In this issue
- A message from the Commissioner
- Why have pit lakes been given so much attention?
- A focus on the Latrobe Valley Regional Rehabilitation Strategy technical studies
- Frequently asked questions
- Next steps in mine rehabilitation
- Mine rehabilitation milestones
A message from the Commissioner
Welcome to this special edition of our newsletter, and my last as Latrobe Valley Mine Rehabilitation Commissioner.
My role as Commissioner began in June 2017 to provide independent assurance to the public and the Minister for Resources that Latrobe Valley mine rehabilitation planning is being undertaken effectively.
Over the last three years, the three Latrobe Valley mine operators and public sector bodies have made significant progress on mine rehabilitation planning. This will continue with oversight by the new Mine Land Rehabilitation Authority, which supersedes the Commissioner’s role from 30 June 2020.
This progress is underpinned by: mine rehabilitation knowledge and learnings from the history of mining in the Latrobe Valley; the outcomes of the Hazelwood Mine Fire Inquiry; seeing first-hand the success story of Germany’s changed landscape from brown coal mines to lakes driven by a shared vision of government and community; and, more recently, the technical studies of the mine operators and the Victorian government’s Latrobe Valley Regional Rehabilitation Strategy project. These underpinnings provide the ongoing basis for future rehabilitation planning and works for each of the mines so that we can achieve the best long-term outcome for the region.
The three mine operators – ENGIE Hazelwood, EnergyAustralia Yallourn and AGL Loy Yang – are required to rehabilitate their sites to a safe, stable and sustainable condition and to prepare and submit a rehabilitation plan outlining how they intend to achieve this. All three mine operators are currently proposing a pit lake as their preferred rehabilitation landform. As brown coal power generation ends over the next 30 years, the water previously used for this purpose could become available for other purposes, including mine rehabilitation. If approved by the Victorian government, water may be used to fill the mines as part of rehabilitation to achieve a safe, stable and sustainable landform. However, significant questions have been raised by community and government stakeholders about the availability of this water for rehabilitation given the predicted reductions in surface water flows due to climate change. The Victorian government and the mine operators will have to address these questions when deciding the final rehabilitation approaches for all three mines.
ENGIE Hazelwood has recently submitted its Rehabilitation and Closure Plan (RCP) for the mine to Earth Resources Regulation (ERR). The RCP is supported by more than 90 technical and site-wide studies predominately undertaken over the last four years – all of which have been reviewed by my office and our assessment and recommendations submitted to the Minister for Resources. ENGIE has proposed a staged approach to rehabilitation with the plan to develop a full pit lake at the end of Stage 2. If the plan is approved, progression to Stage 2 will depend on the successful implementation of the first stage.
Building community awareness of the reasons for investigating lake options for the final landform and the work being undertaken by the government and mine operators has been at the forefront of our engagement activities with the community. From biannual public forums, to displays at local libraries, meetings with many local groups and representatives, and in art workshops to raise awareness about mine rehabilitation as part of the Coal Hole project, we continue to have discussions with community members about the proposal to rehabilitate the Latrobe Valley coal mines as pit lakes, and the identified difficulties with this option.
Community participation is valuable in that it gives us the opportunity to share information and aims to help you better understand the work behind what’s proposed. My independence has been integral to listening to the views of the community, raising these views with mine operators and the government, and relaying responses back to the community – providing all stakeholders with an understanding of the competing need for natural resources and the community’s vision of a future for the mine sites.
I would like to thank and acknowledge all of you who have shared your views with us. Creating a collective vision of the goals for mine rehabilitation will leave a positive legacy for the future. The journey is only just the beginning.
Latrobe Valley Mine Rehabilitation Commissioner
Final public forum
With the Commissioner’s office working remotely in the lead up to the establishment of the Mine Land Rehabilitation Authority on 30 June 2020, our engagement with you will continue online.
To stay up to date on our events, please visit lvmrc.vic.gov.au/events and connect with us at facebook.com/lvminerehab. We’re also here to answer your questions by calling 1800 571 966 or email email@example.com. Thank you for your support, and we hope you are keeping safe and well during this time.
Why have pit lakes been given so much attention?
Did you know that six alternative mine rehabilitation options for the three Latrobe Valley coal mines were investigated as part of the reopened Hazelwood Mine Fire Inquiry (HMFI)?
In 2015, on behalf of the HMFI, Jacobs Group (Australia) examined six rehabilitation options for the mines, selected based on submissions to the inquiry. Each option was assessed against 14 criteria reflecting key issues and challenges identified through public consultations and submissions. These included the ability to mitigate potential fire, landform stability, biodiversity, groundwater and surface water risks, and the ability to support beneficial future land uses.
Jacobs’ report found four options were unviable overall:
- Full Pit Backfill – due to the likely lack of readily and practically available fill material and the high costs.
- Partial Backfill Above the Water Table – due to the lack of available material and the high costs but also the need for ongoing management of drainage to address instability
risks associated with water entering the mine pit.
- Lined Void – due to high technical difficulty, impact on environmental amenity, high costs associated with creating a pit lining, ongoing maintenance and the dependence on a
specific end land use (e.g. waste disposal).
- Rehabilitated (Empty) Void – due to difficulty of achieving adequate stability, significant ongoing management similar to an operational pit, and limited availability of cover materials.
The remaining options – a Pit Lake and Partial Backfill Below the Water Table – were found potentially viable to manage and mitigate the key fire and stability risks by placing overburden in the pit and filling the void with water to achieve fire cover and weight balance. These options are close to the rehabilitated landforms proposed in the mine operators’ work plans prior to the HMFI. These landforms remain the mine operators’ preferred plans.
While Jacobs considered these options as appropriate for further investigation, it noted uncertainty regarding:
- water availability and potential impact to other water users;
- ongoing management to maintain water level and quality; and
- the amount of material needed to cover exposed coal.
The report further suggested that studies were needed to understand the impacts on other users and regional environmental values to inform future water allocation decisions. It also acknowledged that potential future climate change impacts added uncertainty to the availability, security, and reliability of water sources. The HMFI concluded that some form of pit lake is the most viable rehabilitation option for the three mines, but that considerable further investigation was needed to determine feasibility, as new knowledge could result in an alternative preferred option. In response to the HMFI, the Victorian government launched the Latrobe Valley Regional Rehabilitation Strategy (LVRRS) project to address these knowledge gaps. Its aim has been to develop a strategic framework that will guide the rehabilitation of the Latrobe Valley coal mines to achieve safe, stable and sustainable landforms that meet the long-term needs of the region. The LVRRS doesn’t seek to impose a particular rehabilitation landform on each mine in recognition of the mine operators’ rights and responsibilities but requires the decisions on rehabilitation proposals to take proper account of potential regional impacts and community views.
A focus on the Latrobe Valley Regional Rehabilitation Strategy technical studies
The Latrobe Valley Mine Rehabilitation Commissioner provides independent advice and recommendations to the LVRRS project, which is led by the Department of Jobs, Precincts and Regions (DJPR) and the Department of Environment, Land, Water and Planning (DELWP).
Geotechnical, water, and land use studies underpin the LVRRS. To recap, here’s what the studies found:
Regional Geotechnical Study
This study found that active controls including groundwater pumping and drainage, surface water management and extensive monitoring can’t guarantee there won’t be major ground movements or coal fires similar to those which have occurred over the life of the Latrobe Valley coal mines. The study found that passive controls achieved through landform design would better manage stability and fire risk and ensure that post-closure risks to the community and environment are minimised. Landform design elements include using sediments and water to stabilise mine floors and walls (batters) and placing materials on coal to prevent coal fires. A pit lake rehabilitation option was found to achieve a safe, stable and sustainable landform by providing a counterweight to the upward pressures from aquifers below the mine and prevent floor heave and provide lateral pressures that can help to stabilise the batters. Once stability is achieved, groundwater pumping and drainage can be stopped, and surface water and ground management outside of the pits can also be reduced. The study found that over the last 50 years, groundwater pumping for mine stability has caused land levels to drop by up to two metres. If pumping can be stopped, land levels will slowly rebound – though the extent of the rebound is expected to be less than the subsidence that has occurred. Coal fire risk has been shown to be best managed by covering the coal. A pit lake would provide extensive coverage of the coal below the water line. Coal above the water line would need to be covered with a vegetated soil cover that is resistant to erosion. A number of other studies were identified that would need to be undertaken to further develop and implement the findings of the study.
Regional Water Study
This study looked at the projected water availability and use in the Latrobe River system. Latrobe Valley power stations have historically accessed around 78 billion litres per year of surface water from the Latrobe River system for power generation. The study found that the Latrobe Valley has experienced dry conditions since 1997 with a reduction in the Latrobe River’s annual volume from around 800 billion litres per year to 600 billion litres per year. This means any potential water supply for mine rehabilitation will need to account for uncertainty around future climate and water availability and plan for the expectation of a drier future. Importantly, if the recent dry conditions continue, there is a risk of impacts if water is supplied for mine rehabilitation without conditions that protect other water users and the environment. Furthermore, minimum flow requirements in the Latrobe River need to be maintained to help protect the wetlands at the lower end of the Latrobe River including the Gippsland Lakes Ramsar site. However, the study acknowledged that the physical function and ecological character of the Latrobe River would change if drying conditions persist, even without supply of water to the mines. Nevertheless, the study did find that while filling the mine voids with water would pose a significant demand on the Latrobe River system for a long time, supply of water for pit lakes could be feasible if the filling rate is limited to the power stations’ net annual usage (about 55 billion litres per year) and conditions are placed on the rate of supply of water to minimise impacts on water security, other users and the environment. Pit lake water quality risks were not found to be significant. The study also found that there are no alternative water sources that are considered more feasible based on cost than existing Latrobe River water sources for mine rehabilitation, but that this would change if low water availability in the Latrobe River system limits rehabilitation progress. Given the risk of a drier future, the Latrobe Valley Mine Rehabilitation Commissioner and other stakeholders now believe that further evaluation of alternative water sources should be undertaken as part of the LVRRS.
Land Use Planning Study
To help guide future land uses of rehabilitated mines and surrounding areas, it is vital to start with a sound understanding of the connections between the Valley, its people, history and heritage which have contributed to making it what it is today. The Latrobe Valley Social History is the outcome of this research to inform the LVRRS Land Use Planning Study. Led by DELWP and history and heritage consultants CONTEXT, the project gathered knowledge from representatives from the community, government agencies and the Gunaikurnai Land and Waters Aboriginal Corporation. Latrobe Valley Social History will be used to inform future planning and place-making initiatives by identifying and interpreting places of significance and historic themes of importance. You can view the Latrobe Valley Social History at planning.vic.gov.au/policy-and-strategy/latrobe-valley-strategy, or request a hard copy from our office. The LVRRS Land Use Planning Study also involved the development of a Draft Preliminary Land Use Vision which identifies potential land uses that might be able to occur on the land surrounding the mines once they are rehabilitated. Consultation with key stakeholders including the local community informed the Draft Preliminary Land Use Vision and was made available in 2019 for public submissions. Finally, the LVRRS released an Overview that outlines the principles that will guide the final Strategy and was open to public comment. You can view the LVRRS Overview and the Overview Consultation Report at engage.vic.gov.au/latrobe-valley-regionalrehabilitation-strategy.
Frequently asked questions
Why can’t the mines be left empty?
The Latrobe Valley coal mines have complex geotechnical and hydrogeological characteristics and a long-term safe and stable landform cannot be achieved without addressing these characteristics as part of rehabilitation. Groundwater pressures under and around the mine voids can cause the floor of the mine to heave upward (floor heave) and can cause large blocks of coal to slide into the void (block sliding). To maintain stability, groundwater is pumped out of the deeper aquifers, and horizontal bores are installed in the mine walls (batters) to drain the coal water and reduce the pressures around the mine. Pumping groundwater due to mining over the last 50 years has caused the land level in our region to drop by up to two metres. As part of the mine rehabilitation process, filling the mines would provide the weight to counteract the natural groundwater pressures. When counterweight and a stable landform are achieved, groundwater pumping may be stopped and, in turn, stop land subsidence. Covering the coal by filling the void would also reduce fire risk. If the mine voids are left empty, groundwater pumping and draining would need to continue in perpetuity along with other costs including security to control land access, at a cost of approximately $15 million per year per mine to operate and maintain.
Can materials other than water be used to fill the mines?
The potential to fill the voids with other inert materials such as sediment or rock to rehabilitate the mines is not considered feasible due to the lack of materials on site and the costs of earthmoving. We roughly estimated that just to achieve weight balance to stop groundwater pumping using rock in the Hazelwood mine, would require about 280 million cubic metres of material. The cost of placing this in the floor of the mine and on the exposed coal from a range of sources, including the external overburden dumps, cut material in reshaping the batters and bringing rock from a new mine would be about $4 billion and take about 30 years. The costs of using water and the related earthworks would be between one tenth and one quarter of this figure depending on water sources. Water availability for rehabilitation is a key concern for all stakeholders, particularly if the climate continues to get drier in the Latrobe Valley.
Where will the water come from?
Mine operators will need to apply for a water entitlement if they wish to access water from the Latrobe River system for mine rehabilitation. The LVRRS Regional Water Study found that the supply of water for mine rehabilitation could be feasible if it is accepted that the filling rate is limited to the power stations’ current net annual usage and is restricted or halted under dry conditions to prevent unacceptable impacts on water security, other water users and values including river function and the lower Latrobe wetlands and Gippsland Lakes. However, if the climate continues to get drier, water from the Latrobe River system could eventually not be available. Alternative water sources may need to be investigated if this case is considered to be increasingly likely. In addition to alternative water sources or surface water, groundwater will also be used. For filling of the pits, we estimate that a mean inflow of 50 billion litres per year from all water sources (alternative, surface and groundwater) would be sufficient to achieve a safe, stable and sustainable final landform within a reasonable period for all mines – recognising that the amount of water supplied in any one year would have to be varied, depending on source, to ensure no negative impact on other users and the environment.
Are there alternative water sources?
The LVRRS Regional Water Study assessed the feasibility of using alternative regional and state water sources for mine rehabilitation. The options included recycled water from Melbourne, water sourced from the Victorian Water Grid, desalinised seawater and local recycled and stormwater. The study found that new or alternate water sources would be either too expensive because of the need for new water treatment and delivery infrastructure, too difficult to access water source sites and/or would provide too small a volume to materially contribute to rehabilitation. A more thorough assessment of alternative options could be warranted, particularly if the Latrobe River system drought conditions are observed to continue.
How much water is needed for a full pit lake?
- Hazelwood – 650 billion litres
- Yallourn – 725 billion litres
- Loy Yang – 1,420 billion litres
How long will filling take?
The LVRRS Regional Water Study suggests it would take at least 15 to 30 years to fill each mine pit with water using existing water sources. Keeping a drying climate in mind, these timeframes could be extended significantly to ensure filling occurs seasonally such as only during wetter periods, to protect other water users and the environment.
Where can I learn more?
We encourage discussions with community members on mine rehabilitation planning. If you have any questions or would like more information, please contact us on 1800 571 966, email firstname.lastname@example.org, send us a message at lvmrc.vic.gov.au/contact or connect with us at facebook.com/lvminerehab.
Next steps in mine rehabilitation
About the Mine Land Rehabilitation Authority
The Latrobe Valley Mine Rehabilitation Commissioner’s office is changing.
From 30 June 2020, the Mine Land Rehabilitation Authority is being established under amendments to the Mineral Resources (Sustainable Development) Act 1990. These amendments are in response to a recommendation by the 2015-16 Hazelwood Mine Fire Inquiry that the Victorian government establish an independent statutory body to provide greater oversight of mine rehabilitation across the state to ensure safe and stable final landforms and transition to beneficial post-mining land uses.
The Mine Land Rehabilitation Authority supersedes the role and functions of the Latrobe Valley Mine Rehabilitation Commissioner who has been monitoring mine rehabilitation in the Latrobe Valley from June 2017 to 30 June 2020.
The Authority will:
- Coordinate rehabilitation planning activities and monitor evaluate risks posed by geotechnical, hydrogeological, water quality or hydrological factors for declared mine land.
- Provide assurance to the Victoria community that the LVRRS is being implemented by public sector bodies and mine operators.
- Engage with communities, mine operators, other stakeholders and public sector bodies, inform and education the Victorian community, and ensure communities have a say in relation to the planning for rehabilitation of declared mine land.
- Provide advice and recommendations to the Minister for Resources in relation to the regulatory framework, outcomes of stakeholder engagement, and planning for rehabilitation and monitoring, maintaining and management of registered mine land in accordance with the relevant registered post-closure plan.
- Investigate, audit and report on public sector bodies and declared mine operators in relation to the implementation and effectiveness of rehabilitation planning activities, and on matters referred by the Minister for Resources.
- Rehabilitate, monitor, maintain and manage registered mine land in accordance with the relevant post-closure plan, establish and maintain a register of declared mine land, and purchase, acquire and dispose of declared mine land or land in close proximity.
Further information regarding the Authority and its objectives and functions can be found in Part 7A of the Act, available through ‘Victorian Law Today’ at legislation.vic.gov.au.
Stay up to date
Over the coming weeks, we will continue to share news and information with those on our mailing list, which will then transfer to the new Authority. If you’d like to sign up to our mailing list or wish to unsubscribe, please visit lvmrc.vic.gov.au/contact or email email@example.com.
Mine rehabilitation milestones
- February 2014 Hazelwood Mine fire
- August 2014 Hazelwood Mine Fire Inquiry commenced, concentrating on fire management and health
- April 2015 Hazelwood Mine Fire Inquiry was reopened with a broadened scope to include progressive and final mine rehabilitation, and identified pit lakes as the most viable option, but recognised significant uncertainties around their feasibility considering water availability
- December 2016 Latrobe Valley Regional Rehabilitation Strategy project commenced, which initiated the feasibility studies for pit lakes
- March 2017 Hazelwood Power Station closed
- June 2017 Latrobe Valley Mine Rehabilitation Commissioner appointed
- September 2017 ENGIE Hazelwood Work Plan Variation began, involving the continuation of ‘no regrets’ rehabilitation and the start of the development of a Rehabilitation and Closure Plan
- November 2018 Latrobe Valley Rehabilitation Monitoring Framework 2018-20 published
- October 2019 Latrobe Valley Regional Rehabilitation Strategy geotechnical, water and land use studies were published, and a Draft Preliminary Land Use Vision was released for public consultation
- November 2019 Latrobe Valley Regional Rehabilitation Strategy Overview was released outlining principles for public consultation
- February 2020 ENGIE Hazelwood Rehabilitation and Closure Plan submitted for assessment in a staged approach to allow for review and reflection
- May 2020 Latrobe Valley Regional Rehabilitation Strategy Overview Consultation Report released
- June 2020 Publication of the Latrobe Valley Regional Rehabilitation Strategy, the closure of the office of the Latrobe Valley Mine Rehabilitation Commissioner, and establishment of the Mine Land Rehabilitation Authority
- TBC Implementation of declared mines regulations and new rehabilitation plan requirements for mining and prospecting projects
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