Controlling acid mine drainage in the Western Basin not enough

- Advertisement -

Acid mine drainage (AMD) decant at the Western Basin in Gauteng is slowly being brought under control, with the flow halted. Mariette Liefferink, CEO of the Federation for a Sustainable Environment (FSE), said, however, that the uncontrolled decanting of the AMD might have stopped, but water quality remained the same. She said the water was not totally desalinated, but only neutralised by the addition of lime.

“This means that about 70t of salt is being deposited into the Tweelopies Spruit every day,” she said. “This is still a high percentage which renders the water unusable.” According to Liefferink, more than 11 000 people downstream depended on this water. What was more, the same measure was planned for the Central and Eastern basins, she said. “This means we’ll have about 500t of salt deposited into the Tweelopies Spruit every day.”

Liefferink said government was not solving the problem – merely reacting to it. “We are not only calling for neutralisation, but also complete desalinisation of the water,” she said. According to Prof Anthony Turton, director of TouchStone Resources, the war had not yet been won. He said that on 20 September the AMD decant at the Western Basin, as measured by Mogale Gold (one of two companies still operating in that mining basin) registered as zero at the Black Reef Incline Shaft monitoring station. “The flow has remained zero since 10 October,” said Turton.

- Advertisement -

Meanwhile, the Trans-Caledon Tunnel Authority’s short-term solution has been to pump polluted water from the Number 8 shaft and partially treat it. “This is now manifesting as zero discharge, which is progress,” said Turton. However, he added that the AMD debate had shifted attention away from a larger crisis in the water sector – eutrophication, which is caused by malfunctioning sewerage systems. 

Last year, Turton said the AMD from the Witwatersrand Goldfields, if not treated, would put an end to irrigation farming in the lower reaches of the Orange River and the Hartbeespoort Dam in the next 10 to 20 years. He said AMD accounted for about 4% of the total flow of the Vaal, but 20% of the total salt load if left un-managed.