Addressing the Environmental Risks from Shale Gas Development

III.Environmental Risks and Best PracticesShale gas has received a good deal of attention recently for the potential negative impacts that itsdevelopment may have on the environments and communities in which it occurs. Instances ofwater contamination, air pollution, and earthquakes have been blamed on gas extractionactivities. A thorough understanding of the techniques used to extract gas from shale formationsand the safeguards that exist to prevent environmental damage is critical to assessing the sourcesand magnitudes of risk involved in shale gas development.Subsurface Contamination of Ground WaterA frequently expressed concern about shale gas development is that subsurface hydraulicfracturing operations in deep shale formations might create fractures that extend well beyond thetarget formation to water aquifers, allowing methane, contaminants naturally occurring information water, and fracturing fluids to migrate from the target formation into drinking watersupplies. With the notable exceptions of the shallow Antrim and New Albany Shales, manythousands of feet of rock separate most major gas-bearing shale formations in the United Statesfrom the base of aquifers that contain drinkable water. 18 (See Figure 5.)Figure 5. Target Shale Depth and Base of Treatable Groundwater in Select Shale PlaysSource: GWPCBecause the direct contamination of underground sources of drinking water from fracturescreated by hydraulic fracturing would require hydrofractures to propagate several thousand feet7