An initial fire broke out on a carton dryer of an asphalt cellulose board manufacturing unit. According to the operator, the dryer’s operating conditions had not been adapted to a series of cardboard sheets that were thinner that what it was accustomed to. The fire was contained by the sprinkling system but caused the ridge cap production line to shut down. Some ridge caps, which had remained immersed in the 180 °C-heated bitumen tank, ignited. The 40 firefighters on the scene brought this second outbreak of fire under control, but weaknesses were highlighted in the collaboration between the emergency services and the plant’s employees. Activity was resumed the next morning following repairs. The cost of the fire amounted to 40,000 euros. Contained in the building’s basement which acted as a retention area, the fire extinguishing water (15 m³) was pumped, stored in containers placed on the site’s external flagstone, then reused in the process. However, the inspection authorities for classified facilities noted that any fire extinguishing water flowing over the external flagstone could only be contained for a limited period. Indeed, such effluents would be collected in a channel continuously fed with effluents from unidentified plants, before passing through an isolation structure and being discharged into the SEINE river. In addition, the isolation valve was not closed correctly and did not provide perfect sealing.