JOHANNESBURG (miningweekly.com) – Although acid mine drainage (AMD) in the Witwatersrand basin is the result of a legacy of environmental mismanagement of water resources by mines and lax enforcement of regulations by government, these role-players are working to constructively address this problem, says Department of Water and Sanitation (DWS) senior manager Marius Keet.
Keet was a speaker during the first day of black-owned training and conferencing company Intelligence Transfer Centre’s two-day EnviroMining conference, held in Johannesburg, in March.
The Witwatersrand basin, a largely underground geological formation that surfaces in the Witwatersrand region of Johannesburg, comprises the Western, Central and Eastern basins.
A current key focus for government is to prevent further decanting of AMD from the basins by pumping underground water to protect the environmental critical level (ECL). The ECL is the level above which the water in the mine voids at critical locations, which is where environmental features that need to be protected are at the lowest elevations.
AMD should not be allowed to rise to this level, to protect specific environmental features, including groundwater resources. The DWS has implemented an ingress control system to reduce flooding of the basins, thereby preventing further AMD decanting.
“The treatment of AMD and water-quality management involves immediate, short-term . . . [and] medium- to long-term plans,” Keet explained, adding that the short-term solutions implemented to date had cost the DWS about R2-billion.
The neutralisation and removal of metals from AMD forms part of the immediate and short-term plan of dealing with AMD. The removal of salt loads from river systems for direct use or desalination to potable-water quality forms part of the government’s medium- to long-term strategy for counteracting AMD.
Keet stated that the DWS’s monitoring of other sources of AMD, such as slimes dams, also improved the level of monitoring. “Government has placed increased emphasis on the research of AMD to ensure that better decisions can be made in future,” he said.
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