State and federal agencies have allowed a company mapping the Marcellus Shale gas formation to detonate 10 of 131 underground charges it installed without authorization on a mine-reclamation site in Fayette County.
And the state Department of Environmental Protection and the federal Mine Safety and Health Administration could soon allow detonation of many of the rest.
In April, the DEP and MSHA ordered CGGVeritas Land Inc. to remove all the explosives because some were outside the company's state-approved seismic testing area and others raised concerns about the stability of a coal ash dump and slurry impoundment on the site.
But DEP said Thursday that 10 "shot hole" charges, each containing 3.3 pounds of explosives buried 20 feet to 30 feet deep, were detonated Tuesday and Wednesday. All were outside the area approved for seismic exploration in CGGVeritas' DEP blasting permit.
CGGVeritas uses the explosives to produce seismic shock waves that are measured to create a map of gas-bearing shale. Natural gas drilling companies use those maps to determine where to locate their wells.
Also Thursday, MSHA said that, based on its "technical reviews," the Texas-based seismic testing firm can detonate all of the "shot holes" drilled on the 500-acre Matt Canestrale Contracting Inc. coal ash disposal property, except for 20 on or near the slurry impoundment.
MSHA spokeswoman Amy Louviere said the agency is collecting additional information at the site and might eventually allow detonation of those.
Last week, CGGVeritas, which is gathering geological information for Chevron, had to dig up three of the charges from holes less than 300 feet from homes in the village of LaBelle in Luzerne.
Residents hear the explosions and are concerned, but regulators haven't provided any information or reassurance, said Lisa Graves-Marcucci of the Environmental Integrity Project, a Washington, D.C.-based advocacy group that has been active about air pollution problems in LaBelle.
"This is a mine site, and DEP should require the operators to comply with blasting rules for mine sites, which requires notice to the citizens, a pre-blasting survey and a publicly available blasting schedule," Ms. Graves-Marcucci said.
DEP spokesman John Poister said department inspectors were at the Canestrale property earlier this week to oversee the detonation of the charges and collect information to determine which of the remaining ones can be detonated.
"The information ... should be useful in assessing the appropriate solution for all the remaining charges, which are located both within and outside the coal refuse disposal and coal preparation plant permit area," Mr. Poister said.