Pollution
Humain
Environnement
Economique

At around 6:00 p.m., a fire broke out in a cell containing sulphur-contaminated soil at a hazardous waste storage site. The operator extinguished the area with inert materials and doused it. The technicians finishing their shift at 9:00 p.m. were instructed to monitor the area closely using the site’s video cameras.

At around 7:45 p.m., they saw smoke rising from 350 m² of contaminated soil. The operator tried smothering the fire, but this failed. The firefighters were called in. Assisted by a unit of experts in chemical fires, they put the fire out at around 10:15 p.m. The area was monitored. The eyes of three firefighters were irritated by the dust. The firewater was treated with leachate.

The sulphur in the contaminated soil (10% on average, with a content ranging from 4.8% to 23%) ignited. The dry and very windy weather dried out the contaminated soil inside the cell, creating ideal fire conditions. The fire may have been ignited by mechanical friction from a crawler excavator that was used to level the area shortly before. The technician had left the area immediately after these operations without noticing anything unusual.

Before the contaminated soil had been received, it had been tested by an independent body that had established that it was not flammable solid waste. The tests will have to repeated under worst-case conditions, i.e., maximum sulphur content of the waste and minimum moisture content likely to be reached during storage in a cell.

Following the accident, the entire area was doused once more and then covered so that it was no longer on the surface of the cell and to allow the moisture content of the sulphur-containing soil to rise. The operator implemented a number of actions:

  • heavy machinery (especially tracked vehicles) may circulate only in certain areas and care must be taken not to place sensitive waste in or around traffic areas;
  • the site’s spray must be used to keep all types of contaminated soil wet;
  • the areas where contaminated soil is stored must be kept small by piling soil into several layers.