outside the car window at a lovely landscape and suddenly you spot a big hole, a missing part of land, as if carved out, from a hill? You may have noticed the same while taking off with a plane. Have you then wondered why this piece of land was missing? Usually, it is because of the mining of fossil fuels or other precious stone or mineral.
When it comes to extracting coal, underground mines and strip mines, or otherwise known as surface mines, are the two techniques at our disposal. Both are damaging, but strip mines, which represent 40% of the world’s mines, are the most damaging of the two.
Negative effects of surface mining on the environment
It is important to know that there are three key ways in which coal extraction and in particular surface mining affect wildlife and biodiversity:
- the direct impact of extraction activity;
- the indirect impacts of infrastructure development and expanded human activity (road building is in fact the main catalyst for irreversible ecosystem change);
- and the consequences of extraction disasters [2,3].
Why is surface mining so destructive?
Surface or strip mining damages and pollutes ecosystems to a great degree. This is because by definition the process of strip mining involves striping away trees, plants and topsoil so that the coal can be accessed underneath. This means that surface mining destroys mountain tops, landscapes, forests and wildlife habitats.
The land is left barren and usually in such a state that it is impossible to render it back to its original condition. In the US along, over a period of 70 years, coal mining altered about 2.4 million hectares of natural landscape, most originally forest .
Extensive water pollution around mines
But it is not just the immediate changes to the landscape that are a cause for concern. Rainfall washes off the topsoil that has been disturbed by mining into streams and these sediments pollute waterways. The earth that is upturned contains minerals and heavy metals within then dissolve into mine wastewater and seep into the water table contaminating groundwater, streams, soil, plants, animals and humans.
This is also called acid drainage. It is easy to identify as the water takes up an orange colour which covers different water bodies, rendering the water unusable for drinking. The impact of acid drainage is long-term: acid mine drainage can continue for decades or centuries after a mine closes unless costly reclamation projects are done. Needless to say, this can be damaging to fish and can smother plant life downstream [1,2].
The process of strip mining also lowers groundwater levels around the mine. In order to remove the coal, vast quantities of groundwater are pumped out of the mine and as a result, surrounding ecosystems and farmland may become drier, and erosion may start to change the landscape. Strip mining also uses significant amount of water to suppress dust.
Overall, the impact of coal mining in general on water is worth noting: it is not just the water used and depleted during the extraction process, but also the amount of water needed for converting coal into energy.
According to statistics, mines, coal washeries and coal-fired power plants account for about 7% of global water withdrawals with the number reaching 11%, in watersheds with coal power plants .
Dust and noise overload
A less commonly cited impact of strip mining is that it also causes noise pollution and dust as heavy machinery disrupts topsoil and mining activity creates coal dust.
Problems with ecosystem recovery after strip mining
Some other data is equally concerning when it comes to how much companies invest in regenerating the land that has been destroyed by mining. In China, coal mining degraded the quality of 3.2 million hectares of land, but total mine wasteland was restored at a rate of only 10%.
The situation is not particularly different in the US: in Montana, replanting projects were only 20-30% successful whereas in Colorado, there is an even lower survival (about 10% in some locations) for oak aspen seedlings.
It is therefore important to note that while technology and best practice could minimise the impacts of strip mining, in reality these are never put in practice in the same way and often do not bring about results in the long term.
Yet the industry often prefers to strip mine because it takes less labour and yields more coal than underground mining. In some countries, such as Australia, strip mines make up 80 percent of mines. This is a very sobering reality given the local, short and long term impacts of strip mining.