To be a bit more specific acid mine drainage and acid rock drainage is a natural process.
In the case of mines it is triggered by man but in nature acid rock drainage occurs all the time especially where there ground is disturbed.
What happens in lay man's terms:
Mine shafts are dug below the water table so pumps need to be used to pump out the water for mining to continue.
Once the mine closes the pumps are stopped and the water seeps back into the empty mine shafts and tunnels.
With the rock now exposed to air and water the metals in the rock start to oxidize and certain natural bacteria and archaea accelerate the process.
This oxidation process creates very acidic water which contaminates the surrounding water. In our case the problem is that the water table is rising rapidly and so the acid water has to come to the surface somewhere.
http://en.wikipedia.org/wiki/Acid_mine_drainage
My worry is that the ANC will treat this just like they did with AIDs.
They pretend the problem doesn't exist, they accuse the scientists of making up scare stories and then at the end of the day they blame it on apartheid.
Enough finger pointing and excuses, just do something, damn it!