An automatic fire alarm operated in a warehouse storing various materials including oxidising materials, solvents and various other chemicals in drums. The fire alarm was transmitted to the local fire service. By the time the fire service arrived, flames were shooting through holes in the roof. An explosion then occurred which broke the glass in the site gatehouse.
15 minutes into the incident another explosion occurred in a store holding oxidising materials. This blew out a roller shutter door, which hit the wall of a building about 10m away. This was now a serious fire engulfing both the oxidising materials store and an acid pen area. Drums of solvents were beginning to explode in the intense heat. Some of these exploding drums were propelled several hundred feet into the air.
The fire also spread to the roof of a nearby building on the boundary of the site and after 30 minutes from the alarm being raised another offsite building 30m away was beginning to be endangered. Several explosions then occurred engulfing the front of this second building. A flying, burning solvent drum also crashed through the roof in the main store area, immediately starting another fire. The off-site emergency plan was progressively implemented during the course of the incident.
The Fire Brigade was advised of the broad generic basis of the materials involved in the fire, and a print out of stored materials was obtained. This list was too detailed for the needs of the emergency services. The resulting smoke from the fire contained a cocktail of eleven different chemicals including hydrogen chloride. Approximately 3,000 residents were evacuated from their homes.
Failings in technical measures
- Lack of chemical segregation in the storage of a vast range of chemicals led to the extremely rapid and violent spread of the fire. Although the specific root cause of the fire has not been identified with a degree of certainty, a number of chemical routes to ignition in the event of spillage or exothermic reaction were present in the oxidising materials store where the fire started. The probable cause was leakage of a corrosive substance onto organic materials.
- Segregation of Hazardous Materials: incompatible substances
- The building was constructed in 1982 in accordance with the building regulations in force at the time. However, later HSE guidance suggests that a more substantial thermal barrier, such as a double brick wall, should have separated the store from the adjacent area containing drums of flammable liquids.
- Design Codes - Buildings / Structures: design of buildings to withstand plant excursions
- The drainage system on-site was adequate and able to cope with firewater run-off. Some minor pollution in the harbour did occur but this produced no obvious acute effects.
- Emergency Response / Spill Control: fire fighting