The level of contamination around one of Switzerland’s largest former landfills is much higher than predicted. Remediation of the site has revealed hazardous waste five metres below ground – five times deeper than expected.
After a seven-year clean-up process, the former Kölliken landfill in canton Aargau was emptied of its 600,000 tonnes of waste this past June. However, hazardous materials have seeped into the deeper layers of soil and bedrock.
“The contamination has gone deeper than the metre that was anticipated by the experts,” Benjamin Müller, managing director of the landfill, told Swiss public radio, SRF, on Monday.
For stability and safety reasons, it is not currently possible to see if the soil has been contaminated even farther down; exploratory surveys involving deeper drilling are planned for 2016.
The waste, the exact composition of which was partially unknown, was removed very carefully over a seven-year period involving high security measures and constant air monitoring. The costs of remediation have so far totalled CHF900 million ($915 million), more than twice the initial estimate of CHF445 million.
The costs are mainly borne by taxpayers in cantons Aargau and Zurich, as well as the Basel chemistry industry, the city of Zurich and the federal government.
The landfill was opened in 1978 and closed in 1985 following protests by inhabitants due to major environmental problems.
swissinfo.ch with agencies