On 25th July, pollution was discovered in a channel adjacent to a refinery. After investigation, it turns out that the pollution comes from maintenance operations on the site of a refinery on 21st July. Specifically, the valve that during heavy thunderstorms made it possible to bypass industrial water treatment and directly discharge it into the environment was being tested: in assessing the valve seal, technicians loaded the pipeline by filling it with hydrocarbon-fouled water. The downstream hydrocarbon detector failed to indicate the passage of fluid. On 22nd July, another test handling error led to the discharge of 500 litres of material, which this time was detected. A floating boom was immediately set up in the given zone. 3 days later, the polluted channel could be signalled. In fact, the valve was in an open position, thus allowing 350 m³ to empty into the natural environment without the detector being tripped. Given the influence of tides, which were rising at that point, only a small fraction of hydrocarbons actually flowed up the LOIRE over a short distance. The bulk of product remained in the channel. Hydrocarbons in the mix were of the diesel type and accounted for a volume of 150 to 200 m³.

Duly informed of the situation, the inspection authorities for classified facilities proposed an emergency measure order, signed by the Prefect on 29th July. The refinery operator deployed floating booms and a pumping facility, the latter of which was scheduled to last until the 1st week of August given the quantities requiring removal. The estimated amount of hydrocarbons recovered by 31st August was 50 to 80 m³. The operator proposes to introduce subsequent modifications to reduce the probability that this type of situation recurs.