At about 11 a.m., in a plant manufacturing fire-extinguishing equipment, 500 litres of emulsifier were released into the stormwater system. The release occurred during a periodic maintenance operation on a fixed fire protection installation located on a mezzanine. It was stopped. The technician didn’t notice any foam in the system and decided not to inform the authorities of the release. The origin of the release was caused by the rupture of the proportioner.

A lack of real-time communication slowed down the implementation of pollution management measures

In the afternoon, local residents noticed foam in the canal into which wastewater was discharged and sounded the alarm. The mixing of the emulsifier in the network’s downpipes generated a much higher quantity of foam than that observed at the plant at the time of the accident. The city’s services department closed off the storm drain and took samples for analysis. They investigated the origin of the release by contacting all the manufacturers in the area, and firefighters set up a floating barrier on the canal at the outlet of the basin. Two days later, the operator came forward, and a crisis unit was formed to determine the appropriate course of action. Three days after the release, the operator treated the tank with 200 litres of defoaming agent and, following approval by the wastewater treatment plant, its contents were discharged to the wastewater system where it was processed. The following day, there were no more visible signs of foam.

An underestimation of the possible risk was at the origin of the event

The analysis of the causes of the accident revealed several points:

• failure of the proportioner resulting in the loss of containment;
• absence of a retention tank under the emulsifier tank;
• underestimation of the risk of product expansion;
• absence of an emulsifier safety data sheet on site;
• inactivation of emergency measures regarding the containment of the stormwater network;
• failure to notify the local authorities of the accident.

In order to prevent another discharge, the operator has considered modifying the installation with the installation of a 3-way valve. The emergency procedure, environmental analysis and prevention plans were also modified.