Why does integration in mine closure matter?
June 29, 2022
June 29, 2022
How technical disciplines working together can strengthen a mine’s closure plan
Think about building a house. You’ll need a team of people from different disciplines. You’d want carpenters, electricians, plumbers, drywallers, and maybe an interior designer and a general contractor. When we’re talking about mining, we also need to consider the importance of multiple disciplines coming together. While this is true throughout the planning and operations of a mine site, it becomes even clearer during closure.
With a decade of experience closing mines around the world, I’ve seen how important it is to involve all parties and stakeholders during the planning and execution of closure.
A successful closure returns the mine site to a state that is both physically and chemically stable, as well as compatible with the surrounding natural environment. The closure process can involve remediation (management and cleanup of contamination) or reclamation (making the site compatible with the surrounding environment as outlined in the mine’s closure plan). And often, it is a combination of both.
When to plan for mine closure? At the beginning is the obvious but no less true answer.
Regulators require detailed progressive reclamation or closure plans, but these plans often do not include what is referred to here as a closure roadmap. It’s critical to involve stakeholders and various technical specialists at the beginning of the project to develop a closure roadmap. This roadmap is an integrated plan outlining the sequence of closure. The first day and the last day are planned in the roadmap, and every step taken in between should have the closure plan in mind. Things will likely change in the multiyear span of the mine’s life, but that’s the nature of the business. If you don’t adapt within the guidance of the roadmap, you could go from having a solid closure plan to having a lot of potentially expensive and time-consuming work to do.
There are many professionals involved in mining. On any day at a mine site, you could see a geologist, biologist, engineer, or construction manager. Here are some examples of unlikely pairings of professions and how technical disciplines can (and should!) work together during closure and closure planning.
Geochemists and geotechnical engineers
As part of closing a mine, tailings and waste rock need to be stored safely. Unlike the mine, which has a finite lifespan, the remnants from the mining will remain forever. Here’s where our chemists and engineers can work together. We need a storage solution that does not release harmful chemicals into the environment. Often, the storage requires built components.
For example, to reduce exposure to oxygen, tailings are often stored under water. This means they are typically contained by a tailings dam. The dam needs to meet global standards and undergo annual safety inspections. Here, our geochemists and geotechnical engineers have an opportunity to work together on how to keep materials stored safely without creating a dam-liability burden. There are other tailings storage options, such as in natural depressions or old pits, that would likely not require the same level of design and inspection rigor.
Geotechnical engineering and hydrogeology
Although geotechnical engineers and hydrogeologists are often studying the same fundamental phenomena—water flows and pressures in the subsurface—they use different vocabularies and techniques to complete their work. They usually require input from each other to adequately capture site conditions. However, they might work in isolation, and this could lead to misunderstandings or costly design issues.
Geotechnical engineers and hydrogeologists need to begin talking at project onset. Geotechnical engineers need to know where the water table is, and the hydrogeologists can provide that information. The hydrogeologists need to know what stability implications any groundwater seepage is going to have, which geotechnical engineers can provide.
Taking steps now allows mine operators to make sure they have the right people talking to each other to prepare for an efficient and safe closure.
Construction management and surface water specialists
A blueprint that’s perfect on paper might work differently in the real world. So, it’s critical for construction and water specialists to plan closures together. For example, in an area that gets snow, the spring melt needs to be considered. If snow is stockpiled over the winter, what are the impacts on managing water runoff as the snow melts in spring? In contrast, berms built during summer to manage surface water may accumulate snow during the winter. This is a great opportunity for the construction managers and hydrologists to work together, sharing locations of snow stockpiles and berms as well as site drainage survey and analyses, so impacts on water across the site can be considered. The same can be true in tropical areas where construction managers need to be able to plan for extreme rain seasons.
Climate change modelers and many disciplines
Because closure plans must work for centuries, they need to account for climate change. Although the site may have acted a certain way during a certain climate, there is no guarantee it will act the same if there is more/less humidity or lower/higher temperatures in the future. Technical teams planning for closure need to work with climate change modelers. This collaboration increases the likelihood that a closure solution will be effective under varying hypothetical conditions. A simple example: if temperatures are projected to increase 10 degrees at a site, the closure team cannot rely on permafrost to immobilize contaminated areas.
I’ve seen integration opportunities from experience, both by closing legacy sites and by designing closure plans for clients. I put out a call to the engineers and scientists that are working on closing mines. When you spot an opportunity for disciplines to work together for the benefit of the project, even if it is not in your scope, speak up.
The adage is that there are no stupid questions, and that has never been truer than in mine closure. If a question sparks a discussion that otherwise wouldn’t have happened, then it is not a stupid question—far from it. And if you don’t ask it now, you might miss some great opportunities for a truly integrated mine closure plan. Taking steps now allows mine operators to make sure they have the right people talking to each other to prepare for an efficient and safe closure.