A primary by-product of CSG developments is water, which is often rich in salts and other constituents that render it unsuitable for many direct beneficial uses. The predicted large volume and variable quality of this water make water management a critical issue associated with CSG production.

Strategies for the management and beneficial use of the water are dictated by water quality and quantity at each CSG development site. URS has developed a risk management modelling tool, the ‘RISQUE’ method. This method is designed to assess, with increased certainty, the impacts of CSG water and the associated costs and risks on the environment, community and economy.

The RISQUE method has been audited against the Australian and New Zealand standard for risk management, AS/NZS 4360, and has been successfully used on a range of projects to assist decision-makers in gaining an appreciation of risk. The methodology provides a mechanism for comparing all sorts of risks. These risks vary from the strictly quantitative; lost production and downtime, to the qualitative; the loss of endangered species and reputation impacts, on the same scale. The model allows for the translation of complex uncertain information into dollar terms to provide information to allow for improved, rational, and cost effective decision making.

This has major benefits for production, sustainability and the life of the project given the uncertainty surrounding the unknown quality of CSG by-products. It is expected that the model will be of major benefit to the CSG industry in its ability to ensure more precise and accurate management of the risks and costs associated with water re-use. This model is also expected to enable CSG project teams to achieve a co-operative and co-ordinated approach for CSG water management. It is also a critical planning tool; addressing uncertainty both in the impact of events and in the possibility of events occurring.

Using a systematic procedure that deliberately focuses on uncertainty in the calculation, the RISQUE model follows a process of gathering information on a situation from knowledgeable employees and advisors. The model then develops event trees that define the risk issues, the outcomes from the events if they occur, the probabilities of occurrence and the potential cost outcomes. Events are prioritised on the basis of risk quotient. This information is then translated into risk and exposure profiles to develop management actions based on the nature of risk. This produces outputs that can be easily used by decision-makers.

Using the RISQUE model

The URS team has assisted clients in quantifying the risks associated with a range of CSG water management strategies, and helped them select preferred management options, which include:

• Municipal use – including potable water supply, community uses;
• Agricultural use – including small to large scale irrigation schemes, stock watering, local farm uses;
• Industrial use – coal mine, feedlots, cooling tower water;
• Injection – of CSG water or the waste stream, following treatment, into underground isolated formations;
• Impoundments – dams; store and release, evaporation ponds, constructed wetlands, recreation; and,
• Surface discharge – to surface water systems either via direct discharge or via overland or subsurface flow paths.

A key aim is to maximise beneficial re-use opportunities as opposed to discharging water to the environment. Key considerations for beneficial re-use include: the location of the production area and proximity to communities, industries, and agricultural lands; confidence in the water extraction rates that can be guaranteed for beneficial use; water quality; environmental sensitivity of surroundings; responsibility for capital costs for potential beneficial use schemes; and, regulatory guidance – in particular the Environmental Protection Agency.

For each water management option, a process of risk identification and assessment is conducted. This involves ranking risks so that a threshold can be established: namely, what risks can be tolerated and what risks must be mitigated.

Critical to the success of the model is identifying the risks and project objectives with an integrated team. For example, to accurately define the issues surrounding water management URS would involve risk management specialists, environmental scientists and hydrogeologists. The diversity of the team and areas of specialty bring the experience required to adequately identify and assess project options.

The RISQUE model allows for greater flexibility in project management and most importantly, improved water management and assessment of land use/disturbance and impacts on the environment and community. It allows for a rational assessment of options and gives a clear understanding of corporate risk.