How Buried Heating Oil After the Blatten Landslide Could Threaten Groundwater
When the Birch Glacier broke away, it did not just reshape the mountain. It buried the entire village of Blatten under more than three million cubic metres of rock and debris. Whole houses disappeared. So did machinery and, as Swiss news outlet 20 Minuten reported, around 150,000 litres of heating oil and fuel.
That oil is now the focus of a new worry.
A month after the catastrophe, the Canton Valais environmental office detected hydrocarbon residues in the lake that formed on the debris. Oil stains became visible on the surface. In plain terms, part of the buried substances had already leaked out.
The problem below the surface
A debris pile is not a sealed tomb. Rain seeps through it, water moves through the rubble, and whatever lies beneath can travel with it. The authors of a study cited by 20 Minuten say the central risk is that these pollutants could reach the groundwater.
They also add a reassuring note: measurements so far have been unremarkable. No dangerous contamination has been confirmed yet. But the risk is not theoretical, because the leak has already started.
Why this is harder than a single tank
Most landslide contamination cases involve one tank or a small fuel store. Here, the scale is different. Hundreds of thousands of litres of oil and fuel are trapped under millions of tonnes of material. Recovering that oil is not straightforward. Digging through the debris could disturb the site further. Leaving it in place means accepting a long-term source of possible pollution.
The study authors say one open question is whether drainage systems are needed to control how water moves through the debris. That decision affects both the environment and the rebuild.
A return in 2029 depends on the answer
Authorities currently plan for the first residents to go back to Blatten in 2029. Before that can happen, the contamination question needs an answer. If groundwater protection is not guaranteed, the return could be delayed or require expensive engineering. If the oil stays contained, the reconstruction can proceed.
The buried oil is a reminder that a landslide's damage is not only what it destroys on impact. What it locks underground can become a problem years later. For Blatten, the next few years will decide whether the village comes back clean.