At around 10 a.m., the upper part of the fume stack of the pickling condensation scrubber at an iron and steel plant fell to the ground as a result of gusts of wind. The fire department was alerted. The area on the ground was secured and taped off. The pickling and pickling condensation scrubber systems were shut down and the energy sources were locked out. The systems started up again the next day in the evening after replacing the fan, using the low stack of estimated height 6m and taking additional measures to limit the health impacts of releases into the atmosphere. The operator set up a “lengthened” fume stack of total height 15m, surrounded by a consolidation structure pending the construction of a new 28m stack. A dispersion study was also carried out with additional measures. The cost of the incident was estimated at several hundred thousand euros

The cause of the event was the failure due to weakness of the fume stack of initial height 22m following strong 108km/h North-West gusts of wind, whereas the prevailing winds were South/Southwest. This stack had been designed as self-supporting but, following weak signals in 2012, a retaining arm had been added. Moreover, this stack had a completely resin structure.

Following the event, the operator reinforced the structure of the new stack, which is now of steel. A more stringent preventive maintenance plan was finalised, with the introduction of inspection by drones. The operator planned to carry out stack verticality measurements within two years and recorded this in the maintenance plan (oscillation test performed like on wind turbines).