Between 142 and 340 m³ of diesel fuel were spilled in a railway yard when a flexible coupling ruptured. Part of the hydrocarbons (HC) polluted the wastewater system and a water table, and menaced a treatment facility and a canal of the Rhone River. The coupling had been installed in June during an installation involving the replacement of a section of pipe connecting a 200 m³ buffer tank to the locomotive fuel distribution station. The installation is supplied by a 1,000 m³ tank whose catchpit is interconnected with the buffer tank’s catchpit via an older section of piping that had not been dismantled or plugged.

The accident took place on a Sunday. An operator the presence of diesel fuel at around 8 am in the large catchpit and alerted the agent on duty who closed the storage valves at 9.30 am. As the catchpits were not equipped with alarm-type level sensors, the tank continued to automatically supply the buffer tank while it was emptying into the large catchpit. The gravel bottom of the catchpit was not hermetic. The HCs flowed through the trench to the decantation tank associated with the distribution station. The executive on duty noted that the decantation tank had reached saturation at noon and alerted the rescue services at 1.10 pm. An employee plugged the trench connecting the settling tank to the rainwater network at 1.30 pm. At the same time, part of the polluted wastewater system was isolated and the effluents to be treated were deviated to a specific catch tank. Upstream, the firemen set up a preventive dam on the Rhone outlet canal into which the treatment station releases its effluents, requiring river traffic to be stopped until the next day at 10 am; no notable impact was reported on the river. The DRIRE was informed of the accident on Sunday at 3.30 pm and the Prefecture initiated the Operational Defence Cell. The spillage also infiltrated below the catchpit and polluted the water table, where 1 m of HC was noted at 7 pm.

The use of industrial well water or private wells for sanitary purposes was strongly discouraged. An emergency shutdown order required the operator to clean up the pollution (pumping of the HC in the networks, cleanup of the water table and piezometric monitoring, soil treatment…) and to secure the site (including the drainage of 2 tanks, expert evaluation of the installations prior to restart, installation of HC alarms in the catchpits, networks and settling tanks…). On October 10, 2006, 61.2 m³ of hydrocarbons were pumped from the water table and 446 t of products were destroyed by the operator.