New federal bitumen study fuels fear over spill impacts
VANCOUVER — Diluted bitumen, the molasses-like product that would be transported by the proposed Northern Gateway pipeline, sinks in salt water when battered by waves and mixed with sediments, according to a new study by the federal government.
However, when free of sediments, the crude floats even after evaporation and exposure to light, the study determined.
The report, conducted by Environment Canada, the Department of Fisheries and Oceans and Natural Resources Canada, also said the commercial dispersant Corexit 9500 used in cleaning up conventional spills had a limited effect on dispersing diluted bitumen.
Whether the oil sinks or floats in the event of a spill has been a source of debate, pitting environmentalists against supporters of projects such as the Northern Gateway pipeline. Part of the argument has been that if the oil sinks to the ocean floor, it’s harder to recover.
The study examined two blends of crude, the Access Western Blend and Cold Lake Blend, which represent the highest volume of diluted bitumen, or dilbit, products transported by pipeline in Canada between 2012 and 2013.
“This work demonstrates that, in waters where fine- to moderatesized sediment is present, these oils are at risk to sink, when there is a high degree of mixing energy available,” the report said.
The experiment compared the two dilbit blends to an oil used as marine ship fuel. The oils were evaporated at what the paper said was a typical marine temperature range. They were also exposed to 120 hours of light under a UV lamp. The dilbit samples did not sink in either case.
When mixed in a tube with salt water, the dilbit samples remained afloat. However, when mixed with three types of sediments of various sizes, the results differed.
The study acknowledged the tests were conducted in a synthesized environment, and it’s possible oil products could behave differently in the natural environment — a point echoed by Owen McHugh, manager of emergency management with the Northern Gateway pipeline.
“What does that 12 hours of mixing really hard in a jar (become) equivalent to in the environment? That’s something that we need to do additional studies on,” McHugh said.
He said it is important to consider the actual circumstances surrounding a spill. “The wind and the waves, and the sediment concentration and how that spill is responded to will all affect the ultimate state of that oil.”
McHugh said he has conducted a similar study with similar results, and the findings were presented during public hearings on the pipeline project last year.
Karen Campbell, staff lawyer with Ecojustice, said the study reinforces what many environmental groups have suspected.
“If we now have a conclusion that says this stuff is going to sink and it’s not going to stay floating on the water, so you’re not going to be able to use skimmers, you’re not going to be able to use dispersants, then we actually have a much greater risk of the impacts of a spill,” she said. “It changes the conclusions about the impact of the project.”
In the federal study, the dilbit samples were also placed in a wave tank facility in Dartmouth, N.S., to see how they would react to a chemical dispersant that has proven effective with conventional crude spills. In non-breaking waves, the oil remained on the surface, but under breaking waves, the chemical caused only partial dispersion, the study said.
Conducting research on how diluted bitumen would behave in a marine environment was one of 209 conditions announced by a review panel that approved the proposed Northern Gateway pipeline.