Acid mine drainage bug

14 March 2013 - 03:00 By SCHALK MOUTON

The Department of Water Affairs is racing against time to halt rising acid mine drainage in the central basin under Johannesburg.

Acid mine drainage in the Krugersdorp area
Acid mine drainage in the Krugersdorp area
Image: Thys Dullaart

The drainage is expected to reach environmental critical level - the highest level that mine water can be allowed to rise in the mine void before adverse impacts can be detected - by September.

As a short-term solution, construction of a pump station has started on an old mine east of Germiston, but this is expected to become operational in November.

"We do have confidence that we would work in the necessary time-line," said Sputnik Ratau, spokesman for the Department of Water Affairs. "We are hoping that we don't get too much rain."

Should critical levels be reached, one of South Africa's historical museums - the underground mine museum at the Gold Reef City theme park - could be flooded, and might have to be moved.

"If pumping of the underground water is not implemented . we will have to move the museum up to level two in the medium term," said Thembi Makhaye, spokesman for Gold Reef City.

The museum currently takes visitors 215m below surface, which would be changed to 75m.

The Trans-Caledon Tunnel Authority was contracted to implement the short-term solution, which involves pumping 27 megalitres, 57 megalitres and 82 megalitres of acid mine drainage out of the Western, Central and Eastern mine basins respectively on a daily basis, treating it and releasing it into the Vaal River system.

Ratau said the department has already stopped acid mine drainage from decanting (emptying out) into the Western Basin by upgrading an old Rand Uranium plant in Carletonville, and pumping the drainage from the basin.

"There has been an improvement of water quality in the Tweelopiespruit into which acid mine drainage has been decanting."

Other issues looked at in the long-term feasibility study include finding out the extent of the damage already done by acid mine drainage.

The aim is to make sure that the water level stays below the environmental-critical level.

The study would also look at the possibility of treating the water to potable levels, or for industrial or agricultural use.