Jim Letourneau's Blog

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Oil Sands Tailings in the News

A recent article by reporter Mike De Souza has the headline Oilsands tailings leaking into groundwater, Joe Oliver told in memo. De Souza does a great job of linking to original sources. Who wouldn't love to know the contents of a secretive sounding "internal memo" related to the oil sands? The news is more exciting than the science, but any new data on the oil sands is politically charged.

You can navigate to the memo and the abstract of Geological Survey of Canada Open File 7195 A local test study distinguishes natural from anthropogenic groundwater contaminants near an Athabasca Oil Sands mining operation and the original report

The internal memo made 2 key points in the summary:

  • The studies have, for the first time, detected potentially harmful, mining-related organic acid contaminants in the groundwater outside a long-established, out-of-pit tailings pond. This finding is consistent with publicly available technical reports of seepage (both projected from theory, and detected in practice).

  • Importantly, concentrations of the measured mining-related organic acid contaminants decrease rapidly with distance from the sample tailings pond. No mining-related organic acids were detected in the Athabasca River at the point where its channel is nearest to the tailings pond. Similarly, no mining-related metals from groundwater reached the river from the test site, and no mining-related metals were detected in the river itself.

The second point gets less attention in De Souza's article. This is not a crisis. The reason for the study in  the first place is that it is difficult determining contamination of the Athabasca River by oil sands development. It naturally eroded through oil sands deposits so there's natural oil sands gunk everywhere. Scientists have to pull out an advanced toolkit to distinguish man made (anthropogenic) compounds from the natural ones. They  used new ways to analyze isotopes of carbon, lead, and zinc to help make the distinction. Leading edge science. 

The metals don't seem to be going anywhere so the main nasties in question are a class of compounds called napthenic acids (NA). They concentrate in oil sands process water because that water is continually re-used. By analyzing acid extractable organics, the scientists were able to characterize the origin of napthenic acids. To quote the study, "Acid extractable organics (AEO) containing classically defined NAs represent a diverse class of organic compounds that are very difficult to characterize chemically."

The GSC report shows that process water AEOs (which include the NAs) are seeping from the unnamed tailings pond (but which is almost certainly the massive Mildred Lake Settlement Basin - see Wikipedia and Wikimapia). The text and map below are directly from the report.

Mining-derived AEO concentrations between 7.3 and 14.1 mg/L in groundwater at approximately 1.6 km down-gradient from the edge of the tailings pond are relatively high compared to the ambient level of less than 1 mg/L for groundwater in the glacio-fluvial aquifer of the studied area. This observation suggests that, on a local scale, groundwater contamination with mining-related AEO may be an issue. 

AEO concentrations attenuate rapidly further down-gradient. The big picture is that  tailings ponds tend to "leak" or seep. The more important question is how much of what substance and is that substance harmful?  This is not an Ajka situation. There are many ways to ameliorate this seepage now that it has been detected.

The science is great but I wouldn't consider it policy changing.

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I'm going to sleep well tonight knowing that Joe Oliver has a good advisor who writes sensible memos and that Canada is developing some of the best science for contaminant detection in the world.