Bitumen can float, making cleanup possible
To the question of whether diluted bitumen sinks or floats when it hits water, the short answer is it floats, most of the time, according to a growing body of research being compiled by Natural Resources Canada scientists.
That and how to clean it up are key concerns that have B.C. considering restrictions on increased shipments of the product through B.C. that put Kinder Morgan’s $7.4 billion Trans Mountain pipeline at risk.
Researcher Heather Dettman, a senior scientist with Natural Resources Canada in Devon, Alta., is leading a team looking into some of those questions. Postmedia’s Derrick Penner caught up with her and a spokesman from Western Canada Marine Response Corp. to talk about answers.
Q What is diluted bitumen?
A Dettman said bitumen is the basic, tar-like petroleum product extracted from the Athabasca oilsands. Producers inject lighter components into bitumen to make it thin enough to flow through pipelines.
Q Does diluted bitumen float or sink when it hits the ocean?
A Dettman’s tests, between 2014 and now, using varying grades of diluted bitumen typical of oilsands production shows that the material will float on the surface for up to three to four weeks, even under wave conditions that would cause conventional crude to mix in with the water column. “The fear is that as soon as (diluted bitumen) hits the water it sinks,” Dettman said. “That’s the messaging that’s been out there and that’s not what we’ve been finding, even in fresh water.”
Q How would rough seas change the behaviour of diluted bitumen?
A “From a density perspective, it will be floating unless it’s really stormy, then it can go anywhere, the same way any other petroleum product,” Dettman said. If a storm pushed bitumen ashore, it would pose the problem of having to clean it up on land. Q Has there ever been a spill of diluted bitumen on the coast?
A The biggest spill that the Western Canada Marine Response Corp. has dealt with involved a mix of bitumen and synthetic oil, said spokesman Michael Lowry. That was the 2007 puncture of Kinder Morgan’s Trans Mountain pipeline in Burnaby that led to about 100 tonnes of oil flowing down storm drains into Burrard Inlet. In nice weather and close to the industry-funded spill responders’ facilities, Lowry said they were able to recover 90 per cent of the oil. “Those are ideal conditions, I can’t extrapolate those to other spills for sure,” Lowry said.
Q How do you clean up a bitumen spill?
A Lowry said methods haven’t changed much over the years. Chemical dispersants, in situ burning and mechanical recovery are the techniques that responders use, but since the first two require government permission, the corporation focuses on mechanical recovery — booming and skimming. From its 2007 experience, Lowry said responders learned that its brush skimmers — conveyors that rotate heavy plastic brushes over the surface to collect oil — were particularly effective.