Fire broke out at the end of the morning on a former chemical plant production site; 10 tonnes of sodium dichloroisocyanurate pellets (DCCNa, chlorinated disinfectant salt) scheduled for recycling were stored in big-bags on a trailer parked at the platform in front of a building.

A product decomposition reaction that was activated in the presence of localised humidity (dew?) then became a runaway reaction when exposed to the intense heat, thus producing considerable smoke containing chlorinated and nitrogenous gaseous compounds. The nearby combustible materials (bags, wooden pallets, trailer floor, etc.) caught fire.

The smoke overwhelmed an employee of an adjacent company and, pushed by the wind, drifted towards the metropolitan area. Responders evacuated a total of 110 individuals from the plant and industrial zone, then confined a day care centre and its 15 children, a nursing home with 80 seniors and a school of 180 students. The Prefecture issued a press release and asked residents to remain indoors. The electricity company cut a 225-kV power line near the lorry, yet without interrupting supply service to individual customers.

Fire-fighters had the blaze under control by 2 pm using water, foam and powder. The extinction water was recovered and discharged to a specialised treatment firm. The emergency support unit was contacted in order to select the appropriate final extinction strategy. Since the operator refused to flood the products in a sealed skip due to the costs involved; the 5 to 6 tonnes of pellets remaining in the lorry were left to burn without supervision, while avoiding any contact with water.

On the following morning, the load of the trailer next to the burning trailer was conveyed for elimination at a specialised subcontractor’s facility. The treatment steps were not completed immediately; an incident occurred on the inventory 2 days after the load arrived, followed by a fire on 15th July (ARIA 36488). The waste treatment firm refused to accept any new deliveries in this form. The remaining pellets were ultimately neutralised by being placed into solution; the 100 m³ of liquid wastes were treated by another specialised firm. The remnants of the charred trailer were then cut up using a hydraulic grip and scrapped.

The classified facilities inspectorate reported the poor management of production scraps during the site’s period of operations, hence leading to an excess stock of wastes, as well as the lengthy time required to implement cleaning procedures following site closure. The operator was supposed to oversee the elimination of all wastes still present onsite, in addition to formally stopping activity and incorporating the lessons from this accident into the new site’s activities.