Pollution
Humain
Environnement
Economique

Biocide used to treat wood overflowed at a wood wholesaler after a water inlet valve was unintentionally left open. The water/biocide mixture then flowed to an infiltration basin containing a lifting pump that sent it on to the site’s stormwater network and then to Hespérides creek.

The operator immediately took the following actions when it realised the discharge at around 7:00 a.m.:

  • it shut off the water supply to stop the incoming pollutant;
  • it turned off the lifting pump;
  • it covered the storm drain to contain the pollution on the site and limit discharges to the natural environment;
  • it pumped the remaining pollutant into a tank and its bunding.

Environmental consequences

An estimated at 80 m³ of pollutant was discharged to the natural environment. However, given the flow of water, which lasted all night long, the biocide was diluted. A laboratory was contacted to analyse the pollution levels of the groundwater and surface water as well as the creek’s sediment. The pollution killed some of the creek’s aquatic life. The initial laboratory results showed cypermethrin pollution in the groundwater and high concentration levels in the surface water and sediment. To determine changes in the pollution levels, the operator conducted a second round of pollution tests. The results confirmed the pollution.

Pollution management

A third round of tests was conducted. At the same time, a study to remediate the soil along Hespérides creek was conducted.

Measures taken

In a guideline memo, the operator reminded its employees of the consequences of such an event. A solenoid-operated device to automatically shut off the water supply is being considered in order to eliminate the risk of human error. The audible alarm system currently in place did not prevent the accident.