Pollution
Humain
Environnement
Economique

In a meat products factory, a deliveryman emptied sodium hydroxide into a tank normally meant for ferric chloride. Both these products were used for treating effluents. The deliveryman left the site without realising his mistake. A few days later, the operator found out this error due to the malfunctioning of the physico-chemical treatment plant.

A specialised company transferred the sodium hydroxide into a stainless steel tank brought onsite. During this operation, at around 11.30 am, an exothermic reaction took place in the tank and a light gaseous emission was released. The operator had not warned the specialised company that the sodium hydroxide had been polluted with ferric chloride, a product that strongly reacts with steel resulting in the production of hydrogen. The fire-fighters evacuated the 200 employees of the site and a set up a 100 m safety perimeter. The contents of the tank whose temperature had reached 55°C were transferred into three 1m³ plastic containers. The fire-fighters rinsed the steel tank and continued cooling and monitoring the containers where the reaction was in progress due to the presence of trace quantities of steel. Around 7.00 pm, when the temperature was back to normal, a specialised company took charge of the containers. The employees resumed work during the afternoon.

The inspection authorities of classified facilities were informed of this accident. The operator had planned to secure and improve identification of transfer fittings of tanks and the products would be delivered in the presence a factory employee qualified to supervise the operation.