Alberta is developing technologies that will speed up the transformation of tailings into reclaimed land so that the land can receive a reclamation certificate and be returned to the province.
The engineered dam and dyke systems known as tailings ponds are present in many types of open pit mines around the world. Once in the pond, the solids sink to the bottom and the water from the top three meters (9 feet) is recycled.
Tailings ponds help oil sands operators recycle 80-95 per cent of the fresh water used in mining operations, reducing use of fresh water from the Athabasca River and other sources.
Tailings ponds present a number of challenges:
- Fluid tailings: This combination of water and clay will take decades to consolidate and dry out, which can delay reclamation. Even after many years fluid tailings can maintain their thick consistency, and it can take up to 30 years to separate. New technologies are accelerating the timing of consolidation.
- Water quality: The remaining water, because it has come into contact with oil during the extraction process, contains natural chemical concentrations that are toxic to fish.
- Wildlife: Residual bitumen can be found at the surface of most tailings ponds. This can pose a threat to birds and waterfowl that land on ponds.
Managing tailings ponds
The Government of Alberta requires all oil sands operators to have plans in place to convert fine tailings to reclaimable landscapes. Due to the environmental impact of tailings ponds, the industry is constantly working towards accelerating reclamation time.
Recognizing that tailings are an important part of mining activity, the TMF is a detailed policy to manage pre-existing (legacy) and future tailings production. Project-specific targets are set for each operation to ensure fluid tailings are ready-to-reclaim within 10 years of the end-of-mine life.
The TMF requires:
- Detailed fluid tailings management plans
- Triggers, limits and thresholds to hold operators accountable for their fluid tailings management plans
- Annual performance reports submitted by oil sands operators
Mine operators employ multiple methods to deter waterfowl from landing on tailings ponds. These mechanisms include propane cannons, scarecrows, decoy predators and radar/laser activated acoustic deterrent systems like those used at airports, to alarm birds as they are about to land. Operators also reclaim bitumen from the surface of the ponds to reduce the risks if birds land despite the deterrents. Even with these precautions, birds have landed on the ponds and drowned as a result of oiling.
Reclaiming tailings ponds
Tailings ponds can support mine operations for 30 to 40 years. To ensure tailings reclamation plans get carried out, the government requires financial guarantees for each mining project. Oil sands mining operators contribute to the Mine Financial Security Program, a contingency fund held by the government for reclamation of land impacted by mines. The funds are used if operators do not carry out their reclamation plans. To date, there has never been a need to draw on this fund, so it continues to grow.