Weather variability due to climate change is now a complicating factor for South Africa's mines, as they engineer solutions to traditional water-scarcity challenges.
As water-intensive operations, mines generally require large volumes of water in their processing plants to facilitate effective mineral extraction. Many of the country's mining regions also happen to be located in provinces where annual rainfall is relatively low.
"The design of water management systems has tended to rely on historical rainfall and weather data, which was used to project anticipated conditions into the future", said Tiaan Bauman, Partner and Principal Civil Engineer at SRK Consulting South Africa. "With climate change and rainfall variability, this is no longer sufficient, so engineers and scientists are building new models of forecasting into their design".
Too Little, Too Much
The first challenge for mines is, of course, to ensure that there is enough water available or stored to supply their operations through the dry seasons, said Bauman. There is increasing focus on finding alternatives to the scarce and potentially costly water from municipal sources. With greater rainfall variability, dry spells can turn drought conditions more often expected, so storage capacity may need to be expanded.
"The engineering of water retention facilities on mines is therefore demanding more attention", he said. "On the one hand, there may be more frequent droughts due to changing rainfall patterns, while on the other hand, there have been more intense and localised downpours".
For mines, this adds considerably to operational uncertainty and environmental risk, as higher – than – usual rainfall intensity can quickly result in return water dams and settlements ponds filling up and over-topping. According to South African laws, water discharge from a site must meet strict water quality standards.
Compliance and Risk
“Many mines already have dedicated treatment facilities to achieve these standards before they conduct controlled discharge into rivers or drainage networks”, he pointed out. “Non-compliant discharge into the environment or dam breaches can lead to costly fines and even more significant reputational damage”.
The latest standards governing Tailings Storage Facilities (TSFs)– the Global Industry Standard on Tailings Management (GISTM), also shines a spotlight on the risk of higher patterns and their impact on mining sites. The GISTM explicitly requires signatories to consider climate change when developing and applying their engineered solutions.
