More than seven years have passed since an Enbridge oil pipeline ruptured and spilled more than a million gallons of tar sands oil, also known as diluted bitumen, near a tributary leading to Michigan's Kalamazoo River. Once in the water, the oil — which spill responders initially did not know was tar sands oil — ended up sinking to the sediment on the river bottom and causing major environmental impacts for wildlife and plants.

Yet even today, the oil industry still claims that tar sands oil floats.

For example, tar sands oil pipeline operator Kinder Morgan has an FAQ page for its Trans Mountain pipeline, and according to that page, one of the company's top questions of 2017 was the following: “Does diluted bitumen sink or float?”

Diluted bitumen (also known as dilbit) is the industry term for tar sands oil. Dilbit is a mixture of two distinct materials. One is the heavy tar-like bitumen that is mined from tar sands deposits. The other is a highly flammable natural gas condensate that is mixed with the bitumen to allow a product that starts out with the consistency of peanut butter, once diluted, to flow through a pipeline or be pumped into a rail tanker car.

The answer to this question of whether dilbit sinks or floats isn’t a simple yes or no. But the response on the Trans Mountain FAQ page ends up being quite misleading:

“Products carried in the Trans Mountain system must meet criteria for density (max 0.94) and viscosity (350 cst). That maximum density of 0.94 means that diluted bitumen is less dense than fresh water (density 1.00) and seawater (density 1.03). In fact, diluted bitumen (or dilbit) has the same spill-recovery characteristics as conventional heavy oil.”

Notice how Kinder Morgan didn’t answer the question directly but instead discussed the various densities of water and their products, implying that because diluted bitumen in the pipeline has a density lower than water, it must float.

On a separate page on the Trans Mountain site, the same information appears under the heading: “Myth: Diluted bitumen sinks.”

However, a 2015 National Academy of Sciences conference on the Effects of Diluted Bitumen on the Environment made quite clear one key lesson of the Kalamazoo incident: Yes, diluted bitumen floats immediately after released, but as soon as it is exposed to the elements, the mixture begins changing — the light and volatile condensate diluting the bitumen evaporates — and with time the remaining oil product begins sinking.

Greg Powell of the U.S. Environmental Protection Agency was involved in the Kalamazoo cleanup and he explained this complex reality to the conference attendees. “Once the oil started to sink, it made things a lot more difficult on our recovery,” he said.

The oil industry has been sticking to its claim that diluted bitumen floats, but real-world experience seems to indicate that while dilbit floats for a short time, it soon interacts with the weather, water, and sediments, and ultimately sinks.

In the Kalamazoo case, the oil began sinking within two weeks. And the cleanup took five years and cost over a billion dollars.

National Academy of Sciences Contradicts Trans Mountain’s Claims — With Science

The 2015 National Academy of Sciences conference on dilbit's environmental effects was just one part of a larger research effort by the academy, which also resulted in a 2016 report on the topic. This report makes clear that diluted bitumen spills in water are “unique” and difficult to clean-up precisely because the bitumen sinks:

“For any crude oil spill, lighter, volatile compounds begin to evaporate promptly; in the case of diluted bitumen, a dense, viscous material with a strong tendency to adhere to surfaces begins to form as a residue. For this reason, spills of diluted bitumen pose particular challenges when they reach water bodies. In some cases, the residues can submerge or sink to the bottom of the water body.”

Which is exactly what happened in the Kalamazoo River spill. Trans Mountain is correct that diluted bitumen is less dense than water, but that fact didn’t help the Kalamazoo River. Once exposed to the environment, dilbit breaks down into its components and the heavy bitumen portion sinks. And the National Academy found that this could occur even when the bitumen was still less dense than water:

“Importantly, the density of the residual oil does not necessarily need to reach or exceed the density of the surrounding water for this to occur. The crude oil may combine with particles present in the water column to submerge, and then remain in suspension or sink.”

This report comes to the same conclusions about dilbit sinking as the people working to contain and clean-up the Kalamazoo River spill. However, the report also directly contradicts Trans Mountain’s other claim that “diluted bitumen (or dilbit) has the same spill-recovery characteristics as conventional heavy oil.” A dilbit fact sheet from the Canadian Energy Pipeline Association makes a similar case: “In the event that diluted bitumen were to be spilled, the procedures for cleaning up the spill would be similar to cleaning up a conventional crude spill.”

The National Academy of Sciences reaches a far different conclusion: “In comparison to other commonly transported crude oils, many of the chemical and physical properties of diluted bitumen, especially those relevant to environmental impacts, are found to differ substantially from those of the other crude oils,” and that “spills of diluted bitumen should elicit unique, immediate actions.”

In a move that spells trouble for Kinder Morgan's Trans Mountain pipeline, the government of British Columbia this week took steps to limit the growth of the tar sands oil industry until scientists and officials reach a better understanding of the impacts of dilbit spills.

“We are proposing we restrict the transport of diluted bitumen until we hear back from the B.C. scientific community about the impacts of a spill and what we would need to mitigate that,” B.C. Environment Minister George Heyman told DeSmog Canada.

Planning Is Everything

The National Academy opens its report on diluted bitumen with a quote from President Dwight D. Eisenhower:

“I tell this story to illustrate the truth of the statement I heard long ago in the Army: Plans are worthless, but planning is everything. There is a very great distinction because when you are planning for an emergency you must start with this one thing: the very definition of ‘emergency’ is that it is unexpected, therefore it is not going to happen the way you are planning.”

The recent sinking of the oil tanker Sanchi in the East China Sea is yet another example of how the oil industry moves various oil products across land, oceans, and rivers without having clear plans on how to deal with major spills. That spill involved a tanker full of condensate (the lighter component of diluted bitumen) and is the largest condensate spill ever.

Despite the oil and maritime industries' experience transporting condensate for decades, they appear baffled about how to deal with this disaster in the East China Sea. Spill expert Rick Steiner told Nature News: “This is charting new ground, unfortunately. This is probably one of the most unique spills ever.”

The oil industry has a long history of pushing forward recklessly in the pursuit of profit and then claiming ignorance when things go wrong, resulting in “unique” disasters.

After the deadly Bakken oil train disaster at Lac-Mégantic, Quebec, the industry assured the public that Bakken oil was safe and no different than other oils. That was wrong.

When the Sanchi was initially on fire The Washington Post reported that the Chinese government said that much of the oil “would probably evaporate in hours.” That was wrong.

And the oil industry continues to claim that diluted bitumen floats in water and is no different to clean up than other oils — despite the scientific and real world evidence showing this isn’t true.

Main image: Forward on Climate Rally in Washington, D.C. Credit: DCErica, CC BY-NC 2.0