Line 5: Separating fact from fiction
Michigan deserves the truth about Enbridge's deep commitment to safety
By Tom Prew
Enbridge Senior Regional Engineer
As an engineer who once worked for the state pipeline safety agency in my region, I was trained to identify prospective threats in an oil and gas pipeline system.
Tom Prew, Senior Regional Engineer, Enbridge Pipelines
Through regular audits, my colleagues and I learned to tell the good pipeline operators from the bad. I’m proud to say my experience with Enbridge puts them squarely in the category of best operators with a deep commitment to safety.
Having taken my agency experience and applied it to industry, today I see my job at Enbridge as protecting the Great Lakes and Straits of Mackinac every single day. I can say with certainty that Line 5, part of which crosses the Straits, is in astonishingly good condition. This is in large part due to a combination of a very robust initial engineering and construction, and an aggressive program of inspection and maintenance.
I’m not suggesting Line 5 is perfect – in fact, there are nine small features along the onshore portion of the nearly five miles of twin pipes that our integrity teams are monitoring closely. While it's true that there are variations in the wall thickness in some places, that is due to original manufacturing process, and is absolutely not a result of metal loss or corrosion. Even though those features have not changed since the pipe was manufactured and installed, we continue to track and monitor them through bi-annual in-line inspections.
Nevertheless, there is a continuing public discourse over Line 5. In fact, you may be hearing a lot of that discussion yourself. This is an important discussion, but one that should be based on facts and not fearmongering that only serves to create a climate of concern and uncertainty over a pipeline that has safely operated across the Straits since its installation. The Great Lakes and the Straits of Mackinac are simply too precious to do otherwise.
In fact, the Line 5 crossing of the Straits of Mackinac is located in an area that minimizes one of the biggest threats to a pipeline: exterior corrosion. Corrosion growth on the pipeline is limited because there’s very little oxygen at these depths (from 65 to 250 feet), the water temperature is so cold, and it crosses in fresh water.
The initial engineering and construction of Line 5 was considered a marvel. Today it remains our most robust pipeline. Its walls are three times thicker than a typical pipeline and it benefits from exceptionally good, durable enamel coating that remains as effective today as the day it was commissioned.
The interior of Line 5 is aggressively monitored—every single inch of it—through a variety of advanced diagnostic tools. These tools travel through the pipe along with the pipeline fluid, giving us medical-grade imagery and detailed measurements within the steel walls of the pipeline. Even very small features can be identified, tracked and monitored. On the outside of the pipeline, we use remotely operated vehicles fitted with cameras and survey equipment allowing us to closely monitor the exterior condition of this pipeline crossing.
Line 5 is operated far below the maximum pressures. In other words, there is virtually no stress on the line. The pipe shows very minimal corrosion, is very securely supported on the bottom of the Straits of Mackinac and is exceptionally well looked after.
From my perspective, it’s only through rigorous internal and external testing and inspection that we’re able to confirm that a pipeline is fit for service, no matter its age. In fact, we take no special comfort just because a pipeline is new. In the case of both newer and older infrastructure, the question we continually ask ourselves remains the same: is the pipeline fit for service and is it safe? In the case of Line 5, the answers are ‘yes and yes.’
How can I be sure? Because I help make certain that Line 5 is the most closely inspected and respected pipeline in the Enbridge system—by far.
At the end of the day, Michigan needs Line 5 and the energy it delivers safely and reliably to help power its homes, businesses and infrastructure. And equally, Michigan deserves the truth—verified facts—about the continued safety of Line 5.
Tom Prew is a senior regional engineer for Enbridge. Based in Wisconsin, he previously worked as an employee of the Minnesota Office of Pipeline Safety (MNOPS)