Risk assessment of groundwater contamination from hydraulic fracturing fluid spills in Pennsylvania

Abstract

Fast-paced growth in natural gas production in the Marcellus Shale has fueled intense debate over the risk of groundwater contamination from hydraulic fracturing and the shale gas extraction process at large. While several notable incidents of groundwater contamination near shale gas wells have been investigated, the exact causes are uncertain and widely disputed. One of the most frequently occurring and widely reported environmental incidents from shale gas development is that of surface spills. Several million gallons of fluid are managed on each well site; significant risk for spill exists at several stages in the extraction process. While surface spills have been primarily analyzed from the perspective of surface water contamination, spills also have the potential to infiltrate groundwater aquifers. This thesis develops a risk assessment framework to analyze the risk of groundwater resource contamination in Pennsylvania from surface spills of hydraulic fracturing fluid. It first identifies the major sources of spills and characterizes the expected frequency and volume distribution of spills from these sources using results from a preliminary expert elicitation. It then develops a stochastic groundwater contaminant transport model to analyze the worst-case potential for groundwater contamination in local water wells. Finally, it discusses the range of risk perception and incentives from a wide-ranging stakeholder base, including industry, communities, environmentalists, and government. This thesis concludes that while the vast majority of shale gas operations do not result in large spills, the worst-case potential for groundwater contamination is high enough to warrant further attention; it also recommends increased inclusion of community stakeholders in both industry and government risk management strategies.