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Jury still out on risk from bitumen spills: researchers

Green party leader suggests that science is settled on dilbit; scientists disagree
Diluted bitumen subjected to weeks of agitation in a test tank continued to float | Submitted

The main argument that the B.C. government, BC Green Party Leader Andrew Weaver and activists have used against the expansion of the Trans Mountain pipeline is the risk it poses to B.C.’s coasts and rivers.

Critics of the expansion are concerned by the potential for spills resulting from a rise in tanker traffic, and the nature of the product – diluted bitumen – being conveyed over land and water.

Dilued bitumen (“dilbit”) has been characterized by some as some kind of “Frankencrude” that could cause more environmental damage and be harder to clean up than conventional crude.

However, there have been so few dilbit spills to study that the jury is still out on the question of whether they are worse for the environment and harder to clean up than conventional oil spills.

A number of studies have called for more research to settle the question of how readily dilbit will sink – a crucial question, since sunken dilbit might be harder to clean up.

While many scientists say more research is needed, Weaver asserts the science is settled.

“We can’t clean up the diluted bitumen if there were a spill,” Weaver said April 16 during a debate on Alberta’s recent moves to defend the Trans Mountain pipeline project. “You don’t have to believe me, you can believe the Royal Society of Canada or the National Academy of Sciences in the U.S. expert panel reports.”

Except that’s not what either study says.

“The quote from the politician is factually incorrect, but contains a grain of truth,” Peter Hodson, one of the scientists involved in the Royal Society of Canada study that Weaver cited, said in an email to Business in Vancouver.

“Spilled dilbit can be cleaned up by conventional methods when it is floating on the surface of water or is spilled onto land, but if it is not cleaned up immediately, it ‘weathers’ and the cleanup challenges increase significantly.

“There are likely circumstances in which the special properties of dilbit may facilitate cleanup, but it is difficult to generalize.”

Michael Lowry, communications manager for the Western Canada Marine Response Corp., was more blunt when asked about Weaver’s assertions.

“He’s categorically wrong,” he said. “We do find it frustrating that people are out there saying that we can’t clean it up, because we know we can clean it up because we have cleaned it up.”

Dilbit spills in recent years include a 2007 incident in which a backhoe ruptured a Kinder Morgan (TSX:KML) pipeline in Burnaby, causing a spill of 100,000 litres of synthetic crude made from bitumen, about 40% of which drained into storm sewers and made its way into Burrard Inlet.

Three years later, an Enbridge (TSX:ENB) pipeline burst in Michigan, spilling at least 3.7 million litres of dilbit into a tributary of the Kalamazoo River.

Weaver has written that “it’s a pretty safe statement” that such spills can’t be effectively mitigated, “given that we have never cleaned up more than 15% of a crude oil spill and 2% of a dilbit spill.”

But Heather Dettman, a research scientist at Natural Resources Canada who has been studying the behaviour of both crude oil and dilbit, wonders where Weaver’s 2% figure comes from.

“Both Burrard and Kalamazoo had relatively high recoveries [70% or more] using surface oil cleanup methods,” Dettman said. “Submerged oil was found at Kalamazoo and so dredging was done to remove it. Neither area is showing long-term impacts.”

According to a report by Stantec, 95% of the oil from the Burnaby spill was recovered; 5,636 litres were not recovered.

As for the two studies Weaver referenced, the scientists who produced a study for the Royal Society of Canada in 2015 looked at all forms of crude, not just dilbit.

They concluded more research is needed on the behaviour of various crude oils, and also noted that conditions – weather, currents, temperature, sediments – were just as important as the type of oil involved as factors in how they behave in the marine environment.

“The unique features of the environment where an oil spill takes place are at least as important as the type of oil in determining effects on aquatic ecosystems,” the report’s summary states.

It also noted that spills from oil tankers have been dramatically reduced since the 1989 Exxon Valdez oil spill in Alaska.

“The good news is that transporting oil at sea is safer than it has ever been,” the report states.

As for the National Academy of Sciences study, it focused on pipeline spills, not marine spills. It recommended spill response plans be modified to address the concerns that dilbit might behave differently in the event of a spill in a river.

Both studies noted knowledge gaps and called for more research. The Canadian government has earmarked $45 million for oil spill research, and Dettman is one of the scientists who has been doing some of that work.

Her work, most of which hasn’t been published yet, suggests that the National Academy of Sciences’ recommendations for response plans may have things backwards. The academy’s report, she said, assumes spilled dilbit will sink and will have to be recovered, “and this is not right,” she said.

Dettman’s experiments suggest that, when subjected to artificial weathering, conventional crude mixes with water through a process called entrainment, whereas dilbit continues to float, even after prolonged weathering. When they interact with sediments, both oils will sink, but the dilbit is more easily recovered.

Using a specially built tank that simulates the wave action, temperatures and interactions with sediment that might occur in a river, Dettman has tested both conventional crude and dilbit.

She has subjected both conventional crude and dilbit to artificial weathering for three weeks at a time. Whereas the dilbit continued to float, the conventional crude immediately became entrained.

“We’re watching and the tank all went black,” Dettman said of the experiment with crude oil. “With the waves and the energy that was there, it just mixed it in. So the analogy is like adding cream to coffee. We’re looking at that and we’re going, ‘Well, that can’t be good.’ We lost about 50% of the oil into the water and sediment.”

The diluted bitumen, on the other hand, continued to float, even after weeks of artificial weathering.

“The first diluted bitumen to sink was after three weeks,” Dett
man said. “So in fresh water, with sediment, at different water temperatures, we’re finding that it’s floating. We’ve done eight tests, we’ve done different temperatures and we’re getting very consistent results. About five tests with diluted bitumen, they were all floating.”

Dettman and her team modelled two spills: the Kalamazoo River dilbit spill in 2010 and an incident in 2000 in which a Pembina (TSX:PPL) pipeline ruptured, spilling nearly 100,000 litres of light crude into B.C.’s Pine River north of Chetwynd.

She notes that, though the Pine River conventional oil spill was much smaller than the Kalamazoo dilbit spill, the impact on fish was worse.

“They’ve been having trouble for years with thousands of fish dying in that part of the river,” Dettman said. “That was conventional crude. That is consistent with the tests that we did.

“When you look at the Kalamazoo, less than 200 fish died, and as of the next year, nothing was affected. So for all that oil that was there, it was not mixing into the water.”

Hodson said a spill in the Fraser River might be more of a concern than a spill at sea, because dilbit would be less buoyant in fresh water than in salt water.

“The sinking behaviour of dilbit will be most evident in fresh waters with high concentrations of suspended sediments or in waters receiving dilbit that has flowed over bare soil,” he said. “Both these conditions occurred in the Kalamazoo spill, and could occur in a river such as the Fraser with high concentrations of suspended solids.”

He added that the kinds of lab simulations Dettman has conducted have limitations.

“The problem with lab tests is that the range of conditions and the variations in conditions over time (e.g., diurnal changes in temperature, UV light, wind conditions, etc.) are relatively limited compared to real-
world spills,” Hodson said. “There is still a lot to learn before we can confidently predict how dilbit will behave in any circumstance.”

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