Can man-made aquifers provide a solution for a thirsty mining sector?

Author: FS Botha, Eland Platinum Mine, Xstrata, South Africa

The paper presents results of a case study whereby an existing backfilled mining void is used as an artificial aquifer to enhance water security, improve water quality and reduce water purification costs.  Elands Platinum Mine is located in the northern central parts of South Africa, in close proximity of the capital, Pretoria.  South Africa counts among the 40 driest counties in the word and has quite extreme weather conditions and therefore needs to cater for both extreme drought and flood conditions. As a result the Mine, as part of an integrated water management plan, developed an artificial aquifer using an existing backfilled mining void, which is able to store up to 1 million cubic meters of raw water and also has the ability to capture large flood events and therefore buffering the Mine from extreme floods.

The project was initiated using limited field and laboratory results and was and continues to be carefully monitored and managed.  Basically raw water is pumped into a semi-filled portion of an old mining void and water seeps into the backfilled portion and five ODEX boreholes are used to supply an on-site water treatment plant with water. The system started out in December 2007 and now supplies the Mine with all water requirements.  Major advantages are cleaner water which requires no physical and biophysical filtering, thereby reducing electricity costs and lessening our carbon footprint.  Furthermore, it reduces any risks of the Mine to lose production as a result of water shortages.  Major challenges, for example escalating salts were overcome with simple operating rules.  Two years of results conclusively shows that mining voids within the platinum limbs of South Africa are major man-made aquifers and if properly managed it can become a major water source and will be able to ease the pressure on a diminishing natural resource.