The problem is centred around the Witwatersrand old mining area, and considerable AMD damage has occurred in the Wonderfonteinspruit, Tweelopies Spruit, Tudor Dam and Robinson Lake areas. Depending on the area in which AMD is occurring, the water may contain high levels of salts, sulphate, manganese, iron, aluminium, cadmium, cobalt and radioactive elements. Currently millions of litres of neutralised AMD still flow into streams connected to both the Vaal and Crocodile rivers and groundwater systems – this water is still unfit for use owing to its high salinity. This can have, and has had, devastating consequences for communities and the natural environment in these areas as they carry the cost of the ecosystem loss of functionality and high salinity.
Getting to grips with the extent of contamination
To put this into context, the AMD that has been decanting from the West Rand Basin since 2002 has resulted in the loss of animal and plant life in the Wonderfonteinspruit, Tweelopies Spruit and Robinson Lake near Randfontein.
The Tweelopiespruit is part of the Crocodile River system and the Limpopo River catchment area, where many thousands of people depend on the Tweelopies Spruit system for their drinking water, agricultural water and water for livestock. As a direct result of AMD, borehole water is polluted and in some areas the water has polluted the soil, so people cannot grow vegetables. In fact, the food grown along the river system within the Wonderfontein catchment – stretching from Randfontein about 100km to the west towards Potchefstroom – has been reported to show high uranium levels, and Boskop Dam’s uranium levels have also been reported to be high.
Additionally, water from the Tweelopies Spruit, neutralised by lime, has formed sludge in two receptor dams in the reserve – the Hippo and Aviary dams. Here hippopotami have previously been coated with a heavy-metal residue in the Hippo Dam, and a heavy metal crust has formed on the bottom of the Tweelopies Spruit.
But the full extent of the contamination is yet to be realised. In fact, Mariette Liefferink, CEO of the Federation for a Sustainable Environment, has previously highlighted that the current short-term treatment (neutralisation) of AMD and the currently used sludge disposal option will impact on downstream water users and ecology within the West Rand. The impacts will affect the Vaal River to the south and the Crocodile/Limpopo Water Management Area to the north, as well as the East Rand gold fields’ Blesbokspruit which hosts the Marievale Bird Sanctuary, a Ramsar Site, downstream water users and the Vaal River. This will also impact the Central Rand gold fields’ Klipspruit and Klip River, forming part of the Integrated Vaal River System.
Added to this, it is estimated that 1.6 million people live in informal settlements next to mine residue deposits, most of which are radioactive. Long-term exposure to AMD-polluted drinking water can lead to cancer, decreased cognitive function and foetal damage that leads to mental retardation.
An evolving approach to contamination and solutions
There is unfortunately no long-term treatment solution to the AMD issue in South Africa. The short-term solution to the issue is neutralisation, but this is simply a pH adjustment and the neutralised water is still not fit for use.
The responsibility to oversee and govern the entire process sits with government departments. There has been progress towards addressing the AMD issue, as the country’s environmental policies centred on mining and polluted water are far better today than in the past. However, these need to be enforced far more strictly.
Considering the potential for additional AMD generation, The Inter-Ministerial Committee on Acid Mine Drainage has been established. Additionally, older abandoned AMD-generating mines are controlled under the National Water Act 36 of 1998 and, more recently, the Mine Water Management Policy of 2017.
Conversely, for currently operating mines the onus to develop, own and operate an AMD treatment facility falls on the mine, as mine closure plans are required to adequately account for AMD-prevention solutions. New mines should not be allowed to open without such closure plans in place at the outset and are now required to make financial provision for the pumping and treatment of AMD in perpetuity. This approach will force mines to make suitable financial provision for such solutions. Additionally, there needs to be greater market understanding and recognition that polluted water can be a resource – and not a liability – if it is appropriately treated.
The effects of AMD can never be entirely reversed. Addressing the issue and treating AMD will be a complex and expensive undertaking. AMD is a serious issue that needs to be adequately addressed with a sense of urgency – and there are sustainable solutions that can be used and will help to restore the natural environment. Increased pressure therefore needs to be placed on the government and mining houses – to ensure adequate responsibility, funding and support for AMD treatment and prevention is being taken seriously.
First published in SA Mining Magazine.