Chemical companies in Basel have agreed to foot the bill to clean up a toxic waste site they used in Bonfol, canton Jura, near the French border.
Cantonal authorities and environmental organisations called for the clean-up in 2000 after the companies had dumped chemical and industrial waste at the site between 1961 and 1975.
An agreement signed on Thursday between the Basel Chemical Industry (BCI) and the Jura government has now unblocked a clean-up project for the site, which had been frozen for several months.
The costs are expected to total around SFr280 million ($215.3 million).
At the BCI's request, canton Jura will work out how much the companies will have to pay individually, according to their responsibilities in dumping the waste.
The accord exonerates canton Jura and the commune of Bonfol, which have expressed their satisfaction.
The chemical industry had presented a clean-up plan in 2003 for the 114,000 metric tons of solvents, pesticides and pollutants, including dioxin.
The Swiss environment agency is to be part of the project by acting as a watchdog for the clean-up operations.
"We will do all we can to look into and settle any problems and conflict situations that might arise," said the agency's Bernhard Hammer.
Representatives from canton Jura and the chemical industry said they were happy that a solution could be reached to avoid legal action.
An observer from environmental group Greenpeace also expressed satisfaction.
"The agreement establishes the principle that the polluter pays," said Mathias Wüthrich.
Approval of the plan will now permit the chemical industry to put forward the names of firms that will carry out the clean-up operations.
Excavation work is expected to start in the second half of next year, with the waste being incinerated.
swissinfo with agencies
The Bonfol site was used from 1961 to 1975 by the Basel chemical industry.
It contains 114,000 metric tons of toxic waste.
In 2000 the Jura cantonal authority called for the clean-up of the site.
The operation is expected to cost SFr280 million ($215.3 million).
The Basel Chemical Industry (BCI) is an interest group founded in 1962.
Its members are Novartis, Roche, Ciba Specialty Chemicals, Clariant, SF-Chem, Syngenta, Henkel and Rohner.