An investigation from Technical Safety BC has found the cause of an explosion at CFB Comox was an excavator hitting a gas line.
The explosion saw debris shot away from the site, with a boom that could be heard across the Comox Valley last November. It injured 28 personnel with one of the individuals flown to Vancouver for surgery sustained on their legs.
Investigators found that an excavator hit and ruptured a natural gas line while installing new perimeter drains around occupied military barracks.
They say the gas may have travelled from the damaged pipe and into a 1.2-metre-tall crawl space and then further into the mechanical room.
Once inside, the fuel and air would have mixed. According to the report, natural gas appliances were running at the time and it is likely the fuel and air mixture came into contact with a pilot light.
“The proximity of the break/leak in the natural gas line would allow the natural gas vapours to flow through the passive air openings and an open doorway into the mechanical room,” said the report.
“The natural gas/air mixture would first accumulate in the upper portions of the room. When the air/fuel within the proper mixture came in contact with a competent ignition source, ignition of all of the air/fuel mixture would be almost instantaneous.
“This would result in an overpressure inside the structure and would cause the damage observed. “
The report says debris was found as far as 106 metres from the explosion site. The building was undergoing exterior renovations and multiple areas collapsed in the explosion.
The report adds natural gas was the only ignition source on the site.