Canada oil wastes leaking into northern lakes, study finds
08 November 2013
According to the Canadian Press, a recent study suggests melting permafrost could be allowing oil-drilling wastes from buried pits to leak into lakes in northern Canada. Joshua Thienpont of Brock University and colleagues tested the ongoing effectiveness of sumps still being used in the Northwest Territories to dispose of oil drilling wastes.
Sumps are large pits dug near a well site and intended to permanently get rid of wastes such as drilling mud, rock cuttings and drilling fluids, which commonly contain detergents and highly concentrated salt solutions. The sumps — which can contain tens of thousands of cubic metres of waste — are capped with clean material and frozen into place by permafrost.
The Mackenzie Delta has at least 150 sumps that date back as far as the mid-1960s. But permafrost in the southern Arctic has been gradually degrading as a result of climate change. In the delta, permafrost has warmed by an average of two degrees over historic levels.
Thienpont looked at 101 lakes in the area. Some were near a sump, some were far away but affected by permafrost slumping, and some were unaffected by either. Of the 20 lakes near a sump, up to 14 showed high salt levels sufficient to change the micro-organisms that live in the lakes and anchor the food chain.
Drilling in the Northwest Territories is growing after a major discovery of shale oil near Norman Wells, which is underlain by the same kind of warm permafrost seen in the delta, with energy companies committing $637 million to explore the area.
Sumps remain a recommended method of waste disposal under federal guidelines for drilling in the Arctic. Figures from the government show that between January 2009 and June 2011, seven sumps were constructed for drilling wastes. Wastes from another seven wells were trucked outside the territory for disposal.