While cleaning the lids and moulds used to produce Comté cheese in a cheese dairy, a certain quantity of cleaning solution accidentally entered the stormwater network resulting in aquatic mortality.

The cheese dairy stopped its industrial activity on 25/08 for 11 days in order to perform industrial maintenance. As a result, the usual discharges to the municipal WWTP were halted during this period. The employees took advantage of this stoppage to thoroughly wash the cheese moulds and pressing lids.

In order to perform this cleaning operation, a protocol for using an alkaline agent and a wetting additive (an oxygenated acidic liquid) was developed to impregnate the dirt in the cheese moulds. The protocol was established after consulting the cleaning product supplier which had already performed this operation in other cheese dairies. The soaking solution was prepared in a stainless steel tank in accordance with the recommended protocol. The process consisted of two cleaning cycles. The first one was performed on 27/08. During the second cycle, 3 days later, after the moulds had been allowed to soak, the technician forgot to open all the compartments in the tanker truck when emptying the solution from the tank. The only open compartment then overflowed as it was unable to contain the entire amount of solution. The technician stopped the transfer pump, opened the valves in the other compartments, and then completed the solution transfer operation. Six hundred-sixty litres of cleaner was reported to have been spilt into the stormwater system (i.e. 3.7% of the initial quantity).

The operator did not measure the exact consequences of this incident. As a result, the company’s management and the environmental safety manager were informed during the day of a minimised incident. As such, it was not considered necessary to inform the Inspection authorities for classified facilities. On Friday 02/09, the water enforcement board (water police) informed the environmental safety officer of abnormal aquatic mortality in the Lavernay sector, and then he went to the scene of the accident.

The operator took the following measures:

• the technician at fault was reprimanded;
• the technicians were reminded of the risks associated with the handling of cleaning products.

An action plan was established:

• all cleaning operations of an exceptional nature must be defined in accordance with a protocol validated by the environmental safety manager and conducted under his control;
• all of the site’s employees received remedial training on the use of cleaning products;
• review and formalisation of the information and alert procedure in the event of any incident affecting safety and the environment.

One of the 2 products used in the cleaning solution was identified as harmful to aquatic organisms and, given the consequences of the release, a special order was signed on 20/09. A monitoring programme was installed upstream and downstream from the site’s stormwater discharge point. Analyses are now conducted every 6 months.