Report clears CSG impact on water quality
02 Jun 2014
The NSW government has been given the green light to lift a ban on coal seam gas near Sydney after a report found coal seam gas and long-wall coalmining posed no threat to the quality of drinking water.
In a boost for companies such as AGL and BHP Billiton, the report by the NSW chief scientist and engineer Mary O’Kane said: “Water quality issues can largely be managed through treatment works.”
But the report said NSW could consider banning fracking in the Sydney water catchment because of concerns about some of the chemicals used.
In November, NSW banned coal seam gas exploration and extraction in the Sydney water catchment’s most sensitive “special areas” pending Dr O’Kane’s report.
That was a blow to several gas companies, including AGL, which has wells in the areas.
AGL took a $343 million write-down last year on its coal seam gas wells at Camden, south of Sydney, after NSW imposed new restrictions on drilling.
BHPs Dendrobium long-wall coalmine has also faced a campaign from environmentalists partly over the risk to drinking water from the nearby Avon Dam.
However, the chief scientist’s report released over the weekend said there had been no measurable impact on drinking water quality from past coalmines which already run underneath 8 per cent of the “special areas” of the Sydney catchment and coal seam gas is likely to have “less impact than long wall coal mining”. The report said coalmine collapses sometimes cause subsidence under dams increasing levels of naturally occurring chemicals such as barium and chloride. But the effect is so diluted in the huge volumes of water that “from the perspective of drinking water quality, there is no reason, at this stage, for coal mining to be excluded from the catchment”.
saline water risk downplayed
The report downplayed the risk from saline water from coal seam gas that is usually stored at on-site containment ponds and treated.
A study for the inquiry found that even if all the saline water from AGL’s project at Camden was dumped into the main treatment plant at Prospect Reservoir, the dilution rate would be one part to 10 to the power of five million by the time it came out of a tap.
It said dumping of CSG saline water could cause ecological effects on flora and fauna, but “dilution and the absence of high levels of toxic substances would mean that it was safe from a health viewpoint if it were occasionally to occur during an unusually heavy rain event”.
The report did qualify its opinion by saying that chemicals used in fracking, a technique used to encourage gas flow, should be carefully monitored.
“If the risks to human health cannot be known with a very high degree of certainty, it may be advisable that, if CSG extraction activity is allowed, a ban on fracking within the catchment is instituted.”
It said the known toxic agent, BTEX, was already banned for fracking in NSW and other chemicals used to maintain the flow of coal seam wells needed study.
The report said more work was needed on whether the extraction of water for coal seam gas and mining could affect the total volume of water available in Sydney, but it would not affect the quality.
In a separate report issued over the weekend Dr O’Kane said that state-wide coal seam gas companies should be forced to take out more insurance against environmental risks.
The Australian Financial Review
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