Understanding aquifers: the relationship between operational activity and water sources
A common reason for opposing coal seam gas (CSG) exploration and development is the concern that it poses an unmanageable risk to aquifers. However, the research and evidence to date demonstrates quite the opposite, that when properly regulated, the risk to aquifers and groundwater sources is low.
The oil and gas industry is heavily regulated, and companies exploring for and producing oil and gas resources are committed to minimising their environmental impacts, this includes operations that may intersect or draw from aquifers.
Water is a very important resource in Australia, which is why the processes and technology used during the drilling and production stages are designed to protect the aquifers, groundwater and external environment from interference. Water resources are protected through regulatory processes that ensure companies adhere to strict operational standards and restrictions.
To learn more about some of the measures taken to protect water resources visit our website.
But what do the experts have to say about the relationship between water sources and operational activity?
According to the Department of Environment and Energy’s background report, Hydraulic fracturing techniques, including reporting requirements and governance arrangements, the main water-related environmental concerns in relation to the development of a CSG resource were ‘subsurface contamination and risks such as impacts on groundwater resources, their quality and use’.
However, when it comes to groundwater quality, the Queensland Department of Industry’s review of the socioeconomic impacts of coal seam gas in Queensland found that:
‘The evidence to date shows that there have only been negligible impacts on water and air quality, and work is ongoing in order to continue to assess the potential impacts and reduce uncertainties about potential impacts going forward.’
This same conclusion is supported by further evidence such as that from the Department of Environment’s review which concluded:
‘Preliminary risk assessments by industry indicate that the residual concentrations of a chemical of potential concern are unlikely to pose a risk in coal seam groundwater or at the surface.’
And, in relation to potential groundwater contamination The Commonwealth Scientific and Industrial Research Organisation (CSIRO) note that:
‘Groundwater contamination from CSG operations is considered a low risk.’
Regarding water use, the Department of Natural Resources, Mines and Energy’s Office of Groundwater Impact Assessment (OGIA) has undertaken three separate studies since 2012 to assess the groundwater impact from petroleum and gas operations at approximately 6,800 CSG wells within existing production areas in Queensland’s Surat and southern Bowen basins.
According to the draft assessment, the vast majority (more than 97%) of the 22,500 water bores in the Surat and Bowen Basin cumulative management area, less than 3% of water bored are predicted to be impacted in the long term, and all ‘those predicted to be impacted in the next three years have responsible tenure holders identified for follow-up make good arrangements’.
The report also found predicted impacts in two important aquifers, the Hutton Sandstone and the Condamine Alluvium, are now less than those predicted in 2016, and it attributes this difference to changes in industry’s planned development, improvements in modelling and improved knowledge.
While these aquifers have shown some water level reduction, the study found there is no evidence to suggest that these declines are due to CSG water extraction, and that the reduction is ‘unlikely’ to be influenced by CSG water extraction, and particularly that ‘non-CSG groundwater extraction in the [Hutton Sandstone] aquifer is likely to be the primary cause of the declining trends’. The authors note non-CSG groundwater use in these areas include agriculture, irrigation, town water supply and industrial use.
Looking closer at water extraction for CSG, average extraction over the life of the industry in the Surat and Bowen basins is predicted to be around 51,000 ML/year, significantly less than the estimated non-CSG groundwater extraction of 164,000 ML/year.
In fact, CSG operations often reinject water after treating it to reduce possible declines. Between commencement of one Surat Basin scheme in January 2015 and the Department of Natural Resources? review, more than 20,000 ML of water had been reinjected into the Precipice Sandstone, and reinjection was averaging around 5,000 ML/year.
The Office of the NSW Chief Scientist has also recognised Australia’s advanced capability in water management in its review into CSG water usage. The report said:
‘Australia has a strong track record in water technology innovation and management. Water is a key issue for Australia so we have developed significant capabilities in water management. This includes water treatment, operations and infrastructure for water and fluids management, management of byproducts such as salts, waste disposal, remediation and rehabilitation. These activities are backed by considerable research and science expertise especially in government agencies, universities, CSIRO, the Bureau of Meteorology and various Cooperative Research Centres. This means that Australia is in a good position to rise to the challenge of managing the various water issues associated with CSG production.’
When it comes to potential environmental impacts from groundwater changes, a new assessment of environmental value included in the Department of Natural Resource’s review has shown mostly minor areas of risks.
Overall, while careful monitoring of aquifers remains important, the available information demonstrates that when properly regulated CSG operations pose a low risk to water resources.