More lessons from Arkansas tar sands spill


All eyes are now on Mayflower, a quaint little suburban town in rural Arkansas surrounded by streams, lakes and wetlands. And now, tar sands crude.

On Date, Exxon’s underground Pegasus Pipeline  ruptured, spilling as much as 294,000 gallons of dirty tar sands crude in and around Mayflower. And by “in”, we mean down streets, across lawns, and into gardens, canals, storm sewers, creeks, wetlands and even into nearby Lake Conway, a popular among locals for its fishing and other recreational activities.

If Mayflower has taught us anything, it’s that pipeline spills can happen anytime, anywhere, with disastrous consequences (especially when it’s in the path of tornado). “All of us are in shock,” David Fox, the pastor of the local First Baptist Church, told Inside Climate News. “Manmade disasters are so rare in our state … you don’t think this kind of thing can happen to you.”

But there are a few more specific lessons to be mulled over by those, like President Obama, who must decide whether to allow new tar sands pipelines to be built, and like the NEB, who are deciding whether to allow old oil and gas pipelines to carry more corrosive tar sands crude, through communities across the United States and Canada.

Tar sands crude is nasty stuff

Seven years ago, Exxon reversed the flow of the pipeline and turned it into a higher-volume line carrying diluted bitumen, or dilbit, flowing under greater pressure from Canada to refineries on the Gulf Coast.

Dilbit, you may be interested to know, is much more dangerous to transport by pipeline than conventional oil. Dilbit is created by diluting bitumen, a heavy tar-like substance containing numerous toxic substances, with either conventional light crude or diluent, a cocktail of natural gas liquids. In this form, it has the consistency of conventional crude and can be pumped through pipelines, but it carries additional risks. The exact composition of diluents are secret, but the mixture often includes benzene, a known human carcinogen.

The secret and not-so-secret ingredients in dilbit may mean it’s even more toxic than regular old light crude. “Without more information on the chemical characteristics of the diluent or the synthetic crude, it is difficult to determine the fate and transport of any spilled oil in the aquatic environment,” wrote the EPA in response to the U.S. State Department’s Draft Environmental Impact Statement for the Keystone XL Pipeline. “For example, the chemical nature of diluent may have significant implications for response as it may negatively impact the efficacy of traditional floating oil spill response equipment or response strategies. In addition, the Draft EIS addresses oil in general and as explained earlier, it may not be appropriate to assume this bitumen crude/synthetic crude shares the same characteristics as other oils.”

Dilbit, unlike synthetic crude, also is more acidic and corrosive than conventional oil. This increases the risk of pipeline leaks, something Congress recently ordered the Pipeline and Hazardous Materials Safety Administration (PHMSA) to study. Studies also indicate that pipelines operating at temperatures above 100 degrees Fahrenheit spill up to 23 times more often due to external corrosion than conventional oil pipelines. The State Department estimates the proposed Keystone XL tar sands pipeline would operate at between 130 to 150 degrees. It was corrosion that caused an Enbridge pipeline to rupture and spills not once, but twice near Marshall, Michigan.

It is also harder to clean up when, inevitably, it spills. When Enbridge’s Pipeline 6B split open in 2009 and spilled one million gallons of dilbit into the Kalamazoo River, near Marshall, Michigan, the dilbit initially floated on the water like conventional crude. But once the volatile diluents evaporated into the atmosphere, the heavy bitumen sank into the water. Because you can’t see it, it’s more difficult to remove.

“[It’s] not something a lot of people have dealt with,” said an Environmental Protection Agency (EPA) official at the Kalamazoo River clean-up site. “When you can’t see [the oil], you don’t know where it is, so it’s very hard to clean it up.”

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