Evidence-based approaches to managing Canadian oil sands tailing pond waste: tighter regulations and greater transparency are needed

Résumé fourni par la source

The mining of oil sands in northern Canada has resulted in the production of vast amounts of a waste byproduct called oil sands process-affected water (OSPW). These OSPWs are chemically complex and spatially varied toxic mixtures stored in human-made lakes called tailing ponds, which collectively hold more than 1 billion m3 of OSPW, cover 300 km2, and are leaking pollutants into groundwater and connected watersheds. Governments have permitted extraction from the oil sands for decades despite the industry’s inability to develop methods to safely treat and dispose of OSPW as a precondition for continued operations. As an alternative to building more tailings ponds to enable continued operation and storage, the federal government is reviewing a proposal to permit the so-called “treat-and-release” of OSPW from existing tailing ponds into the already-compromised Athabasca watershed, despite an existing information asymmetry: operators and governments know more about the risks than do those who are asked to accept them. Treat-and-release of OSPW represents the transfer of risk from operators to the public and the ecosystems. This approach must apply the highest standard of care to ensure that no further harm is incurred at these waste storage sites and in the downstream receiving environment. This opinion piece summarizes the OSPW problem, offers a new approach for setting acceptable exposure standards (no further exposure), and requests transparent and credible independent scientific assessment of releases and alternate options. No further exposure combines metrics in baselines of indicator chemicals, standard toxicity reference values (TRVs), and biological indicator species to provide the requisite fundamental protection of humans and ecosystems. Transparency requires: a robust chemical and toxicological characterization of OSPW; the creation of a government-run public website for data exchange; and consensus decision-making principles.

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