Report: Leaky Philly Gas Pipes Pose Climate Hazard

A report from an NPR project says leaky gas pipes in Philadelphia, and other large cities with aging pipe stock, are contributing to climate change.

A report from StateImpact Pennsylvania says that leaking gas pipes in Philadelphia are a massive problem. Those old pipes leak enough methane to cause changes to the climate.

It’s not just Philadelphia, of course, but Philly is an obvious example of a place where the problem is worst: An old, large city. Philadelphia has some of the leakiest pipes in the nation. It’s a long, interesting piece.

In Philadelphia, the city gates feed natural gas into 6,000 miles of pipe that run beneath city streets. The “mains” are the pipelines that run along streets, while the “service lines” connect to houses and businesses. About 1,500 miles of main – a quarter of the total – are made of cast iron, some of it dating back to the 1890’s. Cast iron is problematic. It’s strong but inflexible. Joints leak. Countless freeze-thaw cycles cause the cast iron to crack. Heavy trucks rumbling on top can make a pipe give way.

When the lines were installed, the natural gas running through them was wetter, and more suitable to cast iron.

Bare-steel pipe is also prone to leak because it rusts. Some steel pipe has a small electric current running through it, which prevents rust. This is called “cathodized steel.” Today, PGW is replacing its older cast iron and bare steel pipe with the more state-of-the-art plastic pipe. It costs an estimated $1 million to fix each mile of pipe. By PGW’s estimates, at the current replacement rate, today’s leak prone pipes, which includes both cast iron and bare steel, won’t be fully replaced by the year 2102.

Methane leaking into the atmosphere does cause a warming effect, and has a much more immediate effect than carbon dioxide emissions. A PGW spokesperson tells StateImpact Pennsylvania, an NPR project, that Philadelphia has reduced its leakage rate to 2.7 percent, a generally-accepted range for utilities.