Swiss landfill site found to contain low-level radioactive material

There is no immediate danger to the population, the Solothurn chancellery announced on Thursday. © Keystone / Anthony Anex

Low-level radioactive substances as well as per- and polyfluoroalkyl substances (PFAS) have been discovered in the Solothurn landfill site Stadtmist. The new findings have resulted in adjustments to excavation and waste treatment.

There is no immediate danger to the population, the Solothurn chancellery announced on Thursday. Since waste from the watch industry is also stored in the Stadtmist (city manure) site, radioactive material is to be expected, it said. Until the end of the 1960s radium was used in the production of luminous dials for watches.

The exposure to the low-level radioactive material is minimal, but it complicates the process of landfill remediation, the chancellery said. More heavily contaminated materials must now be sorted out and disposed of as radioactive waste.

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The PFAS also found are chemically, biologically and thermally very stable and hardly degradable substances, it explained. Because there is still no general regulation in Switzerland, the Federal Office for the Environment (FOEN) sets project-specific limits for disposal.

A test operation until spring 2024 will now show how the problem of PFAS can be solved during the ongoing remediation. The costs of around CHF600,000 ($670,000) for the test operation are not included in the project costs of CHF120 million, it said.

Additional costs

Tests at the plant and in the laboratory are to determine the additional costs to be expected. It would be possible to interrupt the remediation work until it is clear how PFAS waste has to be treated.

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Between 1925 and 1976, Solothurn disposed of its waste at the Stadtmist site in the agricultural area to the west of the city. Because the three disused landfills pose a threat to the environment, they are to be totally excavated and the material properly disposed of.

The owners are the municipality of Solothurn and the canton of Solothurn. The remediation costs are paid 40% each by the federal government and the canton and 20% by the municipality.

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