In a diary, a joint ruptured on the valve of a tank containing heavy fuel oil. The hydrocarbons spilled into a completely permeable retention tank. The spill reached the rain water network to finally contaminate the AIRAINES river. A fish farm located downstream was seriously effected: 55 tonnes of trout were deemed unfit for consumption. The opportunity cost was assessed at 1 MF. The rescue services installed oil booms. The tank was subsequently repaired.