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Tailing Ponds – Challenges and Solutions

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Tailings ponds are large earth constructions that hold coarse and fine particles from the oil sands deposit while also recovering water for use at the main processing plant. Regulators in the industry see these ponds as medium to long-term, temporary storage facilities that must be reclaimed once they are no longer in use.

Large amounts of water are trapped by fine materials in tailings streams, making pond reclamation difficult at best.

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Tailings Pond Cross Section

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Do you know?

The 20 tailings ponds near Fort McMurray Alberta that contain the fluid tailings cover an area twice the size of metro Vancouver (176 km2) and contain 1.3 trillion litres of fluid.

Environmental challenges

Problems

Oil sands tailings ponds have a host of issues, especially when it comes to impacts on wildlife and ability to remediate. On average, to produce 1 barrel of bitumen, 1.6 barrels of mature fine tailings (MFT) are formed. Hard to reclaim MFT will take many years to settle at the bottom of the ponds. In addition, because of their location along the migratory pathways, every spring and fall the ducks, loons, herons, raptors, songbirds, and other birds, congregate at the ponds as the seasons are stormy, and send the birds in a hurry to find a safe spot to land.

This is a key focus of the industry and together, regulatory bodies and the mining companies are working hard to provide new and innovative solutions to protect the wildlife and the environment.

Potential Solutions and Mitigations

To keep birds off tailings ponds, oil sands operators have deployed several techniques. Removal of vegetation from around the ponds is done to make them less attractive to the birds. Long range radar is used to allow for early deployment of acoustic deterrents to change flight trajectories away from ponds. Operators are required to place bird deterrents on and around their ponds. The result is eerie: near-constant booms of bird cannons, nightmarish shrieks of radar-activated mechanical falcons and faceless scarecrows perched above the surface.
Boats are also essential to bird monitoring and deterrent work as well as tailings pond management.

Boat crews do daily checks of the propane-fuelled canons and speaker devices that use sound to deter birds from the tailings pond. Bird monitoring technicians are shuttled daily by boat transport to monitor bird activity required for regulatory reporting.

The boat crew also assists with bird activity reporting. They observe geese, cranes, herons, ducks, owls, eagles, and other migrating flocks, which mark the changing seasons.

Crew members also ensure the boom that contains bitumen in certain parts of the pond is maintained and securely anchored. Major projects like dredging also require boat support.

Do you know?

Hercules SLR is a supplier of products and services within the oil sands business sector, but we can supply more than rigging equipment.

Spartan Industrial Marine is part of the Hercules Group of Companies, and via our national distribution network, we can supply Buoys, Flares, PFD’s Foul Weather Gear, and Marine Safety supplies. Want to know more? Give us a call.

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Reclamation

Water capping has been in development since 1980 as a way of reclaiming tailings. It entails depositing the tailings in a mined-out hole and then covering them with water from a nearby body of water.

The assumption is that the tailings will settle to the lake’s bottom over time, creating a healthy environment. Scientists are sceptical of the surgery, while others doubt that it will be successful.

Others think it’s a good approach to separate the tailings, but they’re not sure if the water bodies would support aquatic life. In 2013, Syncrude constructed the world’s first water-capped lake, which is poisonous and unfriendly to most life. Photosynthesis life is inhibited by high quantities of methane, ammonia, and dark water, according to tests. 

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Dredging and dewatering tailings ponds is not a new technology but it`s becoming increasingly popular as more and more miners look at recycling because of the environmental, and profit factors.

Industry and authorities have dubbed these lakes End Pit Lakes (EPLs), which are described as an engineered water feature placed below grade in oil sands post-mining pits.

An EPL could include oil sands by-product materials and receive surface and groundwater from nearby reclaimed and untouched regions. EPLs will be permanent elements in the reclaimed landscape, releasing water into the environment downstream.

Nature Based Solutions

Over the last two decades, scientists have made significant progress in understanding how nature might aid in the resolution of human-caused issues such as land disturbances. Several studies have been conducted to assess plant growth on oil sands tailings and the possibilities for using plants to reduce tailings volume.

Evapotranspiration is a process in which plants extract trapped water from the subsurface and release it into the environment. Poplars growing in soil, for example, have been found to transpire anywhere from six to 757 litres of water every day, depending on their size and condition. Tailings, on the other hand, are not very friendly to plant development since they frequently contain hydrocarbons, naphthenic acids, salts, and heavy metals, as well as a lack of nutrients such as nitrogen.

To avoid further ecosystem disruption, oil sands producers try to avoid importing non-native plant species to northern Alberta. This narrows the plant selection to hardy boreal species, which frequently lack the vigour of fast-growing, invasive species. However, research suggests that adding plant growth-promoting nutrients could assist native species overcome some of their obstacles.

In June 2017, Imperial completed 12.5 ha of reclamation at their Kearl site, which has only been in operation for about five years and has a life expectancy of 40 to 60 years.

The reclamation activity included placement of approximately 100,000 m3 of organic soil (a 60:40 peat-mineral mix) saved from areas that will soon be mined.

The challenges resulting from oil sands tailings are an ongoing issue. The Canadian Oil Sands Innovation Alliance (COSIA) and the Institute for Oil Sands Innovation (IOSI) have called for proposals for innovation to help solve the issues surrounding oil sands tailings. Research requests for proposals are have/are being evaluated by COSIA and IOSI. Hopefully we’ll see further innovative solutions in the near future.

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For all your rigging, forestry, and marine supplies, or to learn more about the Hercules Group capabilities we have 4 locations across Alberta and BC. Stop by or give our expert a call.