Manhole explosions add chaos to morning rush

You might call it The Miracle of the Morning Rush.

Two manhole explosions rocked the Financial District Thursday morning, shattering windows and forcing the evacuation of two office buildings. Yet just one person was injured — and only minorly, at that.

Clearly, it could have been worse.

“I was having coffee at Starbucks with my friend and I heard an explosion,” said Thomas Kader. “We looked outside and there was a large flame that went up in the air.”

“It was a loud boom and it shook the building and it shook everyone on the floor,” said Jeannie Fitzgibbons, who works in the area. “If it’s infrastructure, well this is an old city. So maybe there needs to be a little more quality control.”

It could very well be infrastructure, said Nathan Phillips, PhD, an environmental scientist at Boston University, who has written extensively about the impact of underground gas leaks.

“We have (gas) pipes that are over 100 years old in Boston and they fail,” he said. “They leak. Every twelve feet, they’re called joint leaks where the sections fit together.”

Phillips said Boston shares an aging natural gas infrastructure with many cities on the Eastern seaboard. Explosions happen when the insulation on high voltage lines that run with gas pipes wears down.

“The infrastructure is old,” he said. “It’s leaking. And if it builds up to about five percent gas in a confined space — and if there is a spark — then it can explode.”

The results can be devastating — with manhole covers weighing some 300 pounds.

It’s unclear why these two manholes exploded — though Boston Fire Department Deputy Chief Brian Tully said it may have been an ‘overpressure situation.’

“When a lot of energy is being used sometimes heat builds up, pressure — and sometimes things let go,” Tully said.

Phillips said the manhole explosions could be seen as a symptom of a larger problem.

“The number one diagnostic for problems with gas infrastructure that is kind of not well known are manhole explosions,” he said. “We’re at a decision point as to what direction we need to go for safe, clean energy to heat our buildings.”

Phillips said one approach is to rebuild the current system. He doesn’t favor that.

“Get off combustible, explosive gases that we’re piping under our streets and into our homes and move to electric-based heating,” he said.

But Cynthia Rudin, PhD, a professor of computer science and engineering at Duke University, says that may not be economically feasible.

Rudin developed, for New York City, a way to predict which manholes merit attention — so as to help prevent explosions.

Could that be done in Boston?

“It depends on if the power company can maintain a database,” she said — and New York’s is impeccable.

“They had data dating back all the way to the time of Thomas Edison,” she said. “And they had every cable that was installed underground, when it was installed, what kind of insulation it had, what type of material the cable was — was it aluminum or copper.”

Additionally, the power company in New York had data on power outages and other customer issues with the grid — something suggestive of a manhole in need of attention — as well as manhole inspection data.

“If the database can actually faithfully maintain this data, you can use that data to predict where events are going to happen in the future,” Rudin said. “I don’t know how many cities kept track of their data the way New York did.”

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