Decommissioning is a significant phase in the lifecycle of every mine site and energy asset. One of the greatest challenges facing the mining and energy sector is the decommissioning of retiring facilities and infrastructure.
The permanent closure of a site, plant or mine requires careful management to maintain high standards in health and safety. This involves the timely, safe, and environmentally responsible removal of, or otherwise satisfactorily dealing with, infrastructure, chemicals and by-products that were previously used to support operations.
Decommissioning is a normal and inevitable stage in the lifetime of a project that should be planned from the outset and considered throughout the life of operations.
Why it happens?
Mining at a given site cannot go on infinitely. When extraction of the minerals is complete, there is no value in the mine site anymore, and it is time to withdraw. Sometimes there may still be minerals to extract, however, the financial viability has made mine closure the best option.
Similarly, in the energy industry, as Australia transitions to a net zero carbon future and becoming less reliant on traditional fuel sources, fossil fuel power plants are being closed in favour of cleaner, greener options including hydro, solar and wind.
As environmental, social and governance (ESG) considerations continue to represent key components of mining and energy projects, adequate consideration and planning of long-term environmental and social outcomes are critical to the success of a project.
This is particularly true for medium to large-scale mining corporations, which have the foresight to act in accordance with clearly established standards and to ensure that, through being responsible, they have the social licence and clean track record for future pursuits.
Objective of decommissioning
The object of decommissioning a site is to create a structurally stable landform capable of future productive use, referred to as Greenfields. Greenfield projects allow maximum design flexibility and reduce the required maintenance within the new project.
Once a power generation facility or mine site has reached the end of its service life, operators are responsible for removing all redundant infrastructure while restoring and remediating any legacy environmental contamination.
Once the extraction process is complete, the land can be returned to a natural state and prepared for post closure reuse. Any infrastructure or evidence of mining and power generation must be removed as much as possible, and closure and rehabilitation should consider the local environment conditions, including native flora and fauna. This process is done with an aim to establish an environmentally safe area where the mine or plant used to be.
Challenges with decommissioning
Decommissioning and site preparation is often a complex and lengthy process, as it involves removing hazardous material, soil and groundwater remediation, and the structural demolition and disposal.
Mining sites and power stations often have a flammable or contaminated atmosphere and by decommissioning the site, it can eradicate this risk allowing the landform to be used for future projects, including gardens and public parks. To prevent this contamination and flammability, pipelines must be drained, equipment and parts need to be cleaned, buildings are demolished, and waste effectively and safely disposed of.
The reclamation process can involve reforestation, vegetation, and ensuring no environmentally unfriendly contaminants remain in the area. As part of this, water quality and soil may be tested to ensure it’s not contaminated. Monitoring and obtaining field samples is often a part of the mining agreement. Water quality and end land use should be compared and evaluated so the landscape can support life for centuries to come.
The Australian Energy Market
The Australian Energy Market Operator (AEMO) expects Australia’s reliance on coal to end by 2043. Coal plants have also continued to be decommissioned at a record pace worldwide with many more expected to close in forthcoming years, in transition to achieve the target of net zero carbon. This has resulted in a quickening exit of coal-fired generation from Australia’s energy mix – with 60% of capacity expected to be withdrawn from the National Electricity Market (NEM) by 2030.
As a result, significant levels of decommissioning of coal fired power plants will take place in Australia over the next two decades – the process of decommissioning can differ slightly depending on the site or plant, however, most follow a common process.
The Process
Utilising a specialist industrial demolition and remediation contractor with extensive experience in the resources and energy industries will go a long way to ensure retired sites and plants are decontaminated, deconstructed, and remediated safely, sustainably, and economically.
Early and integrated pre-planning for site closure and decommissioning is essential for many reasons. For example, poor forward planning may result in a corporation failing to salvage soil prior to contamination; or poor decisions about excavation may result in physical land instability post-closure. This can result in the land not being rehabilitated properly, or contaminated soil or water – making the area a danger to the community. It can also be an extremely costly exercise to restore it back to satisfactory levels, leading to blowouts of decommissioning budgets.
Step by Step Process:
- Firstly, the sites infrastructure and plant are safely demolished.
- Initial deconstruction: Methodically taking apart all equipment, facilities, and infrastructure to be able to completely deconstruct the site plant. All waste is either recycled or safely disposed of, with remaining space cleared.
- Stabilise structures: The remaining structure is analysed for stability with issues rectified through construction techniques. Pipes and drainage are also checked to ensure the site is at an acceptable standard for productive use.
- Ensure compliance: As mine sites and commercial demolition sites can be at risk of contamination, the rehabilitated area is then surveyed for compliance with any required alterations made.
- Monitoring: A review of the site decommissioning to guarantee all implemented processes were effective and safety standards have been met.
- Ongoing maintenance: Ongoing maintenance may be needed to ensure all required standards are met. Once final monitoring and maintenance has been carried out, the cleared site and remaining infrastructure is handed over to external parties to finalise the post-closure monitoring and maintenance programs.
Land for future generations
Decommissioning of a site or power station is an important step in the cycle of the energy and mining industries. Ensuring that land is rehabilitated and reconciled for future use is critical and a part of the social license agreement to mine and forms a large part of corporate social responsibility for any organisation.
As the planet transitions to greener, renewable energy sources, deconstructing, and decontaminating land properly by reverting mine and energy sites to a rehabilitated state will ensure that the landscape supports the future growth of the land.
