Pollution
Humain
Environnement
Economique

At around 5:30○p.m. on a Friday evening, operations were untaken to spray down a waste storage cell with water. The decision to spray down the area was made based on a high heat wave forecast for the upcoming weekend in an effort to limit the risk of fire.

When the employees arrived at work at 5:30○a.m. the following Monday, they noted abnormal runoff of leachate from the compacted dirt road leading to the storage area. The leachate continued to flow by gravity towards the rainwater basin via a non-excavated area. The leachate was unable to seep deeply into the soil because the area consists of compacted, low-permeability clay.

The shut-off valve was closed, which allowed the flow to be isolated within the non-excavated area. The storm drain was isolated. No leachate was detected. The dirt road leading to the landfill cell in operation was de-compacted so that runoff water could infiltrate into the storage area and be managed directly as leachate.

It was estimated that 70 to 80○m³ of leachate had been spilt. The leachate was pumped into a concrete ditch, and the flows were diverted to the main leachate storage pond. The contaminated soil from the non-excavated area was stripped and stored in the storage cell in operation.

Human error was identified as the origin of the accident. On Friday evening, after his shift, a technician had forgotten to shut off the water used to spray down the storage area. A reminder was distributed to all staff on the importance of conducting the checks after having turned on the watering system. A warning light was installed in the site’s installations, to ensure that the shutdown operations are performed.