While irrigation with perceived poor-quality water is mainstream in arid countries like Israel, the South African mindset has, understandably, been one of caution. More than 30 years of research has shown, however, that mine water could well be safe for agricultural use.
The project – initiated by the Department of Water and Sanitation (DWS) and the Water Research Commission – has been spurred on by devastating drought conditions currently gripping several parts of the country. It also forms part of government’s national long-term approach to acid mine drainage.
“In a water-scarce country like ours, optimal use should be made of all available resources – mine water included,” says Anglo American Coal South Africa water manager Ritva Muhlbauer.
The research project involves Mafube’s establishment of two 30-hectare trial sites – one on virgin land and the other on ground rehabilitated post-mining. Saline tolerant crops like wheat, maize, soya and ryegrass are to be planted on a rotational basis.
The first crop – maize on virgin land – was irrigated with water from the Mafube pit and has since been harvested. The area yielded 14.5 tonnes per hectare, compared with eight tonnes per hectare from dryland crops.
If proven sustainable over the longer term, the concept could have major benefits, both for both the mining and agricultural sectors.
“Mining activities in the Mpumalanga coalfields result in the production of large volumes of water that need to be carefully managed, both during a mine’s operational life and post-closure.
“If we prove that irrigation with mine water is indeed sustainable, it would be considered a national asset rather than a liability while increasing the profitability of farmland,” says Ritva.
Farmers would be able to plant crops year-round and not just during the rainy season. They would also be able to irrigate without abstracting water from already pressurised catchments.
Agriculture accounts for a respective 80% and 70% of the country’s total land and water use and plays a major role in job creation, particularly in rural areas.
All permissions from the Department of Mineral Resources and the DWS are in place in a unique project that sees government, the industry and academia work together. The DWS is fully involved at both operational and governance levels, to advise the team on any regulatory issues that may emerge, both within the context of the project and later with its potential nationwide rollout. Coal miner South 32 and our own business have covered the cost of two irrigation pivots, while Anglo American’s Mafube Colliery has dedicated employee resources towards the establishment of infrastructure, including the drilling of monitoring holes.
The practice is totally unique in that it would open up opportunities for rehabilitated mine land, thereby averting food shortages, particularly in times of drought, and the creation of post-mining opportunities by enabling small and large-scale commercial farming.