2.3.5 Conceptual models of causal pathways


This section discusses the causal pathways by which impacts on water quantity and quality from proposed coal seam gas (CSG) operations may affect water-dependent assets for the Cooper subregion.

A hazard analysis is used to systematically identify activities that occur as part of coal resource development in the Cooper subregion and which may initiate hazards, defined as events, or chains of events, that might result in an effect (change in the quality and/or quantity of surface water or groundwater). A large number of hazards are identified; some of these are beyond the scope of bioregional assessments, such as accidents, and others are presumed to be adequately addressed by site-based risk management processes, standards and regulation. Hazards associated with CSG operations that are considered to be in scope for the Cooper coal resource development pathway (CRDP) are grouped into eight causal pathways: (i) depressurisation of coal seams and adjacent hydrostratigraphic units from CSG production; (ii) discharge of co-produced water to surface water; (iii) other extraction of surface water or groundwater during operations; (iv) fault-mediated propagation; (v) well construction: integrity, leakage, induced connectivity; (vi) hydraulic fracturing; (vii) unregulated or forced release of water from containment and (viii) disruption of natural surface drainage from infrastructure.

For the groundwater causal pathways, knowledge gaps include hydrogeological architecture around the CRDP; lack of detailed understanding of the three-dimensional distribution of faults and other geological structures; the hydraulic parameters of target and adjacent formations, and the inter-aquifer connectivity between the Cooper Basin and the Eromanga Basin.

Uncertainties around the well spacing, depth, production timeline and size of the CSG resource hamper the assessment of the impact of the CRDP, but do not significantly affect the identification of causal pathways and development of conceptual models for those pathways. Similar uncertainty exists around water production rates and water requirements for the CRDP.

Detailed surface water hydrology and geomorphological information would assist in refining the surface water causal pathway. This includes the hydrology of Strzelecki Creek and the interaction between proposed storage ponds and the surface water network.

Last updated:
31 October 2018