A practical framework for assessing low-emissions post-closure land uses

Mine closure is inevitably the end of a mine’s operation, but it doesn’t have to be the end of the shared benefits a mine site can offer.

In this article WSP’s mine closure experts introduce a simple yet practical framework for assessing innovative and durable low-emissions options for post-mining land use.

A second life for mine sites

It’s never too early to start planning for responsible mine closure. In Australia, the CSIRO projects that around 240 mines will cease operations by 2040; however, mining will remain critical to Australia’s economy, delivering the ongoing need for ore as well as the critical energy minerals and metals that will underpin the energy transition. Thinking about the post-closure value of a mine site from the beginning of a mine’s life will pave the way toward achieving a meaningful second life and successful long-term outcomes for the environment, communities and economy. 

Post-closure innovations for a net-zero future

Several innovative approaches have emerged to enhance environmental and socio-economic outcomes following mine closure, such as reusing some or all of the land for agriculture, tourism, recreation, science hubs and data parks.

However, with targets in place for carbon reduction and renewable energy production, repurposing mine sites for renewable energy projects has become increasingly appealing as a way to offset processing-related emissions and provide sources of energy on already disturbed sites, thereby contributing to the energy transition. 

Solar farms and wind farms, for instance, are being installed on post-operational mine sites that have a suitable location and sun and wind resources. The energy generated can be sold back to the grid or used locally to power new low-carbon industries. 

Pumped hydro energy storage is an option for appropriately located mine sites that have large voids at different elevations. Water can be pumped from a lower pit or void to an upper reservoir during periods of low energy demand and high renewable energy generation (e.g. wind and solar). During peak energy demand, the water is released back downhill, passing through a turbine to generate electricity. In this way, the pumped hydro scheme operates as a battery, smoothing and stabilising electricity supply and providing the necessary storage and grid support services to enable more renewables in the power system. 

Growing energy crops like switchgrass or algae for biofuel production is another opportunity for repurposing mine sites. Biofuel cultivation and processing can offer new economic opportunities for communities impacted by mine closure, while also potentially contributing to soil health and renewable energy.

Post-mining land uses based on land capability and suitability 

Evaluating physical and environmental characteristics – such as topography, geotechnical characteristics, climate and surface water flows – is a critical foundation for determining the possible post-mining land uses (PMLUs) that a mine site can support (ie the land capability). Given the size of most mine sites, however, the land is unlikely to have uniform characteristics, and spatially zoning land around these characteristics and the associated land capability allows multiple complementary land uses to be considered, preferably integrated with surrounding land uses and the priorities of communities and stakeholders.

A holistic view of the practicality of a PMLU also requires consideration of social, cultural, business and regulatory/political factors relevant to the time of closure and the ability of these factors to support any given PMLU (i.e. the land suitability). Without consideration of all of these, achieving a successful and durable PMLU could be unlikely – or substantially more costly and time-consuming. 

These factors can be evaluated from an actual/current or potential/future perspective. For example, what land capabilities may need to be in place by closure to provide the maximum flexibility for post-mining opportunities? What can be embedded during design and operation rather than being retrofitted, often at great expense, on closure? Can building societal resource capability be incorporated into social investment strategies? How can flexibility be retained?

It is also critically important to regularly review the closure plan during the life of the mine to keep it aligned with the current context. Getting closure-related stakeholder engagement and discussions underway early will help identify desired and practical PMLU categories, as well as the necessary actions and shared responsibilities involved in progressing towards viable uses.

“Achieving successful mine closure often requires a combination of site-specific solutions. A combination of approaches can maximise the durability and value of post-mining land uses, optimised to the capability and suitability of the land to address multiple closure challenges simultaneously.” Kim Ferguson FAusIMM, Director of Mine Closure (Global)

Key criteria for assessing low-emission PMLU options 

Selecting the right PMLU options that support net-zero targets but also align with broader sustainability goals is not a one-size-fits-all process. To ensure long-term success, these PMLU options must satisfy several key criteria, each of which is essential for delivering successful, durable outcomes.

“The development of criteria for selecting low-emission PMLUs and associated technologies involves several key considerations to ensure sustainable and effective closure. These criteria must address land capability and land suitability, including the existing and potential future risks (threats) and benefits.” Bob Boshrouyeh AAusIMM, Senior Mine Closure Planner

Based on this, the selected technologies should be: 

• suitable to the land capability (i.e. environmentally sustainable)
• suitable to the land suitability (i.e. regulatory compliant, economically viable, and socially acceptable)
• technologically feasible.

While testing a particular strategy against these criteria, it can also be subjected to a (SWOT) analysis, to explore its particular strengths, weaknesses, opportunities and threats.

Working together for a positive low-emissions legacy

It takes diverse perspectives, collaboration and shared responsibility from communities, industry, regulators and governments to create the optimal next life for each former mine site, but the effort is a valuable investment for the future.

The best strategies and outcomes for successful low-emissions PMLUs involve local communities, industry partners, governments and regulators working together. Involving local communities and Traditional Owners from the earliest stages helps achieve outcomes that are inclusive, well-supported and aligned with local needs and priorities.

“The mining sector is in a period of multiple challenges and rapid change. Ultimately, this sector needs to build positive partnerships across communities and industries so that we can keep learning and working together towards responsible solutions that will deliver long-term benefits.” Paul Williams, Managing Director of Mining

By working together, industry partners in mining and renewables can leverage their collective strengths, resources and learnings to drive ambitious, large-scale projects, explore new solutions and innovations, and share knowledge that advances leading practices.

With strong, strategic frameworks, we can identify renewable energy and low-emissions projects that will bring new life to former mine sites and unlock value for generations to come.

This article was originally published on the WSP website here and is republished here with permission.