A 200 kg flexible intermediate bulk container (FIBC) of 30% sodium percarbonate (an oxidiser) spontaneously combusted at around 3:00 p.m. on a Sunday at a company that manufactures and packages detergents. A private security officer who was patrolling the site during non-operating hours and checking the temperature of FIBCs containing oxidisers with an infrared thermometer noticed that the temperature of one of the FIBCs was abnormally high. By the time the officer sounded the alarm, smoke had set off the fire alarm. Firefighters had difficulty accessing the site because the access gates were locked. They were forced to cut the fence to get in. They drenched the four FIBCs and placed water-resistant fabric over the storm drains. The firewater was collected in containers. An on-call manager arrived 3.5 hours after the start of the incident. It was declared over at around 6:30 p.m.

The operator estimated the event’s cost at €2,000, which consisted mainly of material losses. The smoke remained confined in the operations building.

The spontaneous combustion was caused by the extremely hot weather. According to the operator, the temperature in the FIBC rose exponentially. Semi-finished products containing 30% sodium percarbonate were stored in a room that did not have a prevention system for keeping the temperature below 40 °C, as recommended on the substance’s material safety data sheet (MSDS). Although the security officer followed the alert procedure correctly, he did not have instructions to implement protective measures in response to abnormal temperatures. The operator’s emergency response plan did not provide for the transmission of information about substances used at the site. Similarly, the FIBCs were not labelled because the task of characterising their risks had not been completed. The lack of a map of hazard-prone areas also made it difficult for firefighters to do their job. The stormwater network’s shut-off valve, upstream of the connection to the public network, was not actuated until one hour after the event’s start. The water-resistant fabrics put in place by firefighters prevented the firewater from entering the stormwater network.

Following this event, immediate precautionary measures prohibiting the operator from storing any semi-finished products containing sodium percarbonate on the site until suitable storage conditions were put in place were ordered by the prefect. The operator is exploring how to permanently eliminate the presence of semi-finished products at the site by improving production management.

Two similar accidents had already occurred on the site (ARIA 48314 and 45176).