Arrival 

Mines and Environment Welcome 

Mining projects typically invest significant resources in baseline groundwater characterisation, including groundwater level monitoring, hydrochemical sampling, hydraulic testing, and surface water assessments.

These datasets support environmental approvals and operational water management, but they must also provide the evidence needed to answer questions that may arise decades later during rehabilitation and closure.

At that stage, some of the most important questions are often questions of attribution: Is seepage originating from a tailings storage facility or another mine component? Are elevated solute concentrations associated with current operations, legacy mining impacts or natural geochemical processes?

Do changes in groundwater quality represent a mining-related impact, or variability that was already present within the groundwater system? Resolving these questions can be challenging when the available baseline dataset was not designed with future closure investigations in mind.

Environmental isotopes can provide an independent line of evidence for understanding water provenance, mixing, connectivity and, in appropriate settings, contaminant pathways. However, isotopic characterisation is not routinely incorporated into mine groundwater baseline programs. Once mining has altered groundwater flow, recharge, water chemistry or mixing relationships, the opportunity to establish an undisturbed isotopic baseline may be permanently lost.

Drawing on lessons from mining and industrial water investigations, this presentation examines case examples where isotopic techniques provided valuable evidence for understanding water sources and environmental impacts, but where the absence of pre-disturbance isotopic data constrained retrospective interpretation. These examples highlight an important distinction: additional monitoring can be undertaken later in mine life, but the original hydrogeological and geochemical conditions cannot necessarily be reconstructed with confidence after disturbance. 

The presentation considers how targeted isotopic characterisation can be incorporated into baseline monitoring as part of a broader multiple lines of evidence approach.

A relatively modest investment early in the mine life can preserve valuable evidence for future investigations, strengthen attribution of potential impacts, and reduce uncertainty in rehabilitation and closure decision-making.

Ultimately, isotopic baseline data can support more robust water management, rehabilitation planning, closure outcomes, and post-closure performance assessments throughout a project's life, particularly in complex hydrogeological settings and environmental regulatory contexts.

The key lesson is simple: baseline programs should be designed not only to support today's approvals and operations, but also to answer tomorrow's closure questions.​​

​Remote mining operations frequently rely on stormwater capture-and-pump systems to prevent uncontrolled release of mine-affected water (MAW) to sensitive receiving environments.

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These systems are often designed against rainfall statistics that are now more than a decade old, and increasingly out of step with the intensities being observed on site. This paper uses a hydrologic and hydraulic study of a remote manganese export port to demonstrate how updated, site-specific rainfall analysis exposes a growing gap between legacy design assumptions and current-climate performance, and how that gap can be closed through an adaptation-led options strategy.

The port had experienced a higher-than-expected frequency of uncontrolled MAW releases to an adjacent bay. Rather than treating this as a purely mechanical pump-capacity problem, the study rebuilt the design basis from first principles.

At-site Intensity-Frequency-Duration (IFD) relationships were derived from 8.2 years of quality-controlled sub-daily rainfall records using a Peaks-Over-Threshold extreme value analysis and a Generalised-Pareto-Distribution (GPD) fit. For the frequent events that govern this system, the resulting at-site intensities were materially higher than the published 2016 design IFDs, by up to approximately 30 percent for critical durations, reflecting the more intense recent rainfall record.

A TUFLOW rain-on-grid model was then developed and validated against water-level records from a recent storm, using on-site rainfall from a nearby buoy gauge.

The updated modelling showed that peak inflows now exceed the installed pumping capacity even for events as frequent as the 63% AEP (approximately annual), confirming that the system had effectively been designed with negligible tolerance.

The modelling also isolated dominant inflow pathways that would not be apparent through typical catchment delineation and lumped methods, as the distributed approach captured overtopping and flow-splitting behavior that conventional techniques tend to miss.

Four adaptation options were assessed against the updated design events, including upstream catchment diversion, road-crest raising, stockpile regrading and pump upgrades. The key finding for practitioners is that upstream inflow reduction consistently outperformed simply adding pumping capacity, delivering larger and more durable reductions in discharge frequency while reducing reliance on mechanical systems prone to sedimentation and wear.

The paper draws out transferable lessons for climate-resilient mine-water management: why site-specific rainfall analysis should be revisited when recent records diverge from published values; how distributed modelling and monitoring data (rainfall, sump water levels) function as an early-warning and validation system for water-quality risk; and why designing explicit tolerance for rainfall uncertainty, antecedent conditions and infrastructure degradation is essential.

While framed around an operational port, the approach applies directly to closure-phase water systems, where long-term compliance depends on infrastructure performing under a shifting rainfall regime.

Plenary Panel, Q & A  

Break 

As Queensland experiences increasingly variable rainfall patterns, intense storm events and prolonged wet seasons, mine-impacted water systems are facing new and evolving challenges. Legacy mine voids, pit lakes, tailings storage facilities and acid-generating waste rock landforms are being exposed to hydrological conditions that were not anticipated in historical closure designs.

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This session examines how extreme rainfall events can influence acid and metalliferous drainage (AMD), contaminant mobilisation, groundwater interactions and downstream water quality outcomes throughout the mine life cycle and into post-closure. Discussion will explore emerging approaches to pit lake management, predictive water quality modelling, contaminant transport assessment, catchment-scale risk management and adaptive closure strategies designed to withstand future climate variability.

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Attendees will gain insights into regulatory expectations, monitoring technologies, rehabilitation design considerations and practical case studies from Queensland mining operations working to reduce long-term environmental liabilities while maintaining water quality performance and closure objectives.

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Key Discussion Areas:

• Acid and metalliferous drainage (AMD) management in a changing climate

• Pit lake evolution, water quality prediction and closure planning

• Extreme rainfall impacts on contaminant mobilisation and transport pathways

• Groundwater and surface water interactions across rehabilitated mine sites

• Monitoring, modelling and early-warning systems for water quality risk

• Regulatory expectations and long-term stewardship of mine-impacted water systems

• Building climate-resilient water management frameworks for closure success

Dredge Robotics 

Queensland’s recent regulatory reforms for critical minerals and State Strategic Projects mark a significant shift in environmental compliance expectations, particularly in relation to groundwater protection.

Under the new Guideline – General conditions for critical minerals projects, traditional risk-based contamination frameworks are being replaced with an absolute prohibition on groundwater contamination, fundamentally changing how mining projects must be designed, operated and closed.

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This policy shift introduces a stricter compliance environment where any measurable groundwater contamination may trigger expanded liability exposure, including potential criminal enforcement mechanisms. For the mining sector, this represents a material departure from legacy closure approaches that relied on dilution modelling, attenuation zones, and managed exceedance thresholds.

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The implications extend across the full mine life cycle - from feasibility and environmental approvals through to closure planning and relinquishment. Operators must now demonstrate near-zero risk pathways for contaminant migration, particularly in relation to pit lakes, tailings facilities, waste rock dumps and legacy voids.

This raises the bar for predictive hydrogeological modelling, containment engineering, progressive rehabilitation and post-closure monitoring systems.

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For closure practitioners, the change also intensifies scrutiny on residual risk assumptions and long-term liability transfer to the State, requiring more conservative design standards and earlier integration of closure outcomes into operational planning.

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Key Discussion Areas

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• Shift from risk-based groundwater management to absolute prohibition standards

• Implications for mine closure design, tailings storage and void management

• Expanded liability exposure and potential criminal compliance triggers

• Redesigning hydrogeological models under zero-contamination expectations

• Impacts on Progressive Rehabilitation and Closure (PRC) planning frameworks

• Long-term monitoring, stewardship obligations and relinquishment barriers

• Regulatory alignment challenges between fast-tracked approvals and environmental protection obligations

Engagement Audience Q & A included 

Break 

As mine closure frameworks evolve, increasing attention is being given to whether certain mine-derived water assets -such as pit lakes, retention dams, and water storage structures—can be retained and repurposed rather than fully decommissioned at closure. In water-stressed and climate-variable regions such as Queensland, these assets may present opportunities for regional water supply, agricultural use, flood mitigation, or environmental enhancement.

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This session explores the emerging concept of “surrendering” mine water assets into post-mining use, where infrastructure is formally transferred to subsequent landholders, local authorities, or regional water systems.

It examines the regulatory, technical, and liability challenges involved in converting mine water infrastructure into long-term public or third-party assets, including questions of structural safety, water quality stability, contamination risk, and extreme rainfall resilience.

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The discussion will also address the governance gap between mine closure obligations and long-term asset stewardship, highlighting the need for clear handover criteria, funding mechanisms for ongoing monitoring, and legal frameworks that define responsibility beyond relinquishment. Case-based insights will be used to explore when water retention structures can transition from mining liabilities into productive regional water assets, and when decommissioning remains the safer option.

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Key Discussion Areas

• Transitioning mine water infrastructure from closure liability to regional asset

• Pit lakes, retention dams and post-mining water reuse opportunities

• Regulatory requirements for asset handover and relinquishment approval

• Long-term ownership, liability transfer and governance frameworks

• Water quality, contamination risk and climate resilience considerations

• Integrating mine closure planning with regional water and land-use strategies

• Defining “safe and stable” criteria for retained mine water systems​

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Managing Complex Water Quality, Treatment Residuals and Environmental Liabilities During Operations, Rehabilitation and Post-Closure

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Mine-impacted water presents significant environmental, operational and long-term liability challenges for Queensland mining operations, particularly where acid mine drainage, dissolved metals, salinity and persistent contaminants affect water quality and rehabilitation outcomes.

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This session examines advanced and emerging treatment technologies for managing complex mine water, including contaminant removal, treatment efficiency, residual waste management and compliance with environmental discharge requirements.

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Particular attention will be given to selecting sustainable treatment solutions, managing long-term water quality risks and reducing ongoing treatment obligations and environmental liabilities throughout rehabilitation and post-closure.

Remote mining operations across Queensland rely on highly decentralised water supply systems to ensure continuous, safe, and compliant water availability for workforce camps and essential site infrastructure. In many inland and coastal mining regions, access to potable water is limited or variable, making modular treatment systems a critical component of operational resilience.

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This session explores the deployment of containerised reverse osmosis (RO) desalination and brackish water treatment systems as standard infrastructure in remote mining environments. These systems are designed for rapid deployment, flexible capacity scaling, and autonomous operation, enabling sites to treat groundwater, brackish aquifers, or seawater into potable and industrial-grade water.

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Key discussion areas include system design and integration challenges such as pre-treatment requirements, membrane fouling control, energy efficiency, and brine disposal management. The session also examines how these systems are engineered to perform under Queensland’s variable climatic conditions, where drought, extreme heat, and episodic rainfall can significantly impact water availability and quality.

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A further focus is the role of modular desalination systems in supporting operational continuity and workforce health and safety requirements, particularly in remote camps where alternative water supply options are limited. Increasingly, these systems are also being incorporated into broader site water strategies, providing redundancy, emergency supply capability, and transitional support during closure planning phases.

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The session highlights how modular RO and brackish water treatment technologies have become a foundational element of remote mining infrastructure in Queensland, supporting both operational reliability and long-term water security in geographically isolated and environmentally constrained settings.

Panel Session, Audience Engagement 

Afternoon tea 

Incudes Audience Engagement 

Close