Water and CSG

The Great Artesian Basin is one of the leading underground water reservoirs in the world.

The area of the Great Arterian Basin (GAB) is equivalent to approximately 22 per cent of Australia’s land mass, spanning Queensland, New South Wales, South Australia and the Northern Territory. The Great Arterian Basin comprises different geological layers including sandstone, mudstone and siltstone. Some of the layers are permeable and allow water to flow through them. These are called aquifers. The other layers are relatively impermeable and do not allow water to pass through them freely. These are called aquitards. Where aquifers are shallow enough, landholders and other water users commonly drill bores into them to access groundwater.

_______________________________________________________________________________________________________________________________________________________

In CSG production, water is only extracted from the coal seams, not commonly used aquifers.

_______________________________________________________________________________________________________________________________________________________

The Bungil, Mooga and Gubberamunda aquifers, known in some areas as the Kumbarilla Beds, are the most commonly used aquifers in the Surat region. Where used by landholders, these aquifers are generally located at depths between 50 and 250 metres, much shallower than the gas-producing coal measures. There are some relatively small areas around the margin of the basin where landholders have used the coals for water supply, because the commonly used aquifers are not accessible to them and the coals are the shallowest water-bearing formation.

CSG impact on the Great Artesian Basin

Much of the current information being presented about the US natural gas industry refers to shale gas, not CSG. While both are classified as ‘unconventional’ gas resources, the geology is very different and the extraction processes also differ. With CSG comprising of mostly methane, it has far more simplified drilling, production, storage and treatment processes.

Using water from coal seams

Australia Pacific LNG considers the water produced as part of the CSG process as a resource. We focus on utilising it for the greatest beneficial use possible, as well as minimising groundwater impacts to aquifers.

Water management

The management of water is critical to our operations. Our practices consider how we can treat and re-use water that’s produced from the coal seams during extraction. We also ensure our operations have limited impact on groundwater resources, especially from the Great Artesian Basin.

Treating and re-using associated CSG water.

The brackish water extracted from the coal seams is treated to very high standards to make it suitable for use in agriculture, groundwater systems and environmental flow enhancement.

Reverse Osmosis (RO) treatment facilities have been constructed at Spring Gully, Talinga, Condabri and Reedy Creek using cutting-edge water management and treatment technology to purify and desalinate up to 112 megalitres (million litres) of water each day. Treated water produced from the Talinga and Condabri water treatment facilities is provided for irrigation and livestock drinking water via the Fairymeadow Road Irrigation Pipeline scheme, near Miles.

The high quality water provided meets recognised irrigation and stock water standards for beneficial agricultural use (ANZECC Guidelines). Routine water sampling and plant safeguards are in place to provide assurance that all water supplied under the scheme meets these standards.

The diagram shows where the coal seams are typically positioned relative to the commonly used aquifers.

Find out more about Water to Landholders in Environmental Reports

Treated water produced from the Reedy Creek and Spring Gully water treatment facilities is injected into a groundwater aquifer in the Great Artesian Basin to artificially recharge an aquifer and make this water available for use by others. The water produced from the Spring Gully facilities is also used to irrigate a 300ha Pongamia plantation.

Brine

The salt that is removed from the CSG water during treatment to make it suitable for beneficial use forms part of a residual solution known as brine. The brine is contained in fully-lined dams that are subject to strict construction regulations to prevent it from entering the surrounding environment. This stored brine is further concentrated through thermal processes prior to forming salt crystals which are suitable for disposal in encapsulation facilities.

Monitoring water quality and levels

All existing research and experience in producing CSG over the past 10 years, along with computer modeling, shows that CSG production is likely to have negligible impacts on the most commonly used water supply aquifers.

Modeling

Our modelling has been subject to comprehensive reviews by both state and federal regulatory agencies. Decisions about groundwater management will be guided by modelling, but any action taken will be based on monitoring results. Together with other participants in the CSG industry, we work with the Federal Office of Groundwater Impact Assessment in the development of an independent cumulative regional groundwater model. Their first Underground Water Impact Report (UWIR) was released in December 2012, and the second was released in 2016. The latest UWIR with associated updated modeling, was released in November 2019.

Read the 2019 report

Monitoring

We undertake extensive groundwater monitoring throughout the entire duration of our operations, monitoring water levels and quality in the most commonly used aquifers as well as geological layers not generally accessed for groundwater. We monitor for pressure and water quality changes in the geological layers above and below the coal seams. This early detection monitoring is designed to provide Australia Pacific LNG with sufficient time to implement appropriate mitigation strategies.

The monitoring program is undertaken at both local and regional scales. Local programs focus on the existing operational gas fields at Talinga and Reedy Creek to gather data and improve the understanding of potential risk and adapt monitoring if necessary. Regional monitoring extends across the full extent of Australia Pacific LNG/Origin CSG tenements, and is undertaken in partnership with the other CSG tenure holders across their leases to provide comprehensive and seamless coverage.
Make Good Agreements

If CSG-related impacts on groundwater are predicted or detected,we will mitigate these impacts and ‘make good’ as required by the Water Act 2000 (Qld). This means that ‘make good’ requirements must be assessed and negotiated with potentially impacted landholders.

Actions could include increasing the depth of landholder bores,sinking new bores for the impacted landholder,lowering,modifying or replacing pumping equipment or supplying treated CSG water to supplement landholder supplies.Decisions on the appropriate course of action will be made on a case-by-case basis.