Styrene is an aromatic organic compound having the chemical formula C8H8. It is a liquid at ambient temperature and pressure. It is used to manufacture plastics, and in particular polystyrene. Styrene is a colourless, oily, toxic, flammable and odorous chemical compound in very low concentrations (from 0.02 ppm in air and 0.04 ppm in water)
On Saturday, at 9.25 p.m., nearby residents complained of styrene odours. The operator carried out investigations without finding the source of the odours. The next day, at around 9 a.m., the operator of a plastics manufacturing plant noted traces of iridescence in the Deule river. It sent water from the site to the confinement basin. At 4.42 p.m., after checking at the point of discharge and finding that the water was clear, it was sent back to the Deule. At 5.33 p.m., the fire department contacted the operator following detection of the presence of hydrocarbon residues on the Deule. Styrene odours were perceived. The fire department established a safety perimeter and a sand bag absorbing hydrocarbons. The operator again sent water from the site to the confinement basin. It established visual surveillance of the discharge channel. The next day, the operator noted that the hydrocarbon presence detector was inoperative due to contamination. The operator cleaned the sensor which detected the presence of hydrocarbons in the effluents.
35kg of styrene was released. A person indisposed by the odours was taken to hospital. The discharge generated 20kg of contaminated absorbent sand bags.
Following malfunctioning of the burner of the boiler fuelled with degraded monomer, employees detected the presence of water in the styrene tank. The water present was drained. The tank’s drain valve was closed belatedly, contrary to good drainage management practices, and this gave rise to the presence of styrene in the effluents. The operator also suspected a malfunction of the final separator at the level of the site’s discharge channel. The absence of an alarm by the infrared hydrocarbon detection system could be explained by the presence of wastes on the surface.
Following the discharge, the operator took the following corrective measures:
- reminder to the technicians and emergency response teams regarding compliance with good drainage practices;
- a study concerning the design of the final separator;
- a study to install an atmospheric detector in parallel to the infrared detection system.
