"PITTSBURGH -- Unions and environmentalists have found one point of agreement in the bitter debate over the natural gas drilling boom: fixing leaky old pipelines that threaten public health and the environment. It's a huge national effort that could cost $82 billion."
"The leaks are a problem because methane, the primary component of natural gas, is explosive in high concentrations and is also a potent greenhouse gas that contributes to global warming.
The Department of Transportation estimates that more than 30,000 miles of decades-old, decaying cast-iron pipe are still being used to deliver gas nationwide. In 2011, the American Gas Association estimated the billions in costs for replacement or repair."