South Africa and Africa’s largest acid mine drainage (AMD) plant will begin operations within the next two months.

The Central Basin pump station and treatment plant is located in Germiston and will treat 70 million litres of toxic mine water a day. It is scheduled to begin operation in either March or April and forms part of government’s short-term intervention to pump and neutralise the corrosive heavy metals and potentially radioactive water seeping from the Witwatersrand’s mining basins.

The R600 million pump station and treatment plant is made up of a sophisticated network of concrete structures, AMD-proof piping and electrical systems. It will draw up and treat polluted mine water that is flooding abandoned, underground gold mines in the Central Basin, with the aim of preventing the toxic water from decanting on the surface and poisoning ground and surface water.

John Otto, the chief resident engineer of Aecom, the design engineers of the project, says it has been a race against time to build the plant since the construction began in January last year. “It hasn’t been easy because the programme had been tight. But it’s the first time this has been done in the country. The gold mining companies have treated effluent gold mining water in the past, but in a very amateur fashion,” he says.

Treating one problem, creating another

There is already a small plant on the West Rand treating decanting AMD. The water it treats has a pH of 2.5. The treated water, with a pH on eight or nine is discharged into the Elsbergspruit, which flows into the Vaal Barrage.

Environmentalists are worried that the neutralisation process does not remove the high salt content of the AMD. There is concern that there won’t be enough water to dilute the high salinity of the Vaal when both treatment plants are running and 800 tons of these salts flow into the Vaal on a daily basis.

The Department of Water Affairs’ Vaal River reconciliation strategy shows the need to desalinate the AMD from the Witwatersrand gold fields which is a source of pollution in the Vaal River system.