At a plastics factory, fire broke out at 4:50 pm in a settling basin for hydrocarbon residue containing mainly sands, polyethylene and polypropylene pellets and heavy hydrocarbons (e.g. sewer clearing sludge), on a floor area of roughly 50 m². A thick black smoke was released and could be seen as far as the city of Le Havre. The internal emergency plan was activated, and in-house responders extinguished the blaze by 5 pm using foam, at which time the plan was lifted. The released heat flow did not reach the 2,500-m³ spherical butylene tank located 50 m from the basin, nor did it reach the 2 naphtha tanks 200-250 m away. Sparks originating from the structural work taking place on a nearby unit were the cause of this fire. A technician was cutting with a grinder (installing rebar for a future reinforced concrete wall) at a distance of 2 m from the settling basin. Following this fire, the site operator notified authorities from neighbouring towns as well as members of the Local Information and Consultation Committee.