Enbridge Northern Gateway's characterization of the risks of tanker spills associated with the marine transportation component of its project are so opaque that it begs the question as to whether a deliberate attempt is being made to conceal the true risks from the general public. In the Marine Shipping Quantitative Risk Analysis ( QRA ) Enbridge submitted in support of its application for approval, terminology is used that even a highly educated lay person would find hard to
understand. Thus, the QRA talks of “return periods” for spills, rather than
probabilities, chances or odds. Similarly, it measures the amounts of oil potentially
spilled in cubic meters ( m3 ) rather than barrels, which is the way most
people think of oil spills, if they ever do think of them.
A case in point is Enbridge’s calculations for a “major” or “extremely large” spill which they define as a tanker spill of 40,000 m3 or greater ( >40,000 m3 ). The company estimates the return period for this category of spill, with return period basically defined as the period within which one can expect at least one such spill to occur, at roughly 15,000 years. Applying a formula for converting return periods into
probabilities that was developed by Professor Shane Rollans, a Mathematics
professor, for Mr. Kelly Marsh, and relying on calculations that were made,
using that formula, by Professor Shane Rollans and Dr. Tom Haslam-Jones, a
tanker spill of >40,000 m3 with a return period of 15,000 years translates,
in layman’s terms, into a .3% chance of at least one spill greater than c. 252,000 barrels
occurring over the fifty year lifespan of the project. So, not much chance of
that happening, if Northern Gateway’s estimates are accurate. For the record, that's about the same size spill as the Exxon Valdez incident in Alaska in 1989.But the risks are significantly higher for some of the other spill ranges for which Enbridge provides calculations; for instance, spills <5000 m3, and spills
>5000 m3. The estimated return
periods for these types of spill are 570 and 550 years respectively. Put these
into layman’s terms, and
there is a 10.0% chance that at least one spill under 31,500 barrels will occur, plus an 8.7
% chance of at least one spill over 31,500 barrels. All told, there is an 18.1% chance that at least one spill of any size will occur.Moreover, if the pipeline is expanded from the outset to 850,000 barrels per day
capacity, as Enbridge has indicated it could be, up from the 525,000 barrels
per day capacity that the company is currently applying for, then, This will seem like an acceptable level of risk to some observers, while others will view the marine transportation component of the project as little more than a crapshoot.
At the very least, it undermines Enbridge's assertion that a tanker spill is "...very unlikely to occur", and a similar assertion by the President and CEO of the Pacific Pilotage Authority that the chances of such a spill are "...extremely small". And now, thanks to the work of Shane Rollans, Kelly Marsh, Tom
Haslam-Jones and myself, a lay person should be in a better position to
visualize these risks, before making an informed decision as to whether the project should go ahead. Because if the Joint Review Panel currently reviewing the application had only one factor it could consider in making a go/no go decision vis a vis this project, that factor would undoubtedly be risk; everything else is secondary. Gerald Graham, Ph. D -30- |

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