Around 10 am, a brewery received delivery of a mixed load of acids within five 1,000-liter containers: 4 nitric acid (HNO3) containers, and 1 hydrochloric acid (HCl). The labelling of these containers provides the only distinctive indication of delivery contents. Unloading proceeded normally with the first container of nitric acid being transferred into a 10 m³ stainless steel tank that already contained 3,000 litres of HNO3; then transfer of the 1,000-liter container of hydrochloric acid was erroneously routed to the same destination. Once aware of his mistake, the delivery truck driver notified onsite staff. In collaboration with the shipper, who sent two of his own agents to the brewery, it was decided to drain the reservoir by pumping the acid mix via the tank emergency valve; this operation started up around 11:30 am. With 2,000 to 3,000 litres of the acid mix already pumped, the operators suspended the transfer for 2½ hours after remarking that the liquid pouring into the containers was coloured red. At the same time, the tank drainage pipes burst and 2,600 litres of acid solution overflowed into the retention basin, with a brownish cloud of nitrous vapours being emitted into the atmosphere for 10 to 15 min. Local emergency services were alerted, the control room staff of the nearest workshop was evacuated and a safety perimeter laid out inside the brewery. The firefighting team, which included one CMIC chemical emergency specialist, arrived on the scene 5 minutes after being called. The overflow solution was then pumped, placed into a container and removed for treatment at an authorized centre. The burst pipe was no doubt caused by hydrochloric acid attack of the stainless steel, further stimulated by diluted nitric acid that formed an aqua regia type of mix, as well as by destruction of the oxide films protecting the steel from deep attack (passivity). The brewing company requested its supplier to ensure the reliability of its in-house procedures relative to both the loading and identification of chemical products delivered in order to avoid all risk of confusion between products; the in-house transfer procedure was also to be updated and strengthened. Moreover, the brewery operator had to consider the risk of mixing acids when redesigning the storage facility.