If you haven’t seen it yet, the NTSB Pipeline Accident Report on the 2010 Enbridge spill in Marshall, Michigan is a riveting– and revealing– document. Still, we understand that 100-plus pages of fact-finding released by a federal regulatory agency isn’t exactly everyone’s idea of fun summer reading. So for that reason, we’re launching a new series, in which we’ll tell you some stories drawn from the NTSB report and try to draw some lessons relevant to the Line 6B project. Here’s our first installment:

Part 1: Does Enbridge Learn from its Mistakes? 

About a week ago, I had a conversation with a staff member from the office of a local congressman. When the subject of the Marshall spill came up, he assured me that, given the cleanup costs to Enbridge of that disaster, the company certainly doesn’t want anything of the sort to happen again. “Well, sure,” I replied. “And I’ll bet they’d also have said in, say, June of 2010 that they didn’t want to spill a million gallons of oil into Talmadge Creek. But they did.”

Of course, the staffer’s real point was a simple and, I suppose, not altogether unreasonable one: that Enbridge had learned from its mistakes, that the Marshall spill was an accident and a wake-up call, and that the company was taking appropriate corrective action to prevent another similar accident in the future– all of which, I guess, was meant to assuage whatever worries I might have about the new pipe Enbridge is about to install in my backyard.

But here’s the thing: it’s a lot harder to accept that line once you know about the 10-Minute Restriction.

Let me explain: the 10-Minute Restriction is one of Enbridge’s safety precautions. According to their control center operational procedures, any time a pipeline is operating under unknown conditions–such as an unexplained change in pressure– for 10 minutes, the pipe is to be shut down and evaluated until a cause for the condition can be definitively established. Yet despite alarms indicating abnormalities in the line near Marshall– conditions that should have triggered the 10-minute rule– Enbridge failed to recognize that the line had ruptured for 17 hours and only then because they were notified by an outside caller.

In fact, the NTSB discovered that Enbridge control center staff routinely ignored the 10-Minute Restriction, a practice that the NTSB attributes to “a culture of deviance” at Enbridge. From the report:

Although Enbridge had procedures that required a pipeline shutdown after 10 minutes of uncertain operational status, Enbridge control center staff had developed a culture that accepted not adhering to the procedures.

A culture that permits the flouting of the company’s own safety precautions is troubling enough, of course. But this little episode is of even greater concern to those of us looking for signs that Enbridge learns from its mistakes. That’s because the 10-Minute Restriction was originally adopted by Enbridge as an added preventative measure in response to yet another spill– from way back in 1991.

On March 3, 1991, a rupture in an Enbridge pipe (at that time, the company was called Lakehead Pipe Line) spilled 1.7 million gallons of crude oil in Grand Rapids, Minnesota, making it the largest oil spill in Minnesota state history. In a scenario that would be repeated almost 20 years later with the Line 6B pipe, control center staff in 1991 misinterpreted or disregarded alarms and other indications of abnormalities in the line and as a result pumped oil into the ruptured line for another hour.

Which returns us to our original question: does Enbridge learns from its mistakes? Well, here is what we know: in response to a pipeline rupture in 1991, made worse by the failure of Enbridge control center staff to act on indications of a problem, Enbridge put in place a new operational procedure– the 10-Minute Restriction. And when another pipeline rupture occurred in 2010, it was made worse by the failure of Enbridge control center staff to act on indications of a problem AND by their failure to adhere to the new operational procedure put in place in 1991– the 10-Minute Restriction.