Within a refinery storage zone, the shell of a fragile 15,000-m³ tank (at the end of its filling cycle) containing 13,500 m³ of HTS residue (at 130°C) split open. The flow of HC then destroyed two other tanks (15,000 m³ each) located in the same retention basin. The wave submerged the dike walls and flooded a 8-ha area of the site. During this incident, pipes burst (including a GO pipe) or got repositioned. The absence of an ignition source prevented the outbreak of fire. Rerouting the flow into a stormwater basin and installing a floating boom avoided pollution from spreading into a nearby pond. Submitted to a hydraulic overload (at the highest filling level heretofore ever reached), cracking initiated on a door weld in the lower part of the tank and then propagated by means of ductile fracture.