Scientific studies are ongoing to ensure dilbit behaviour understood

Extensive research shows that diluted bitumen behaves much the same way as other heavy oils. Here is an excerpt from the Citizen's Guide to Tanker Safety and Spill Response on BC's South Coast, published earlier this month. 



Read about and download the full Citizen's Guide here

Better ability to predict behaviour of oil in water

In response to concerns raised by indigenous and coastal communities regarding risks posed by existing tanker traffic, under the Oceans Protection Plan the Government of Canada will ensure that its scaled-up research initiative includes further analysis on how various types of oil and petroleum products behave when spilled in a marine environment. This will provide scientific advice to oil spill responders that will improve the Net Environmental Benefit Analysis approach to a spill and the resulting decision-making process.

Kinder Morgan Canada has undertaken considerable research in oil fate and behaviour to inform and improve oil spill response. Industry is continuing this type of research in collaboration with government scientists as part of continuous improvements in the area of spill response planning.

Diluted bitumen behaves much the same as other heavy oils

A major aspect of spill response has been ongoing work to understand the exact nature of the spill risk. One of the concerns for oil spill recovery has been how heavy crude oils such as diluted bitumen, or dilbit, behave if such oils are spilled on water.

The definitive answer is that extensive research shows that diluted bitumen behaves much the same way as other heavy oils. Below, we review the considerable literature that illustrates this.

Trans Mountain carried out research in 2012 which determined this to be the case. This research, which also involved the Western Canada Marine Response Corporation, confirmed that oil recovery equipment currently stockpiled by response organizations can successfully remove spilled dilbit from the water’s surface.

Subsequent studies carried out by Government of Canada researchers — now widely reported in the media — have confirmed this. At the national scale, authoritative, independent and peer-reviewed work to refine scientific understanding of the behavior and environmental impacts of bitumen in water continues, overseen in 2018 by experts from federal departments, provincial ministries and universities in five provinces including Alberta, Saskatchewan, Manitoba, Ontario and Quebec. This work includes research taking place at the world’s foremost freshwater ecosystem science research centre, Canada’s Experimental Lakes Area )ELA) in northern Ontario. The ELA is an internationally administered facility operated by the International Institute for Sustainable Development (IISD). The IISD receives funding from the United Nations, the Organization for Economic Co-operation and Development (OECD), the World Bank, OXFAM, 18 countries spread across three continents, and a wide range of other sponsors.

The Canadian Association of Petroleum Producers has noted that “asserting dilbit is different from other crude oils is a fallacy that allows critics to lament a lack of dilbit-specific research or regulations.” During Ministerial Panel hearings for the Trans Mountain Expansion Project, it was expressed that diluted bitumen was less safe for transportation than other heavy oils because it would not float. The scientific evidence does not support this claim.

Bitumen is a heavier, thicker form of petroleum. The oilsands of northern Alberta are one of the world’s largest known deposits of bitumen. This oil has fewer lighter hydrocarbon molecules — such as those used to manufacture gasoline or diesel fuel — compared to conventional crude. In order to make it flow through a pipeline, it is either partially refined into a synthetic crude which is very similar to conventional crude oil, or natural gas liquids or condensate (diluents) are added to allow it to flow more easily through a pipeline. Synthetic crude may also be added.

Dilbit can be refined to make gasoline, diesel and jet fuel and a wide range of consumer products including plastics for making clothing and sports gear, kayaks and canoes, medical equipment, containers, automotive lubricants, fertilizer and many other essential day-to-day items.

Research shows that the diluent and bitumen together comprise a single-phase product that does not simply separate into its various components. The product floats on water and can be contained using booms and recovered using mechanical recovery methods such as skimmers.

Transportation safety concerns

During Ministerial Panel hearings for the Trans Mountain Expansion Project, it was expressed that diluted bitumen was less safe for transportation than other heavy oils because it would not float. The scientific evidence does not support this claim.

Canadian research to date has determined there is no difference between the behaviour of diluted bitumen and other heavy crudes in the very unlikely event of a spill into the marine environment. It floats on water unless exposed to high water temperatures and weathering.

As part of its Application to the National Energy Board, TMEP carried out a 10-day meso-scale test that included oil sample analysis of representative samples of dilbit as well as assessing their behaviour or ‘weathering’ in brackish water such as would be found in Burrard Inlet.

The results of TMEP’s research, known as the Gainford Study, were submitted as evidence to the NEB. The study found that spilled dilbit behaved similarly to conventional heavy crudes during the 10-day weathering cycle of the research and could be recovered at all stages from the surface using conventional methods and equipment.

Research has subsequently been carried out by researchers from Fisheries and Oceans Canada, Environment and Climate Change Canada, and Natural Resources Canada. This work has corroborated the findings of the Gainford Study. The following Q&A looks at some key findings of the Gainford Study on the behaviour of dilbit in water, considered by the National Energy Board:



Does dilbit sink in water when spilled?

Both Cold Lake Blend (CLB) and Access Western Blend (AWB) dilbits are lighter than freshwater. Dilbit spilled into fresh, brackish, or saltwater will stay on the water surface unless another mechanism mixes it into the water column, as would be the case for any oil. Only after extensive weathering may some portion become submerged or sink in freshwater, without invoking additional parameters that can modify the density of the spilled product.

Can dilbit be recovered from water using conventional spill response skimmers?

Fresh dilbit oil is much like most medium to heavy crude oils and can be recovered using a variety of skimmer systems, ranging from weirs to oleophilic units. As dilbit weathers, the oil viscosity increases significantly but skimmers designed for more viscous oils, including brush, belt, and mechanical systems, can continue to effectively recover weathered oil (demonstrated in up to 10 days of weathering in tank tests).

Can chemical dispersants be effectively used on dilbit spills?

Given appropriate safety, environmental, and operating conditions, dispersants may be effective within the first day of a spill before weathering results in oil that is too viscous to effectively disperse.

How toxic is dilbit relative to other crude oils?

The BTEX (benzene, toluene, ethylbenzene, and xylene) components in crude oils are some of the key chemicals of concern for toxicity. The BTEX content in CLB and AWB dilbits is approximately 1 to 1.2 percent by volume, respectively, which is slightly less than that found in Alaska North Slope or Alberta Sweet crude oils.

How variable are the weathering patterns and oil properties between different dilbits and synbits?

The Gainford tests showed that the weathering patterns between CLB and AWB are similar and that oil physical and chemical properties are consistent with other heavy crude oil. The full range of properties of dilbit blends are well known and published (see CrudeMonitor), although weathering characterization of the range of oils is the subject of ongoing research.

Can spilled dilbit be effectively cleaned off shorelines?

The Gainford meso-scale tests showed that fresh to very weathered CLB can be effectively removed from a hard substrate through a combination of shoreline cleaner (Corexit 9580) and low to moderate water pressure flushing. These techniques may not be suited for all types of shorelines; however, they generally are appropriate for coarse-grained materials (gravel, cobbles, and boulders and including coarse sediment mixes).

Dilbit does not separate in pipelines, tanks or tankers. It floats, just like any crude oil, in calm or slow-moving water. Petroleum products float on water if they are lighter than water. The American Petroleum Institute has developed a standard (API gravity) for measuring the density of any particular petroleum liquids. The higher the number, the lighter the liquid. For example, the API gravity of water is 10 degrees and the API gravity of dilbit is 20 to 22 degrees, which means it floats easily.

Over an extended period of  "weathering" or if mixing with sediments, surface oil could submerge and be driven below the water surface by waves or currents. Research carried out by Natural Resources Canada — widely reported in the media since 2016 — indicates that the recovery strategy for dilbit would be the same as other heavy crudes. In fact, research indicates that dilbit is easier to recover from water than conventional light oils — which are more likely to disperse into the water column.

Three weeks to clean up before risk of sinking

According to a June 2016 Bloomberg News story, the NRCan study results “may help dispel some concern that a spill of diluted bitumen would be more difficult to clean up and help companies make the case for pipeline projects such as Kinder Morgan Inc.’s Trans Mountain expansion.”

This study, led by NRCan researcher Heather Dettman, diverged from a 2015 US National Academy of Science report which stated that dilbit tended to sink quickly when spilled into fresh water. This report  bases much of its conclusions from experience gained through response to a pipeline spill on land affected by overflow of the Kalamazoo River where water temperatures ranged to 29 degrees. This is about double the typical summer maximum sea temperature along the southern BC coast as measured for communities such as Richmond and Vancouver by the US National Ocean Administration.

“Under typical Canadian climatic conditions you’ve got up to three weeks to clean it up before you’ve got any major sinking,” Merv Fingas a former Environment Canada spill science expert who was one of the authors of the US National Academy report, told Macleans magazine in 2016.

Dettman is a senior research scientists working at the CanmetENERGY laboratory in Devon, Alberta. She told the Globe and Mail in a January 2018 story that, based on her research, the claim that bitumen sinks in water is “misinformation.” The Globe’s lead on the story was that the BC government’s intention to strike a scientific advisory panel to investigate interactions between dilbit and waterways and wildlife “is seen as an attempt to block Kinder Morgan Canada Ltd.’s proposed expansion of its Trans Mountain pipeline.”

In a February 2018 interview with CBC Early Edition hosts Stephen Quinn, Dettman said NRCan’s tests, carried out in a 1,200-litre tank, focused on whether or not dilbit would sink in fresh water. She said her team chose freshwater because it is less dense than salt water and therefore more likely to allow oil to sink into it. The tests also included buffeting dilbit with breaking waves in various temperature conditions to see if that made a difference in how quickly it would sink.

In tests ranging to 10 days, she told Quinn, the bitumen continued to float. Subsequent tests were extended to four weeks of exposure. “The first diluted bitumen product that came out, that started to sink, was actually after three weeks. As you can imagine, three weeks is a fair chunk of time to be recovering it.”

The Vancouver Sun in a subsequent interview with Dettman said “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.”

Ongoing research

In its Application to the NEB, Trans Mountain asserted that existing information about dilbit and other fuel oils is sufficient for modelling of their fate and behaviour for purposes of the Expansion Application and spill response planning. The NEB in its report published in May 2016 has corroborated this.

The NEB’s comment that research “should continue to inform the potential fate and behaviour of spilled oils and assist companies and spill response agencies in spill response planning” is widely supported by industry, including Trans Mountain which says it is committed to continual improvement into oil spill response planning  supported by research and better understanding of the fate and behaviour of oil in water.

Following up on the NEB’s comments on this topic and recognizing the research initiatives recommended by the Royal Society of Canada, the Canadian Association of Petroleum Producers, the Canadian Energy Pipeline Association and other stakeholders are funding a multi-million dollar independent scientific study encompassing the behaviour of a variety of conventional and unconventional crude oils in freshwater, saltwater and estuaries in a wide range of temperature and water conditions.

This work, which began in 2017, is intended to be authoritative on the topic of oil fate and behaviour resulting from spills in Canadian waters. It is being carried out by an independent third-party researcher who is evaluating the fate and behaviour of a wide variety of crude oil products including dilbit. A scientific advisory committee, including representatives from Environment and Climate Change Canada, Fisheries and Oceans Canada, the National Energy Board and Natural Resources Canada is providing technical knowledge and guidance.

Research scheduled for 2018 also includes two investigations of the behavior of dilbit in Canada’s largest outdoor laboratory, the Experimental Lakes Area which is operated near Kenora, Ontario, by the International Institute for Sustainable Development (IISD).

The Experimental Lakes Area is a globally unique research station encompassing 58 lakes and their watersheds in the Kenora, Ontario area. It was established 50 years ago in a remote area where human activity was unlikely to compromise research results. It was originally funded by Fisheries and Oceans Canada but taken over by the IISD in 2014. Hundreds of peer-reviewed articles based on ELA research have been published in science journals and the facility itself has received several international awards for landmark discoveries in water-based research.

In November 2017 the IISD announced a three-stage project to learn more about what oils do in freshwater systems.

As the IISD notes on its website, “Several studies are currently being pursued at the IISD-ELA to address public and regulatory concerns regarding potential environmental effects of oil spills and uncertainty regarding the best cleanup methods following a spill, especially for freshwater environments. One study, led by Drs. Jules Blais (University of Ottawa), Mark Hanson (University of Manitoba) and Diane Orihel (Queen’s University) will examine the ecological impacts of contained diluted bitumen model spills in a freshwater boreal lake. A companion study, led by Dr. Vince Palace (IISD-ELA) will compare the effectiveness of different methods for cleaning spilled oil from shorelines. Both studies are part of a large multidisciplinary program that includes participation from governments (Environment and Climate Change Canada, Fisheries and Oceans Canada, Natural Resources Canada, Ontario Municipal Employees Coordinating Committee, Ontario Ministry of Natural Resources and Forestry), regulators (National Energy Board), academic partners (universities of Manitoba, Ottawa, Queen’s, Institut national de la recherche scientifique, Calgary, Saskatchewan, McGill) and industry (Canadian Association of Petroleum Producers, Canadian Energy Pipelines Association).”

The first stage of the project, a pilot study examining the chemical and physical behaviour of dilbit in fresh water, is complete.

“The second stage is a field study,” the IISD stated. “Researchers will use large enclosures (10 m diameter) placed in a lake to examine how diluted bitumen reacts in fresh water over longer periods of time. Researchers will also be directly testing changes in the oil’s toxicity in freshwater bugs, fish and amphibians.

“The information from these first two studies will guide a third study, where researchers will examine the most effective methods of cleaning spilled oil from shorelines. Again, only small, contained model spills in an IISD-ELA lake will be used. This study will focus on the shoreline, which is most sensitive to oil and presents the biggest difficulty in terms of cleanup efforts.”

Scientific studies of bitumen in water

There is a considerable literature of diluted bitumen research, and the work continues:


2013 — Federal Government Technical Report: Properties, Composition and Marine Spill Behaviour, Fate and Transport of Two Diluted Bitumen Products from the Canadian Oil Sands. Study carried out by Environment Canada, Fisheries and Oceans Canada, Natural Resources Canada. The behaviour of the diluted bitumen products was studied under laboratory conditions, including a wave-tank experiment and literature review. The major results of the studies were that two high-volume bitumen products from Western Canada, Access Western Blend and Cold Lake Blend, floated on saltwater even after evaporation and exposure to light and mixing with water. It said “typical marine temperature ranges seen in Canada (0 to 15 degrees Celsius) is not sufficient to cause oil sinking” in fully salt marine waters. The products sank or dispersed as floating tarballs when exposed to sediment and high-energy wave action.  

2013 — Gainford, Alberta, Study (Witt O’Briens, Polaris Appliled Sciences, Western Canada Marine Response Corporation): A Study of Fate and Behaviour of Diluted Bitumen Oils on Marine Waters. The study carried out for Trans Mountain Expansion Project and presented as evidence to the National Energy Board in 2013 confirmed that dilbit is a stable homogeneous mixture that behaves in a similar manner to other natural crude oils. It did not separate into bitumen and diluent during a 10-day weathering test, nor did it sink.

2013 — (US) National Academy of Sciences: Effects of Diluted Bitumen on Crude Oil Transmission Pipelines . The study found no evidence of any causes of pipeline failure that are unique to the transportation of diluted bitumen.

2015 — (US) National Academy of Sciences: Spills of Diluted Bitumen from Pipelines: The report found that weathering can cause bitumen to sink but noted that weathering process slow as temperature falls. It also reported that “even the heaviest oils will usually float on seawater.”

2015 — Royal Society of Canada Expert Panel: The Behaviour and Environmental Impacts of Crude Oil Released into Aqueous Environments. The Society recommended seven priorities for further research. These included research to better understand the environmental impact of spilled oil, the effects of oil spills on aquatic organisms and a program of controlled research to better understand spill behaviour and effects across a spectrum of crude oil types in different ecosystems and conditions.

2016 — Science of Crude Oil Behavior During Spills in Fresh Water Environments: Test Tank Study Results, a presentation to the Senate Committee on Transport and Communications by Heather Dettman, Natural Resources Canada. Dettman reported that laboratory tests show weathered bitumen continued to float during an eight-day test at temperatures of 15 degrees celcius — which is within the normal annual seawater temperature range on the BC south coast. At a water temperature of 26 degrees, more than 85 per cent of weathered dilbit continued to float and was recoverable. She noted that there was 95 per cent recovery from a spill of diluted bitument into Burrard Inlet in 2007 (after a road contractor working for the City of Burnaby breached the Trans Mountain pipeline).


NRCan, led by senior researcher Heather Dettman, is carrying out more extensive testing of the behaviour of bitumen in water.

IISD’s 2017-2018 study of bitumen in water in the Experimental Lakes Area.

Trans Mountain must provide a report to the National Energy Board regarding current and future research programs. The NEB requires the report include research on the behaviour of oil in water and cleanup and remediation options. Trans Mountain must also report how it is incorporating oil research results into its emergency preparedness and response plans. The report must be developed in consultation with Indigenous groups in British Columbia, the BC Ministry of Environment, BC Ministry of Natural Gas Development, BC Oil and Gas Commission, Canadian Coast Guard and Environment and Climate Change Canada. Trans Mountain must report to these groups prior to the start of expanded operations at Westridge and provide progress updates one year and five years after operations start.

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