The Watermark Coal Project is a planned greenfield open-cut coal mine located approximately 25 km south-east of Gunnedah, in the Gunnedah Basin of north-west New South Wales. Environmental consultants Hansen Bailey engaged AGE, on behalf of Shenhua Watermark Coal Pty Ltd, to complete a groundwater study for the project’s Environmental Impact Statement.
The planned mining area occurs in a ridge area adjacent to a deep alluvial groundwater system known as the Liverpool Plains alluvial aquifer. Irrigation from the aquifer, supports a large agricultural industry within the region. The key challenge with the project was to characterise the nature of the connectivity between the mining area within the Gunnedah Basin coal measures and the Liverpool Plains alluvial aquifer. To address this issue, Shenhua Watermark Coal Pty Ltd employed an ‘in house’ hydrogeologist and implemented an extensive exploration and testing program. AGE used this information to develop conceptual and numerical models of the groundwater systems.
The numerical model was developed to simulate natural groundwater processes and the stresses on the groundwater system including mining and irrigation in order to predict potential changes due to the project. The outcomes included:
- quantification of groundwater take from the Namoi unregulated and alluvial water sources for licensing purposes;
- predicted changes in water levels in the various aquifers; and
- assessment of impacts on key receptors, including private landholder bores.
As part of the approvals process, AGE also helped respond to submissions on the project and provided support during community consultation sessions, engagements with governments and the Planning and Assessment Commission