Carcinogenic extinguishing foam Chemical company discharged toxic wastewater into Zurich's Thur river

PFAS did not only end up in Lake Constance. 120 cubic meters of contaminated wastewater also found its way into the Thur in Zurich. The company responsible admits negligence.

120 cubic meters of wastewater contaminated with chemicals entered the Thur near Andelfingen ZH at the beginning of 2021. This water pollution started with two incidents involving fire-fighting foam at a company in Goldach SG. This contained PFAS chemicals.

In addition to Lake Constance, the Thur was also polluted with waste water from the company Amcor Flexibles AG in Goldach SG, which was contaminated with chemicals. The Office for Waste, Water, Energy and Air (Awel) of the Canton of Zurich confirmed a corresponding investigation by the "St. Galler Tagblatt" newspaper on Tuesday at the request of the Keystone-SDA news agency.

The two incidents at the Amcor company at the end of 2020 and beginning of 2021 were already known. At that time, toxic fire-fighting foam was released into Lake Constance via wastewater treatment plants, among other things.

This foam contained perfluorooctane sulfonic acid (PFOS), which belongs to the group of per- and polyfluorinated alkyl compounds (PFAS). PFOS in extinguishing agents have been banned since 2011; the transition period expired in 2019. The company received a fine of CHF 5,000.

Poorly degradable chemicals

A disposal company also brought some of this foam to Andelfingen ZH, as the Tagblatt article revealed. "The extinguishing water was fed into the sewer system via an oil separator," Awel wrote to the Keystone-SDA news agency. From there, it made its way to the wastewater treatment plant and finally into the Thur.

According to the Awel, no "acute" water pollution was detected. However, the problem is that PFOS hardly degrade in the environment and are therefore harmful in the long term.

According to Awel, the disposal company "credibly" explained that it was not aware of the contamination of the transported and disposed wastewater at the time. Amcor itself did not respond to an inquiry from Keystone-SDA until late afternoon.

However, the company told Radio SRF 1's "Regionaljournal Ostschweiz" that it recognized that there had been omissions in the past. A lot has been invested in safety since the incidents. The Tagblatt also reported that large quantities of extinguishing foam had been disposed of correctly.