Federal data says 85,000 miles of bare-metal and cast iron gas mains carry natural gas to communities in the U.S. Many of these lines in the densely populated Northeast are more than a century old.
Mark McDonald, a natural gas expert who investigates gas explosions, says aging mains like those found under New York City are at risk for cracks and leaks. “That infrastructure is way past its service life, which is dangerous,” says McDonald. Explosions due to leaking gas lines happen at an alarming rate, according to a USA Today report that states a damaging or fatal gas leak has occurred nearly every other day in the U.S. for the past 10 years.
Kimberly Archie is a documentary maker who investigates and chronicles gas explosion cases says, "You can have a ticking time bomb under your house and you don’t even know it.”
Cast iron pipes, which represent a large share of the threat, tend to be most prevalent in heavily populated areas in the northeastern U.S. The natural gas industry is aggressively replacing those pipes with more durable materials such as plastic, but the cost of such replacement can run as much as $1 million per mile. Utility companies such as Con Ed and Public Service Enterprise Group (PSEG) are speeding up their efforts to replace old gas mains. New York's Con Ed has increased its line check surveys to 13 times a year and expects to replace 100 miles of line in 2016.