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Lonza legacy Clean-up finally underway at mercury pollution site

Workers began removing soil heavily contaminated by mercury from eight plots of land in Raron, canton Valais, on Wednesday


Workers have started excavating mercury-contaminated soil from gardens and private land in the small Swiss town of Raron. Mercury waste was discharged by the local chemical firm Lonza into a nearby canal between 1930-1976 and seeped into the ground. 

Using diggers and spades, workmen started removing soil heavily contaminated by mercury from eight plots of private property in Raron, canton Valais, on Wednesday. Similar operations will continue next year in nearby Visp and Tutig. In total, 100 plots of land in residential areas have been affected to different degrees. 

The initial clean-up covers a 4,000 square-metre area. In all, 3,000 cubic metres of soil will be removed and, depending on the degree of contamination, sent to either Germany or the Netherlands or kept in Switzerland for treatment. Once the most contaminated layer is removed, a new layer of soil will be put down. 

The soil was polluted by mercury waste produced by chemical company Lonza between 1930 and 1976. The discharge of waste water was carried out in accordance with Swiss laws and regulations in place at the time. 

Some 50 tons of mercury ended up being released into a local canal and accumulated in mud and sediment, which was spread on nearby farm land or used as embankments up until the 1990s. The pollution problem was first uncovered in 2010. 

A sign explaining the clean-up process in Raron, canton Valais

A sign explaining the clean-up process in Raron, canton Valais


In September 2017, it was finally agreed that private owners of polluted land should not pay for any clean-up measures. Canton Valais, along with the Visp and Raron communes, will together pay a maximum of CHF3.5 million ($3.6 million), and any additional costs will be covered by Lonza. However, the firm says this pre-financing arrangement does not signify sole responsibility for the contamination. 

Reinhard Imboden, president of Raron, told the Swiss News Agency that he was relieved that the clean-up had finally started as residents had become increasingly impatient. The pollution had caused sleepless nights for many locals, he added. 

The cantonal authorities are also closely following the work. Independent checks of air quality will be carried out to ensure that mercury-contaminated dust is not released. 

In addition to the residential property, the extent of mercury contamination on farmland close to the canal is still being studied. The results should be ready in the first half of next year, the Valais environment office told

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