An agency for the protection of flora and fauna reported a pollution event on the River Bonnée. Bacterial growth was observed at the bottom of the river bed and there were visible signs of oxygen depletion in the water. The pollution came from a municipal stormwater buffer pond supplied mainly by stormwater from a beverage production plant. The water in the pond was coloured and cloudy and covered with a layer of biofilm similar to that seen in the river. This indicated a one-off pollution event caused by the plant. Samples taken during this period downstream of the two parts of the plant show a normal COD for one part and an abnormally high COD for the other (between 50 and 150 mg/l, the maximum regulatory concentration being 90 mg/l), indicating that this part of the plant was the source of pollution.

The operator did not identify the exact origin of the pollution. The inspection authorities for classified facilities noted that the proper operation of the plant’s water abstraction systems was not fully guaranteed. The boreholes did not have break tanks to isolate the industrial water networks. One of the boreholes was in disrepair and two others were not inspected periodically every 10 years. The operator failed to carry out inspections to check the condition and integrity of the networks, which led to recurrent pollution of the environnment.

The inspection authorities for classified facilities asked the operator for a comprehensive map of its networks, including all the water abstraction systems. He must provide the inspection authorities with weekly COD analyses, proof that the damaged manholes on the stormwater network have been repaired, and the results of the video inspection of the stormwater networks. He must also provide proof that the first borehole has been repaired and the two other boreholes have been cleaned.