Report: Oil Sands Tailing Ponds Leaking Some 11M Liters per Day
9 December 2008
Oil sands tailing ponds are leaking more than 11 million liters of contaminated tailings water per day—more than four billion liters (1.056 billion gallons US) per year—into the groundwater in Canada, according to a report derived from industry data by Environmental Defence.
|The current leakage rate of contaminated water from Tar Island Dyke into the Athabasca river is estimated to be almost 6 million litres a day. Click to enlarge.|
The report, 11 Million Litres a Day: The Tar Sands’ Leaking Legacy, calculates that the addition of new oil sands projects could increase this number to 72 million liters a day, or more than 25 billion liters a year, in the next decade.
Tailings ponds contain toxic contaminants such as heavy metals, polycyclic aromatic hydrocarbons (PAHs) and naphthenic acids. Naphthenic acids in particular break down very slowly and therefore pose a long-term threat to the groundwater of the region. The tailings ponds sit upriver from the Peace-Athabasca Delta, one of the world’s largest inland freshwater deltas and home to Fort Chipewyan, where residents already have serious concerns about pollution and their health.
Tailings ponds are built on bare ground with walls made out of earthen materials. Companies deploy measures to capture some of the leakage from the ponds, but these measures are imperfect, the report says. Company applications for new projects admit that leakage is lost to the groundwater, and these applications were used to arrive at the overall leakage rate.
This study uses industry information to estimate what the overall leakage rate is for tar sands tailings ponds both now and into the future. This information is estimated on a project-specific basis by companies in their project applications, but it has never been publicly put together to come up with an overall leakage rate.
Environmental Defence contracted Pembina Corporate Consulting to calculate the figure. Based on the companies’ own data, Pembina produced several scenarios for leakage rates using different assumptions. Environmental Defence says that it chose a conservative scenario:
Wherever it exists, Pembina used the specific company information on leakage rates.
Where companies did not provide this information, Pembina applied an average leakage rate calculated using the numbers from the companies that did. These averages were applied on the basis of leakage per barrel of bitumen proposed to be produced.
Benefit of the doubt was given that tailings ponds largely “self seal” over time, and it was assumed that all ponds largely self seal after 18 years, but that some leakage still occurs. Pembina estimated that sealed ponds leak 85% less than un-sealed ponds.
Due to lack of information, it was assumed that existing ponds have largely “self sealed,” even though this is probably untrue and therefore under-estimates the current leakage rate. Tar Island Dyke, though, is a special case, and Pembina applied the leakage numbers calculated by the University of Waterloo, but assumed that leakage from Tar Island Dyke would reduce to a long term ‘normal’ leakage rate after 5 years.
The numbers were added together on an annual basis, using start-up dates and production numbers provided by the companies, and therefore arriving at overall leakage rate by year.
The final overall leakage rate is what escapes from the ponds after recovery steps have been taken. In other words, this is the leakage that the companies don’t catch.
Both Alberta and federal legislation prohibits the discharge of toxic materials into the environment, but tailings ponds leakage is sanctioned by the Alberta permitting process. The report calls on the Canadian government to enforce the federal Fisheries Act to end the leakage problem.
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