Présentations Colloques

Oral Presentation
Session 7.06: Groundwater protection and governance: examples of groundwater protection models, and the role of the private sector
Cresswell Richard
Protecting Critical Groundwater Resources above Coal Seam Gas Operations- The Roles of Chemistry and Isotopes
The Great Artesian Basin (GAB) in Australia is an iconic groundwater resource providing water for the environment and for stock, domestic and industrial users across one fifth of the Australian continent. In SE Queensland, coal measures within the GAB are targeted directly for coal seam gas (CSG). In northern NSW, Santos Limited (Santos) extract CSG from coal measures in the underlying (older) Gunnedah Basin. Minimising impacts from CSG extraction on any critical overlying groundwater resources places stringent controls on CSG extraction and on-going monitoring and evaluation is undertaken to ensure critical groundwater users and receptors are not compromised by CSG extraction activities. **Santos has installed a network of nested monitoring bores across the Narrabri Gas Project region that augments existing State and private bores. Targeting multiple formations, the Santos bores are equipped to monitor pressure and chemistry and this data helps us understand hydrogeological processes whilst providing baseline data for potential future CSG development. **The characterisation, patterns and trends seen in the chemical and isotopic data demonstrate an isolated coal measures sequence and identify critical parameters that may be used as indicators of any inter-formational connectivity. **Groundwater chemistry is strongly influenced by biogeochemical processes operating along different flow-paths and stable isotopes of carbon and water provide the greatest distinction between different sources+ provide a means to distinguish the deeper groundwaters from those in the GAB and highlight the hydraulic separation between formations.**