

The new assessment states that the coating on the 1953 pipeline is indeed CTE, as Enbridge maintains; a recent report authored by former Dow engineer Edward Timm, released by the National Wildlife Federation, questioned whether another coating may have actually been used.

Timm says in his report that while the order for the pipeline called for coal tar enamel, other documentation is less clear about what the actual coating used was made of. Timm concludes it’s more likely it was “a solvent-based asphalt primer, two layers of asphalt-saturated glass fiber fabric and a white protective overlayer of white craft paper bonded with asphalt enamel.”

Possible Plans

Alternatives discussed initially in the assessment include:

  • Building an alternative pipeline that does not cross the open waters of the Great Lakes and decommissioning Line 5;
  • Using existing pipeline infrastructure that does not cross the open waters of the Great Lakes and decommissioning Line 5;
  • Using alternative transport methods such as railcar or tankers and decommissioning Line 5;
  • Replacing Line 5 with a new pipeline system under the straits, using either trenched or tunnel installation methods;
  • Maintaining the existing Line 5; and
  • Maintaining portions of Line 5 but decommissioning the section that runs under the straits.

During the process of preparing the report, though, Dynamic Risk screened out several of the alternatives. There is not enough capacity to route the crude oil and natural gas liquids that currently flow through Line 5 into other existing pipelines, the firm said. Decommissioning only part of Line 5 was also ruled out as nonviable.

Line  alternatives
Dynamic Risk

The only new pipeline route not screened out is one that would pass south, through Chicago (pictured here as the yellow dotted line).

The only new pipeline route not screened out is one that would pass south, through Chicago, and the only alternative mode not screened out is a rail route that would also pass south. All other rail or barge possibilities were ruled out due to cost or logistical prohibitions.

The five possible courses of action that received a semi-quantitative discussion in the report are:

  • Maintaining Line 5 as-is;
  • Replacing Line 5 with a new trench crossing under the Straits;
  • Replacing Line 5 with a new tunnel crossing under the Straits;
  • Replacing Line 5 with a new-build pipeline passing south through Chicago; and
  • Replacing Line 5 with rail transport passing south of Michigan.

A new trench crossing would likely cost $27 million, the firm says, while a new tunnel crossing would cost $153 million, according to the report.

If a new pipeline were to be built under the Straits, it would likely be coated with a three-layer polyethylene coating as well as a two-inch, welded-cage reinforced concrete coating, the report notes.

Pipeline Safety Spotlight

Enbridge has been subject to increased scrutiny in Michigan in recent years after its Line 6B pipeline suffered a rupture in 2010, releasing at least 843,444 gallons of oil, much of it into the Kalamazoo River as well as a nearby creek and shorelines, according to the EPA.

The pipeline failed despite a series of In-Line Inspections (ILl) that Enbridge performed on the 30-inch-diameter segment as part of its Integrity Management Program (IMP), according to a Notice of Probable Violation (NOPV) issued by the Pipeline and Hazardous Materials Safety Administration in July 2012.

The Line 6B rupture resulted in $3.7 million in fines from the PHMSA. In 2016, the company entered into a consent decree with the Department of Justice, stemming from that and another spill in Illinois in 2010.

The Michigan Pipeline Safety Advisory Board is holding public meetings for input on the information presented in the assessment; the first was scheduled for Thursday evening (July 6). Three more meetings will take place July 24-25, and public comments are being taken on the board’s website as well.

Line 5, which has never experienced a rupture, recently passed a 1,200 psi pressure test as required by Enbridge's consent decree.

   

Tagged categories: Environmental Protection; Infrastructure; NA; North America; Pipeline; Program/Project Management

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