An integrated approach to mine water management, which entails a combination of expertise in hydrology, hydraulics and hydrogeology as well as geotechnical, environmental and mining skills, can assist in various challenges presented by mine water, including the management of groundwater, containment studies and water supply, reports SRK, a firm of consulting engineers and scientists.

“Aspects, such as mine dewatering, which are linked with the geotechnical aspects of mining, are key when dealing with the challenges of mine water,” states SRK hydrologist and partner Peter Shepherd, adding that mine water control is designed to save on unnecessary pumping costs and potential water treatment costs.

He explains that water balances have an increasingly important role throughout mine management and are a management tool that is increasingly used by mines.

“The main objective of water balancing is to understand where the water is coming from and where the water is being sent. It is important to know how much water can be extracted from water resources, such as dams and rivers, to sustain a mine.

“Ideally, the flow of water within mines goes through the plant, then to a tailings dam and, after it has been treated, is circulated back to the plant. This recirculation of water within the mining environment cuts costs and is environment friendly, but it cannot be done without performing water-balance studies,” he notes.

Shepherd states that the most important aspect that a water-balance study identifies is where mines are losing water.

“Often, the water is lost through evaporation and seepage, which can be mitigated using a lining below waste facilities and installing smaller evaporation areas,” he says, adding that the main goal is to reduce the additional water required from rivers and clean water sources.

“Legislation on lining depends on the country. In South Africa, there is legislation that requires lining, depending on the waste material being dumped in waste dumps. All dumps for hazardous materials, such as petroleum and oil, require a lining,” Shepherd states.

He notes that one of the biggest challenges that mining companies face is minimising the volume of dirty water that originates from mining sites.

“If the water cannot be reused or reintroduced into the mine, it has to be treated. If water needs to be constantly treated, it incurs ongoing costs,” Shepherd says.

He notes that a more cost- effective approach would be to introduce cleaner water back into the mining process.

“This reduces the water that needs to be treated, so it is important to ensure that it does not mix with dirty water.

“If clean water mixes with dirty water, it needs to be treated, so there has been a large focus from mines to try to increase the separation of clean and dirty water,” Shepherd says.

He explains that mines are increasingly containing their dirty water to avoid dis- charging it into the environment, trying instead to reuse it in the mining process.

Meanwhile, Shepherd states that stormwater dams, which are used to capture extreme rainfall events, are being misused as additional storage facilities.

“Stormwater dams are not being used for their intended use, which is to capture stormwater runoff. The current mindset is that, if there is a dam that can be used as additional storage on the mine itself, it should not stand empty,” he says, adding that stormwater dams should be used as emergency backup systems, rather than being incorporated into ongoing operations.

“If the stormwater dam is full when it rains, the dam spills and the water could mix with polluted water or contaminate the environment with polluted water. “These dams are built according to legal requirements, but spill more often than they should. This needs to be dealt with using an integrated approach to mine water management,” he says.

Shepherd states that the active dewatering of mines is important, because if mines are not regularly dewatered, they pose a potential risk to mineworkers underground.

“Mining in a wet environment is hazardous in terms of stability and logistics. A wet environment can also lead to a range of unwanted challenges, from tyre wear to blast holes being affected,” he says.

Shepherd states that mines can be dewatered in a passive way by placing a submersible pump at the lowest point in the mine. This does not prevent the ingress of clean water into the mine workings, however.

“Alternatively, an active dewatering system consisting of the installation of dewatering boreholes and horizontal drainage systems can be used, which reduces the ingress of clean water into the mine workings.

“We implement this latter type of system once we have completed a study of the hydrological conditions of a particular mine so that we can improve the dewatering system,” he says.

“The company also assists mines in reducing the impact on surrounding water users, such as on farmers’ water tables, by understanding the hydrogeology of the area and conducting a numerical model search to improve the placement of boreholes that dewater on the slopes of the mine, without having the radius of impact going further than it needs to,” he notes.

Shepherd says the company is working, throughout the continent on water-management projects to reduce the effects of overspillage from mining projects and to assist in protecting the environment while cutting costs.