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Large dams of mining waste leaking into Athabasca River: study

Polluted water from large man-made lakes of oilsands mining waste is fouling the Athabasca River, says a new federal study.

The new report by the Joint Oil Sands Monitoring Program shows that waste from dams covering 176 square-kilometres of land (an area 1.5 times bigger than Vancouver) is leaking into groundwater.

The study, which found a better way to track and separate oilsands pollution from natural bitumen sources in the region, describes one dam seeping mining wastewater at a rate of 75 litres a second or 6.5 million litres of waste a day into groundwater feeding the Athabasca River. 

It also describes a plume of tailings contaminants in groundwater that extends out at least 500 metres from another tailings pond.

The dams contain a variety of chemical hazards including bitumen, naphthenic acids, cyanide, phenols and metals such as arsenic and cadmium.

"In short, [the study] highlights past studies identifying tailings ponds as significant sources of groundwater contamination, and brings to light that groundwater contaminated by leaking tailings ponds is almost certainly flowing into the Athabasca River," says William Donahue, an Edmonton-based specialist in freshwater science and policy.

The chemical fingerprints of pollution from the tailing ponds are complex, but can now be separated out from natural sources.

Polluted groundwater contains more dicarboxylic acids than naphthenic acids, while natural groundwaters in the region hold less dicarboxylic acids than naphthenic acids.

Given that groundwater pathways are highly variable, "there may not be sufficient numbers of existing monitoring wells to actually identify the presence or sources of contamination," adds Donahue.

"For this reason, the number and location of groundwater wells needs to be reconsidered, and more wells will be needed in areas where groundwater flow is highly variable and complex."

Although the numbers of sites and samples used in the study are small, "it certainly represents a promising advance in the ability to fingerprint and detect contamination from oilsands tailings ponds in groundwater in the Lower Athabasca River basin," says Donahue.

In 2012, Natural Resources Minister Joe Oliver was warned that federal scientists found "potentially harmful mining related contaminants" outside of one dam in an earlier study.

The problem of how to dispose of polluted mining waste has existed for a long time.

A 1973 report by the Alberta government on the "Athabasca Tar Sands" identified the growth of tailing ponds as a major public liability, describing the "large open bodies of polluted water" as "the most disturbing aspect of mining in tar sands from an ecological as well as an aesthetic point of view."

Since then, the Alberta government has persistently failed to contain their growth. Premier Alison Redford recently told a Washington, D.C. audience that the dams would "disappear from Alberta's landscape in the near future."

But the Pembina Institute reports that mining waste is projected to grow by more than 40 per cent over the next two decades.

To date, the Alberta Energy Regulator has not enforced new rules introduced in 2009 to shrink the volume of mining waste produced by the energy project. When oilsands developers failed to meet new targets curtailing mining waste set for 2013, no fines were levied.

In a special edition of Geoscience Canada, University of Toronto geologist Andrew Miall described the ponds as "some of the largest man-made disruptions of the Earth's surface, easily seen from space (visible using Google Earth), a major hazard for birds, and a continuing concern regarding the potential for leakage into the surface water system."

Andrew Nikiforuk has been writing about the tar sands since 1998. His best-selling book, Dirty Oil, was the first to document significant leaks from the tailing ponds into groundwater and the Athabasca River.

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