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Mines and Environment Welcome 

Session Overview

Drawing on field and experimental research from mine rehabilitation areas in Queensland’s Bowen Basin, this presentation examines how soil microbial functionality can strengthen the assessment of rehabilitation performance under Progressive Rehabilitation and Closure Plans (PRCPs).

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The research explores the relationship between soil physicochemical conditions, microbial activity, nutrient cycling, vegetation performance and long-term ecosystem development. It considers how biological indicators—including microbial respiration, biomass, carbon cycling and microbial functional profiles—can complement conventional physical and chemical soil criteria.

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The presentation will also examine a proposed two-stage assessment framework linking initial soil suitability following growth media placement with ongoing soil quality evaluation through rehabilitation and mine closure, providing a more holistic basis for assessing whether rehabilitated landforms are progressing towards stable, resilient and self-sustaining ecosystems.

Mine closures in regional Australia face a chronic topsoil deficit. Open-cut operations strip finite native soil reserves; decades-old stockpiles degrade to the point of biological uselessness; and hauling in replacement material is expensive, carbon-intensive, and logistically fragile for remote sites. Existing approaches don't resolve the problem at scale.

This paper presents a modular soil manufacturing framework that converts locally available organic waste and mineral by-products into engineered growth media for mine rehabilitation. The approach is built around the Groundswell® humification process - a North Queensland-developed system now replicated globally - which produces stable humus from waste feedstocks without power infrastructure, using minimal water and equipment available in regional settings.

The methodology operates in four stages: waste stream mapping and ingredient characterisation within approximately 100 km of site; technical profiling of inputs for C:N ratio, contaminants, and physical compatibility; six-month humification via Groundswell® to produce stable, biologically active organic material; and blending with local mineral components to produce growth media designed to functional rehabilitation specifications.

Soil is manufactured in discrete 5,000-tonne modules matched to the pace of rehabilitation earthworks.

This keeps each batch below major development approval thresholds, enables independent quality verification, and decouples production from site rehabilitation timing. If one module underperforms, the next adjusts without holding up the project.
Economic modelling for a western NSW pilot (Cobar region, 2026 cost basis) found avoided landfill and haulage costs of approximately $206/t against all-in processing costs of approximately $108/t — yielding a net benefit of ~$490,000 per 5,000-tonne module. Three sequential modules: ~$1.35M in net value. Carbon and biodiversity benefits are excluded from this figure.

The methodology is applicable across commodity types and regional settings. Any site with access to organic waste streams — municipal green waste, agricultural residues, abattoir by-products — and a rehabilitation obligation can run this model. It integrates with existing closure planning frameworks and aligns with the QMRC's explicit support for alternate growth media.

The presentation will cover methodology, the Groundswell® process, the Cobar economics, and practical steps for operators considering a first pilot module.

Plenary Panel, Q & A  

Morning Tea 

Predictive erosion and landform evolution modelling plays an important role in supporting the design and assessment of stable post-mining landforms, particularly as Queensland mining operations plan for long-term rehabilitation and closure obligations.

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This session will examine the practical application of erosion and landform evolution models in mine rehabilitation planning, including model selection, calibration, validation and the importance of site-specific data in predicting erosion, surface runoff, gully development and long-term landform stability.

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Particular attention will be given to modelling uncertainty, limitations and the interpretation of predicted outcomes, alongside how modelling results can inform rehabilitation design, monitoring programs and performance assessments.

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The presentation will also explore how predictive modelling can support evidence-based decision-making and contribute to demonstrating post-mining landform stability within Queensland's Progressive Rehabilitation and Closure Plan (PRCP) framework.

Ecosystem rehabilitation on mined lands begins with the establishment of novel soil-plant systems that can support target vegetation communities and deliver key ecosystem services.

The success of this process depends on the development of sustainable and resilient soil systems with the structural and functional capacity to support long-term ecosystem recovery.

Historically, the creation of soil systems at mine rehabilitation sites has relied heavily on agricultural soil science principles and practices.

This approach typically applies a narrow set of soil criteria and standards derived from agricultural soil research, which emphasizes physical and chemical uniformity to maximize short-term biological productivity.

In contrast, soils that support native plant communities in natural ecosystems are often characterized by considerable structural and functional diversity, resulting from substantial variability in their physical and chemical properties. Such heterogeneity promotes biodiversity, ecosystem resilience, and long-term sustainability.

Furthermore, many Australian native plant species are highly adaptable and tolerant of a wide range of soil conditions, including alkaline, sodic, and saline soils.

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These species can actively modify soil properties over time, enabling successful establishment even when soils are initially moderately alkaline or saline. Consequently, the direct application of agricultural soil standards to mine rehabilitation may create unnecessary constraints, reducing both cost-effectiveness and feasibility to establish diverse and sustainable native plant communities.

This presentation will draw on case studies involving native vegetation sites, mine tailings and degraded topsoil to demonstrate the limitations of using agricultural soil standards to assess ecological soil functionality. The examples will illustrate why rehabilitation success should be evaluated in terms of a soil system's capacity to support native ecosystems, rather than its conformity to criteria developed for agricultural production.

Soil contamination and geochemical disturbance remain critical challenges in mine rehabilitation across Queensland, particularly in legacy operations and increasingly complex critical minerals projects. Acid mine drainage, metal(loid) mobilisation, hydrocarbon impacts and saline or sodic spoil materials continue to influence long-term land stability and post-mining land use outcomes.

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Under Queensland’s Progressive Rehabilitation and Closure Plan (PRCP) framework, there is growing emphasis on identifying, characterising and managing contaminated or potentially contaminated soils early in the mine life, rather than deferring treatment to closure.

This shift is driving more risk-based approaches to soil classification, containment design and rehabilitation planning, with increased scrutiny of long-term environmental liability.

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At the same time, regulators are placing greater weight on whether contaminated materials can be safely contained, remediated or reclassified into non-use management areas, particularly where full soil restoration is not technically feasible.

This is reshaping how closure risk, residual contamination and rehabilitation success are assessed across Queensland mining operations.

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This session explores modern approaches to managing soil contamination in mine rehabilitation, with a focus on risk-based design, regulatory expectations and long-term land stability outcomes.

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Key Discussion Areas:

• Types and sources of soil contamination in Queensland mining environments
• Acid mine drainage, metal mobility and geochemical instability in waste materials
• Risk-based soil classification and rehabilitation decision-making under PRCP
• Containment, encapsulation and treatment strategies for contaminated soils
• Long-term monitoring and stability of rehabilitated contaminated landforms
• Linking contamination risk to residual liability and closure approvals

Panel Session, Audience Engagement 

Lunch and networking 

Tailings, by products from extracting economic minerals are the largest environmental challenge facing the world’s mining industry. Conventional method to cover the tailings using geomembrane is not only expensive but unsustainable.

This presentation introduces a nature-based ecological engineering approach developed through more than 15 years of field-based, industry-partnered research across multiple climate zones. The methodology enables the systematic mineralogical, geochemical, and biophysical transformation of bio-toxic tailings and mine wastes (e.g., bauxite residue) into a productive soil system resembling natural lateritic soils.
 
Through carefully designed ecological processes, the treated tailings develops stable soil structure, supports diverse microbial communities, and establishes self-sustaining nutrient cycling without the need for ongoing fertiliser inputs.
The resulting eco-engineered soil can be harvested within 2-3 years for use in the remediation of severely degraded landscapes, or utilised in situ to construct stable landforms with functional soil profiles.
 
Field trials demonstrate the development of persistent vegetation cover and long-term ecosystem function, supported by ongoing natural bioweathering processes and stable interfaces between engineered soil layers and underlying residue.

By moving beyond containment-focused approaches, this work demonstrates how nature-based design can transform tailings rehabilitation, enabling more sustainable mine closure outcomes and creating new opportunities for land restoration and post-mining land use.

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Securing sufficient quality topsoil remains one of the most persistent challenges in progressive mine rehabilitation across Australia.
In many Queensland operations, topsoil depths vary significantly, and available volumes are often inadequate to support final landform objectives.

Additionally, both topsoil and subsoil resources may contain physical and chemical constraints that limit vegetation establishment.

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This presentation introduces a structured, evidence-based framework for developing manufactured growth media to address topsoil deficits and support achievement of the proposed Post-Mining Land Use (PMLU).

Initiated by the Queensland Office of the Mine Rehabilitation Commissioner, the project combines insights from an industry survey of environmental professionals with an extensive literature review to identify common soil constraints and practical amelioration strategies.

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The session outlines a five-stage approach:
•    Defining the PMLU and determining soil performance requirements
•    Identifying and characterising available growth media resources
•    Developing tailored growth media strategies, including constraint identification and amelioration design
•    Trialling amendment strategies under site conditions
•    Implementing ongoing monitoring and adaptive management
•    The framework emphasises early material characterisation, strategic soil inventory management, and site-specific amendment design to transform subsoil and spoil into functional growth media.

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By shifting from reliance on scarce topsoil to engineered growth systems, operators can reduce closure risk, improve vegetation outcomes, and enhance regulatory confidence.
The approach provides a practical, scalable pathway to achieve resilient landforms and sustainable PMLU outcomes where natural topsoil resources are limited.​

Not all disturbed mining areas can be returned to a pre-mining or productive post-mining land use, requiring long-term management of Non-Use Management Areas (NUMAs).

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These areas present ongoing challenges for soil stability, contamination control and environmental risk management, particularly where final voids or permanent landforms remain.

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Regulators require clear justification and long-term management strategies for these areas under PRCP frameworks, with ongoing liability considerations.

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This session examines how NUMAs are being assessed and managed within modern closure planning.

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Key Discussion Areas:

• Definition and regulatory treatment of NUMAs
• Final voids and permanent landform management
• Soil and surface stability in non-use areas
• Long-term environmental risk considerations
• Justification requirements under PRCP frameworks
• Ongoing monitoring and management obligations

Panel session, Audience engagement 

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