Six scary facts about New York City's ancient gas lines

An apartment building explosion in lower Manhattan Thursday left at least 12 people injured, three critically. The Wall Street Journal is reporting a preliminary investigation has determined the incident was caused by a gas explosion.

It comes just a year after a similar incident in Harlem left eight people dead.

Last year, the Center for an Urban Future issued a report on the state of New York City’s aging infrastructure. It’s pretty grim all around, but we pulled the six scariest figures as they relate to New York’s gas delivery system.

The average age of New York City gas mains is 56. A that’s not even the oldest infrastructure in the city. The national average for leaky pipelines is 44.

Sixty percent of Con Edison’s gas mains are made of leaky materials. It’s 48 percent for National Grid, the other gas main company in New York City. ConEd has not yet commented on the incident. That adds up to 3,321 miles of leaky gas mains, double the rate of Philadelphia, which actually has about the same miles of gas pipes.

Con Edison experienced 83 leaks for every 100 miles of main in 2012. That’s according to the federal Pipeline and Hazardous Materials Safety Administration. Corrosion was responsible for a total of 427 of these leaks.  Con Ed has 2,234 miles of gas mains.

The city gets 98 percent of its electricity from natural gas. And it meets 65 percent of heating needs. Natural gas is cheap and environmentally friendlier than other fuel sources, and demand is growing, the center said.

More than one in five of ConEd’s gas “services,” the pipes that carry gas from the mains to individual buildings, were built before 1960. And 24 percent of these are made of leaky materials. National Grid has a much lower rate for these thanks to an “aggressive” replacement program undertaken by the Brooklyn Union Gas Co., it predecessor.

Replacing a mile of main in New York City costs approximately $2.2 to $8 million. Con Edison is targeting the replacement of an average of 30 miles of cast iron pipe each year, but the center said “a more aggressive replacement schedule may be warranted.”

Rob covers business, economics and the environment for Fusion. He previously worked at Business Insider. He grew up in Chicago.