Darien Fire Marshal Bob Buch said weather conditions made it much less likely that when natural gas started coming out of a gas main opened up by a construction crew, “we didn’t end up with a catastrophe.”
Hot, muggy conditions or an atmosphere “heavy air” that would have kept concentrations of the gas lower to the ground would have needed just a spark near the pipe to blow up, Buch said.
Crews work on the ruptured gas main at the intersection of Abbey Road and Intervale Road.
But natural gas is lighter than air, so it tends to rise if conditions don’t hold it down, he said.
“It’s really tough to judge, but it could’ve been an ugly scene had we had a spark at the [gas] main,” he said. “We were very fortunate that we had no injuries and we didn’t end up with a catastrophic incident.”
The smell from a natural gas leak does linger — it’s a chemical additive put together with the gas during the production process in order to alert people to the presence of the gas, which is naturally odorless, he said. The chemical gas is heavier than the natural gas itself.
The odor was “very prevalent as far as Middlesex Road and Noroton Avenue,” after the leak, he said.
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About 35 firefighters, volunteers from all three town departments, went to the scene, and they joined police in going door to door for about a quarter mile around the leak site at the corner of Intervale and Abbey Roads, strongly urging residents to evacuate, Buch said.
No one was forced to leave, but firefighters delivered “a strong message that we were trying to get people to leave,” he said. “Most people were extremely cooperative” and did leave, he said. By about 1:30 p.m., he recalled, Eversource had shut down the gas going to the leaky pipe, which had been ruptured shortly before 12:30 p.m.
With gas service being restored a bit less than 24 hours after the incident, and with temperatures in the 20s rather than much lower, the risk of pipes freezing in unheated homes is less, Buch said — but it could happen if the wait was longer.
“You’ve got pretty close to a good 24-hour window when you don’t have things freezing up,” in these conditions, he said. “At the temperatures we’re at [overnight] most of the homes should’ve been safe.”
He added that there were a good number of homes in the neighborhood that had oil heat systems rather than natural gas, despite the availability of the cheaper fuel.
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