Extracting coal can often have significant environmental impacts including altered landscapes, lowered air quality and deterioration of water resources by extracting clean water, decanting dirty water and Acid Mine Drainage (AMD). While advances in mining techniques have reduced many negative impacts traditionally associated with coal mining, the paradox exists: industry needs clean water for its processes while the same processes adversely affect the quality and quantity of clean water. Additionally, coal-rich areas in South Africa are often located in water stressed areas or where wetlands and river courses are already over-utilised or degraded. The nexus is thus: it takes a significant amount of water to mine coal and generate energy, and it takes a significant amount of energy to supply and treat water for these operations.
As a result of this nexus, the coal mining industry needs a two-pronged approach for water management: minimise the volume of water extracted, polluted and discharged into the environment through reuse and recycling, and: manage water impacts using strong management controls through monitoring, mitigation and offsets.
SRK is working with our mining clients to improve their water management strategies, aiming to reduce demand through efficiency and technology, using lower quality and recycled water, where possible. Dirty mine water can be treated and reused in various ways by active methods (water treatment plants) and passive methods, like passive wetland systems. The treated water can be used within the mining area for beneficiation and processing plants, dust suppression, fire control and reused as potable water. The eMalahleni Water Treatment Plant is an example of a successful partnership with Anglo American Thermal Coal and BHP Energy Coal South Africa (BECSA) joining forces to treat an excess of 130 million m3 of dirty water stored underground, to the benefit of the local municipality and community by ensuring the supply of potable water.
This has set the standard for many mines in the area to investigate water treatment options, minimising the risk of decant while reducing the effect of AMD.
Passive wetland systems may provide benefit to ecosystems services by reinstating wetland functions like water purification, flood attenuation, erosion control and water storage. These functions may have been destroyed and/or are no longer functioning at their full capacity due to mining activities. Passive wetlands can thus be considered a type of offset, and offset projects should consider ecosystem services as a central concept.
The challenge is to manage and limit the impact of mining on water resources and energy needs while still providing sufficient coal to meet power demands. This goal can be achieved by integrating water policy, planning and management within the mine planning to encourage conservation, motivate innovation and ensure sustainable use of the water resource.
