Mine Tailings Storage: Safety Is No Accident

Estimated cost of mine clean-up – an example from oil-sand mining in Alberta, Canada

The Alberta Energy Regulator (AER) estimates that mine clean-up costs in the province have increased with the growth of oil-sand mining and in 2016, topped more than Can$23 billion (approximately US$18 billion; Cryderman 2017). The extraction of bitumen from surface oil sands in north-eastern Alberta produces an enormous amount of fluid tailings – for every barrel of bitumen extracted from the oil sands, 1.5 barrels of tailings waste is produced (Grant et al. 2013; Figure 16). It is estimated that Alberta currently has more than 1 billion cubic metres of oil-sand tailings (AER 2017).

from end-of-life project closure costs. The programme requires a base security, which increases when the mine has less than 15 years of life remaining. The fund currently holds about Can$1.38 billion – it is designed to cover the cost of making the site safe and providing ongoing management if the approval holder fails to meet its obligations (AER 2017). The AER has recently introduced measures to improve tailings management and ensure compliance with legislative requirements (AER 2016). However, there is concern that the programme does not currently obtain sufficient financial security from mine operators to safeguard the public from clean-up liabilities (Cryderman 2017).

The Alberta Mine Financial Security Program collects a security deposit from oil-sand miners to protect the public

Growth in the volume of stored oil-sand tailings

2013

2008 >11 million litres/day Constant seepage from tailings ponds

2009

2005

Equivalent to 4.4 Olympic swimming pools per day

2016 Not reported 2040 Estimated to be 26 million litres/day

50 km 2

Equivalent to 10.4 Olympic swimming pools per day

130 km 2

220 km 2

Source: Grant et al, 2013.

Figure 16. The increasing volume of oil-sand tailings stored in Alberta, Canada, evidenced from the increase in the surface area of storage ponds

Impacts of tailings dam failures on biodiversity and associated ecosystem services

Immediate environmental impacts

Changes in ecosystem structure and function

Social implications

Long-lasting effects

Directional effect

Decreased water quality and oxygen content High levels of toxicity Decreased populations of aquatic species Loss of vegetation and nursery habitats

More floods Reduced fish catches Reduced carbon capture Loss of tourism revenue

Loss of regenerative capacity Bio-accumulation of heavy metals Persistence of heavy metals in floodplain sediment

Altered species composition Change in vegetative structure Loss of ecosystem connectivity Increase in bank/bed erosion

Decreased clean-water supply

Source: UNEP-WCMC

Figure 17. A summary of potential impacts of tailings dam failures on biodiversity and associated ecosystem services

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