Leaks, like the one that is believed to have led to the explosion that killed eight people in East Harlem this month, are startlingly common, numbering in the thousands every year, federal records show.
Consolidated Edison, whose pipes supplied the two buildings leveled by the explosion, had the highest rate of leaks in the country among natural gas operators whose networks totaled at least 100 miles, according to a New York Times analysis of records collected by the federal Department of Transportation for 2012, the most recent year data was available.
The chief culprit, according to experts, is the perilous state of New York City’s underground network, one of the oldest in the country and a glaring example of America’s crumbling infrastructure.
In 2012 alone, Con Edison and National Grid, the other distributor of natural gas in the city, reported 9,906 leaks in their combined systems, which serve the city and Westchester County. More than half of them were considered hazardous because of the dangers they posed to people or property, federal records show. (There are more than 1.2 million miles of gas main pipes across the country. Last year, gas distributors nationwide reported an average of 12 leaks per 100 miles of those pipes.)
Most of the leaks in New York proved harmless, simply dissipating into the soil or air. But when gas finds an ignition source, the results can be deadly. Three separate episodes in Queens in recent years killed people, and a half-dozen others in the city left people injured, according to federal records dating back 10 years.
Elsewhere in the country, a rupture in a major pipeline in San Bruno, Calif., in 2010 caused an explosion that killed eight people. In 2011, a leak from an 83-year-old cast-iron main in Allentown, Pa., caused a blast that killed five people.
“It’s like Russian roulette,” said Robert B. Jackson, a professor of environment and energy at Stanford University who has studied gas leaks in Washington, D.C., and Boston. “The chances are, you are going to be lucky, but once in a while, you’re going to be unlucky.”
Striking in federal records is just how frequently there are near misses.
Last year, a Bronx woman awoke in the middle of the night to the pungent odor of gas. Her husband checked it out, but after smelling nothing unusual, he lit a cigarette. Suddenly, there was a flash of fire that left his face badly burned. In 2011, a 28-year-old man in Bayside, Queens, saw smoke coming from a basement utility room just before a small explosion blew the door open. The cause was traced to a leak in a 54-year-old steel main in the street nearby.
Nearly half of the gas mains operated by Con Edison and National Grid were installed before 1940, according to federal records. More than half of the mains are made of cast iron, wrought iron, or unprotected steel — materials that are vulnerable to corrosion and cracking, especially in cold weather. Indeed, there was another scare in the city on Saturday when a leak from a crack in a 108-year-old cast-iron main, maintained by Con Edison, in the Bronx caused the Fire Department to briefly evacuate two apartment buildings.
Communities across the country have been struggling to replace thousands of miles of these old, metal pipes with pipes made of plastic or specially coated steel that are less prone to leakage. Few, however, face as daunting a challenge as New York City.
