In a paper mill, the accidental mixing of incompatible wastes generated gas with a pungent smell that caused headaches among several workers.The paper mill is installed on 2 sites a few kilometres apart. As part of the manufacturing process, sludge from the wastewater treatment plant (WWTP) of the 1st site is provided to the 2nd site using a tanker truck. A subcontractor collects the waste and dumps it in a chest that supplies the production line L5 on the 2nd site.

On the day of the accident, the sludge removal lorry was still carrying 30 litres of pyrolysis gasoline (pharmaceutical solvent residue) that, when mixed with WWTP sludge, generated gaseous emissions. The 2 technicians present during material loading noticed a slight odour but were unable to identify the origin. The mix was therefore poured into the chest at 10 am before supplying the L5 line, where the odour had become very pungent, causing 5 workers to complain of headaches.

The ambient heat led to gassing Lobby 5, where employees were evacuated. Machine L5 was shut down. Notified by the operator, fire-fighters conducted onsite surveys using gas detectors, resulting in the shutdown of Line L6 and the evacuation of all plant personnel. The chest at the source of this accident was ultimately located and the buildings ventilated. Fire-fighters approved restart of production line L6 at 2:30 pm. Since irritating odours may have lingered for another several hours, they advised workers to be paired up. The chest was drained and cleaned the next day and then aerated for 3 full days; non-toxicity controls were performed following the resumption of water flow on 11th January; results of the analysis on potentially fouled circuits authorised restarting Line L5. The Classified Facilities Inspectorate, alerted during the afternoon of the outbreak, requested a 24-hour monitoring of benzene concentrations in effluents stemming from Lines L5 and L6: all benzene rates were below 1 µg/litre. The operator commissioned a subcontractor to dispose both the contaminated sludge and paper output during the accident. He strengthened material receipt controls and wrote a building emergency evacuation procedure.