Remediation of Solothurn's municipal manure landfills

Ecosens investigates underlying contamination

Between 1925 and 1976, the city of Solothurn disposed of waste on the "Stadtmist" in the agricultural area to the west of the city. The three landfills "Unterhof", "Spitelfeld" and "Oberer Einschlag" were created as a result of this disposal. The landfills are spatially separated by the two streams Brunngraben in the west and Brühlgraben in the east.

A total of around 360,000 cubic meters of household waste was disposed of in the city dung, which is roughly equivalent to the volume of 500 single-family homes. The leachate from the landfills contaminates the Brunngraben and Brühlgraben rivers, which flow into the Aare around 200 meters to the south. At the largest of the three landfills - Spitelfeld - the groundwater is also contaminated with chlorinated hydrocarbons (CHCs). Due to these environmental problems, it was decided to clean up the landfills.

Remediation work began at the Unterhof landfill site at the start of July 2022. The aim is to remove all municipal solid waste over a period of 6 to 8 years and to separate and process most of it in an on-site treatment plant. After this process, the pre-treated waste is sent to the appropriate recycling or disposal facility. In a final step, two of the three landfills are recultivated for agricultural use and ecologically upgraded.

Current studies by Ecosens AG

Ecosens AG is supporting the canton of Solothurn in dealing with the CKW issue in the Spitelfeld. Possible remediation options, as identified in an early project phase, were reassessed and evaluated. In order to be able to successfully remediate the CHC contamination at a later stage, it is first necessary to localize any contamination in the subsoil. Ecosens has drawn up a corresponding concept for this, which is to be implemented as part of the remediation work currently underway and in the coming years.

Further information on the remediation of urban dung in Solothurn City dung - Canton of Solothurn


Klaus Reuter
Project manager for contaminated sites