At night, the lorry containing a solvent regeneration unit was loaded with acetone (5 m³). The pump however could not be shut off. Alone on site to monitor a distillation process and load the lorry, the employee decided to remove the fuses and return. During this time, the lorry overflowed. The vapours ignited (causing an explosion). The ensuing fire reached the retention zone away from the loading dock where empty or full barrels were stored along with flammable liquid containers. The acetone and isopropanol originating from the lorry, whose compartment isolation valves had been damaged, in addition to an enflamed vat and hose all served to fuel the fire (which raged for 3 hrs). The employee was burned. The retaining wall (despite a 4-hour fire rating!) was partially destroyed. The two dam valves proved defective, and the OISE River received 15 m³ of pollution from the 300 m³ of fire extinction water.