In a paper mill, a delivery driver mistakenly deposited 1.2○m³ of fabric softener into a bleach tank. As the 2 products are incompatible, a gas emission occurred. A security perimeter of 100 m was established, and 130 employees were evacuated from the site.

The tank was cooled by injecting water through its double jacket. The softener-bleach mixture was pumped out and then sent to a containment tank for treatment in the site’s wastewater treatment plant. The tank was deformed by the heat of the reaction.

Several operating circumstances led to the event:

• installation design: unloading area common to several products, identical unloading connections, locked unloading ports but with identical key,
• technician training: the technician responsible for the accident was used to draining sodium hypochlorite, but this was his first time unloading softener, and the delivery driver did not speak French.

Moreover, risk management related to the effects of incompatible product mixtures had not been taken into account in the site’s hazard study.

In addition, the containment tank collected water used during the reprocessing of the confined water, thus diluting the products collected. This operation diluted the confined products and delayed their processing. This can also be problematic if the confined water is not quickly evacuated.

The inspection authorities for classified facilities required the manufacturer to examine the possibility of modifying its collection networks.

Following the accident, the facility operator removed the personal keys for the unloading flanges and revised its procedures.

The incident did not generate any water pollution. The concentrations measured at the outlet of the wastewater treatment plant during the treatment of the confined water remained below the expected regulatory values.