At around 9:35 a.m., shortly after a contractor had collected hazardous waste (pallet boxes) at a household waste recycling centre, an overturned can of paint was found at the entrance to the hazardous waste room and 4 l of spilt paint were on the floor. An operative of the centre placed the can in the room and cleaned the paint off the ground.

At 12:00 p.m., a worker at the nearby wastewater treatment plant reported the presence of pollution in the plant’s stormwater pond (white substance across the pond’s surface). The worker set up a containment barrier to prevent the pollution from exiting the pond. The spilt can of paint was identified as the source of the pollution. As the operative, who was not an official employee, could not remember how to close the site’s containment valve, he had to wait until 2:00 p.m. for an official operative to arrive and close the valve. A cleaning contractor cleaned the stormwater network between the waste recycling centre and the pond. Another contractor cleaned the oil and sand separator and pumped the water out of the pond. The waste resulting from the pumping was disposed of in the appropriate way.

The can of paint was overturned by the person who brought it in, the workers at the facility or the hazardous-waste collection contractor.

The operator identified the following problems that contributed to the pollution event:

• presence of a can outside the designated storage areas;
• underestimation, by the non-official operative, of the consequences of the presence of spilt paint on the ground;
• at the time of the event, the operative was unaware of the centre’s emergency containment instructions;
• malfunction of the oil and sand separator: the pollution was not treated by this equipment, so the water was discharged via the bypass;
• the stormwater gully was located in the immediate vicinity of the hazardous waste room (which has since been relocated);
• the viscosity of the acrylic paint, combined with the rainy weather, allowed the effluent to quickly flow into the network.
• The operator has since taken the following measures:
• as the shut-off valve was not a sufficient means of response in the event of a spill, drain covers are now stored near the hazardous waste room;
• all operatives receive training based on feedback from this event;
• the lessons learnt from this event have been passed on to the group’s other facilities;
• the oil and sand separator’s design has been modified (position of the bypass).