In addition, "Refiners have found tar sands-derived crude to contain significantly higher quantities of abrasive quartz and sand particles than conventional crude. This combination of chemical corrosion and physical abrasion can dramatically increase the rate of pipeline deterioration."

The relatively high heat and pressure needed to move the thick DilBit through pipelines also increases stress on the system.

What's disturbing, environmentalists say, is that the federal agency that oversees pipelines — the Pipeline and Hazardous Materials Safety Administration (PHMSA) — "does not distinguish between conventional crude and DilBit when setting minimum standards for oil pipelines."

While the question of DilBit's effects on pipelines continues to be investigated and debated, the difficulties it poses when it leaks into waterways was seen with certainty as a result of the Marshall spill.

Although portions of the river that had been closed since the spill were reopened last week, that doesn't mean all the oil has been cleaned up. Unlike other, less dense forms of petroleum, tar sands crude oil sinks instead of floats. Consequently, it can't be cleaned up by skimming it from the top of the water, as is usually the case with oil spills. 

Instead, it must be dredged from the bottom of riverbeds, greatly disturbing the aquatic habitat, explains Stephen K. Hamilton, a professor of aquatic ecology at Michigan State University and president of the Kalamazoo River Watershed Council.

Because of the harm caused by dredging, and the difficulty involved, it was deemed "impractical to go after every last bit of submerged oil," Hamilton explains. "There's going to be some residual oil in the system. It's important to get people to accept that. The only alternative would be to practically destroy the ecosystem you are trying to save."

As for the effects of letting the oil remain, that's an unknown at this point. "We have no experience with this kind of oil in this kind of ecosystem," Hamilton says.

What hasn't happened, at least to this point, is any large-scale retooling of regulations regarding where these pipelines are placed, how they are operated, or how DilBit should be handled.

Sara Gosman, an adjunct professor at the University of Michigan Law School and a water resources attorney for the National Wildlife Federation, authored the April report titled "After the Marshall Spill: Oil Pipelines in the Great Lakes Region." The report focuses on regulations and government oversight of Enbridge and other pipeline operators. 

We asked via e-mail if there have been any regulatory changes or changes in industry practices instituted that will reduce the likelihood of similar spills occurring in the future?

"In 2012, Congress amended the federal Pipeline Safety Act to address some issues raised by the Marshall spill," she replied. "For example, PHMSA must study methods of leak detection and report to Congress. The agency must also study the risks of diluted bitumen, the heavy crude oil that spilled in Marshall. Since these are studies, it remains to be seen how PHMSA will decide to regulate."

In other words, no big changes yet. And that is disturbing.

"We conclude in our report that pipeline laws do not adequately address the risks of pipelines, particularly risks to water resources," she noted.

 

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