What should we do with a growing mountain of toxic waste?

What should we do with a dangerously growing mountain of toxic waste? | The Guardian

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Employees in a mining gallery of the Stocamine hazardous waste storage centre in Wittelsheim, eastern France.
26/06/2025

What should we do with a dangerously growing mountain of toxic waste?

Phoebe Weston Phoebe Weston
 

Burying problems is generally a bad strategy, and in an industrial area of Alsace, in eastern France, lies a mess that no one wants to deal with: 42,000 tonnes of toxic waste, including mercury, arsenic and cyanide, that is 500 metres at the bottom of a disused mine.

Over the years, authorities and waste producers around the world have used former mines as supposedly safe eternal graves for toxic waste – out of sight, out of mind. But the rock here in Stocamine (pictured top) is in motion due to its unstable geology and water seeping in, meaning it may not be such a safe place after all. The mine is below one of Europe’s largest aquifers, so if the waste leaks it could poison the water of millions of people.

I was there reporting on the story from the old industrial town of Wittelsheim, learning about seven football pitches of waste below our feet, while also testing the limits of my French vocabulary.

It is a local dilemma and a symbol of a global issue: what do we do with our growing mountain of toxic waste? First, this week’s most important reads.

In focus

An aerial view of the Stocamine hazardous waste storage centre in Wittelsheim.

We’ve tried to do all kind of things with harmful waste – dilute it in rivers, dump it in the sea, deposit it in trenches or old gravel pits, and then finally settled on putting it into abandoned mines deep underground. Swiss geologist Marcos Buser describes the history of hazardous waste disposal as “a history of failures”, because burying waste and trying to forget about it doesn’t make it go away.

In the late 1990s, shoving toxic waste in Stocamine (above) was billed as a temporary solution until a better idea came along. The mine was presented as a model for safe underground storage – it should be stable and water-tight, so if anything went wrong waste could be lifted out.

But those earlier predictions have not been borne out: a court ruling last month said it was already too dangerous to get the waste out. In the decades since it was put in, the ceilings and walls within are already sagging and caving in, making the waste harder to access. The government’s decision to seal it up for good – essentially pouring tonnes of concrete down it – will continue, the court found.

Projections vary, but research suggests that over the next 300 years water will gradually flood Stocamine. “Water inflows are flooding the mine and contaminants will be squeezed out in the future,” says Buser, who first studied the case in 2010 when he was appointed by the French government as part of a steering committee.

A cautionary tale comes from Germany, where the Asse II salt mine – once used for nuclear waste – started leaking. It had been closed for decades, and now experts are struggling to get out thousands of barrels before it contaminates the groundwater, with costs looking to hit €4.7bn.

“If you look on the long-term issues of such waste deposits, they will be retrieved if in 50, 100 or 200 years. So it’s better to do it now,” Buser says about Stocamine.

This cover-up and hope for the best approach doesn’t only apply to sticking waste in mines – much industrial and domestic also seeps out of landfill.

There are more than 21,000 landfill sites across England, with 80% of the population living within 2km of a landfill site, either historic or functioning. Since 2000, more than 100 old landfills in England have been flooded, potentially leaching out toxic substances.

Although councils were supposed to keep track of the dangers of these sites, some local authorities had no idea they were responsible, as funding had long since disappeared. Governments change, priorities shift, and perhaps people will forget about what happened at Stocamine: it will be a problem for politicians in the future to deal with.

“It won’t be for tomorrow. Maybe I won’t be impacted any more. I’m too old. But my children, my grandchildren, surely they will,” Yann Flory, a retired sports teacher who has campaigned against rubbish in Stocamine since 1989, told me.

Buser says burying waste is a moral as well as technical question. “We have to completely change our strategy when it comes to this type of long-term dangerous waste,” he says, highlighting the need to change production methods, fundamentally moving towards a circular economy, substituting in toxic elements for ones that are less dangerous. “We are just leaving this burden for our dependents.”

Techniques using robotics mean waste can be more easily retrieved (such as in the case of Stocamine) and recovery and treatment of these materials get better. “We have to fundamentally realise we cannot dispose of very dangerous products in the environment. They are coming back,” he says.

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