2.1.6.7 Caroona Coal Project (ACRD)

Coal Mines Australia Pty Ltd (a subsidiary of BHP Billiton) was seeking consent to develop the Caroona Coal Project, a proposed underground coal mine. On 11 August 2016 the progression of this project was ceased and the exploration licence was cancelled by the NSW Government. However, as per companion submethodology M04 (as listed in Table 1) for developing a CRDP (Lewis, 2014) once the CRDP is determined, it is not changed for BA purposes, even in cases such as this, where BHP Billiton have discontinued the progression of the project.

The information in this section has been derived from BHP Billiton (2014) unless otherwise stated. The development application includes proposed longwall mining on Doona Ridge and Nicholas Ridge, both of which will target the Hoskissons Coal. Within the Caroona Coal Project underground mining area, the Hoskissons Coal is 8 to 16 m thick and has a depth of cover between 130 and 710 m. Cover depth is shallowest in the north and the east of the mining areas, with depth increasing to the south-west (Nicol et al., 2014).

It is estimated that the Caroona Coal Project will produce up to 260 Mt of ROM coal over the life of the development and up to 10 Mt/year of saleable coal. The mine life is expected to be approximately 30 years. During the operation 67 longwall panels will be constructed either side of the Mooki River alluvial plain.

2.1.6.7.1 Mine water use

At the time of writing, no information was publicly available on the predicted volume of water that will be required to operate the mine site.

2.1.6.7.2 Surface water management

Little information is currently available on the proposed surface water management infrastructure for the proposed mine. A site water balance will be developed for the project and this would inform the development of the water management strategy, which would incorporate the following:

The project area drains to the Mooki River and Quirindi Creek through a number of ephemeral drainage lines from the ridgelines. The Mooki River flows south between Doona Ridge and Nicholas Ridge. Quirindi Creek flows east to west, with its confluence with the Mooki River in the centre of the exploration area. Runoff from the western side of Doona Ridge flows towards the Yarraman Creek alluvial plain.

Approximately 2103 ha of protocol verified Biophysical Strategic Agricultural Land (NSW Government, 2013) within the project area is predicted to have subsidence impacts. The predicted total maximum subsidence varies between 1.6 and 3.1 m. Typical surface cracking widths vary between 10 to 100 mm depending on depth of cover (BHP Billiton, 2014).

2.1.6.7.3 Groundwater management

BHP Billiton note the following Water Access Licences that are available for the Project:

The predicted annual groundwater extraction volumes for the groundwater sources impacted are summarised in Table 24.

Table 24 Predicted volumetric impacts to groundwater sources from Caroona Coal Project

Data: Nicol et al. (2014, p. 120)

The project is estimated to induce a loss of baseflow to the Mooki River of up to 256 ML/year (0.7 ML/day), and potentially contribute to a cumulative impact of 329 ML/year (0.9 ML/day) when the impacts of the Watermark Project are considered (Nicol et al., 2014). The impacts are predicted to occur primarily between Caroona and Breeza. This impact to baseflow represents a significant impact to the low-flow rates in the Mooki River at Breeza (Nicol et al., 2014, p. 98).