Do you ever unwind from a stressful day by playing video games? More than 270 million Americans do the same. When you enjoy a break from reality with a game like Skyrim or World of Warcraft, you only need to wait a while for monsters, mines, and ores to repopulate. Mine rehabilitation isn’t a concern.
The real world doesn’t work like that. The minerals and raw materials we mine from the earth’s crust exist in finite amounts, and they won’t repopulate, even after a few centuries of inactivity.
Historically, mining companies would abandon a mine site once it’s mined out. But as we move forward with the energy transition, we know this behavior is no longer acceptable.
First, we must look into any secondary materials from a mine. Launching a new mine is a paperwork nightmare, so dedicated sites should be repurposed for other materials whenever possible. Secondly, once a mine is finally truly exhausted of resources, there are environmental concerns to solve and damage to mitigate.
Today, we’re talking about mine rehabilitation and replenishment, and we’ll cover ideas like reforestation and wildlife reintroduction. But first, let’s talk about how and why we should rehab abandoned mines.
Why Should We Rehabilitate Abandoned Mines?
From individual tragedies of accidental death to long-term effects on wildlife and water tables, let’s examine why we should rehab abandoned mines.
The Acute Human Losses
Abandoned mines are extremely unsafe. According to the US National Parks Service (NPS), drowning is the most common cause of death associated with abandoned domestic mines. Water that collects in quarries and shafts is deceptively cold, the walls may be slippery or crumbling, and there may be sharp equipment just below the surface.
Beyond drowning, people die in abandoned mines by:
- Inhaling deadly gases
- Cave-ins and collapses
- And unstable explosives
Real-world explorers on vacation should avoid mine shafts and quarries. This isn’t EverQuest, and there’s no treasure chest to be looted at the bottom of the mine. Even if you explored a mine safely in the past, it may have deteriorated since then.
Remember that mines are constructed and maintained while they are operating. Once the miners depart, they leave vertical openings uncovered and remove ventilation systems. Support structures, like timber or pillars of ore, are removed or left to decay. So mines are much less stable than when they were operating.
Beyond the imminent danger posed to adventurers, abandoned mines can harm the local environment.
Long-Term Dangers of Abandoned Mines
In the US, abandoned mines associated with acid mine drainage (AMD) significantly threaten ground and surface water quality. Active and abandoned mines disturb the land and alter the local hydrologic balance, as the quality and quantity of nearby freshwater are affected. Most domestic mines are now reclaimed after the completion of mining activities, but before the enactment of environmental laws in the 1970s, most abandoned mines were not reclaimed.
This is a global issue. While domestic mine sites — and their acidic discharges — must be remediated in the US, undeveloped nations aren’t yet on board. Some countries, like China, seem to have minimal regard for water quality, and we’ve covered this before.
The chronic effects of abandoned mines include:
- Unhealthy water for agriculture and wildlife
- Illness and congenital disabilities in nearby communities
- And cognitive disabilities in children born near mines
Now that we know how vital mine rehabilitation is, let’s discuss how to get it done.
Mine Rehabilitation Explained
Mine rehabilitation is a sustainable response to the destruction of lands through mining and drilling. Many heavily polluted or toxic mining sites have been successfully restored to a safe and functioning ecosystem through mine rehabilitation.
Mining and extraction provide the critical metals and minerals our global society needs to function. But the environmental impact of mining is significant. American Mine Services, LLC (AMS) says it best, “If not properly managed, mining activity can impact surrounding environments and their biodiversity. This can result in disastrous erosion and release toxins and heavy metals.”
So, how does it work? Well, that depends on the type of mine and the ultimate goal of rehabilitation.
How Mine Rehabilitation Works
You might think the first step to rehabbing a mine site is to fill in the holes and shafts. But it’s a bit more complicated.
Doing the Research
Before filling in a mine, we must conduct studies to understand things like erosion and groundwater movement. The goal isn’t just to fill a hole with debris but to return the site close to its original state or make it otherwise useful.
Mining companies use a combination of boots-on-the-ground, software, aerial surveillance, and soil and water testing. Then they can choose which type of rehabilitation will cost-effectively produce results.
One of the most pressing problems for miners is chemical containment, and the problem starts during the mining process when chemicals are used to leach materials from the host rock. (Check out our previous articles if you want to learn more about that process.)
Chemical containment is an ongoing issue. We cannot simply leave acids at a site to eventually leak into the ground and poison local water tables. So that’s one of the first tasks an organization undertakes when rehabbing a mine.
A standard answer to this question is the use of settling ponds. Operations that extract coal, copper, gold, diamonds, lead, nickel, salt, uranium, and other materials produce wastewater containing dissolved heavy metal ions. These ions can affect the pH of receiving waterways if not treated. Settling ponds or basins can remove impurities and improve the quality of the water leaving the site.
Settling ponds work by holding water until the suspended solids settle. Then we can remove those solids. Chemical treatments can hasten the settling process. These settling ponds, called basins, are lined with geomembrane material to prevent groundwater contamination.
Filling the Site
Next, we fill the mines using a combination of draining materials and mineral-rich soils or whatever that specific site requires. Then we compact this material very hard to prevent settling and erosion. Now the site is ready for reuse.
Types of Mine Rehabilitation
There are four primary types of rehabilitation for mine sites, and farmers or biologists can sometimes interchange them to produce nutrient-rich soil.
Once the mine is filled and covered with topsoil, it’s farmed sustainably. Agriculturists try to match the crop production at the site with the crops of surrounding farms for the best chances of success. Here in the US, we like to plant orchard grass, which we can then harvest for hay or use to create pasture.
Grazing relies on domestic livestock consuming grasses or vegetation to redistribute nutrients to the soil. It can maintain and increase the area’s biodiversity, returning it to a viable farm. The type of livestock pastured at a site depends on the local topography. Cattle, for example, do well on flat, grassy pastures with access to fresh running water. On the other hand, goats are happy on rocky cliffs and can survive on the scrubby brush as long as they have access to shelter.
Conservation is a broad term encompassing:
- Forest management
- Naturalization, or restoring the land to an unmolested state
- Water management
- And heritage protection on/near tribal lands
The goal of native restoration is to bring back the native vegetation to a mine site in hopes that the wildlife will follow. It usually does. Reforestation is a popular method and brings all sorts of benefits like cleaner air and CO2 capture.
Success Story: The Reintroduced Elk of Central Appalachia
As the coal mining industry of our Appalachian mountains drifts into the mists of memory, locals are rehabbing vast swaths of strip-mined land near the tiny town of Grundy, VA (population: 875).
A million acres of land has recently been repurposed for Rocky Mountain elk, who love grazing on open flat lands and disappearing into the groves of locust and autumn olive trees.
This site was initially used for coal mining via shafts and then was subject to mountain-top removal mining. As the name implies, this radical and controversial mining method requires entire mountain tops — and all the flora and fauna that live there — to be blown to bits, leaving a flat top and access to the precious coal beneath.
Mountain-Top Removal Mining
Of all the types of coal mining, this may be the most environmentally destructive. Now that coal mining is mostly obsolete in America, it’s time to rehabilitate those cropped mountains. Now, it’s impossible to put a mountain back together again exactly as it was. And there’s no way to undo the deaths of billions of lifeforms. But we can plant grasses and trees and reintroduce grazing wildlife, like the elk, which will spread some biodiversity and nutrients via their manure.
The good news is that the elk seem to love it there. Residents near Grundy enjoy (highly controlled) hunting activities, and there’s a future market for recreational hunting and hospitality that never existed in the tiny coal town.
The Ultimate Goal of Mine Rehabilitation
As we shift from a fossil fuel-based energy system to a mineral-based system, it’s our responsibility to leave as little waste as possible at mine sites and find other uses for mining sites if we can. But the ultimate goal should be to return spent mines to nature’s possession. Mine rehabilitation isn’t a game. There’s no final boss. But we could still win.
Related Reading & Resources:
Miningtechnology.com: Mining Vehicles – A Ride Through Time
Dendra.io: Progressive Restoration for Mine Reclamation