"In 2007, Rick Kinder was working for a contractor, building a house in southern Colorado. The workers had just finished putting in all the doors, windows and sealing the house. Kinder and a colleague were working in the crawlspace, hanging insulation.

"And we just heard this big roar and then a big boom, and it threw us against the walls, and it just blew the whole top of the roof off," Kinder says.

He and his colleagues didn't know it, but they were building on top of an abandoned gas well that was leaking methane — an odorless and highly explosive gas. No one was killed in the explosion, but the blast sent Kinder into cardiac arrest. He ended up having a quadruple bypass. ...

In most states, there is no requirement for homeowners to be notified about abandoned oil and gas wells on their properties."

5 minute audio story

http://www.npr.org/2016/05/30/474100388/hidden-abandoned-dangerous-...

also, map of abandoned gas wells in Pennsylvania:

http://frack.skytruth.org/abandoned-orphan-wells/pa-abandoned-and-o...