(A version of this post, co-written by Lucija Muehlenbachs and Beia Spiller, has also been published by Resources for the Future.)
Alison Redford, the premier of Alberta, Canada, came to Washington, D.C., April 10 to promote the Keystone XL pipeline project. In an appearance at the Brookings Institution, she responded to a question about pipeline safety in the light of Exxon Mobil’s recent oil spill in Mayflower, AR, where a ruptured pipeline sent some 5,000 barrels of crude oil into a residential area.
Such spills, Premier Redford said, are “very isolated incidents, and they don’t happen as often as people might suggest that they could.”
How isolated is “very isolated?” Records from Alberta’s Energy and Resources Conservation Board (ERCB) show that, from 1975 to 2010, there were 25,942 company-reported releases from pipelines that transport oil, gas and water. Of these, 9,011 involved the release of crude oil, diesel oil, oily sludge, synthetic crude or oil crude bitumen.
The average quantity of oil spilled per year has been decreasing over time, and was much lower from 1992 to 2009 (See Figure 1 below), which is likely due to advances in leak detection, emergency response and inspection tools, but could also be driven by changes in reporting requirements. For example, spills of less than a barrel were not reported before 1992, and so the drop in average volume seen after that date could be the result of having smaller spills in the sample. (The frequency of spills is also function of how much oil is being transported, for which we have no data.)
Figure 1: Average barrels spilled and number of pipeline spills of crude oil, diesel oil, oily sludge, synthetic crude or oil crude bitumen in Alberta, 1975-2009, using ERCB data.
But the data also shows that there were 27 oil spills larger than 5,000 barrels from 1975 to 2012. (The ERCB data end in mid-2010, but in Alberta there was a 28,000 barrel spill on First Nation land in 2011 and a 22,000 barrel spill in 2012.) That’s 29 sizeable spills over 37 years.
The EPA calls any spill larger than 250 barrels a major spill. Plotting the major spills over time shows that, while their frequency has been decreasing, there have been at least 4 major spills each year, according to the ERCB data.
Figure 2: Average barrels and number of pipeline spills for spills greater than 250 barrels, using ERCB data.
The Keystone XL would likely be a higher quality pipeline than most of those in the ERCB data, and leak detection has improved over the years. But there is also the long term question of pipeline integrity, since most of the leaks tracked by ERCB were caused by corrosion (and the Arkansas pipeline was 65 years old).
Overall, the ERCB data leaves open a number of questions concerning the Keystone XL:
- How likely is it that a major spill would occur in this new pipeline?
- What can be done to avoid or minimize corrosion over time?
- What would be the likely environmental impacts of a spill on biodiversity, habitat, and water quality?
Answers to these questions would go a long way toward determining the costs the United States might face if it allows the Keystone XL pipeline to be built.