The Pennsylvania Department of Environmental Protection on Monday approved two disposal wells for wastewater from oil and gas production, attaching special conditions to the permits to control for seismic activity associated with similar wells in other states.

The wells in Highland Township, Elk County, and Grant Township, Indiana County, had attracted fierce local opposition from residents, who fear they might pollute groundwater or cause earthquakes. DEP said the operators, Seneca Resources Corp. in Elk County and Pennsylvania General Energy Co. in Indiana County, would be required to operate the wells at lower pressures to reduce the chance of tremors. It also will require the operators to install seismic monitors.

"After a thorough review, DEP determined that both applications meet all regulations, are sufficient to protect surface water and water supplies, and would abate pollution," said acting DEP Secretary Patrick McDonnell.

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