Regulating Mine Closure in Western Australia.
Dr Danielle Risbey

Team Leader Mine Closure & Technical Advice, Department of Mines, Industry Regulation and Safety.
 

Summary
The Department of Mines and Petroleum (now Department of Mines, Industry Regulation and Safety) published Guidelines for Preparing Mine Closure Plans in 2011.  Since then, the guidelines were revised twice (see current version Mine Closure Plan Guidance) and over 3,800 Mine Closure Plans have been submitted for assessment.  This presentation will highlight the key findings from our journey with mine closure in Western Australia (WA) over the past ten years and will cover:
•    Our approach to assessing and approving an evolving document such as a mine closure plan;
•    Developing guidance to target weak areas of mine closure plans;
•    Cultivating effective communication between industry and regulators to clarify expectations on mine closure;
•    Demystifying the relinquishment process.

The presentation will conclude with a preview of the next steps planned for regulating mine closure in WA.

 

Community legal rights in mine closure planning; a comparative analysis of three Australian States. 

Authors:  Professor Alex Gardner, University of WA  

and Laura Hamblin

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Presenter: Professor Alex Gardner

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Abstract

Rigorously regulated mine rehabilitation and closure planning (hereafter, ‘mine closure planning’) is central to a future of responsibly managed mine closure. Mine closure planning needs to balance paradoxical principles underpinning the key regulatory goals of safe, non-polluting and sustainable post-mine land use. Mine closure planning should be part of the initial mining proposal, progressive, effective and consultative. The regulation of mine closure planning also needs to be adaptable, as the life of a mine often spans several decades. Yet adaptability can be at the expense of consistency and legal enforceability.

 

Ultimately, the regulatory framework needs to balance the interests of local communities, government bodies and industry stakeholders to achieve a social transition to post-mine land use with minimal residual risks.

This paper presents a comparative analysis of the regulation of mine closure planning through the operation of mineral resources, environmental and planning law across three Australian States with unique mining industries. It highlights the regulatory evolution and notes, especially, how each State defines the rights of community consultation in that planning process, proposing future research to consider what effective community engagement might entail.

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Facilitating Open Pit Mine Closure with Managed Aquifer Recharge

Peter G. Cook,

Ilka Wallis, Shannon Sloan, and Anthony D. Miller

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Presenter : Professor Peter Cook, Flinders University 

 

Abstract

 

Controlled groundwater reinjection, or managed aquifer recharge (MAR), is an established and increasingly applied technology within the urban environment, centered around reinjection or infiltration of stormwater, reclaimed wastewater, and excess surface water to augment limited urban water resources.

 

It is, however, increasingly recognized as a promising water management tool that enables the re-use of water produced during mining and unconventional gas extraction and allows the return of water from dewatering operations back to the source aquifers. In the context of mining, MAR has the potential to reduce the environmental impacts associated with surface discharge, while minimizing the stress on local groundwater resources.

 

However, there is also increasing consideration of the role that MAR can play in mine closure. Dewatering of open pit mines can lower the regional water table for distances of several kilometers from the pit. Groundwater levels surrounding the pit will rise the following cessation of dewatering operations on mine closure. However, in the absence of MAR, stabilization of groundwater levels may take tens to hundreds of years.

 

If any excess water extracted to dewater the mine is re-injected into the subsurface, then this may accelerate the recovery of the water table.

Re-injection thereby needs to occur sufficiently far from the mine to minimize the amount of groundwater that flows back to the pit during mine operations but is still close enough to speed up the water table recovery post-mine closure.

 

The optimal injection distance increases with the aquifer hydraulic diffusivity and the mine life (duration of dewatering and injection). We present simple modeling results that illustrate the benefit of MAR for mine closure.

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​Environmental monitoring and managing water quality on rehabilitated landforms

Andrew Nelson 

Principal Hydrogeology

Mineral Resources Limited

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Synopsis 

The process of re-establishing ecosystems on historic mining landforms is necessary to meet mine closure criteria and eventual land relinquishment but is also increasingly a consideration in the planning process of new mining ventures.

 

Commonly, the ecosystem component which presents the biggest threat to successful mine closure and rehabilitation projects is water-related risks.

In this presentation, the key themes of rationalization of environmental monitoring, catchment management of rehabilitated landforms, and environmental data management in closure are presented for consideration in new and existing mine closure implementation projects.

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Building Better Mine Rock Stockpiles
– Integration with Mine Planning for Source Term Control and AMD Risk Management –
Mike O'Kane
Senior Technical Advisor, Okane Consultants

 

Synopsis 
This presentation will illustrate how our industry can de-risk future cash flow projected for projects.
The International Council on Mining & Metals (ICMM) defines integrated mine closure as: “…a dynamic and iterative process that considers environmental, social, and economic factors from an early stage of mine development and throughout the life of an asset...”. In this presentation and the subsequent discussion, we will define integrated mine planning and closure planning as: “…the process of considering both the extraction plan and the closure plan concurrently, such that one plan directly affects the other…”.

A substantial proposition of acidity generation and resulting acid and metalliferous drainage (AMD) risk arises from the presence of mine rock stockpiles (MRSs) at mine sites.
 
This is a result of site-specific climate conditions, the inherent reactivity of the run-of-mine (ROM) rock placed into an MRS, and the manner in which the rock is placed within the MRS (i.e. the physical conditions). 
Integrated mine planning and closure planning in respect of AMD risk arising from reactive or leachable material placed within an MRS focuses on applying rock placement methodologies that are atypical of most MRS construction practices.
 
This presentation will discuss how MRS construction strongly influences its AMD ‘behaviour’ during operations, and in closure, to substantially decrease unrecognized and underfunded risk to water groundwater and surface water resources. 

Case studies will be presented to illustrate opportunities to incorporate integrated mine planning and closure planning from the strategic project planning stages, through to active closure planning and execution.

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Using Imagery to Develop a 3D Resource Model of Waste Rock Landforms for Closure Design
Kim Bennett: Stantec, Australia

Jared Erickson: Stantec, USA

David Blaxland: Gold Fields Ltd, Australia

Alex Langley: Gold Fields Ltd, Australia

Phil Crouse, Stantec, USA

Petina Wallace, Stantec, Australia

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Presenter : Kim Bennet, Senior Principal Mine Closure Specialist Stantec 

 

​Abstract

Closure of large mine facilities (e.g., tailings storage facilities (TSFs)) often requires sourcing large volumes of variable material with specific characteristics.

Where feasible, identifying and sourcing appropriate material in the required volumes from local waste rock landforms (WRLs) is recognised as best closure practice. However, many WRLs are constructed during the mining process without considering the materials as a borrow resource for future mine closure.

Material investigations which characterise the composition of the material within a WRL and delineate the extents of similar materials are often constrained to the upper surfaces of the WRL.

 

Due to the height and variability of material within numerous WRLs, mine closure plans will often include knowledge gaps on material suitability and quantities.

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This paper will present how imagery has been used to produce a 3D resource model of two WRLs at the Gold Fields St. Ives Gold Mine, located approximately 60 kilometers south of Kalgoorlie Western Australia, and how this has supported the closure design of three TSFs located adjacent to the WRLs.

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The TSF closure plan requires sourcing various material types, including coarse fractured rock material for erosion protection, clean and competent material for the construction of new roadways and embankments, and fines material with suitable geochemical properties to support long-term vegetative growth to cover the TSF surface. Each of these closure material types will be sourced from specific pre-determined zones using the 3D resource model of the WRLs. 

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St Ives and Stantec worked together to correlate mine pit geology, historic aerial imagery and/or aerial elevation data, and investigation data to develop a 3D Model that provides zones of waste rock materials having the required physical, chemical, geochemical and geotechnical properties required for cover systems.

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Mapping and delineation of the zones of similar material that can then be quantified and targeted during closure planning and implementation is key to a cost-effective method of sourcing the different material types needed for closure.

 

Delineations are produced through having a sound understanding of the site geology, enhanced by reviewing any details related to the mining of the deposits from which the waste rock material was excavated, including historic aerial images, and numerous material characteristic test results of samples collected near the WRL surface at targeted locations.

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The Social Aspects of Mine Closure

Presenter : Dr Sarah Holcombe 
Senior Research Fellow 

Centre for Social Responsibility in Mining, UQ. 

 

Abstract

This paper maps out some of the dominant themes on the social aspects of mine closure that have emerged from the literature to date. It draws from a paper written with colleague Nick Bainton (of the same title, in the journal of Resources Policy 2018) and expands on this to include more recent research that Holcombe has undertaken on this topic. A broad purpose is to characterise the social dimensions of the mine closure process.

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The social dimensions of resource extraction have always presented a major challenge for the extractive industries.

 These dimensions include social and economic impacts, human rights, gender considerations, cultural heritage and human development, among others.

These challenges and risks are particularly acute towards the end of the project life-cycle when multiple pressures align.

 

These include financial constraints as production rates decline, unfulfilled socio-economic development expectations, and increased complexity surrounding legacy issues, to name but a few.

 Mine closures can, therefore, have significant adverse effects on local economies, contribute to impoverishment, trigger the loss of key services, and lead to out-migration. Poorly managed closure processes exacerbate these impacts and can damage corporate reputations, where operators are held responsible for the social mess that they have left behind.

It is increasingly the case that stakeholders expect mining operators to proactively manage the multi-dimensional impacts of closure – just as they are expected to manage impacts at other stages of the mine life.

 

Post Mine Futures 

Dr. Guy Boggs
Chief Executive Officer
Cooperative Research Centre for Transformations in Mining Economies

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Synopsis

As the mining industry turns its attention to closure a new relationship is developing between mining companies, governments and communities. “Post Mine Futures” is evolving as a new component of the mining value chain.  Much can be done during mining operations to facilitate post closure outcomes that benefit industry, state and people alike – for example:

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• Delivery of sustained value to regional communities

• Creation of national and international opportunities to METS companies

• Healing Country and enabling enduring First Nations value

• Support to governments and mining companies in achieving relinquishment 

• The building of confidence incentivising future resource sector investment and meeting expectations of sustainability based investors.

 

This presentation will discuss the work of the Cooperative Research Centre for Transformations in Mining Economies (CRC TiME) in its first two and half years as it implements a research agenda to unpack this complex systems challenge and develop innovative solutions to unlock the value associated with mine closure  A semi-quantitative and indicative analysis of this model suggests more than $ 2 billion in value could be generated for all stakeholders.  Key research findings support the development of new value paths through alternative land-use, incentivisation of new investment, globalisation of commercial IP and services, agricultural development, indigenous social benefits, reduced Government costs, progressive  rehabilitation and regional closure service livelihoods.

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