Blast from the past

1. Fifty-one out of 61 engine companies attended the blaze.

2. The blaze underway.

3. One Meridian Plaza before the blaze.

4. One Meridian Plaza in flames as seen from above.

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PHOTO: BOB LARAMIE, PHILADELPHIA DAILY NEWS

ONE MERIDIAN PLAZA FIRE, PENNSYLVANIA, USA—1991

PHOTO: SUPPLIED

2

PHOTO: JOHN AXFORD

BARRY LEE OAM

One Meridian Plaza was a 38-storey office building in Philadelphia, Pennsylvania.

The US$40 million, 150 m-tall steel and concrete structure was located across the street from Philadelphia City Hall. It was completed in 1972, in line with the city’s 1949 building code, which made no distinction between high-rise and other buildings. This was superseded in 1984 by codes requiring automatic sprinklers in new buildings.

At the time of construction, sprinklers were installed in below-ground service levels only. The building was being retrofitted with sprinklers at the time of the fire, but protection was installed on floors 30, 31, 34, and 35 only, together with parts of floors 11, 15, and 37.

On Saturday 23 February 1991, a fire broke out around 8.30 pm on the 22nd floor when a pile of renovators’ rags, soaked in linseed oil, spontaneously ignited. It burned for 19 hours, spreading from floor to floor and gutting each, until it reached the 30th floor and was extinguished by ten sprinklers fed through the fire brigade ‘Siamese’ connection.

By the time firefighters reached the 11th floor, the building had lost power due to fire-damaged cables. The emergency generator did not function, and the building was without electricity for the entirety of the event, causing firefighters to work in darkness and without the aid of elevators.

The original dry riser hydrant system was replaced by a wet riser system in 1988 to facilitate the installation of automatic sprinklers. Two fire pumps were also installed.

However, the height of the pressure zones and the installation of these pumps caused standpipe (hydrant) pressures to exceed National Fire Protection Association code requirements. This meant that pressure reducers were necessary, so pressurerestricting devices were fitted on floors 26 to 30, and pressure-reducing valves on floors 13 to 25. The pressurereducing valves were on incorrect settings (resulting in insufficient pressure for firefighting) and could only be adjusted with a special tool, but no technician who could do this was available until several hours into firefighting operations.

At the height of the fire, 51 of the city’s 61 engine companies were operating at the scene. Twenty-four firefighters were injured, eight had near misses, and three tragically lost their lives after becoming disoriented in heavy smoke on the 28th floor.

One Meridian Plaza never reopened and was demolished in 1999. The fire had caused an unprecedented loss of US$4 billion in litigation and US$100 million in direct property loss.

Many lessons were learned from the fire, including: „ the need for automatic sprinkler protection in very tall buildings „ acknowledgement that combined sprinkler and hydrant risers should be zoned so that pressure-reducing valves are not needed at hose connections „ if pressure-reducing valves are fitted, they need to be inspected regularly to assure reliable operation „ curtain walls should be protected to limit fire and smoke spread at exterior walls between floors „ primary and secondary power cables should be routed separately.