Tailings are a mixture of water, sand, clay and residual hydrocarbon, and are the by-product of the hot water extraction process used to separate the oil from the sand and clay. Tailings are stored in engineered dam systems called tailings ponds, designed to settle out the solid particles from the water.
Water is continuously recycled from the tailings ponds back into the extraction process, reducing withdrawal of fresh water from the Athabasca River and other sources. Although sand separates quickly from the tailings, smaller particles of clay and silt remain in suspension and form fluid tailings which in the past could take decades to separate.
As our mining operations have expanded, the volume of fluid tailings has increased. However, with the implementation of TRO™ in 2010, fluid tailings volumes at site have remained steady and we’re now working to decrease the inventory. Suncor currently has about 300 million cubic metres of fluid tailings.
New technologies are accelerating the separation process. Over the past several years, Suncor’s holistic TRO™ approach has allowed us to:
- reclaim a tailings pond, Wapisiw Lookout
- make another one trafficable through the use of coke capping technology
- convert a third tailings pond to a fluid tailings treatment area
Fluid tailings treatment capacity was increased in 2018 by commercially implementing our permanent aquatic storage structure (PASS) fluid tailings treatment process. This has allowed for a significant reduction in untreated fluid tailings inventory at Base plant operations. Additionally, in the next few years, another tailings pond will be removed from Base plant operations because of our PASS technology.
Fort Hills, operated by Suncor, ramped up earlier than anticipated and started producing bitumen in 2018, achieving average utilization of 94% in the fourth quarter of the year. Suncor is treating fluid tailings from the start of operations with extraction thickeners and enhanced beach capture to reduce the amount of fluid tailings and minimize further treatment requirements.
Fort Hills tailings operations feature an out-of-pit tailings area with plans to transition to below-grade tailings treatment once space is made available in the first mining area. The peak fluid tailings inventory at Fort Hills is expected to be below 130 million m3. This represents a significant change in fluid tailings management compared to industry demonstrated inventories.
As a new mine in the oil sands region, the project has the opportunity to apply the knowledge acquired from past mining, tailings and reclamation operations while not being burdened by legacy constraints.
To ensure fluid tailings volumes are managed appropriately, the Government of Alberta released the Tailings Management Framework in 2015, which is intended to ensure fluid tailings are in a ready-to-reclaim state within 10 years of the end-of-mine life.
In 2017, the Alberta Energy Regulator (AER) finalized a new oil sands directive called the Fluid Tailings Management for Oil Sands Mining Projects (Directive 085). This regulation includes tailings management plan application and tailings performance reporting requirements aligned with the government’s Tailings Management Framework.
In 2015 and 2016, Suncor was invited to work with Indigenous communities, the AER and other stakeholders to support the development of Directive 085.
To meet the new requirements, Suncor requested permission and received approval in 2017 to add treatment capacity to our TRO™ operations at Base plant. Meanwhile, Fort Hills received approval in 2019. Both updated plans are based on what we’ve learned through our implementation of TRO™ and from members of Canada’s Oil Sands Innovation Alliance (COSIA).
Through shared research, experience, expertise and financial commitments, we are able to investigate new tailings technologies faster. We anticipate this resource-sharing through COSIA will improve tailings management now and at future oil sands mine operations.
Raising the bar: tailings collaboration
As a member of COSIA, Suncor is sharing details of our tailings technologies with other member companies. In return, we are given access to technologies that others are using to manage their tailings. Highlights in 2018 included:
- 17 new projects started
- 189 contributed technologies
- 77 active projects, with a cost of approximately $260 million
Coke capping technology
Thanks to breakthroughs that have come from research and development, Suncor continues to make progress in tailings management. Following the surface reclamation of Pond 1 (now known as Wapisiw Lookout) in 2010, we began creating a trafficable surface on Pond 5, with a reclamation technique called coke capping. Thanks to teamwork and dedication, Pond 5 can now support heavy equipment – more than two years ahead of what we had planned.
The coke capping technology we developed and commercially deployed at Pond 5 involves placing a geofabric/geogrid on a tailings pond and then placing petroleum coke (a byproduct of upgraded bitumen) to create a solid surface. Giant straws, called vertical strip drains, are added to dewater the fluid tailings. In the future, we will spread sand over the coke to allow placement of a soil cover and vegetation (trees and shrubs).This is the first full-scale soft tailings cap of its kind in the industry.
Originally, Suncor anticipated completing the cap on Pond 5 in 2019. However, based on how well the dewatering had already progressed, an opportunity to mobilize a team to install the rest of the cap allowed for the pond to be fully trafficable in 2017.
Now that the cap is complete, settlement will continue and Suncor will work to understand how to apply this technology to further improve our operations. In addition, we will share our lessons learned with other oil sands operators through COSIA.
Suncor manages a robust dam safety program, protecting the integrity of tailings dam structures through extensive checks and balances for design, construction and monitoring, including a series of internal and external reviews.
We employ specialized experienced engineers, referred to as geotechnical engineers of record, for each tailings facility and/or dam structure. These individuals are qualified to lead the design work of each area, and work in collaboration with internationally experienced design consultants, referred to as geotechnical designers of record.
In addition to using these experts, an independent external review board called the Mine Development and Reclamation Review Board (MDDRB) reviews and critiques ongoing design work several times a year. The review board is comprised of internationally recognized experts in their field. The board also reviews our annual performance report for each of our operating ponds and associated dams. Lastly, designs must be approved and licensed by dam safety engineers at the Alberta Energy Regulator in accordance with Alberta’s Dam & Canal Safety Directive.
Once designs are approved, we exercise caution during construction by ensuring our facilities are constructed in ways that strictly adhere to the appropriate design specifications. This is completed through administering Suncor’s Resident Engineers Quality Assurance Program which monitors and provides technical oversight during construction.
In addition, Suncor’s Dam Safety Engineer has technical oversight of the performance of all dams during and after construction. Geotechnical instruments are placed in the structures at strategic depths and locations during the construction and operating phases to monitor facility health. We use the data we obtain to monitor the integrity of the structures during all phases of the tailings facility lifecycle.
Suncor’s tailings facilities are actively operated and monitored as part of a disciplined tailings facility management system. In addition, Suncor’s supporting Dam Safety Management System incorporates continuous monitoring, rigorous third-party reviews, government inspections, and collectively form the process required by Alberta’s Dam & Canal Safety Directive.
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