Custom Search
Top Stories
Go to Site Index See "Top Stories" main page
CONTRIBUTION · 4th December 2010
Kelly Marsh
I have heard and read many comments recently regarding Enbridge’s Northern Gateway Project and the chances of a bitumen or condensate spill being “minimal”. I am unaware of anyone running the numbers to accurately estimate the chances of a spill in reference to the tidal waters and pipeline. I have therefore calculated these numbers as a percentage of a spill along with the size of the spill to better understand the risks associated with this proposed project.

Enbridge Northern Gateway established a Marine Quantitative Risk Analysis (QRA) Working Group to provide advice on the design and completion of a quantitative risk assessment for the marine components of Northern Gateway. Enbridge supplied the data used in the following calculations remembering that the QRA group was chosen by Enbridge to determine these values. Although I question their accuracy, I will use them at face value until they are proven different. You may be surprised at the results of my calculations.
Considering Enbridge has presented the Northern Gateway project as a minimum 30 year lifespan, I wanted to know the chance of a marine spill as a percentage in that 30, 40 and 50 year timeframe. I also wanted to know how large that spill could be.

Enbridge estimates the probability of a marine oil spill of any size is 1 occurrence in every 250 years. That mathematically converts, using the Poisson distribution model, to the chance of a spill being:

- 10.64% over the proposed projects 30-year lifespan,
- 13.63% over 40 years and
- 16.37% over 50 years.

It’s tough to get a handle on the possible spill sizes in relationship to these percentages as Enbridge only clearly provides the size of spills for the most extreme timeframes not the one in 250 year occurrence. Readers of the Enbridge’s application without reference to the draft QRA can only read between the lines to determine the spill size for the 1 occurrence in 250-year estimate. It must be understood that any sized spill can occur at any time. The spill size associated with the 250-year estimate is up to 5 million liters. This is equivalent to the volume of two Olympic sized swimming pools.

To summarize, the chance of a marine spill of up to 5 million liters during the 30-year lifespan of Enbridge Northern Gateway’s project is 10.64 percent. The chances of a spill increase to 13.63% over a 40-year lifespan and 16.37% chance over 50 years.

The chance of a spill is between 10.64% and 16.37% of up to 5 million liters in the Douglas Channel or British Columbia Coastal waters. That’s better than a one in seven chance of a sizable spill over a 50-year project.

This is quite the contrast to The Pacific Pilotage Authorities’ remarks reported in the October 21, 2009 Kitimat Northern Sentinel who said the chance of a potential spill here in the future is nil. “There should never be an incident”. I confirmed this quote as it was surprisingly displayed on Enbridge’s Northern Gateway website.

The irony is that the marine division where there is a high risk of a spill isn’t even the responsibility of Enbridge. It will be the responsibility of the owner of the oil or condensate and the shipping company who is transporting it.

There is also a greater risk of a spill on the pipeline side.

The probability that a bitumen or condensate leak would occur along the pipeline route was calculated using the National Energy Board’s (NEB) failure frequency information. Using the data Enbridge filed in their application, there is:

- A 27.6% chance of a medium sized spill over the 50-year lifespan of the pipeline in the Interior Plateau (east of Burns Lake to just east of Terrace) and,
- A 15.03% chance of a large spill over the 50-year lifespan of the pipeline in the Interior Plateau (east of Burns Lake to just east of Terrace) and,
- A 9.85 % chance of a medium sized spill over the 50-year lifespan of the pipeline in the Coast Mountains (east of Terrace all the way to Kitimat).

A medium sized spill for a pipeline is classified as between 30,000 and 1,000,000 liters. A large sized spill is greater than 1,000,000 liters. Spills smaller than 30,000 liters occur more frequent.

To me minimal means the least possible or very small; not a 1 in 7 chance of a spill in our coastal waters or 1 in 4 chance for the proposed pipeline.

From now on when referring to chances of a spill in regards to the Enbridge Northern Gateway’s proposed pipeline and marine component, we should be using other adjectives to describe the risk, but minimal shouldn’t be one of them.
Comment by Shawn Ksisiiaks on 6th December 2010
Even one drop of spillage is intolerable, yet many thousands of litres are spilled each year as runoff into our waterways from leaking vehicles, small spills from filling up lawnmowers, from the rags used to check your oil that end up in the garbage.

This pipeline is not the problem. We are the problem. Consumption is the problem. Ask yourself how many waterways does is cross before it reaches your pick-up? Is there any difference between this and the Enbridge pipeline other than the destination? Why are we so special by taking advantage of the resource but not accept the risks of it?

Your abolutely right Don, how do we prevent even one spill? We stop consuming. Problem lies in that most of us won't be driving anywhere.
Not one drop
Comment by Gary Edwards on 6th December 2010
The possibility of even one drop of spillage is intolerable let alone 30,000 litres. Wake up people, the pipeline is wrong.
this reminds me
Comment by Don MacLeod on 5th December 2010
...of the debate over driving after drinking alcohol; each individual (read tanker) has a different tolerance (read capacity /seaworthyness) and may drive without incidents (read ideal weather conditions) to his/her destination. The ideal solution in the car driving situation to prevent an accident is to invoke a zero tolerance law, ie no driving after consuming ANY amount! So, how do we prevent even one oil spill?
Comment by Shawn ksisiiaks on 5th December 2010
Is, for example the 10% chance in 30 years, mean there is a 10% risk of the 1 in 250 year spill event occurring within the first 30 years? And does this mean the next 250 years will be spill free?

Also spill of any size is a spill of any size could mean a spill of 1 litre?

Your comments are quite a contrast to the pacific pilotage authority. Are you are more experienced in marine navigation?
Comment by Karen Dedosenco on 5th December 2010
It is interesting to note that, during the Kalamazoo River spill, Enbridge considered the age of the faulty pipeline at about half it's lifespan - it was 40 years old!

One of the factors in this terrible accident was that the material from the tarsands was found to breakdown the inside of the pipeline due to the acidic nature of the condensate. Silicate particals were deemed coarse enough to add to the break-down of the inner core.

It has not been revealed how long this corrosive and coarse material from the tarsands has been shipped through pipelines and in what amounts. Therefore we have no idea how fast a pipeline will break down or what a realist lifespan of the pipe will be. I doubt that Enbridge even cares about this at this point as they probably feel they will deal with it when the pipe starts bursting - just as in the Kalamazoo spill.
Comment by Dr. B. A. Bidgood on 5th December 2010
Thank you Kelly for spending the time to sit down and run the calculations. It is very enlightenining. To me, any risk that goes beyond 1% (or the level of statistical significance) is unjustifiable.