At around 10:00 p.m., a fire broke out in an outdoor IBC at a Seveso-classified hazardous waste treatment plant. The IBC was stored alongside other similar packaging at a storage area for soiled IBCs awaiting destruction. The security firm guarding the site notified the operator after seeing white smoke and flames as high as 2–3 metres. The work of the firefighters was hampered by their search for the plant’s pressure-reducing valve. They then extinguished the fire and left the premises at around 11:15 p.m.
Two tonnes of waste were burnt by the flames. The firewater was contained and treated on site.
The IBC had previously been used to neutralise chlorine tablets. The fire was caused by a reaction in the IBC between chlorine reside (an oxidiser) and rain that had fallen the evening of the fire. This reaction was fuelled by the hot conditions. The storage area for soiled IBCs was more cluttered than usual due to delays in crushing operations. Two factors contributed to these delays: the plant was operating with reduced staff due to the holiday period and destruction operations were being performed with a single crusher because the scrap shear usually used was down for maintenance. Besides the problem of clutter, the IBC in question should have been destroyed immediately after use instead of being placed among the other IBCs to be disposed of.
After the accident, the operator:
- identifies among the IBCs to be destroyed, those used to neutralise chlorine tablets (placement of an ‘oxidiser’ logo). Such IBCs are to be destroyed immediately after use. If this is not possible, they are to be stored in a workshop, not in the uncovered outdoor storage area.
- Improved the signage indicating the pressure-reducing valve’s location.
- Increased its workforce.
- Returned the scrap shear to service.
- Informed its employees about the new instructions.
Several accidents involving unintended reactions of products or product mixtures had previously occurred at the plant (ARIA 48694, 48925). Each time, hot weather was a triggering or aggravating factor.