Understanding the public health implications concerning shale gas production and hydraulic fracturing
The intent of this document is to synthesize scientific information related to public health concerns of relevance to Canada about shale gas production (including the pre-production stages of drilling, hydraulic fracturing, and well completion, as well as abandonment). Current policy and regulations are not considered. For the most part, the environmental and public health implications relating to shale gas production also apply to other types of unconventional natural gas production using hydraulic fracturing, including that of tight gas and coal bed methane. Basic descriptions and definition of terms for shale gas production and the hydraulic fracturing process are provided in the NCCEH summary Overview of Shale Gas and Hydraulic Fracturing in Canada.
In general, public health impacts related to hydraulic fracturing and shale gas production are determined by the relative proximity of communities as well as by the pathways of exposure. In addition to distinct differences in the extent of shale gas production across Canada, it is recognized that there are variations in geological, hydrologic, landscape, cultural, social, and economic conditions, which also have a bearing on the potential public health impacts of shale gas production.
Shale gas production involves continuous activity over the day for seven days a week, often for a number of years. With hydraulic fracturing, there is added effort of injecting large volumes of water mixtures at high rates and pressures required to extract natural gas; more trucks are involved, drilling times are longer, pumps are more powerful and holding ponds are larger than in conventional gas production. The multi-stage fracturing is repeated consecutively on multi-well pad sites, which may house six to 21 wells per drilling pad. Due to the large number and size of the storage containers, mixers and pressure pump trucks, and the control operations, a multi-well pad can be 3-7 acres in size.