Fear about environmental damage from Marcellus Shale natural gas drilling is often trained on what could happen deep underground, but some of the gravest hazards posed by the process are driven in trucks, stored in tanks, carried through hoses and left in surface pits at natural gas well sites.

Concentrated chemicals, as well as wastewater containing toxic levels of salts and metals, are stored, produced or transported in large quantities at each well site, creating the potential for tainting drinking water or seeping into ponds and streams.

While recent enforcement action against Cabot Oil and Gas Corp. - the company deemed responsible for methane leaks and nearly two dozen spills in Susquehanna County in the last two years - has drawn attention to the danger of spills, information about the industry-wide frequency and impact has not been reported publicly.

See: Cabot Oil & Gas’s Marcellus Drilling to Slow After PA Environment Officials Order Wells Closed, Lustgarten, Abrahm . ProPublica. (2010.

See: Commonwealth of Pennsylvania DEP takes aggressive enforcement action against Cabot Oil.