Concern over CSG cumulative impacts

Concern over CSG cumulative impacts

Farm Online News

Scientist warn lack of understating about effects from multiple projects


Related: Will gas gain be a bore drain?

AS FEDERAL pressure mounts on state governments to enable industry to ramp up onshore gas production, scientists warn the widespread impacts of the extraction process must be better understood.

Queensland Natural Resources Minister Anthony Lynham wants more federal funding for infrastructure to boost gas development; ​NSW is assessing a proposal from Santos to drill 850 wells at its Narrabri project; South Australia has launched a landholder royalty scheme to encourage property owners to cooperate with industry and Victoria maintains its moratorium amid criticism from the likes of federal Resources Minister Matt Canavan.

.In the most rapidly developing gasfield, Queensland’s Surat Basin, it is estimated on current industry projections that 3,570GL of groundwater (an average of 80GL a year) will flow from the coal seams which both underlay productive aquifers and deliver their own supplies in other areas.

Dr John Williams is a recipient of the Farrer Memorial Medal in agricultural science and Fellow of the Australian Academy of Technological Sciences and Engineering who served for nearly six years as Commissioner of the NSW Natural Resources Commission.

He said the cumulative effects of the large gas projects have not been properly assessed.

“Assessments for development approval are still made on a project by project basis,” Dr Williams said.

“Every analysis shows that CSG must impact on groundwater when you de-pressure a coal measure by water removal , but the question is how much water will have to be replaced, and where does it come from?

“There are no formal papers or reports that have shown the impact of increasing the size of gasfields. We haven’t seen a cumulative assessment and the industry has only built about half of the gasfields anticipated to be developed.

“Each project proposal is assessed one at a time, but need to assess the how industry will develop over the next 40 years.”

Dr Gavin Mudd, Associate Professor at RMIT University specialising in environmental engineering, agreed that cumulative impacts were not fully understood

There is no statutory requirement to monitor for methane in groundwater or soil, which Dr Mudd said was an “extraordinary gap” in Queensland’s regulations.

“The impacts have been consistently underestimated and some assumptions from the past have proven to be very wrong. For example, we are now seeing gassy bores, and the speed that their prevalence has increased at is amazing,” he said.

“It was previously assumed by regulators that the presence of aquitards, or purportedly impermeable layers of rock which separate underground strata, would prevent impacts to bores, “but groundwater systems are not that simple.”

Dr Mudd said the current network of 491 monitoring bores across the Surat is still insufficient “given the massive area involved and large numbers of aquifers and other features to monitor”.

“I would double that at least, plus put all of the data online and make it publicly available.”

Dr Mudd said while GABSI has returned significant groundwater to the GAB, “it’s not just about volumes, it’s also about pressure”.

“CSG is taken from a concentrated source, and this is causing significant reductions in pressure in the Surat Basin, whereas the 200GL a year from GABSI is across the entire GAB.”


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