Acid Mine Drainage – West Rand

The Department of Water Affairs (DWA) as part of the Government Task Team on mine closure and water management together with mining companies have agreed on a model to deal with the Acid Mine Drainage (AMD) challenge that is affecting the Western, Central and Eastern Basins (the Witwatersrand gold fields area) which is impacting mainly on the Vaal and the Crocodile River systems.

Following a series of consultative meetings the parties agreed on co-operation, in the form of a partnership between Government and the Mining Houses (Public- Private Partnership Model) so as to formulate a collaborative solution to the AMD problem.

The stakeholders have agreed that the model will consist of the following key elements:

  • Mine water collection and conveyance to a central point;
  • Development of new infrastructure and refurbishment of existing infrastructure to facilitate the collection & treatment of mine water;
  • Treatment of the mine water which address low pH, high levels of metals and salinity;
  • Encouraging re-use of treated mine water;
  • Discharge of treated mine water to meet Resource Quality Objectives; and
  • Augmentation of stressed river systems.

This model provides for the establishment of a public-private partnership and the setting up of a Non-profit making entity. The entity will assume the technical and operational responsibility for executing the technical solution to AMD in the Witwatersrand area. This will involve a contract between Government and the Mining Houses as the funding of the Entity will in as far as possible take into account apportionment of liabilities between both parties.

The Department acknowledges the seriousness of the threat posed by AMD to the environment and is mindful of the urgency with which the matter has to be addressed. Once the proposed model has been signed-off by all stakeholders, the feasibility study will commence.

In the meantime, interim measures will be implemented to control decanting from the Western Basin and the anticipated decant from the Central basin. These measures include:

  • Immediate maximization of pumping and treatment at existing facilities in the Western basin; and
  • Utilizing temporary storage facilities to contain any overflows.

AMD arises when Sulphate bearing minerals are exposed to oxygen. The process, termed pyrite oxidation, is enhanced when water moves through and over the surfaces of acid bearing rock having been exposed because of mining activities disturbing the underlying geology.  AMD is generally characterised by one or more of the following: low pH, high Total Dissolved Solids (TDS), high Sulphates (SO4), and high levels of heavy metals particularly Iron (Fe), Manganese (Mn), Nickel (Ni) and/ or Cobalt (Co).  Heavy metals, being mobilised at low pH, and elevated salt levels can pose a risk to human health and to the integrity of the aquatic ecosystems while also having a significant negative economic impact.

For many decades the Gold Mining Industry in South Africa has formed the backbone of the country’s Gross Domestic Product and is still contributing substantially to socio economic development and securing valuable foreign revenue for South Africa. Although mining could possibly be seen as the biggest source of manmade pollution, more stringent legislation came into effect around 1992.

The issue is further complicated by the fact that some of the mines in the affected area are no longer operational or ownerless, making it difficult to enforce compliance. This requires that the state takes liability in the interest of the public, especially when the matter has to be dealt with as a matter of urgency.

Affected areas: (Eastern, Central, West and Far West Rand Basins stretching from Springs (Eastern Basin), Germiston, Johannesburg, Roodepoort, (Central Basin), Krugersdorp and Randfontein (Western Basin) and Westonarea and Carltonville (Far Western Basin)

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