Durban - A senior South African groundwater expert has warned that large-scale gas fracking could have “devastating” pollution impacts on the country’s priceless pool of clean underground drinking water.
Presenting the results of water-flow modelling experiments at a national groundwater conference in Durban on Tuesday, Professor Gerrit van Tonder said it could take less than two months for contaminated “fracking fluids” and other pollution to contaminate boreholes, or just a matter of days to reach the surface in parts of the Karoo.
Fracking is a term used to describe the artificial fracturing and shattering of underground rock to extract methane and other gases by pumping a high-pressure mixture of water, chemicals and sand up to 6km below ground level.
Van Tonder, from the University of the Free State’s Institute for Groundwater Studies, said the exploitation of shale gas could well be a “game-changer for energy supply”.
“On the other hand, it may have a devastating impact on the environment,” he said.
Referring to a recent Time magazine feature which proclaimed shale gas could power the world, Van Tonder observed: “If shale gas powers the world it will also destroy the world, which is why we need to find a middle path.”
The professor said he might be prepared to support very strictly controlled fracking of just 0.5 percent of the country’s identified gas exploration blocks. “But if you want to frack 30 percent of the Shell lease area in the Karoo then I would say, ‘No way.’
“In Pennsylvania in the United States they have only fracked three percent of the shale gas area and they already have problems. But you will see the real mess within 100 years.”
If fracking were to go ahead in large parts of South Africa, the government might be able to reduce the risk of water pollution by plugging up all gas wells afterwards with a high-density resin or concrete sealant.
The government should also force all gas companies to disclose the chemical composition of all fracking fluids and also monitor groundwater reservoirs near fracking sites.
Van Tonder and a group of colleagues from the University of the Free State and consultants in Australia recently used two-dimensional computer modelling to simulate the flow of groundwater and pollution from proposed fracking wells in the Karoo Basin.
They noted the underground structure in several parts of the Karoo was such that pollution would always move upwards to the surface.
For example, hot water from underground springs in the Karoo took only a matter of days to reach the surface. And if pollutants from the fracking process leaked from failures in gas drilling wells, the computer models showed an area of 300 hectares could be contaminated over 30 years, depending on direction of groundwater flow.
However, if a gas well failed along a natural rock fault zone or dyke, pollutants could contaminate boreholes in days.
Dhesigen Naidoo, chief executive of the Water Research Commission, told the conference that South Africa stood at a watershed moment similar to the situation in 1886 when gold was discovered on the Reef.
“We are a water-scarce country, but at the same time we are an energy-stressed country. For us to ignore a viable energy source sitting under our soil is not easy.”
However, water scientists were still far from having a complete picture of the risks involved with fracking.
“This is a decision which is very easy to get wrong,” Naidoo warned. - The Mercury