Old mines and open pits – often abandoned and left derelict by former owners – can be found in any region of the world that has some semblance of a mining history.
The legacy? Unregulated practices in bygone mining eras, economic hardship leading to company bankruptcies as well as a general lack of technical know-how left most mined land barren, exposed to untreated waste materials and rife with hazardous mining shafts and cavities.
The negative impacts are obvious: safety and health hazards to people and animals; environmental concerns, such as water quality; concern about neglected mining assets, and the lack of alternative economic opportunity in former mining communities.
It has only been in the last quarter of the 20th century when measures have been enacted to offset or reverse any degradation. Mining companies in many jurisdictions now need a detailed environmental blueprint for mine closure before going into operation. Rehabilitation and accounting for whom is responsible is now a government-regulated sub-sector of the business of mining.
Closure bonds at start-up are required so that governments are not left to pay for the clean-up costs left behind by a company that may go bankrupt in the future.
The goal is to ensure that the quality and quantity of socio-economic benefits developed during and after the life of a mine are sustainable — everything from royalties to government funding for public projects, to tourism initiatives or new land uses.
A working paper called Mining for the Future, done early last decade for the International Institute for Environment and Development, says that there are more than 10,000 abandoned mines across Canada requiring varying degrees of rehabilitation.
In the U.S., accurate inventories are also difficult to come by, because stateby-state definitions differ. Estimates show as many as 27,000 abandoned sites in Arizona and another 17,000 to 20,000 in Utah. The environmental damage at these sites also varies greatly.
And while taking an old site and replicating the dynamics of the original ecosystem that existed there is next to impossible, governments and non-government agencies and environmental groups are actively trying to mitigate hazards, restore the land to something resembling the “before picture” of the minesite or coming up with creative and sustainable new uses.
Canada initiated a National Orphaned/Abandoned Mines Initiative (NOAMI) in 2002. More than $1 billion has been spent on closing abandoned mines, including a substantial amount north of the 60th parallel, where the federal government is responsible for managing contaminated minesites in the country’s territories.
There have also been partnerships in some provinces, where one company’s non acid-generating tailings are poured over the acid-generating tailings pond of another company, to provide a cover that stops drainage and opens the way for the water table to rise up and saturate what is there.
“It’s a nice way of collaborating between various industries, where one industry can solve the waste issues of another industry,” says Gilles Tremblay, a Natural Resources Canada manager who oversees mine closure and ecosystem risk management.
He says that the NOAMI initiative is but one of many initiatives intertwined with various globally-minded agencies around the world: the International Network for Acid Prevention, which comprises some of the world’s largest miners; the Sustainable Minerals Institute Knowledge Transfer; the International Council of Mining and Metals, and the Mine Environment Neutral Drainage Program, to name a few.
Caius Priscu is an associate geotechnical engineer and regional technical leader for AMEC Earth and Environmental’s Saskatchewan and Manitoba division. He has been working closely with the Manitoba government to rehabilitate derelict mining sites deemed to be the most hazardous. Some 10 years in the making, the program has completed remediation work on 14 highhazardous sites and one high-priority site. Another 15 sites should be remediated by 2012, he says.
“You’re trying to make them safe for public access, trying to limit environmental impact and restore the ecosystem so that it’s compatible with the surroundings,” he says. “Some of the hazardous areas identified were unbelievably close to campgrounds and tourist regions or located in provincial parks.”
Specialists must be brought in to provide the needed know-how: geotechnical engineers, scientists, re-vegetation specialists, hydrologists, environmental experts, all providing a mix of expertise needed to restore an old minesite.
“Once complete, the land can be used for a variety of uses,” Priscu says.
Underground living and storage quarters, soccer stadiums, golf courses, eco-friendly flora projects and solar power farms have all been created to paint over a post-mining snapshot to directly benefit the community.
Tremblay says British Columbia’s Butchart Gardens and the U.K.’s Eden Project in Cornwall — both old quarries — are classic examples of what happens when a person or group finally decides to step in and change an abandoned mine landscape. Both greenfield projects have blossomed into world-renowned flora sites that generate tourist dollar and benefit the surrounding community by creating a socio-economic domino effect.
The 11-year-old Eden Project — a complex dominated by two giant “biomes” that house plant species from around the world — is a fount of environmental education, focusing on the interdependence of plants and people.
While tourism is an obvious choice for a mine’s alternative use (such as turning Poland’s 800-year-old Wieliczka salt mine into an attraction that includes a chapel carved out of rock salt and dozens of statues), other mines have become something different entirely.
A training track for running was built in an old mine shaft in Yanahara, Japan. Portugal’s Braga municipal stadium was built inside a quarry that overlooks the city, with the stands on each side of the stadium connected by a 5,000-squaremetre plaza under the playing field.
In southern Australia’s outback, half the population in a town called Coober Pedy live underground; artisanal opal mining and a harsh desert climate drove them into a convenient hole in the ground, where temperatures remain a comfortable 20 to 25 degrees Celsius.
A one-megawatt solar farm is being built on mining land in New Mexico that is owned by a subsidiary of Chevron. More than 170 solar panels will be installed across 20 acres of tailings lands where contaminated soil is being removed. And in Wyoming a coalmine is being converted into a 158-turbine wind farm, producing enough power for 67,000 households a year.
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