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Elizabeth Shope’s Blog

Keystone XL Spill Risk: A Reanalysis of the Environmental Impact Statement - Guest Blog by David Malitz

Elizabeth Shope

Posted April 24, 2013

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This is a guest blog post by David Malitz, Ph.D. David is a consultant living in Austin, Texas with over 30 years of experience in statistical analysis.

As a statistician, I expected the Keystone XL draft supplemental environmental impact statement (SEIS) to address the risk of oil spills if the pipeline were built.  More specifically, if an 875 mile pipeline were built which carried as much as 800,000 barrels per day of heavy crude, what would be the risk of spills such as the 20,000 barrel spill in Michigan’s Kalamazoo River or the recent spill in Mayflower, Arkansas?  Surely, we should be able to estimate the degree of such risk using historical data. 

The SEIS partially addresses such spill risks, but in a way that seemed to me to be oddly incomplete.  The report discusses (in Section 4.13.2 and Appendix K) an analysis by Keystone of data available from the Pipeline and Hazardous Materials Safety Administration (PHMSA), a federal agency which is part of the Department of Transportation.  PHMSA’s database contains information about reported pipeline spill incidents including the size of the spill (in barrels) and the type of equipment which was the source of the spill (mainline pipe, tanks, mainline valves, and other discrete elements).  The SEIS used data from 2002 through 2012 to calculate the historical risk associated with pipeline operation and used these data to present information regarding the distribution of spills by size (small, medium, and large) and the prevalence of spills by cause (e.g., internal corrosion, incorrect operations, etc.).

What interested me was not what the report said, but what it didn’t say.  Tables in Appendix K showed the calculated rate of spills per pipeline mile per year (per “mile year”) as well as the average size of those spills.  This tells us the rate (and volume) of spills per mile year.  So couldn’t we just multiply this rate (and volume) by the length of the proposed pipeline (875 miles) to compute the average number of spills per year and the average size of those spills? 

The SEIS didn’t take this step and it seems an obvious gap.  Imagine buying carpet for your living room and knowing both the cost per square yard of the carpeting and the size of your room.  Wouldn’t you want to multiply these two factors together to find out the total cost of carpeting your room?  Of course you would, but Keystone XL’s SEIS fails to take this simple step which would tell us the environmental cost (or, at least, one of the environmental costs) of the proposed pipeline.

I performed this exercise and detailed my methods and results in a comment that I submitted to the Department of State (you can read my paper here).  For this analysis, I used only statistics that were reported in the SEIS.  I didn’t utilize any outside data sources, nor did I verify the accuracy of Keystone’s analysis of the PHMSA database.  I also didn’t resort to data manipulation that was more sophisticated than addition and multiplication.

This analysis showed that based upon reported historical industry experience, we would expect about 1.9 spill incidents per year from the 875 mile proposed pipeline, with an average total spill volume per year of 805 barrels (almost 34,000 gallons).  About 1/8 of these incidents on average (0.126) would be “large” (the SEIS classified spills of 1,000 to 20,000 barrels as “large”). 

Over a longer time span, say a decade, we would expect about 19 spill incidents with an aggregate spill volume of about 8,000 barrels, enough to fill about half of an Olympic-sized swimming pool.  We would expect about 1.3 of these spills to be “large,” which means that on average we would expect a “large” spill to occur about once every 8 years or so.  Clearly, based upon reported historical industry performance, spills in general and large spills in particular would not be a rare occurrence for the proposed pipeline.

Since the statistics reported in the SEIS and in my reanalysis are entirely dependent upon the PHMSA database, it is reasonable to ask how accurate the PHMSA data are.  A data quality assessment that was performed by PHMSA itself in 2009 details serious problems with the data that are reported by industry to the agency.  The agency outlines many deficiencies with the data, including underreporting of incidents.  A root problem for data unreliability is described by PHMSA as follows:

Most of our data collection relies on third-party reporting from regulated companies.  This is convenient, and it goes directly to the source.  It also introduces serious biases and gaps in the data we collect.  Despite the best intentions and professionalism, the regulated industry has an institutional bias (and probably a liability aversion) in determining the causes, circumstances, and consequences of failures.  Accident investigations—the limited number that we do—have shown some significant differences between what a company reports and an objective view of these events.  Reports from companies also reflect large numbers of blanks and “unknown” data, particularly in the most serious cases—exactly where it is most critical that we have good data. (PHMSA, page C-12, italics in original).

Thus, it is likely that due to underreporting the spill rates that are reported in the SEIS and in my reanalysis are understated to an unknown degree.  

Thumbnail image for Thumbnail image for Ruptured Enbridge Pipeline from Kalamazoo Spill credit NTSB.JPGRuptured pipe from 2010 Enbridge tar sands pipeline spill into Kalamazoo River in Michigan. Credit: NTSB. 

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Michael BerndtsonApr 24 2013 04:18 PM

Outstanding stuff. I tried to read Section as cited by David Malitz, on how potential spill incidents are calculated - and just couldn't follow the discussion. My problem - not necessarily the dEIS writers.

Parlaying off of the post, I have a question. Is oil or tar sands crude oil or not? How come it's pretty much assumed so in the dEIS language presented below?

" Objectives
The objective of this pipeline incident analysis was to use PHMSA hazardous liquid pipeline
incident data and hazardous liquid pipeline annual (mileage) data to determine the historical spill
volumes, incident causes, and incident frequencies of crude oil pipeline spills in the United
States. Additionally, this analysis provides separate determinations for pipeline mainline pipe
and pipeline system discrete components."

It seems that Transcanada wants it both ways: its not crude oil for tax purposes, but it is crude oil pursuant to operations. Another interesting word choice used in the paragraph above is "hazardous." What's a "hazardous liquid pipeline?" Upon incident, what's the stuff on the ground called then?

John WardApr 24 2013 09:37 PM

I believe you are overlooking an important point. Between 2002 and 2012, oil pipeline spills per 10,000 miles greater than 26 gallons were 16 times as frequent in Alberta as they were in the US, although pipelines in Alberta average 20 years newer than the corresponding American pipelines. Why the difference?

During this period, US pipelines carried mostly conventional oil. Alberta pipelines primarily carried diluted petroleum (dilbit), which is 16-20 times as acidic as conventional oil, contains five to ten times as much sulfur--which weakens and embrittles pipes-- as well as abrasive quartz particles and high concentrations of chloride salts, which increase corrosion in warm pipes. And the high pressure dilbit needs to flow can be as much as 1440 psi, creating friction that raises pipe temperatures up to 158 degrees F. The rate of corrosion roughly doubles with the increase of temperature of each degree Fahrenheit. This heat also accelerates exterior corrosion. And heat and pressure can also cause natural liquid condensate to turn to gas bubbles that form and collapse, releasing bursts of high pressure that can deform pipe, as occurred with the original Keystone pipeline pipe. Given this history, it appears highly likely that the rate of pipeline ruptures on the Keystone XL, if built, would be far higher than the previous American rate of ruptures.
Add to these distressing statistics the fact that making an enormous amount of dilbit available as an energy source would aggravate the already difficult and pressing problem of severly reducing greenhouse gas emissions if we are to have any chance of retaining a semblance of a world we could still recognize, the pipeline appears to be a singularly bad idea.

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