A number of mining proposals in the Hunter subregion were identified as additional coal resource developments (as at September 2105) based on the Bioregional Assessment Programme’s definition but not included in the surface water and/or groundwater model simulations. The reasons for not including these developments are discussed in companion product 2.3 for the Hunter subregion (Dawes et al., 2018), and are also provided in Table 45. Figure 77 shows the location of these additional coal resource developments in relation to the zone of potential hydrological change.
Table 45 Reasons for not modelling some mines comprising the additional coal resource development
GW = groundwater, OC = open-cut, SW = surface water, UG = underground
Since September 2015, Glencore and Peabody Energy have submitted a joint proposal – United Wambo Open Cut Coal Mine Project (Umwelt, 2016) – which includes a northwest extension to the existing open-cut pit at Wambo and establishment of a new pit between the existing Wambo pit and the Hunter Valley Operations open-cut mine. The potential implications of this development are not considered here.
Data: Bioregional Assessment Programme (Dataset 1), NSW DTI (Dataset 2)
Details of the proposals for a number of the non-modelled and partially modelled additional coal resource developments in Table 45 indicate negligible hydrological changes, and therefore the potential for adverse impacts on water-dependent landscape classes and assets is deemed unlikely. These are the Austar underground, Chain Valley underground and Mount Arthur open-cut proposed developments:
- Austar underground – The proposed change at Austar underground mine involves minor modifications to longwall panels approved in September 2009 (MOD 3, Project Approval 08_0111), which would give access to an additional 1.05 Mt of run-of-mine (ROM) coal. These modifications entail retraction of starting locations due to structural constraints and/or extension at the other end of four Stage 3 longwall panels (LW A7-A10). The result is a net increase in longwall extent of 5 to 10% or less than 1% of the total baseline footprint, no change in approved mine pumping rates, no change to the rate of extraction, and no change to the life of the approved operations. An assessment of the proposed changes on groundwater indicated no significant changes to predictions for the approved longwall layout (Umwelt, 2013a). The modifications to Project Approval 08_0111 were signed off by the Minister for Planning and Infrastructure on 17 December 2013 (NSW Planning and Infrastructure, 2013).
- Chain Valley underground – The proposal involves expansion of the approved underground extraction area, an increase in the maximum rate of production and extension of the approved mining period by 14 years. The area of expansion is entirely under Lake Macquarie, which is connected to the ocean by a small channel. The bioregional assessment (BA) surface water models are not intended for use in lacustrine and tidal environments, but even if they were, the effects of subsidence on surface water hydrology are likely to be negligible given the large area of lake and connection to marine waters. The groundwater effects are modelled, but not mine subsidence. At the expert elicitation workshop for coastal landscape classes, impacts on the lagoons, seagrasses, mangroves and saline wetlands from additional coal resource development were considered unlikely because of existing regulatory requirements for managing subsidence, an unknown dependence of seagrass and lake connection to regional groundwater, and the connection to marine waters. These landscape classes were ruled out as unlikely to be impacted due to additional coal resource development (see companion product 2.7 for the Hunter subregion (Hosack et al., 2018)).
- Mount Arthur open-cut – The proposal to expand the area of open-cut was not modelled in the groundwater model because the area of expansion is small (235 ha) and spans a long, narrow belt (i.e. too narrow to represent at the resolution of the model), and the expansion is not predicted to increase mine water inflow rates (AGE, 2013). It was not included in the groundwater modelling of the coal resource development pathway (CRDP) based on the assumption of negligible changes in drawdowns and surface water – groundwater fluxes and, by extension, no additional impacts on landscape classes and assets. The hydrological changes from disruption of surface drainage were captured in the surface water modelling results.
The remaining non-modelled or partially modelled mines in Table 45 could potentially result in hydrological changes off site. The implications on surface water and groundwater hydrology, and in turn landscape classes and assets, from the Mandalong underground, West Muswellbrook open-cut, Wambo underground and Wilpinjong open-cut additional coal resource developments are considered in Section 3.6.2.
