Why are tailing ponds a problem?

There are several environmental concerns that are associated with the existence of tailings ponds. The main problem with the ponds is that they include toxic and harmful chemicals such as ammonia, mercury, and naphthenic acids. The water containing these chemicals is toxic to animals, particularly aquatic organisms.

How are tailings ponds made?

Tailings ponds are lined with compacted sand and a layer of fine clay. The clay has a low permeability rate which helps prevent tailings water from seeping into the groundwater. Vertical pumping wells are installed around the perimeter of the tailings dyke (or dam).

How big are tailings ponds?

As the name suggests, tailings ponds are ponds that hold tailings. The total area of the tailings ponds has increased from around 25 square kilometres in 1985 to over 250 square kilometres in 2016, nearly double the size of the city of Vancouver.

What tailing means?

1 : residue separated in the preparation of various products (such as grain or ores) —usually used in plural. 2 : the part of a projecting stone or brick inserted in a wall.

Where are tailing ponds located?

Tailings ponds are normally located in a part of the lease that has little or no bitumen. Tailings produced in Extraction and Froth Treatment normally contain about 50% water.

What chemicals are in tailings ponds?

Tailing ponds are filled with toxic elements such as arsenic, cyanide, mercury waste, and other heavy metals with effects on the environment and human health.

How are tailings ponds used in the extraction process?

Tailings ponds are engineered dam and dyke facilities used for storage of tailings materials. Tailing ponds are also used to enable water to separate from the tailings. Water from the tailings ponds is recycled back into the extraction process, reducing the use of fresh water from the Athabasca River and other sources.

How is a tailing pond built in a gorge?

Tailing Pond. A tailing pond is usually built in a depression—for example, a gorge, a creek valley, or a basin—at a distance of several kilometers from a concentration plant. It is impounded by a dam, which is built up from the tailings, and is buttressed. In a tailing pond, tailings in the solid phase gradually settle out,…

What makes up the tailings pond in an oil sands deposit?

A typical oil sands deposit is 10-30% fines, which report to the following streams within the Bitumen Production plant: 40-50% to Fine Tailings: mostly flotation tailings from Extraction but can also include cyclone overflow. 10-30% to Coarse Tailings: mostly underflow from the Primary Separation Cell but can also include cyclone underflow.

When do tailings ponds need to be reclaimed?

Project-specific targets are set for each operation to ensure tailings are ready to reclaim within 10 years of the end of the mine’s life. To enable this goal, it is also recognized that treated water will need to be released from oil sands mining operations to enable overall reclamation of the mine sites.

Where are tailings ponds usually located in an oil sands lease?

Tailings ponds are normally located in a part of the lease that has little or no bitumen. Tailings produced in Extraction and Froth Treatment normally contain about 50% water.

Why are tailings ponds bad for the environment?

The tailings ponds were built without any proper base liner, so the process water from the ponds has infiltrated the subsoil, causing severe groundwater contamination with chemicals from the milling process (MgSO 4, NaCl, etc.). Figure 9.9. Tailings ponds in operation (a) and after closure in August 2000 (b).

What kind of tailings are used in a tailings dam?

A tailings dam is typically an earth-fill embankment dam used to store byproducts of mining operations after separating the ore from the gangue. Tailings can be liquid, solid, or a slurry of fine particles, and are usually highly toxic and potentially radioactive. Solid tailings are often used as part of the structure itself.