PITTSBURGH—Around suppertime on June 3 in Clearfield County, a geyser of natural gas and sludge began shooting out of a well called Punxsutawney Hunting Club 36. The toxic stew of gas, salt water, mud and chemicals went 75 feet into the air for 16 hours. Some of this mess seeped into a stream northeast of Pittsburgh. Four days later, as authorities were cleaning up the debris in Pennsylvania, an explosion burned seven workers at a gas well on the site of an abandoned coal mine outside of Moundsville, W.Va., just southwest of Pittsburgh. The back-to-back emergencies were like a five-alarm...