A leak occurred at the level of a fitting on a 12″ racking pipe located downstream of the foot valve on a 4,525 m³ tank containing unleaded gasoline with a 98 octane rating (SP98). The retention basin of this tank also served as the basin for a 4,500-m³ tank of domestic fuel. The accident took place during remote-controlled valve opening: an aerosol formed, then spilled over the top of the basin wall (H = 2 m) and flowed by gravity onto the parking lot. After about 20 min, the cloud of some 25,000 m³ in volume ignited. The vapour cloud explosion (VCE) fatally injured a driver, seriously hurt 2 employees and caused slight injuries to 3 other drivers. The POI response plan was activated. The fire spread to two compartments of the retention basin, to 2 tanks and to the tanker trucks parked on the lot, in addition to threatening storage areas. The 200 firefighters called to the site cooled a 1.5-m³ LPG cistern located 30 m from the basin and proceeded to protect two 15,000-m³ tanks of leaded gasoline and fuel oil (using a water curtain). It would take a long time to gather the necessary firefighting resources: 80,600 litres of emulsifier were assembled (17,000 litres borrowed from neighbouring industries), a tugboat equipped with a 12,000 l/min pumping station provided sufficient pumping capacity (an 8-m high tidal range on the LOIRE prevented the pumps from operating properly). The ensuing fire, propagating over a 6,560 m² area, was extinguished in 72 min. The explosion caused serious damage to structures as far away as 100 m and broken windows up to a distance of 1 km; it was exacerbated by ignition of the aerosol within an enclosed room at the washing station, which had the effect of both raising the inflammation energy (with the lorries parked at an angle helping accelerate the path of the flame) and increasing the pressure surge generated by the deflagration. The site’s wastewater network was overcome by hydrocarbons and became the site of subsequent explosions. Total material damage was estimated at 16 million euros: 2 tanks, 4 vehicles, 15 tanker trucks and their washing station were all destroyed; 3 other reservoirs and facility offices incurred damage, and system pipes were deformed. Approximately 500 m³ of hydrocarbons polluted the ground over a 2-ha surface area to a depth of 7 m and seeped into the groundwater. A pressurised gasoline leak at the level of a rubber seal for a pipe fitting would have been the cause of the accident; moreover, the lack of wind served to limit dissipation of the vapour cloud that formed. A prefectural order was issued on October 30, 1991 suspending operations, with resumption of site activity requiring completion of a full authorisation request submission. The fuel depot was reopened for business at the end of 1993.

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