In 2010, an inter-ministerial committee was appointed by the South African Cabinet to look into the threat of acid mine drainage (AMD) on the Witwatersrand Basin.
At this point, industry and environmentalists had been warning for years that a crisis was imminent – acid mine water had already started to decant from the western basin, with an impact on plant, animal and ultimately human life. The Witwatersrand’s eastern and central basins were expected to start decanting within the next two years.
At the time, the Gauteng Provincial Housing Department’s deputy director general on human settlements William Bhila said: ‘The impact of acid mine drainage in Gauteng is a significant environmental problem that has a potential to undermine socio-economic development and pose a threat to human lives. The impact of this can already be seen in some municipalities in the province.’
There was a great deal of controversy about who should shoulder the responsibility for preventing such a catastrophe.
A large part of the AMD problem is a result of the tunnels of defunct mines filling with ground water and mixing with the heavy metals exposed therein.
This water becomes acidic or toxic and continues to rise as no mining company has any interest in pumping the water from the unused tunnels.
The problem comes to a head when the water breaches the environmental critical level and begins to decant into the surface environment. However, because these mines are no longer in operation and were closed long before legislation regulating environmental obligations was in place, there has been no one to hold accountable.
Those existing mines still contributing to the problem have taken on the responsibility of cleaning up their own water, but the broader obligation ultimately lies with government.
‘The issue of acid mine drainage is one that the government takes very seriously and is committed to resolving. Even though the current government inherited the problem of AMD, we are intensifying our efforts and making noteworthy progress,’ said former Minister of Water Affairs Edna Molewa at a media briefing in 2012.
A budget of ZAR400 million was dedicated to the AMD clean-up, with additional funding to be allocated as and when it was needed. However, a subsequent report was also released, controversially stating that the initial statement had overinflated the risks associated with AMD. It said that ‘sensationalised coverage of acid mine drainage-related problems in Johannesburg not only by national but also international news media [had damaged] business confidence and corporate image’.
The report refuted claims regarding the likelihood that the underground infrastructure of buildings in the Johannesburg CBD could be flooded with acid mine water in the near future.
Many environmental bodies, most notably the Federation for a Sustainable Environment (FSE), criticised the report as a ‘desktop study’ designed only to calm the fears of business and investors. The organisation cautioned that underplaying the risk would result in apathy that could once again threaten the environment.
‘The result will be what happened on the western basin of the Reef. Warnings of acid mine flooding were ridiculed for years until it finally took place and we have seen how devastating the impact is,’ said FSE CEO Mariette Liefferink.
Regardless of the conflicting reports, the solution began to be implemented. In 2011, the Department of Water Affairs (DWA) appointed the state-owned Trans-Caledon Tunnel Authority to investigate the existing mine water treatment infrastructure in the western and central basin mining areas, and to oversee the pumping system as well as construct a treatment plant at each of the pumping locations.
The problem comes to a head when the water breaches the environmental critical level, and begins to decant into the surface environment
According to Stephinah Mudau, head of environment at the Chamber of Mines: ‘The western basin was the greatest priority due to the fact that there was already a decant, and emergency action had to be taken. An on-site water treatment plant was put in place, and the infrastructure was created to treat AMD.’
At the same time, she explains that there have been some treatment activities in the eastern basin, which is currently being refurbished as part of the short-term interventions.
Although the responsibility for the clean-up of the water from the defunct mines lies with government, the local mining industry has been active in lending their support. Central Rand Gold donated two submersible pumps to the dewatering efforts and work began on the central basin in 2014.
While there is some debate about how soon the impending disaster would arrive, no one has denied that it is coming. Government and the mining industry have stabilised the water levels, which means they are no longer at risk of breaching the environmental critical level.
In June 2014, for the first time since 2008, the rising water in the central basin was halted and reversed. A high-density sludge (HDS) plant is now operating at its full 72-million-litre-per-day capacity, raising hopes that soon flooded areas of Central Rand Gold’s mine could be dewatered and accessed.
This is the first time since 2008, when the previous pump station was flooded, that the rising water table in the central basin has been halted,’ says Johan du Toit, CEO of the mining company. ‘The drop in the water table is a positive indication that the company’s large remaining resource within the central basin can still be realistically dewatered and accessed.
‘With the HDS plant now able to operate at full capacity, it is further hoped that we will see an acceleration in the drop of the water table so that the mining operations can re-access some of the mining areas, which were abandoned due to the rising water table.’
This is significant for Central Rand Gold, as the central basin hosts the company’s significant resource base and exploration target.
The scale of the costs associated with resolving the problem are indicative of the magnitude of the problem being faced
As much as this appears to be good news for the mining industry and the Witwatersrand, however, challenges in maintaining the infrastructure and delivering a long-term solution remain. ‘There will be an ongoing requirement to maintain the infrastructure,’ says Mudau. ‘A long-term solution is envisaged in which it becomes self-sustaining by selling treated water to third parties, and the revenue will cover the costs of the maintenance.’
While it seems that government has been successful in turning around short-term AMD challenges, the ongoing maintenance of the plant and the delivery of future solutions are no small burden. A feasibility study commissioned by the DWA set the costs of developing a long-term water treatment solution for the basin at ZAR6.66 billion in March 2012, and the maintenance and operating costs of the system would be ZAR990 million per year.
Of course, it is hoped that these prices will be offset by revenue generated from the sale of treated water. However, the scale of the costs associated with resolving the problem are indicative of the magnitude of the problem being faced. There are also some concerns about the existing solution.
According to Liefferink, AMD water is not suitable for human consumption even after treatment as it still contains sulphate salts.
She has also expressed concerns that there are no rehabilitation plans in place to clean the rivers into which this toxic water is released. Furthermore, Liefferink is concerned about the disposal of the sludge created in the AMD treatment process. This sludge is generally placed in one of 170 dumps spread around the Witwatersrand.
However, Marius Keet, senior manager for mine water management at the Department of Water and Sanitation reassures: ‘Although it’s a challenge, there will always be sludge. But we deal with this in the best environmental manner we can.’
It is unclear whether the AMD problem was indeed initially overstated. But pressure from the public, media and interest groups – in addition to government’s own commitment to the clean-up – has resulted in effective measures being implemented and the groundwork for a long-term solution being laid.
There is much to be done but it seems that this matter is finally being taken seriously by all involved parties.