On Friday July 11, 1970, staff at the Criterion Hotel on George Street detected the odour of gas in the hotel’s basement. The gas company sent an inspector who soon found a leak in the basement adjoining George Street. He instructed that the wall be ‘clayed up’ to prevent further seepage.
What is LPG?
LPG is a generic name for propane gas and butane gas. Domestic gas at the time consisted of steam reformed liquid petroleum gas – propane and butane, which generated a mixture of hydrogen, carbon dioxide and carbon monoxide which was then enriched with LP gas.
It is highly flammable and dangerous if not used safely, and historically used for heating and cooking. At normal temperatures, LPG is colourless, odourless and heavier than air. In the 1970s and 1980s the Australian government encouraged the use of Autogas as a substitute for petrol by making LPG. Note that it is currently earmarked to be phased out by the year 2045 in favour of low emission and zero emission alternatives.
The city gas supply in 1970 was reticulated via cast iron pipes to consumers. It was this gas that was leaking that day.
Gas ignites
By 1 pm the air to gas concentration had reached optimum concentration. It only required a spark to ignite. It was lunch hour, and the city pavements were filled with pedestrian traffic when disaster struck at 1.05 pm. At the epicentre of the blast, a fireball was unleashed; half metre thick chunks of concrete were hurtled onto the roadway; manhole covers were shot 15 metres or more into the air. Portions of footpaths from Queen Street through to Adelaide Street along George Street were cracked as though hit by a giant sledgehammer.
A witness known to the writer was walking along Burnett Lane near George Street when she heard a rumbling that seemed to follow her, then there was a loud, terrifying blast. As she turned into George Street, she found victims amidst pools of glass as the plate glass windows in the office buildings had been blown out. She described it as a ‘war zone.’
There were three explosions in quick succession that sounded as one. Detectives from the Brisbane CIB which was situated a few hundred metres south on George Street, were soon on the scene to help, then investigate the cause of the explosion.
Young woman is tragically killed
An 18-year-old female office worker was tragically killed as she crossed at the lights at the intersection of Queen and George Streets. She’d gone ‘up town’ to purchase shoes in her lunch hour.
Emergency services personnel assisted the 37 injured who lay crumpled amidst the debris field of iron, concrete and glass whilst hundreds of city workers found themselves locked out of office buildings that had been cordoned off.
Testing a theory
Police had three pieces of evidence to test the theory that the traffic light control box had initiated the explosion.
- There was damage to the control box, especially in the vicinity of the make/break assembly.
- The traffic constable on duty informed the head of the Emergency Squad and chief forensic scientist, Detective Les Bardwell, that when operating the switch and after inserting the key, he normally could hear the click as the switch made contact, but in this instance, he heard the explosion within the control box.
- Bardwell decided to test his theory that the traffic control box had initiated the explosion buy testing with Freon gas, which is a non-inflammable, heavier-than-air, and an inert refrigerant which can be identified with a gas detector. He set out to track, in reverse, the path that the domestic gas would have travelled along the trench and up to the switch in the traffic control box. He obtained a quantity of freon gas and released it from the traffic control box where it permeated down through the traffic box conduit and to the three manholes where the explosion had occurred… thereby confirming his theory.
Cause of gas leak confirmed
The Brisbane Gas Company later discovered a broken gas main in the cast iron pipe at the junction of George and Adelaide Streets. The detectives were present when the broken pipe was removed and it was obvious that it had been a recent break, probably caused by heavy traffic turning at this point.
This story was inspired by Les Bardwell’s story ‘Brisbane Gas Explosion’ from his anthology of works titled ‘No Stone Unturned.’ It was researched and rewritten by Museum Assistant Debra Austin using the best archival resources available.
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“FROM the VAULT – Deadly Gas Leak on George Street” by the Queensland Police Service is licensed under a Creative Commons Attribution (BY) 2.5 Australia Licence. Permissions may be available beyond the scope of this licence. http://creativecommons.org/licenses/by/2.5/au/legalcode