The Atlas Stage 3 Gas Project (the Project) covers an area of approximately 98 km2 and is located approximately 10 km southwest of the township of Wandoan in the Western Downs Region of Queensland. Wandoan is the centre for local cattle and wheat industries. The Project is located within the Upper Dawson River sub-basin, which is part of the Fitzroy River Basin. Key watercourses within the Project area include Woleebee Creek and Wandoan Creek. Watercourse flows in the Project area are characteristically ephemeral and episodic in nature.

Senex Energy Pty Ltd (Senex) proposed to develop, operate, decommission, and rehabilitate new coal seam gas (CSG) wells and the infrastructure in the central part of the Surat Basin in Queensland. The proposed production activities include the installation of up to 151 CSG wells and their connection to gas and water gathering lines, water separation and treatment facilities, water management facilities and the associated infrastructure. The target units for CSG production for the Project is the Walloon Coal Measures (WCM), a formation within the Surat Basin. The Surat Basin forms part of the Great Artesian Basin (GAB), which comprises several aquifers and aquitards. Aquifers of the Surat Basin are a significant source of water for public use, agriculture, stock and domestic supply, with the majority of water beingt used for stock and domestic purposes in the vicinity of the Project.

Senex required federal approval to progress with the project as it activated the ‘water trigger’ under Australia’s Environment Protection and Biodiversity Conservation Act (EPBC Act). A water resources impact assessment was prepared to accompany Senex’s EPBC Act Referral for Project Atlas to the Commonwealth Department of Climate Change, Energy, the Environment and Water (DCCEEW). The Project was assessed by both DCCEEW and the Independent Expert Scientific Committee (IESC), which provides independent advice to DCCEEW.

KCB undertook an assessment which considered the potential impact to water resources and water-dependent assets under the EPBC Act, as a result of the proposed Project activities. The assessment has been conducted with reference to the relevant Significant Impact Guidelines and the Independent Expert Scientific Committee (IESC) on Coal Seam Gas and Large Coal Mining Development information guidelines for proponents preparing coal seam gas and large coal mining development proposals.

Groundwater Dependent Ecosystems (GDEs) within the Project area include stygofauna, and potential terrestrial GDEs associated with the alluvium. These could be impacted by groundwater level drawdown or deterioration of groundwater quality, if the alluvium was connected to underlying units.

To assist Senex with the understanding of the hydraulic connection between the alluvium and the underlying Surat Basin units, drilling and monitoring bore installations were completed across the Project area in early 2023. Eight monitoring bores were installed as adjacent pairs at four locations: four bores installed in alluvium, and four in underlying Surat Basin units (Springbok Sandstone and Westbourne Formation). There are 669 registered existing potential groundwater bores within the Project boundary and in the 25 km buffer zone outside of the Project. Potential impacts considered included excessive drawdown in groundwater levels at water supply bores and deterioration of water quality.

Subsidence was also considered as a potential impact of the project. Should subsidence occur it could have an effect on infrastructure, buildings, rivers and streams, farm irrigation systems, and aquatic ecosystems. If the water used by nearby landowners for domestic, stock, and irrigation purposes are impacted negatively by the mining activities, the livelihoods of the farmers could be in impacted.

The field investigations provided both hydraulic and hydrochemical evidence to support the interpretation that these units are disconnected, and evidence includes water level data and water quality/isotope data.

As part of this assessment, KCB also conducted a thorough review of all existing monitoring data and provided the client with a comprehensive water resource monitoring plan which includes groundwater quality and level trippers, Trigger Action Response Plans (TARPs) as well as various mitigation measures to mitigate risk of unacceptable harm to the environment or water users.

KCB evaluated the potential impacts against the guidelines and criteria mentioned above, and provided the client with detailed comments and rationale regarding the potential impacts that would alter the water quality, hydrogeological characteristics (i.e. low regime, inter-aquifer connectivity, groundwater levels). The assessment concluded that the project will not have a significant impact on water resources.

In July 2024, the Project gained environment approvals from DCCEEW to progress.