It may have been the city of Marshall, Mich., that suffered as dilbit spurted into Talmadge Creek, but the real problem that needed fixing was 2,500 km away, in Edmonton. It was 17 hours before Enbridge controllers in Edmonton—tired, young, inexperienced pipeline controllers working in a somewhat dysfunctional environment—finally stopped ramming the oil through.
How would oil pipeline operators know there was a leak somewhere in their system? The answer is hard to extract, even after a week’s reading, from the various interviews and scientific reports the NTSB produced. Under normal circumstances, it is done just the way one might expect: you observe pressure in the line downstream, indicating that there is oil flowing in the direction of travel, but little or no pressure upstream. If this condition exists for more than a brief moment, the controller is supposed to shut everything down until the problem is located.
But there’s a wrinkle. Shutdowns for maintenance can result in “column separations”—situations in which the oil is no longer one continuous flow through the line, but instead consists of pockets of liquid separated by air and other gases. Column separations are common and, when there has been a shutdown, are anticipated. Yet they cause the same pressure imbalances and trip the same alarms that a leak would. Under those circumstances, it seems from the evidence of the NTSB investigation, controllers simply ignore those alarms.
That led to disaster on the evening of the 6B leak, when there was a planned maintenance shutdown of the section that had either just ruptured or was about to. When the downstream pressure didn’t come back upon restart, the controller in charge and the person handling “material balance” agreed that it was probably a typical case of “column sep.” The control room shut down 6B again and restarted again, without success. Meanwhile, a shift change put Enbridge’s real-time diagnostic process pretty much back to square one. Eventually, Enbridge started getting panicky phone calls from an American utility company, Consumers Energy, whose Michigan consumers were reporting a funny smell.
It is surprising, to say the least, to learn that Enbridge didn’t have a system for leak detection as such—not, that is, until dilbit started splashing onto someone’s boots a couple of thousand miles from the control room. What Enbridge had, instead, was a system for detecting pressure anomalies. That system, in essence, sent out hundreds of “column sep” alarms for every “oil is flowing out onto a frigging ecosystem at a higher-than-optimum rate, and oh by the way the optimum is zero” alarm. The company has modified its doctrines as a consequence of the 6B leak, and takes the alarms more seriously now. Taking the alarms seriously won’t help if they are as non-specific as ever. But clearly there is a lot of remedial action happening within Enbridge, and they gave NTSB investigators an appearance of earnestness.
It bears remembering that Enbridge has spent over a half-billion dollars on cleanup of the Kalamazoo spill. This isn’t a problem of economic “externalities” of the sort often complained about when it comes to the oil economy. The externalities, in this case, have been internalized right down Enbridge’s throat. Moreover, pipelines in general have to be judged against the alternatives to having pipelines. In some cases, those alternatives may have worse environmental effects than spills like the one that Enbridge’s ham-handedness and bad luck caused.
But one can’t help feeling queasily grateful that the 6B rupture did happen in Michigan, in a part of the world where a smell of oil spreads to a human habitat sooner rather than later, and where well-equipped cleanup crews can start work quickly. That doesn’t inspire confidence in the very different proposition that is Enbridge’s proposed Northern Gateway pipeline to Canada’s West Coast. The NTSB’s final report is going to be read closely in Canada—very closely, by thousands of people on both the “drill baby drill” side of the new Canadian political spectrum and the “if God meant us to dig, our hands would be garden weasels” side.
Original Article
Source: maclean's
Author: Colby Cosh
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