Toxic Tailings Ponds
During the process of separating bitumen from the tar sands, large amounts of water are mixed in with the sand, and once the oil has been removed, the leftover mixture of water, sand, clay and residual bitumen – known as tailings – has to be stored in a stable location so that the solution can settle and separate. The storage facilities are known as tailings ponds. Because each cubic metre of bitumen extracted results in three to five cubic metres of tailings that need to be stored, the tailings ponds are so enormous they can be seen by the naked eye from outer space. Other “wastewater” is also stored in human-made holding lagoons such as sewage, water used for cooling, and water that has come into contact with coke, asphaltenes, sulphur, or heavy metals. This tactic is supposed to prevent the contamination of groundwater and river systems, but there is concern that this is not working properly.
What is so toxic about these ponds?
In most mining operations, harsh chemicals are needed to separate the minerals from the sand or rock that they are embedded in. For example, in gold or copper mining, arsenic and cyanide are often used, so tailings in those operations are extremely poisonous. In the tar sands, naphtha and paraffin are used, but they are supposed to be separated from the water before it is pumped into the tailings pond.
However, the byproducts of the petroleum itself are dangerous and known to kill the microorganisms which would ordinarily be present in a river or natural wetlands. Scientists state that the most dangerous contaminant in tar sands tailings water is naphthenic acid, a natural constituent of petroleum that becomes dissolved and concentrated in the hot water used to process the tar sands. Repeated exposure to naphthenic acid can have adverse health effects upon mammals, causing liver problems and brain hemorrhaging, and higher concentrations lead to more serious effects. Another component of the tailings is alkyl-substituted polyaromatic hydrocarbon, which causes deformities and even death to birds exposed to it.
Besides the toxic chemicals that are contained within the tailings, the water in these storage facilities attracts methanogenic bacteria, which produce methane, a greenhouse gas. The methane bubbles change the composition of the tailings pond and make some of the other dangerous toxins in the water more concentrated.
The oil companies’ response to these dangers is to fire airguns around the tailings ponds to prevent any birds and animals from coming near it. A more serious risk is that these ponds are leaking into the groundwater in the area, and into the Athabasca River. Another fear is that companies will stop operating in the area (if the oil runs out, or if profit margins go down), and stop maintaining the facilities.
Naphthenic acids are persistent and hard to disperse from the environment. They are released in high concentrations from tar sands projects, so people who live downstream have serious fears about contaminated water, fish and wildlife. Mercury contamination is another risk, because when the wetlands which originally covered the tar sands are drained, high concentrations of mercury can be released into the surrounding water bodies.
Recently, people living in Fort Chipewyan (a First Nations community downstream from the tar sands projects) began to publicise their concerns about the effects of water pollution on their health. Since tar sands development has been accelerating over the past few years, they have noticed greater incidences of cancer and diseases like lupus and multiple sclerosis in their community.