The incident left 180,000 people without drinking water for several days. On August 17, 2020, a tank at the Châteaulin biogas plant (Finistère), operated by Engie, overflowed following a technical problem. Around 400 m³ of digestate, an organic material resulting from the methanization process, then spilled into the Aulne river, upstream of a drinking water plant, causing an ammonia peak and making the water unclean to consumption.
This pollution case was judged on Thursday before the Quimper criminal court which requested a fine of 150,000 euros, including 75,000 suspended, against the Engie group. Prosecutor Jean-Baptiste Doubli noted during the hearing the “negligence” of the company in this matter. “Nothing has been done to ensure that the alarm levels are sufficient,” he noted.
The magistrate requested a conviction for two offenses including “discharge of harmful substances into groundwater, surface water or the sea”. On the other hand, he requested acquittal for the offense of “pollution by discharge into fresh water or fish farming of substances harmful to fish. »
Engie recognized “a design problem”
The local authorities and associations which had filed a civil suit demanded a conviction for this offence, believing that there was little doubt that a release of ammonia was harmful to fish. In this case, “we used the environment as an adjustment variable,” said Thomas Dubreuil, lawyer for the Eau et Rivières de Bretagne association, pointing out the “unreasonable development of methanization in Brittany. »
At the helm, Antoine de La Faire, general manager of Engie Bioz, recognized a “design problem” in this “recent sector” which is “continuously improving. » “Everything has been done so that there is no more flow into the natural environment,” he assured. The case was reserved until November 16.