NY’s Exploding Manholes Pose Winter Hazard

Salvatore Grillo was walking his dog near Brooklyn’s Prospect Park on a cold morning in February when he heard what sounded like a muffled explosion.

Minutes later, emergency responders were hovering over the 71-year-old as he lay unconscious on the ground. Police said an underground blast had blown a cast-iron manhole cover skyward and the heavy metallic disk had come crashing down on his head.

Manhole “events” causing serious injuries have become all too common in the country’s largest metropolis. In the snowy first week of February, Con Ed tallied about 600 “smokers,” fires and explosions involving manholes.

Manholes are entry points to a labyrinth of electric cables, many of them aged and decaying, that snake underneath the city streets. In winter, melting snow mixed with de-icing salt can seep through, causing frayed low-voltage cables to fail. That can trigger fires, smoke and explosions that can send manhole covers flying.

“These incidents are yet another example of New York City’s outdated infrastructure. It’s well-known that saltwater and exposed electrical wires are a dangerous combination,” said New York’s Public Advocate Letitia James. “If we want a safer city, we must do more to address this issue.”

Cables have an expected lifetime of about 40 years, but in Manhattan, 5 percent of low-voltage distribution cables were installed before 1930. In addition, overheating and gnawing rats can hasten deterioration. It is the oldest electrical system in the nation.

In any single year, New York has 2,100 manhole incidents, or nearly six events per day, Con Ed estimates. Earlier this month, a smoking manhole exploded in Brooklyn, sending a worker scrambling for safety in an incident caught on video. On the same day, a parked Mazda was torched after a manhole beneath it spouted fire.

The problem is attracting attention. Donovan Richards, chair of the City Council’s Environmental Protection Committee, is considering a bill to push Con Ed to spend more on modernizing its infrastructure.

Manhole events “take a considerable amount of time and resources,” said Con Ed spokesman Allan Drury. “But our emphasis is on public safety and we are always looking for new technologies and methods to improve our system.”

For instance, the utility has been installing vented covers that allow for trapped gases to dissipate more easily.

This article appeared in print on page 15 of the March 4th, 2015 edition of Hamodia.