Jim Letourneau's Blog

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Shocking Tailings Tales

The spin doctors at did a nice job on the issue of seepage from oil sands tailings ponds by stating that tailings water seeps past pond walls at a rate of about 11 million liters per day. This creates a compelling visual - until it is put into perspective.

There is always going to be seepage,” says Preston McEachern, science research and innovation chief in Alberta Environment’s oil sands management division. “On the newer ponds and the older ones as well, the monitoring systems are demonstrating that the recapture systems have stopped the migration of any seepages beyond those interceptor systems. Eleven million sounds like a lot, but there are 130 square kilometers of tailings ponds. When you divide that out, you get 0.1 of a millimeter per day. So it would take 10,000 days to go a meter.”

Chris Johns at Alberta Oil did a good job of putting these numbers into perspective by asking the right people the right questions.

Having just returned home from London, I recalled a construction site where they were digging up old Victorian water mains because they were leak prone. Lets revisit the tailings pond seepage numbers using the power of SI units  - fewer zeros take away some of the shock value but make comparisons to other seepage sources easier. The tailings ponds seep 11 Ml/day (mega liters per day).

The UK Office of Water Services (or Ofwat now known as Water Services Regulation Authority.) stated in their annual leakage report for 2001-02 that Thames Water lost 865 Ml/d of water (mega litres per day). This is fresh, drinkable treated water that is leaking out of their rickety Victorian distribution system.

If water pipes can leak such large volumes, the next logical question would be how much do the sewer pipes leak? It is difficult to get absolute numbers from London's system because it is designed to carry both sewage and excess rainfall. However, detailed studies of sewer "exfiltration" (or leakage) in Albuquerque, New Mexico lead to an estimate of 18.5 Ml/d.

The average Calgarian uses 437 liters of water per day. Given a population of 1,042,892 and a leakage rate of 12% (depending on system quality losses range from 8% to 20-25%), Calgary's water system seeps 55 Ml/day of fresh water into the ground.

  • Tailings ponds - 11 Ml/d

  • London water - 865 Ml/d

  • Albuquerque sewage - 18.5 Ml/d

  • Calgary water - 55 Ml/d

I'm no longer shocked about seepage from oil sands tailings ponds. I am more concerned about people who play games by omitting SI prefixes.