Dilbit Floats in Canada, Not US

Living Oceans Society June 28, 2016

Vancouver – Living Oceans Society greeted with skepticism media reports that Natural Resources Canada had discovered that diluted bitumen “doesn’t sink as readily as conventional oil” when spilled into water “unless exposed to high temperatures and weathering”.

“It’s hard to argue with a study you can’t read,” said Executive Director Karen Wristen, observing that the new research does not appear to have been published as yet.  “However, there’s nothing new about dilbit floating in a laboratory test—both Enbridge and Kinder Morgan have filed evidence to this effect with the National Energy Board.  It’s what happens in the real world that should concern us.”

Both of the companies seeking to build pipeline and tanker routes to the Pacific told the National Energy Board that dilbit would float for long enough to be recovered.  Shortly after the last hearing closed, the U.S. National Academy of Sciences published a major study, looking at the notorious Kalamazoo River and Mayflower, Arkansas spills, where the product actually spilled or seeped into fresh water environments.

Apparently, if dilbit spills in U.S. waters, it sinks.  It sinks fast—far faster than predicted in laboratory tests such as those filed by the pipeline companies with Canada’s national regulator.  And it sinks because it “weathers” into dense, sticky globs that rapidly become heavier than water.

A Canadian case in point was the spill from the grain carrier Marathassa in Vancouver’s English Bay last April.  Living Oceans’ Project Manager Rob O’Dea was among the first on the scene and reported the spill.  “I saw oil in globs ranging from the size of a pea to about the size of my arm, already submerged as far as 3-4 feet when I called the spill in at about 5 p.m.,” said Rob.  The Marathassa spilled bunker fuel, a lighter oil than bitumen; and while some of it remained on the surface, clearly large amounts were submerged within hours after the spill began.

In the real world, oil is exposed to “weathering” from the moment it is spilled, which puts the spin on the Natural Resources findings into context.  “No doubt, at a lower temperature, oils weather more slowly,” observed Wristen. “The NAS report tells us that water and air temperature, wind speed and oil slick thickness all have an effect on the rate of weathering; and that the presence of even minute amounts of silt or organic matter in the water can cause dilbit to begin to submerge.  Add in mixing energy supplied by water currents and waves, and you have a good picture of all the variables that can work to send dilbit beneath the surface of the water within as little as 24 hours after a spill.

“Given that the mandated response times for oil spills are longer than 24 hours in most places along the pipeline and tanker routes, it’s reasonable to plan for a scenario in which responders will somehow have to find the oil beneath the surface before they can clean it up,” said Wristen.  “That has proven so challenging that the companies have instead invested heavily in proving that dilbit will float. It hasn’t done so in any actual spill scenario to date and there is little reason to expect it will behave differently in Canada.”

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