Water Tracer Tools for Optimisation of Water Management for Coal Mines

This project provides practical information and demonstration of water tracers used in the mining industry, with a particular focus on underground coal mining. Water tracers can contribute to reducing risks during mining operations, provide valuable information to reduce and mitigate environmental impacts, and can also be used after mine closure.

Water tracers are naturally occurring or anthropogenically produced hydrochemical (e.g. chloride) or isotopic tracers that are part of the water molecule or are dissolved in water. These environmental tracers 'fingerprint' waters and can show distinct zones of water due to hydraulic separation.

The project objectives included reviewing how water tracers are used in mining industries around the world, and demonstrating opportunities for water tracers to manage groundwater and surface-water interactions. A review of global and Australian uses of water tracers is presented along with opportunities for applying suitable water tracers at mine sites for mine site-specific questions, water study objectives and priorities.

This project has demonstrated that water tracers are a useful 'additional line of evidence' to complement hydrogeological-geomechanical approaches and address water related risks to mining operations and potential environmental impacts. Water tracers can also be useful beyond mine planning and operations for mine closure, rehabilitation, and restoration, such as seepages from recovery of groundwater levels.

Using a suitable suite of water tracers and appropriate data interpretation, it is possible to quantifying flow and mixing, even for relatively small proportions of water sources with distinctive end-members. Tracing and fingerprinting of waters can quantify interactions between shallow waters and groundwater near mine sites, aquifer interactions, and show distinct zones of hydraulic separation. Water tracers can also be used to target water treatment and optimise management of water on site, mitigating potential water-related risks.

Key project outcomes includes schematics and tables of factors to consider in selecting suitable and effective water tracers for underground coal mining (i.e. workflows) and demonstrations at two mine sites. The site-specific findings for these demonstration sites are outlined in this report along with implications for conceptual models of water mixing and flow pathways on the sites.