A sodium hydroxide leak occurred at midnight in a sugar refinery. The soda solution spilled into the retention basin of the reservoir.

This incident occurred subsequent to the break of a joint on a shutoff valve at the tank bottom that had been handled while planning for maintenance work. This valve was then reopened to allow for the pumping and transfer of soda from the reservoir to the user; these operations served to work on the joint and restore the situation to normal. The quantity of hydroxide spilled on the block supporting the tank and collected in the retention basin was evaluated at a few hundreds of litres at most, with 2 hours being required to perform the repairs and pump the aqueous solution.

The classified facilities inspectorate was not informed of the incident and only learned about it 2 months later during a site visit, after noticing the state of the retention basin, which had not been repaired by the operator. The basin, devoid of an anti-alkaline protective lining, was damaged, as were the associated tank supports. No infiltration into the soil was apparent. A 2nd incident also occurred around the same time (in December 2009), involving once again soda and this same damaged retention basin (ARIA 38027).

The inspectorate recorded the firm’s failure to inform of these recent events, as well as the noncompliance of the implicated basin. Injunctions and additional prescriptions were proposed to the Prefect in order to adapt the retention basin to the range of products it was capable of storing, in addition to overseeing operational monitoring for the time required to perform repairs and request an appropriate feedback analysis generated from these events.