Expert says gas blasts rare, but danger is present

A chain gas explosion — similar to the one that tore through three Boston suburbs — could happen in Canada, though the possibility is unlikely, energy experts said Friday.

The multiple explosions that caused more than 20 fires and at least one death in Boston on Thursday are “very rare,” the director of the Queen’s Institute for Energy and Environmental Policy said in an email.

Warren Mabee said while the cause of the explosions in Boston is still unconfirmed, it appears the gas-distribution system became over-pressurized during repair work, causing gas to leak into multiple buildings and ignite.

He said most gas networks have alarms that trigger the distribution system to shut down before pressure builds, although it’s unclear why those didn’t work in this case.

“There are a lot of safeties built into the gas-distribution system,” he wrote.

“I can only speculate as to why they didn’t work in this case, but it may have had something to do with the upgrade that was being done.”

While the Massachusetts explosion may be unique due to the sheer volume of buildings affected, Canada is not immune to such tragedies.

In Ontario, there have been 179 natural-gas explosions and two fatalities in the last 11 years, according to the province’s safety regulator.

Those numbers, which do not include incidents caused by homicides and suicides, include 79 explosions at private dwellings.

The figures also do not include a tragic incident that occurred in 2003, when seven people died when an explosion levelled a strip mall in the Toronto neighbourhood of Etobicoke.

Enbridge Gas Distribution Inc. and several other companies were fined hundreds of thousands of dollars in the aftermath of the explosion, which was caused by a backhoe hitting a gas line.

But Mabee says even that incident did not cause the kind of chain event seen in Boston, “because there wasn’t any kind of overload on the system,” he wrote.

About 35 per cent of Canada’s energy needs are met with natural gas, according to the website of the Canadian gas association.