At roughly 1 a.m., 4 t of hot liquid oil was released onto the 400 m² roof of a textile coating manufacturing plant. The release was determined to be coming from the explosion-proof trapdoor on the boiler’s expansion vessel. The oil trickled onto the roof and flowed along the rainwater gutters and then through the gutter leading to an alleyway passing through the plant. The alleyway and 100 m² inside the plant were contaminated by the spill. Production was halted at 4 workstations. The alley was cordoned off, and absorbent materials were deployed at around 2 a.m. The contaminated soil was scraped, and the public road was cleaned up; 3 days after the accident, a temporary vent was made allowing the installation to be restarted the following day. A manhole was also created near the rainwater downspout. A cellar pump was placed in the manhole to recover the last remaining traces of pollution. The various wastes (liquids, soiled absorbent materials and soil) were stored in a container pending their disposal by a specialised treatment facility.
The incident resulted from the vent on the expansion tank becoming clogged by sludge. This prevented the release of air and water vapour from the oil system. The pressure build-up caused the explosion-proof hatch to give way, which thus acted as a valve. The vents had never been checked during the visual inspection of the expansion vessel during the annual technical shutdown period.
The operator modified the vents so that they could be removed and thus facilitate their inspection, which will be carried out during the annual inspection of the expansion tank.