The tailings ponds required at mines are large and impact the landscape. Existing tailings ponds cover 176 km2
). A tailings pond – an engineered dam and dyke system – is used as a settling basin/storage container for the mixture of water, sand, clay and residual oil that is left over after oil sands processing. Once in the pond, the sand quickly sinks to the bottom, and the water from the top three metres is recycled. Tailings ponds present a number of challenges:
The bottom layer, a mixture of clay and water called fine tailings, takes a long time to settle and solidify. Even after many years it will still have the consistency of yogurt, and it can take up to 30 years to separate and dry out.
The remaining water, because it has come into contact with oil during the extraction process, contains concentrations of natural chemicals that are toxic to fish.
The small amount of residual oil that floats to the surface of the pond poses a risk
The Government of Alberta requires all oil sands operators to have plans in place to convert fine tailings to reclaimable landscapes.
COSIA’s Tailings Environmental Priority Area (EPA) is focused on improving the management of oil sands tailings. COSIA and Alberta Innovates – Energy and Environment Solutions (AI-EES) recently released a Tailings Technology Roadmap and Action Plan Project, a collaboration that also involved Alberta Energy, Natural Resources Canada, Alberta Environment & Sustainable Resource Development and the Alberta Energy Resources Conservation Board. This plan provides a comprehensive review of technologies that will help industry identify a suite of actions that will accelerate the development of new and improved commercial tailings treatment technologies.
Tailings Reductions Technology
Suncor Energy has successfully developed a new technology called TRO that more rapidly converts mature fine tailings (MFT) into a solid landscape. This reduces the time it takes to reclaim tailings ponds and eliminates the need for additional ponds. Shell Canada is also using a technology, called Atmospheric Fines Drying (AFD), to speed the treatment of tailings and create a dry material that will allow for faster reclamation. Now, through COSIA, Shell and Suncor in conjunction with the other Tailings EPA members are collaborating to improve this technology cooperatively.
Learn more about TRO
The industry continues to develop better technologies and approaches to tailings management in order to reduce the environmental impact. New technologies are accelerating the timing of consolidation.
Oil sands operators are investing more than $1 billion in tailings-reduction technology. Several technologies have been implemented and more are being tested to reduce the volume of fine tailings and speed their rate of solidification.
Protecting water and waterfowl
Mine operators employ multiple methods to deter waterfowl from landing, including cannons, scarecrows, decoy predators and radar/laser deterrent systems. Operators also reclaim bitumen from the surface of the ponds. Despite these precautions, birds have landed on the ponds and drowned as a result of oiling.
Improvements are underway. Canadian Natural is operating a new radar-controlled bird deterrent system at its Horizon Oil Sands tailings pond. The system detects birds at a distance of up to 2.8 kilometres, automatically activating acoustic and visual deterrent systems. Since deployment in 2009, the system has deterred birds from landing on the pond.
Tailings pond reclamation
Tailings ponds can remain part of an active mine operation for 30-40 years, either for tailings deposits or for storage and water recycling.
Wapisiw Lookout is Suncor’s first tailings pond, developed to support mining operations in the 1960s. As the first tailings pond to be reclaimed to a solid surface, the goal is to establish a diverse, self-sustaining locally common boreal forest ecosystem. And great progress has been made. Many species, from amphibians to bears, now call Wapisiw home.
Wapisiw Lookout before reclamation
Wapisiw Lookout after reclamation