A storm flooded a “Seveso”-rated fertiliser plant employing 97 staff and producing ammonium nitrate pellets.

The installation experienced a 20-hour current outage. During cleanup of a small stream running near the site 48 hours later, the 63-kV line supplying the site was affected by the outage and the plant would ultimately go without electricity for a full 7 days; the production unit however remained operable on backup power throughout this period thanks to its cogeneration equipment.

Damages were estimated at 4.5 million francs: a loading arm was down, unusable rail track, a number of roofs and fences damaged, and an empty railcar derailed subsequent to an SNCF Railway Company switching error that routed to the site a set of 25 railcars, though the line’s capacity was only designed to accommodate 22.

Several areas on the GARONNE River side of the embankment were opened and then completely submerged by the height of floodwaters (2.6 m). An 80-cm wave swept over the Ambès peninsula. The main difficulty encountered was the slow speed at which water was flowing from the ground towards the DORDOGNE and GARONNE Rivers, given that the existing discharge system (consisting of local streams, gates and valves) had not performed adequately as a result of improper maintenance. The damaged rail track throughout the zone was still unusable 2 weeks after the storm had passed, as the teams assigned to clean up and restore service required a long time to access the track due to flooded conditions.

These floods affected some 10 companies (ARIA 17316 through 17324) and underscored the vulnerability of some Seveso sites. An update of the relevant safety reports and internal emergency plans would be requested of the various site operators so as to specifically incorporate flood risks. The creation of a Permanent Secretariat for Industrial Pollution Prevention (S3PI) overseeing the 4 concerned municipalities was viewed as the appropriate entity to coordinate these problems with all actors involved.