Following two home explosions in a rural area of northwest Pennsylvania within three months of each other, Sen. Bob Casey (D-PA) Monday called for federal help to protect the public from risks associated with the development of shale gas in the Marcellus and Utica plays.

"We need to ensure that Pennsylvanians, as well as all U.S. residents, are not in any danger from the extraction of these valuable domestic sources of energy," Casey wrote in a letter Monday to Department of Energy Secretary Steven Chu. "The access to new sources of gas in the Marcellus and Utica fields has the potential to provide good, high-paying jobs. Yet these particularly memorable incidents [home explosions] require credible efforts at mitigating risks to the public."

Since December two homes in McKean County, PA, (the state leader in drilling permits for oil and natural gas wells) were destroyed in explosions -- the first on Dec. 12, 2010 and the second on Feb. 28. "The belief that the source of the explosions is some type of thermogenic gas migration caused by extensive drilling appears to be widespread," he said.

Two elderly residents were injured but survived the first blast. The owner of the second home was not at home at the time of the explosion. "The McKean County homes were located about two and [a] half miles from each other in neighborhoods bordering Hedgehog Lane, where oil and gas drilling activities had caused methane gas infiltration into drinking water wells, leading to taste and smell impacts," Casey said.

Schreiner Oil & Gas Inc., the company involved, was ordered by the Pennsylvania Department of Environmental Protection to restore the water and has been providing bottled water to the impacted neighborhood.

"The explosion of the two houses in close proximity to this troubled area certainly appears to be more than coincidence, yet the phenomenon is poorly understood and there is currently no way of preventing or even predicting when such incidents may occur," Casey said. "According to the Pennsylvania Department of Environmental Protection Emergency Response Program, there have been dozens of gas migration incidents in northwestern Pennsylvania recently."

In addition to the home blasts, there have been other nonresidential incidents in the Mt. Jewett Borough and a well ignition in Tally-Ho, both located in McKean County. "While investigations are ongoing, the initial determinations are that these harrowing incidents were not caused by any gas utility issues. Rather, it appears that the gas may have migrated from deep underground during periods of high barometric pressure coupled with seismic activity and extensive new deep drilling activities," Casey said.