When the lower layers of protection are effective, upper layers may not get much attention. But then something fails and other weaknesses exposed.
The Buncefield oil storage depot fire on December 10, 2005 provides an interesting examination of a fire at a site that most people probably considered safe. It was simply a tank farm, taking in various hydrocarbon fuels in batches via pipeline, and then distributing them in the surrounding area via tanker trucks.
By volume, it was the fifth-largest distribution center in the UK and it provided jet fuel to both Gatwick and Heathrow airports outside London. There were no distillation columns or other production units, and it was located in an industrial park with factories, warehouses and office buildings located quite nearby. Nonetheless, it had the capability to story 194,000 tons of hydrocarbon fuels, so in spite of its benign appearance, dangers lurked below the surface.