Santos missed likely connections between coal seam and aquifers, putting farmers’ water at risk

Published: July 23, 2020

Farmers are crying foul after it appears likely Santos seriously underestimated risks to groundwater from its proposed Narrabri gasfield, with concerns critical data and information was overlooked in the company’s environmental assessment. 

Santos told (P67) the Water Expert Panel advising the Department of Planning on the gas field that, in general, “methane is observed at low and varying levels in all formations above the target formations, though the majority of groundwater samples from across the monitoring network do not record any hydrocarbons above the level of reporting.” Detailed baseline data showing methane levels in groundwater were missing from the project’s environmental impact statement. 

But a scientific paper published earlier this year found significant levels of methane in groundwater samples from aquifers overlying the coal seams, and data indicating geological structures provide pathways for gas movement into these aquifers. 

The UNSW paper found there may be much greater connection between the coal seams and aquifers of the region than Santos and the government believe.

This would mean that if Santos’s proposal is approved, there is significantly greater potential for cross-contamination of groundwater with gas, and leakage of water out of crucial aquifers, than currently assumed.

RMIT hydrologist Dr Matthew Currell, who is speaking at the IPC Hearing this morning (10.08am), said, “Coal seam gas development poses significant groundwater risks in the Narrabri area, where high quality, high yielding aquifers support numerous water users and ecosystems. 

“The area provides recharge for Australia’s most important aquifer system – the Great Artesian Basin and is close to the vitally important Namoi Alluvium. The risks of groundwater and surface contamination and drawdown are real. 

“Santos’s modelling and the department’s assessment assume there is little or no connectivity between coal seams - where gas would be extracted - and critically important shallow aquifers. However, recent peer-reviewed research shows that major geological structures occur in the project area, providing pathways for flow of gas and water. 

“This has major implications for future risks of cross-contamination and leakage from shallow aquifers in response to gas extraction. By failing to properly account for this in groundwater modelling, Santos has not presented a full and comprehensive account of the possible risks to groundwater from the Narrabri gas project.

“Santos has also failed to conduct thorough field-based studies of groundwater dependent ecosystems, inter-aquifer connectivity and groundwater recharge in the project area, despite expert advice urging them to do so in 2017.”

The Department of Planning proposes requiring Santos to provide detailed baseline data on “natural methane leaks and accumulations” after the gasfield is approved, which has local landholders worried.

Narrabri farmer Sarah Ciesiolka, who relies on the shallow aquifers to farm, said letting the gas field proceed before understanding its groundwater impact left farmers exposed to serious risk.

“It is not fair for a company like Santos to come into this region with a plan to totally upend our way of life, and not even do the required and necessary research. This is like giving a fox the keys to the henhouse because it promises it will clean up after itself,” she said.

“We’re not prepared to be guinea pigs so that Santos can make money first and answer questions later.

“I sincerely hope the Independent Planning Commission takes note of this UNSW report which casts doubt on Santos’s studies and ultimately rejects the coal seam gas proposal.”

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Content on this site is authorised by Georgina Woods for Lock the Gate Alliance, Lismore NSW.