Presented by: Professor Wendy Timms, Deakin University, School of Engineering
Session 1 online: Thursday, October 15, 3.00 pm est
Session 2 online: Thursday, October 20, 2.00 pm est
How water is stored and seeps below the ground is critical for mining of minerals and coal. Mining extracts relatively small volumes of water and adds high economic value (1). Mining of metal ores and coal accounts for only 2.6% and 0.9% respectively, of water consumption in Australia(2). Yet, groundwater drawdown can potentially have localised and cumulative impacts on water resources, water quality and environmental assets near open cut, underground and quarrying excavations.
Safety and productivity of mining depends on pumping of groundwater that is balanced with changes in recharge and storage. Groundwater levels must be below the lowest point of an excavation. There are at least three general types of mining hydrogeology ‘tools’: first-order estimates, reliable measurements and monitoring, and numerical models that are fit-for-purpose. Appropriate use of all these approaches, commensurate with project risk, is important for productivity, safety, and protecting environmental assets. Leading practices at mines show innovative managed aquifer recharge and hydraulic barriers to mitigate aquifer interference and losses from surface waters. However, in other cases, knowledge gaps may result in unexpected impacts many years later, missing opportunities for adaptive management.
How can we improve our mining hydrogeology tools to more effectively manage operational and environmental risks? Recent improvements in techniques include: quantitative uncertainty analysis during numerical modelling, the use of environmental water tracers to provide multiple lines of evidence at high risk sites, and advances in analysis tools for high frequency pore pressure. The presentation will give brief examples of quantitative uncertainty analysis and environmental water tracers. More background and examples will be provided for advanced pore pressure analysis, a cost-effective opportunity to measure hydro-geomechanical properties at many points in situ. Advanced pore pressure analysis can measure aquifer confinement, diagnose connectivity through fractured rock and quantify subsidence by directly measuring aquifer and aquitard poro-elastic responses to changing stresses. These tools are also broadly applicable for mining, bore water supplies and unconventional gas projects.
Stakeholders in the mining industry must sharpen the mining hydrogeology tool kit to address current gaps in know-how, and challenges in the future. Long term hydrological conditions are changing, and groundwater level recovery after mining is increasingly important. There are many opportunities for mine hydrogeology along with water sharing and treatment technologies.
Note 1: Economic Value of Groundwater in Australia, 2013.Deloitte Access Economics for NCGRT
Note 2: 2016-2017, Australian Bureau of Statistics
Disclaimers: The views presented in the NCGRT Distinguished Lectures are the author’s, and not of Deakin University, IAH, NCGRT or IESC or mining companies with whom I’ve been associated in various roles as a consulting engineer, as an independent reviewer, or as researcher funded by ARC, ACARP or SPPA (Potash producers association). Information is presented that is publicly available and/or presented with approval.
Research is presented with thanks to many colleagues and students, both current and former. The author acknowledges working with incredible teams of people, and the depth of experience that has been shared over many years by engineering managers, supervisors and mentors.
Professor Wendy Timms is an engineer and geologist with 25+ years of experience in consulting engineering, government and research across mining and agricultural projects. She is Professor of Environmental Engineering at Deakin University based on the Melbourne coast. She is an author of more than 200 technical reports and 50 journal papers, with selected research available freely through ResearchGate.
Wendy has worked on water and waste projects at uranium, potash, coal and gas at sites in Canada, Asia, and across Eastern and Northern Australia. She is currently leading multi-disciplinary projects on fingerprinting water at underground mines and engineering projects, supported by new industry funding to Deakin University. Her research team and collaborators are advancing pore pressure analysis, water tracer techniques, and water-energy nexus studies. Other collaborative projects include Thirlmere Lakes geology, and various hydro-geomechanics projects.
Wendy is a Certified Practicing Engineer (MIEAust, CPEng, NER), a member of AusIMM and a Vice-President of International Association of Hydrogeologists (IAH Australasia & Pacific). Wendy is an invited member of several expert panels for the Federal Minister for Environment including the IESC, Independent Expert Scientific Committee on Coal Seam Gas and Large Coal Mining Development. Wendy was a founding Chief Investigator of the Australian National Centre for Groundwater Research and Training (NCGRT), with a $3.5 million project on low permeability barrier systems (aquitards). She was formerly Director of Postgraduate Coursework at UNSW Sydney’s School of Mining Engineering and affiliated with the Connected Waters Initiative.
The Distinguished Lecture Series is an initiative of the Australian Chapter of the International Association of Hydrogeologists and the National Centre for Groundwater Research and Training.