A hydrochloric acid leak occurred in a municipal waste incineration plant during its period of annual closure for maintenance. Its various circuits (steam, water, etc.) were restored by the end of the day. Many subcontractors were on-site at the time specifically to complete works on a second incineration line. Around 10:50 am, a technician observed a hydrogen chloride release around the 30% hydrochloric acid storage zone (a 4-m³ tank filled to one-third capacity). At 11 am, supervisors manually activated the emergency evacuation signal. All employees present gathered at their designated zones within 5 minutes. Fire-fighters were notified and arrived at the scene 10 minutes later. A safety perimeter was set up around the entire facility. Thirty litres of hydrochloric acid escaped from the PVC pipe running in the retention zone and were recovered in a storage tank.

A pump suction problem had caused this accident: the leak was localised on a PVC connection flange upstream of the HCl circuit pump. Two employees wearing masks with a filtering cartridge and anti-acid suits successfully isolated the pipe and closed the suction valve. As a preventive measure, fire-fighters requested individuals suffering from irritation to take a shower. A subcontracted employee in persistent discomfort even after the shower was treated at hospital (and placed on 2-day leave). Gas sampling inside the plant sought to determine air concentrations but revealed no anomalies. The acid vapour release zone was then sprinkled. Acidic effluent was pumped and routed to the heating water neutralisation-demineralisation basin. The operator ordered replacement of: the PVC connection flange, the PVC pipe, and the HCl circuit pump. Soda crystallisation suggested a slight leak of this substance on the adjacent installation (soda circuit). The operator thus agreed to also replace this connection flange and soda pump.