Pollution
Humain
Environnement
Economique

At around 5:00 p.m. one Sunday, the fire alarm went off at a hazardous waste treatment plant. As the plant was closed, the alarm monitoring company gave the alert. A company technician and patrol unit went to the plant, where they saw a thick acid mist inside the facility. They cut the power supplies, opened the doors and smoke vents, and removed heavy machinery from the facility.

The plant’s processing operations were shut down after the fire. The plant was remediated to clean up the 15‑20 cm of acid that had fallen to the floor and ground. The contaminated remediation water was pumped up and stored in two tanks before being sent to a specialist company.

Damage from the acid mist was extensive and resulted in generalised corrosion of the:

  • electrical equipment (motors, fixings, pumps, gear motors, wiring, lights, electrical sockets, cabinet components, inverters);
  • computer equipment (PCs, screens, Magélis touchscreens, Wi-Fi network);
  • PLCs (boards, power supplies);
  • mechanical equipment (bearings, air/gas pipes, stainless steel pipes);
  • security systems (intrusion alarms, door sensors, fire alarm sensors);
  • rooms in the facility (removal of the acid-soaked roof).

The release was due to acid corrosion of the cap on the storage tank that contains spent acid (used for dezincing). A total of 12 m³ spilled out, producing the acid mist. Six months prior to the accident, on 3 November 2016, the cap had been fitted during repair work on the tank.

Since the accident, the operator now implements:

  • a semi-annual external visual inspection (tanks, pipes, valves, pumps);

an annual visual inspection of the insides of the tanks (pipes, welds, sensors, general condition).