During the morning hours, dead fish and iridescence at the surface of the MORDOUET brook, adjacent to a road tanker cleaning firm, were reported to the local town hall. At 10:30 am, the municipality’s Public Works Director and police visited the firm’s manager, who confirmed the olfactory nuisance, tying it to styrene. Fire-fighters installed a series of floating booms. At 11:30, they located the point of discharge near a drain at the business park periphery and recovered 250 l of product. Around 1 pm, damage to a water supply pipe during cleaning operations heavily diluted the pollutant. The manager commissioned a specialist to excavate the earth, along with effluents, for on-site storage in suitable packages before disposal. The accident was declared to the inspection authorities for classified facilities at 3 pm. The water resources agency sampled the dead fish for analysis.

By the end of the evening, 14 neighbours complaining of a residual odour were offered accommodation elsewhere for the night by the town hall and third parties. The next day, fire-fighters spread absorbents and dispersants.

The operator ascribed the cause to non-compliance with tanker draining instructions: on 29th February, a driver returning from a styrene delivery drained residual product by opening the domes and bottom valve at the property boundary instead of using the zone allocated for this purpose into barrels designated for discharge. The employee was dismissed.

Following the accident, the manager analysed both the soils and groundwater (through piezometers) and recalled pertinent instructions to the firm’s personnel.