On 14 May, a police officer alerted the operator of a PVC flooring plant that a nearby ditch had contained a reddish liquid for four days. The valve used to discharge stormwater from the site to the municipal network was closed. The operator saw that the electrical cabinet of the discharge plant had tripped since 4 May. This cabinet supplies power to lifting pumps that feed effluent to the buffer pond and to the discharge pond’s discharge pump. The discharge pond, no longer impervious, is what caused the cabinet to trip. An alarm should have alerted two managers of this shutdown, but it did not work due to an IT issue.

During production on 7 and 9 May, 41 m³ of wastewater containing ink residues as well as soda ash and citric acid built up in the pipes and was discharged into the municipal wastewater network via a special overflow. An unknown connection between the wastewater network and the stormwater network allowed effluent to discharge into the ditch. Lastly, no environmental technician was on hand to monitor the wastewater because the plant was closed for the long bank holiday weekend since the evening of 9 May.

To prevent the same type of incident recurring, the operator:

• replaced the faulty pump;
• resolved the IT issue related to the alarm and instituted a periodic test;
• had the wastewater and stormwater networks surveyed to find the connection;
• plans to have wastewater continuously monitored.