Anglo American Coal South Africa’s Mafube colliery has been selected as the first trial site to determine the long-term sustainability of using mining-impacted water in agriculture.

While irrigation with perceived poor-quality water frequently occurs in arid countries such as Israel, the South African mindset has tended towards caution. However, Anglo Coal notes that three decades of research have shown 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 – was spurred by devastating drought conditions 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 ha trial sites – one on virgin land and the other on ground rehabilitated after 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 t/ha, compared with 8 t/ha for dryland crops.

If proven sustainable over the longer term, the concept could have major benefits, 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 [after] closure,” notes Muhlbauer.

She says that, if Anglo Coal can prove that irrigation with mine water is sustainable, the mining-affected water would be considered a national asset rather than a liability, while also increasing the profitability of farmland.

“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,” she adds.

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 permits from the Department of Mineral Resources and the DWS are in place for the project. The DWS is fully involved at operational and governance level, to advise the team on any regulatory issues that may emerge, both within the context of the project and later with its potential nationwide roll-out.

Coal miner South32 and Anglo Coal’s businesses 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,” Muhlbauer concludes.