FROSTBURG, Md. (AP) — Researchers commissioned by a state panel studying natural gas drilling in western Maryland have come up with recommendations.

The researchers studied hydraulic fracturing, which uses sand, water and chemicals to free gas from shale. The technique has sparked an energy boom but is blamed for polluting groundwater.

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The authors say that until it can be done safely near drinking water sources, drilling shouldn’t be allowed within 2,000 feet of the surface. They also say wells should be closed-loop systems so that any spills can be contained, and that there should be no net loss of forest land. The report was prepared by researchers at the University of Maryland’s Center for Environmental Science.

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No drilling permits can be issued until the panel issues its final report in August 2014.

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