In an effluent detoxication station of a surface treatment plant, chlorine was released when 800 litres of sodium hypochlorite (NaClO) was accidentally transferred into a tank containing 600 litres of sodium bisulphite (NaHSO3). These products were used to treat some of the effluents of the site. The accident occurred when 1,000 litres of soda lye, 1,000 litres of liquid bleach and a container transporting 24 carboys of hydrochloric acid were being delivered by a company trading in chemicals. The truck driver accidentally connected the NaClO tank of the vehicle to the filling inlet of NaHSO3 despite the clear labelling. This occurred during the temporary absence of a factory employee who was away to get a power lift truck to unload the HCl. The chlorine spread to the effluent treatment workshop, outside the premises and also to the production building connected to the wastewater treatment plant by leaking pipe ducts. The rescue services set up a safety perimeter and the company staff was confined to the entry of the production workshop. A day-care centre and five local companies were evacuated and the 98 people were accommodated in the town gymnasium. The inhabitants of neighbouring buildings were confined indoors. Four employees of the surface treatment plant who took ill due to the chlorine emissions were hospitalised for further examinations. They resumed work later on in the day. The rescue services pumped out the product from the tank and lifted the safety perimeter. Further to the accident, the operator has planned to install double-locked filling inlets on the cases requiring the deliveryman and an accredited company employee to be present at the same time, make the shafts connecting the production workshop to the wastewater treatment plant watertight, organise first-aid training for company staff and regularly carry out evacuation drills. Upon the recommendation of the inspection authorities of classified facilities, the prefect has issued an order on 15 February requiring the implementation of procedures setting out the conditions for receipt and transfer of chemicals within one month and preparation of a safety report on the risks relating to the delivery, storage and distribution of chemicals in the factory.