Mining Water Issues

The environmental impact of mining includes erosion, formation of sinkholes, loss of biodiversity, and contamination of soil, groundwater and surface water by chemicals from mining processes. In some cases, additional forest logging is done in the vicinity of mines to increase the available room for the storage of the created debris and soil. Besides creating environmental damage, the contamination resulting from leakage of chemicals also affects the health of the local population. Mining companies in some countries are required to follow environmental and rehabilitation codes, ensuring the area mined is returned to close to its original state.

Some mining methods may have significant environmental and public health effects. Erosion of exposed hillsides, mine dumps, tailings dams, creeks and rivers can significantly impact the surrounding areas, a prime example being the giant Ok Tedi Mine in Papua New Guinea. In areas of wilderness mining may cause destruction and disturbance of ecosystems and habitats, and in areas of farming it may disturb or destroy productive grazing and croplands. In urban environments mining may produce noise pollution, dust pollution and visual pollution.

Tailings

Tailings are those wastes that have been removed from a mine by digging or tunneling operations. Typically, tailings are soil and rock that has not been processed for its metals content. Throughout the world, mine tailings have been gathered in piles or long rows where they are subject to wind and rain erosion. In the case of gold mine tailings, there is evidence of leaching of other heavy metals such as mercury and lead into the ground water system.

Spoil

A spoil tip (also called a boney pile, gob pile, bing, batch or pit heap) is a pile built of accumulated spoil – the overburden or other waste rock removed during coal and ore mining. These waste materials are typically composed of shale, as well as smaller quantities of carboniferous sandstone and various other residues. Spoil tips are not formed of slag, but in some areas they are referred to as slag heaps. The term “spoil” is also used to refer to material removed when digging a foundation, tunnel, or other large excavation. Such material may be ordinary soil and rocks, or may be heavily contaminated with chemical waste, determining how it may be disposed of. Clean spoil may be used for land reclamation.

Water pollution

Mining can have adverse effects on surrounding surface and ground water if protective measures are not taken. The result can be unnaturally high concentrations of some chemicals, such as arsenic, sulfuric acid, and mercury. Runoff of mere soil or rock debris -although non-toxic- also devastates the surrounding vegetation. There is potential for massive contamination of the area surrounding mines due to the various chemicals used in the mining process as well as the potentially damaging compounds and metals removed from the ground with the ore. Large amounts of water produced from mine drainage, mine cooling, aqueous extraction and other mining processes increases the potential for these chemicals to contaminate ground and surface water. In well-regulated mines, hydrologists and geologists take careful measurements of water and soil to exclude any type of water contamination that could be caused by the mine’s operations.

The five principal technologies used to monitor and control water flow at mine sites are diversion systems, containment ponds, groundwater pumping systems, subsurface drainage systems, and subsurface barriers. A 2006 review of environmental impact statements found that “water quality predictions made after considering the effects of mitigations largely underestimated actual impacts to groundwater, seeps, and surface water”.

Dissolution and transport of metals and heavy metals by run-off and ground water is another example of environmental problems with mining, such as the Britannia Mine, a former copper mine near Vancouver, British Columbia. Tar Creek, an abandoned mining area in Picher, Oklahoma that is now an Environmental Protection Agency superfund site, also suffers from heavy metal contamination. Water in the mine containing dissolved heavy metals such as lead and cadmium leaked into local groundwater, contaminating it.

Even in areas that once were remote but now are populated pollution from past mining operations poses a threat. One example is the Penn Copper Mine in Valley Springs, California. Acidic drainage with high levels of  copper, lead and mercury has seeped into the water table and polluted an aquifer that is used for human consumption. Long-term storage of tailings and dust can lead to additional problems, as they can be easily blown off site by wind, as occurred at Scouriotissa, an abandoned copper mine in Cyprus.

Mitigation

To ensure completion of reclamation, or restoring mine land for future use, many governments and regulatory authorities around the world require that mining companies post a bond to be held in escrow until productivity of reclaimed land has been convincingly demonstrated, although if cleanup procedures are more expensive than the size of the bond, the bond may simply be abandoned. Since 1978 the mining industry has reclaimed more than 2 million acres (8,000 km²) of land in the United States alone. This reclaimed land has renewed vegetation and wildlife in previous mining lands and can even be used for farming and ranching.

The monitoring of wastewater from mining operations is paramount if regulatory agencies are to understand the impact of mining on the ecosystem. Given advances in data sharing via cloud systems many municipalities and regulatory agencies are desiring to have water date in the cloud where it can be accessed by multiple entities. Current state-of-the- art methodologies allow for remote sensing and data transfer via cloud systems where data can be downloaded directly to a regulating agency.

References

1. F. F. Jorgensen, Handling Rock and Waste in Iowa Coal Mines, The Iowa Engineer, Vol. XIII, No. 1 (Oct. 1912)
2. “1966: Coal tip buries children in Aberfan“. BBC
3. “South Yorkshire landslip rail line closed for weeks“. BBC
4. Logging of forests and debris dumping
5. Poisoning by mines
6. Gold mining causing mercury pollution
7. Solid disposal options

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