A team from Nieuwco Drilling is doing test fracking in the Moutonshoek area near Piketberg. Picture: Greg Maxwell

Cape Town - Residents living within one kilometre of fracked shale gas wells appear to be at higher risk of having their drinking water contaminated by stray gases, a new study in the US has found.

Scientists from Duke University in North Carolina analysed 141 drinking water samples from private water wells across the gas-rich Marcellus shale basin in north-eastern Pennsylvania.

Their peer-reviewed study, the results of which are appearing this week in the online Early Edition of the Proceedings of the National Academy of Sciences, documented not only higher methane concentrations in drinking water within a kilometre of shale gas drilling – similar to the findings of past studies – but also higher ethane and propane concentrations.

Methane concentrations were six times higher and ethane concentrations 23 times higher at homes within one kilometre of a shale gas well, while propane was detected in 10 samples, all from homes also within a kilometre of drilling.

“The methane, ethane and propane data, and new evidence from hydrocarbon and helium isotopes, all suggest that drilling has affected some homeowners’ water,” said Robert B Jackson, a professor of environmental sciences at Duke’s Nicholas School of the Environment.

“In a minority of cases, the gas even looks Marcellus-like, probably caused by faulty well construction.”

The ethane and propane contamination data were “new and hard to refute”, Jackson said. “There is no biological source of ethane and propane in the region and Marcellus gas is high in both, and higher in concentration than the Upper Devonian (geologic period) gas found in-between.”

The publication of the study coincides with remarks by deputy president Kgalema Motlanthe confirming the government’s commitment to shale gas exploitation through fracking in the Karoo.

In his keynote address at the South African Green Energy Youth Summit in Cape Town on Monday, Motlanthe said climate change issues compounded development challenges, “to the extent that we have to initiate clean development models even as we move away from old ones that fall foul of clean energy imperatives”.

“Fortunately for South Africa, we have among the best solar energy resources in the world... In addition, we have abundant shale gas resources, the commercial exploitation of which we have to investigate and pursue.”

Positive economic spin-offs would flow from, among other initiatives, “the accelerated exploration of shale gas in the Karoo side by side with pursuing our economic diplomacy efforts to harness natural gas in Mozambique and Tanzania”, he said.

The Treasure the Karoo Action Group that is spearheading opposition to fracking in the Karoo described Motlanthe’s claim as “disconnected with reality and premature”.

“In the face of recent international developments connected to shale gas mining, it’s unthinkable that a senior government leader in South Africa should make such an ill-considered statement,” the group said. - Cape Argus