Pollution
Humain
Environnement
Economique

At around 1:30 p.m., a whitish liquid was reported in a ditch that runs along a cheese factory and flows into the canal joining the River Oust. The liquid was discovered by an employee of an inspection body who was conducting a monitoring round following the incident on 21 August (ARIA 50276). The operator immediately closed the sluice gate at the end of the ditch. This prevented the liquid reaching the river. A submersible pump was subsequently installed to prevent any further releases into the ditch. Between 4:00 p.m. and 6:50 p.m., a drainage services company pumped the 22 m³ of effluent out of the manholes and ditch and transferred it to the lifting plant connected to the wastewater treatment plant. About 1 m³ of effluent was discharged to the natural environment.

The submersible pump was left running to continuously pump the effluent into one of the defective sewers. At 7:00 p.m., the maintenance department began conducting regular rounds to ensure that the pump kept running smoothly. These regular rounds continued until the facilities were repaired. When the networks had been mapped previously that year, the area where the overflow occurred was identified as critical and work was scheduled to take place in mid-September. This work included repairing the secondary lifting station that caused the incident.

The release was caused by the progressive filling and subsequent overflow of the sewer located on the production plant side following the malfunction of the lifting pump that transfers its contents back into the lifting station towards the wastewater treatment plant. The release consisted of a mixture of brine, water, and cheese shavings. This mixture is less dense than milk or cream and the sluice gate retained most of the effluent, limiting the extent of the pollution.

The operator plans to communicate internally on the incident, its causes and its consequences and to establish a schedule for carrying out the work needed to prevent the recurrence of such incidents.