Signals, noise, and eco-disaster at Enbridge

“Learning about Enbridge’s poor handling of the rupture, you can’t help but think of the Keystone Kops,” said Deborah Hersman, chair of the NTSB. “Why didn’t they recognize what was happening? What took so long?” she said in a statement. She said that despite alarms and pressure differentials, Enbridge staff twice pumped more oil, about 81 per cent of the total release, into the ruptured pipeline. Hersman said that oil gushed from the rupture for more than 17 hours before the leak was discovered.

This is a fair bottom line when it comes to Enbridge’s Line 6B leak, which poured about a million gallons of diluted bitumen into a tributary of the Kalamazoo River on July 26, 2010. As an Albertan, with all the prejudices and interests that implies, I’ve been reading primary documents in the U.S. National Transportation Safety Board’s investigation of the spill. What I slowly came to understand, to my considerable horror, is that the leak may physically have happened to a bunch of poor bastards in Michigan, but the real problem was here, in Edmonton. This is where pipeline controllers—tired, young, inexperienced pipeline controllers working in a somewhat dysfunctional environment—struggled for long hours to interpret pressure readings as anything but the unthinkable.

How would oil pipeline controllers know there was a leak somewhere in their system? This is a simple question which defies a direct answer. (Boy, does it ever. Go look through the documentation for an answer: it’s a maddening way to spend a week of your life.) Under normal circumstances, it’s actually pretty clear when there might be oil leaking from a pipeline: you have pressure in the line downstream, indicating that there’s oil flowing in the direction of travel, but no pressure upstream. If this condition exists for more than a certain amount of time, 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. You can imagine how this panned out on the evening of the 6B leak, which was not so close to a populated area that it would be noticed immediately and rectified.

At about the moment of the leak, or not long before, there was a planned maintenance shutdown of the section of 6B that had ruptured, or was about to. The downstream pressure didn’t come back upon restart. The controller in charge and the person handling “material balance” agreed that it was probably same doo-doo, different day—nothing they hadn’t seen a bazillion times before. (It does not seem to have helped matters that the “material balance system” person in the control room had unclear responsibilities. The controllers seem to have regarded the MBS professionals as having enormous advisory authority—as being the go-to source for a true understanding of what was happening in the pipe. But the MBS guys themselves seem to have seen their job as basically perfecting a computer model, and, in NTSB interviews, basically took the attitude that they don’t know nuthin’ ’bout no oil.) The control room shut down 6B again and restarted again, with a shift change in the middle of all the head-scratching. After hours of this activity, Enbridge started getting panicky phone calls from an American utility company, Consumers Energy, whose Michigan consumers were reporting a scent suspiciously like that of liquid petroleum product.

Some of the witnesses who talked to the NTSB noted that northern Alberta has a chronic shortage of skilled labour, and the pipeline controllers probably didn’t have experience quite commensurate with their awesome responsibilities. There were generational differences between a gang of grouchy Enbridge oldies who were supposed to be providing guidance, but who in practice pursued a “throw ’em in the pool and see if they swim” teaching model, and the young recent graduates whose fingers were on the buttons. The final NTSB report will surely contain entertaining subplots concerning sloppy, old-school, laissez-faire personnel management, and there’s even a whiff of sexism scandal.

But it seems to me that the core problem with the way Enbridge was doing business was neither a metallurgy problem or a human-factors problem. The problem is that it didn’t have a system for leak detection, as such. What it had 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. Statisticians call these “false positives”. And they know that a test which reports too many false positives is no damn good, even if it absolutely never ignores a true positive.

So Enbridge couldn’t really tell when there was a leak. Or, rather, they couldn’t tell up until about the point that the leak was physically splashing dilbit onto someone’s boots a couple thousand miles from the control room. This issue, I am sorry to say, should have been foreseeable. The company has modified its doctrines as a consequence of the 6B leak, and takes alarms much more seriously now. Taking the alarms seriously won’t help if they are as nonspecific as ever, but clearly there is a lot of action going on within Enbridge, and an appearance of earnestness.

It bears remembering that the proven permanent implications of the 6B spill don’t amount to much beyond the half-billion dollars Enbridge has spent on cleanup. The economic incentives are correctly positioned here: no one wants another spill less than Enbridge and its bean-counters. This isn’t, as far as I have seen anyone bother to demonstrate, a problem of economic “externalities”. The externalities in this case have been internalized right down Enbridge’s throat, with appropriate effectiveness. Moreover, pipelines in general have to be judged against the alternatives to having pipelines—which, in some cases, may have worse permanent environmental effects than worst-case 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 (even if this work is somewhat futile and clumsy at first). That doesn’t inspire confidence in the very different proposition that is Enbridge’s proposed Northern Gateway pipeline to Canada’s west coast. Nothing at all about the NTSB’s final report, I’m afraid, is likely to. And that 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.

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