Johannesburg on acidic water time bomb

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"This environmental problem is second only to global warming in terms of its impact, and poses a serious risk to the Witwatersrand as a whole. At the rate it is rising, the basin will be fully flooded in about 18 months"

Mining legacy
She said the rising mine water had the same acidity as vinegar or lemon juice, and was a legacy of 120 years of gold mining in the region.

Acid water is formed underground when old shafts and tunnels fill up. The water oxidises with the sulphide mineral iron pyrite, better known as fool's gold. The water then fills the mine and starts decanting into the environment, in a process known as acid mine drainage.

Keet said the problem was not just confined to Johannesburg, which is located atop one of several major mining "basins" in the Witwatersrand, known as the Central Basin.



http://www.mg.co.za/article/2010-07-21-johannesburg-on-acidic-water-time-bomb