Subsequent to a handling error (inversion of transfer openings) during a delivery at a wastewater treatment plant, 1,500 litres of bleach overflowed into a tank containing aluminium polychloride. The vehicle arrived around 8:30 am onsite and was set up at the transfer station by 8:50. The driver’s transport documents were not inspected, and the transfer checklist indicated in site procedures was not drawn up. The driver connected the transfer hose to the cistern; a technician indicated to him both by hand gestures and orally the specific transfer opening on the station’s manifold. Once the sleeve had been connected onto the opening identified by the technician, the driver activated the lorry compressor, and the transfer operation got underway at 9 am. Around 9:15, the station technicians detected “problems with the aluminium polychloride tank level probe”; they recognised their error – the product received was bleach – and initiated the alarm procedure. The ongoing delivery was halted. The incompatible mix had caused a release of chlorine in the premises on the 3rd basement. The lorry-cistern driver as well as 3 site employees experienced a malaise and were hospitalised for medical observation.
An 80-m safety perimeter was set up, and the facility’s custom ventilation made it possible to evacuate the vapours via a chimney towards an undeveloped zone. Pedestrian traffic around the site periphery was prohibited for several hours.
A series of negligent actions led to the accident: failure to verify the driver’s documents upon arrival at the site, wastewater treatment plant technicians without the ADR certification, absence of posted procedures at the delivery point, oral instructions hastily recited by plant technicians without verification, a delivery “out of habit”. The transfer openings were identified, yet were missing the corresponding product ONU codes. The driver, who had been trained, should have noted the instruction error committed by the technician, but instead simply applied the indications without raising any questions.
The transport company reminded its drivers of the safety measures to be respected upon arriving onsite: inspection of the transfer station (environment, indications provided on the openings, safety), transmission of transport documents to the onsite transfer agent along with specifications on the delivered product, refusal to handle the client’s installations without signed authorisation.
