Water, Sewage & Effluent Mar Vol 30 No 2 | Page 15

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Groundwater and mining
To access and use groundwater, mines submit water use licence applications to the Department of Water and
Sanitation (DWS). Pienaar says these include details on the water source and its sustainable use, and gauging
the effect on the environment. Key elements include preventing pollution and which encourages mines to re-use,
reclaim and treat water, and control the discharge or disposal of wastewater.
Mines have to manage the risks on their own sites, adopt a cautious approach to these risks, and pay for
pollution they cause. But when mines develop boreholes or well-fields, Shepherd says, it is vital that the aquifers’
capacity is accurately determined so sustainable yield rates can be calculated to avoid pumping them dry.
Groundwater resources rely on recharge from rainwater for replenishment. According to Pienaar, this is
expressed as a percent of the mean annual precipitation that varies, depending on the strata in which the
groundwater occurs. “Unfortunately most water-bearing strata in Southern Africa are represented by weathered
and fractured hard-rock formations characterised by less productive water-bearing properties and therefore also
lower (<5%) recharge values. These limitations are to some extent overcome where faults, fractures, fissures and
other geological structures enhance the water-bearing properties,” he says.
An important element in recharging groundwater from rainfall is the frequency and intensity of precipitation.
Recharge tends to be greater for higher frequency and more intense rainfall. It is therefore possible for
groundwater resources to recover more rapidly than might be expected. A succession of wetter than average
years will achieve this.

Water Sewage & Effluent March/April 2016

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