An explosion and a fire occurred during the night in a chemical plant during the manufacture of a silicon oil- and additive-based waterproofing agent.

A junior technician (hired 6 months back), recently assigned to this post, was left without supervision around 1.00 am to manage a process modified in June and implemented for the second time. Since the order of addition of reactants was not specified in the operating procedure, he loaded 800 kg of oil into the tank 1702 on level 1, started heating the reactor, went back to level 0 to pump the reagent. While going up to level 2 to fill a tank with water, he observed a kind of fog escaping from the tank 1702. The explosion that occurred around 3.00 am resulted in the formation of hydrogen generated by the decomposition of the silicon oil after the abrupt and uncontrolled addition of an extremely basic alcoholate. The fire that ensued consumed 500 tonnes of chemicals (mainly alcohols), spread to significant part of the site (7,000 m²) and resulted in a huge cloud of smoke.

The technician was thrown 10m away, suffered a concussion and sustained serious burns and injuries. During the rescue operations, 2 fire-fighters were injured and 15 other poisoned. Despite the difficulties encountered, the rescue workers brought the situation under control in 4 hours. Analysis of the air revealed low levels of CO and NOx. The absence of retention devices, unused pipes and malfunctioning of the internal waste water treatment plant led to the disposal of the fire water (cyanide compounds, pentachlorophenols, etc.) in the Brenne river, a tributary of the Cisse river. Both the Cisse and Brenne rivers were polluted over 23 and 5 km respectively wiping out all traces of plant and animal life: 20 tonnes of fishes, aquatic and terrestrial mammals were destroyed. A high phenol index was measured in the Loire river: catchments were shutdown on 9/06 depriving 200,000 inhabitants of Tours and the adjoining area of drinking water. The water supply was restored in 3 days with a ban however on human consumption for 8 days. Drinking water supply was arranged for 10 days. Material damage and operating losses of the company stood at 45 MF and 8 MF respectively.

The chairman of the company was given a 1-year suspended sentence and fined 120,000 F while the plant manager received a 6-month suspended sentence and was fined 60,000 F. The damages to be paid to the civil party stood at 800,000 F.

The accident resulted from a major organisational failure (absence of safety policy, incomplete procedures, etc.).

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