The alkyd resin ‘Vialkyd AT’ (flammable product containing 22% heavy naphtha and 3% xylene) accidentally spilled during an entire weekend onto a transfer zone not equipped with a retention basin. The 8 m³ of viscous product entered the storm drain network and subsequently reached the BASSAC River 1 km away. An outside firm cleaned the site, with recovered product being stored in 1,000-litre containers. The Inspection Authorities visited the facility and requested that the site operator immediately equip the transfer zone and containers with retention capacities. That Friday evening, a technician (who was not a member of the regular team) forgot to close the feed valve connecting a 20-m³ tank to one of the 1,000-litre metal containers. The site operator was required to study a retention facility installation covering the whole site.