The Tweelopiespruit is a stream that flows through the Krugersdorp Game Reserve on the West Rand, near Johannesburg, South Africa
Click here to see photos of the Tweelopiespruit and pH test results taken on 8 May 2010: http://www.earthlife.org.za/?p=1035
In January 2010 the amount of acid mine water flowing into the Tweelopiespruit increased dramatically, because millions of litres of water began to pour out of an old mine shaft near the headwaters of the stream. (See photo below)
The volumes of toxic flowing out of the shaft were about four times more than the capacity of the mining company to deal with them.
In desperation, and after concerns being raised by civil society groups, the government gave R6.9 million towards the treatment effort. This money paid for vast quantities of lime for the partial treatment of the water. (See photo below)
The partial treatment involves adding lime which makes the heavy metals fall out of solution. The iron in the water makes it an orange-red colour.
The partially treated water should be contained in a lined settling pond. The heavy metals fall out of the water into the mud at the bottom of the pond. The sludge is then taken to a tailings dam. But this does not happen to the waters of the Tweelopiespruit.
The Tweelopiespruit and its dams in the Krugersdorp Game Reserve, primarily Hippo Dam, are being used as settling ponds. The heavy metals, including radioactive uranium, accumulate in the mud at the bottom of the stream and dams. Under certain environmental conditions, these metals can become mobilised.
There seems to be no systematic system for monitoring the water flow and the amount of lime needed to neutralise the acid mine water. Often too little lime is added. This means that iron is still dissolved in the water. A chemical reaction between the iron and the water makes the water acidic. If the mud gets stirred up, for example by animals, the heavy metals can get dissolved into the water again and transported downstream.
The above photo shows acid mine water flowing uncontrollably onto the surface from an old mine shaft. The water contains high concentrations of heavy metals dissolved in the acid water. These include iron, cadmium, arsenic, lead and uranium – which is radioactive. The picture below was taken about 200m down hill from this shaft.