Hydrocarbons from the oil separator of a metal waste recovery centre polluted the EVALUDE River. The gendarmerie raised the alert at around 8:30 p.m., and the fire brigade set up floating booms to contain the spill. The pollution spread over 1 km with significant iridescence and odour. The following day, the company began preventive skimming operations on the oil separator using a lifting pump. Two and a half weeks later, the separator was again completely cleaned. On that same day, the structure was drained, the filter was thoroughly cleaned, and the equipment was again filled with water. The waste was collected, packaged into drums, then stored in a covered retention area pending removal by a specialist company.

A particularly violent rainstorm had occurred just a few minutes before the pollution was reported on the day of the incident. According to the operator, the event was associated with a sudden and massive influx of rainwater from the impermeable outside surfaces, which entered the hydrocarbon separator dedicated to processing this water. This influx of water would have carried some of the hydrocarbons contained in the separator towards the outfall. The presence of large quantities of hydrocarbons in the separator could be linked to an operator handling error, which occurred a few days before the incident (fuel spillage in the handling areas).

The operator decided to implement the following preventive measures:

• a weekly check of the condition of the oil separators: supernatant thickness and thickness of the sludge in the bottom of the structure;
• regular visual monitoring (2 to 3 times a week) of the EVALUDE at the stormwater discharges and downstream from them;
• maintain annual monitoring of discharges to prevent any malfunction of the facility.