A waste treatment site, consisting of a waste sorting and composting centre and a post-operational storage facility, was flooded during a period of heavy rainfall accompanied by thunderstorms. Several consequences were observed:

• the site became inaccessible because roads were closed;
• the wetlands, stormwater pond, composting platform basin and leachate basin overflowed and spilt into the surrounding forest;
• the breaker protecting electrical components of the flare tripped under the effect of water;
• a mixture of rainwater and leachate accumulated between the road and a storage bin;
• a landslide of the roadway occurred allowing access to the quay;
• the runoff water drainage system became blocked;
• cracking and clay-laden mudslides occurred in the former storage area;
• the pumping stations of the storage bins were destroyed;
• the tarpaulin covering one of the leachate basins had risen up to the level of the anchoring trench.

The establishment was secured, 19 employees were temporarily laid off for technical reasons. Property damage was estimated at 0.31 M€ and operating losses at 0.1 M€. The operator replaced the damaged pumps and repaired the flare. The spilt leachate was pumped and taken to sewage treatment plants, and the roads were reopened.

Flooding had not been considered in the risk analysis. The operator now plans to monitor weather forecasts and adjust the heights of its basins accordingly.