At around 10:20 a.m., a leak was detected at a sugar and molasses storage site on an 800 m³ tank containing 110 m³ of molasses; 30 m³ of molasses had leaked out and mixed with rainwater present on the site from bad weather two days earlier. The operator noted that the canals bordering the installation were filled with this water-molasses mixture. The sea was also polluted by the mixture from the canals via an outlet. Crabs became stuck in the canals and on the banks.
An earthen dam was built to contain the discharge, while the molasses still present in the leaking tank was transferred to another storage tank. The outlet pipe leading to the sea was blocked off at around 3 p.m. The canal and outlet pipe were cleaned, and 240 m³ of the water-molasses mixture was pumped and transferred to containers, which were then transferred to a processing centre. The polluted soil recovered from the ditch cleaning operations was also sent for treatment at a specialised processing centre. The hole in the bottom of the leaky tank was noticed and sealed 5 days later.
The tank had been manufactured in 1967. The operator has invoked several hypotheses as to the origin of the leak:
- a weakening of the tank due to the rising water during bad weather;
- impact with a blunt object as the water subsided;
- a problem associated with obsolescence and corrosion.
In order to avoid this type of accident from reoccurring, the operator has made plans to:
- review facility integrity control procedures;
- organise a system in which rounds are performed with a verification checklist at the start and end of the day;
- assess the tanks’ structure (wall thickness, weak points, integrity of the concrete, etc.);
- install a retention basin around the molasses tanks;
- install valves on rainwater drainage pipes to close them off in case of problems;
- study the hermitic characteristics of the walls surrounding the installation (tank) and study the possibility of raising them as required.