An HCl leak occurred at around 9 a.m. in a Seveso-rated installation, in the containment area of a pumping facility. The resulting vapour cloud moved throughout the site. The warehouse operator noted the leak and activated the emergency stop on the unloading and distribution pumps. The leak, having lasted between 1 and 2 minutes, was estimated to be a few dozen litres. The site’s emergency response team identified the area, confirmed the location of the leak and conducted HCl measurements in the atmosphere (0.1 ppm near the leak). A two-man firefighting team, wearing protective suits, were able to neutralise the vapours with fire hoses. The fumes stopped at 9:20 a.m.

The Inspection Authorities of Classified Facilities were not informed of the event until 18 March.

The leak was the result of a pierced PVC delivery line on the discharge side of the distribution pump, following an increase in temperature (above 70 °C), caused by an increase in the temperature of the HCl as a result of the pump overheating. The cause of this overheating was not determined.

The operator replaced the damaged pipe, checked the operation of the equipment on the distribution system and temporarily installed a temperature sensor on the pump. The pipe was visually inspected on a daily basis, the distribution of HCl to the production building was secured by placing foolproofing devices on the manual valves, and the pipes and manual valves on the HCl network were clearly identified. Simultaneous HCl distribution and loading operations are now prohibited. Consideration was also given to the implementation of measures to limit fumes resulting from discharges into the retaining basins (polypropylene balls in the pumping facility’s containment area).

The Inspection Authorities required that the operator review its HCl risk analysis and investigate means to detect a leak in the pump facility and storage room in the absence of an operator. Finally, the administration noted serious shortcomings in its informing the authorities and residents.