3.6 Commentary for coal resource developments that are not modelled

Summary

There are over 20 identified coal resources known from the Galilee subregion, most of which are hosted in Permian-age strata near the northern and eastern margins of the Galilee Basin. In central and western parts of the basin, the coal-bearing layers are buried under a substantial thickness of sedimentary cover, and some initial coal seam gas (CSG) resources have been discovered at subsurface depths of around 1000 m. Analysis of all the known coal and CSG resources in the Galilee subregion for this bioregional assessment (BA) helped to define the coal resource development pathway (CRDP), thereby focusing this BA on areas where coal resource development may potentially affect water-dependent ecosystems and assets in the future.

The main focus of the impact and risk analysis for the Galilee subregion is centred on the central-eastern part of the basin, where the initial seven coal mines in the CRDP are most likely to begin operations. However, a further seven potential coal mining projects, and three CSG projects, were included in the CRDP (though not modelled), reflecting the Galilee subregion’s potential for a prolonged and multi-staged coal resource development portfolio across the coming decades. Most of these later-stage coal resource developments will occur in parts of the subregion distant from the initial focal point where the modelling analysis was undertaken for this BA. This includes a suite of five potential coal mines near the northern edge of the Galilee Basin, and a stand-alone operation in the southern part of the subregion (near Blackall), targeting geologically younger coal from the overlying Eromanga Basin. The seven non-modelled coal mining projects in the CRDP are (from north to south) Clyde Park, Hughenden, Pentland, West Pentland, Milray, Alpha West and Blackall. The three CSG projects are Glenaras, Gunn and Blue Energy.

Beyond the seven mines modelled in this BA, any subsequent stages of coal resource development in the Galilee subregion would likely involve similar types of open-cut and/or underground mining methods as proposed for the central-eastern mining area (although detailed development plans and time frames for any of the later-stage projects were largely unknown as of December 2017). Consequently, a similar set of causal pathways are expected for the non-modelled CRDP projects, indicating that these mines would also have the potential to affect nearby water-dependent ecosystems and assets. Numerical modelling of hydrological impacts, adequately informed by accurate mine design, scheduling and planning information, would be needed in future to quantitatively evaluate the impacts of such developments, and estimate the full extent and magnitude of changes to surface water and groundwater systems.

Preliminary spatial analysis has identified the water-dependent ecosystems and assets within a radius of 20 km from each of the non-modelled coal mines in the Galilee subregion’s CRDP. Although actual hydrological impacts may extend over a wider area, an initial focus on those assets and landscape classes within 20 km of each mine site provides a clear indication of which ones would likely experience the greatest levels of hydrological change, particularly to surface water systems and the watertable aquifer. Although the most common landscape group near each of the mining projects is classified as ‘Dryland’ (and hence not a water-dependent ecosystem in the context of this BA), about 10% to 20% of the immediate area is classed as a water-dependent ecosystem. In most cases, the ‘Terrestrial GDE, remnant vegetation’ and ‘Non-floodplain, terrestrial GDE, remnant vegetation’ landscape classes are most widespread within 20 km of each coal project, although various floodplain landscape classes may also be locally important, for example, near Blackall.

There are also many water-dependent assets that could be impacted by any future development of the non-modelled coal mines in the Galilee subregion. In most cases, these are mainly classed as ecological assets of the ‘Vegetation’ subgroup, typically recognised as either some type of groundwater-dependent ecosystem (GDE) (e.g. dry eucalypt woodlands) or the distribution of habitat of a particular species of flora or fauna. There are also some higher profile water-dependent assets nearby these non-modelled developments, including the White Mountains National Park adjacent to the Clyde Park, Pentland and West Pentland sites, and the Porcupine Gorge National Park just east of the Hughenden Coal Project. Additional to these, several economic assets occur around the coal projects, and these mostly relate to basic water rights or water access rights associated with either the Barcaldine North or Barcaldine South groundwater management areas.

The most likely area for any future CSG development in the Galilee subregion spans the central part of the basin, from the Glenaras Gas Project in the west to the Gunn Project in the east. All of the Galilee subregion CSG projects remain at exploration and early appraisal stages (as of December 2017), with no clear understanding at present as to the timing, scale and longevity of CSG production fields. The areas of most interest for CSG development all occur within the Cooper Creek – Bulloo river basin, and any future CSG field development could affect a variety of water-dependent assets and ecosystems that inhabit this catchment. Of particular note is the proximity of the Gunn Project to the ‘Floodplain, disconnected wetland’ landscape class that coincides with Lake Galilee, a large ephemeral salt lake that has a range of ecological and sociocultural values. There are also a number of regionally important springs sourced from the Great Artesian Basin that occur within the Blue Energy CSG project area.