Shale gas and groundwater FAQs

Are there any risks to groundwater associated with fracking?

Shale gas extraction and fracking has received a huge amount of media interest. Just like any other industrial process there will be associated risks, including the potential for groundwater and surface water contamination. This may arise from surface activities that may lead to spills associated with the storage and mixing chemicals at the drill/fracking site or the storage/management of fluids that return to the surface from the borehole, the so-called flowback and produced waters. Other potential pathways for contamination of groundwater include poor well-design and well construction, and the migration of contaminants along natural pathways into overlying aquifers. Understanding these risks is a very important step in the design and approval process and very strict controls and regulations are in place to reduce the risks to an acceptable level.

Is there likely to be an impact on groundwater?

There are two potential impacts on groundwater. The first is associated with the supply and consumption of water for drilling and fracking as groundwater may be considered as a potential source for this water. The second is contamination of groundwater. In both cases the regulations that apply to shale gas extraction will require a detailed risk assessment before any authorisation or permit is granted. Before granting a permit the relevant regulatory authority (e.g the Environment Agency in England) will need to be satisfied that the activity will not cause pollution of groundwater or lead to unsustainable abstraction. Once approved, monitoring of the environment will be required as part of permit conditions to demonstrate that no impact is occurring. To provide an independent environmental baseline against which this compliance monitoring can be compared, BGS is undertaking a National Baseline Methane Survey of UK groundwaters ahead of any shale gas development. The baseline study is not only restricted to methane. A wider range of chemical indicator parameters are also being measured and the results will supplement the data already published by the BGS and used to set groundwater threshold values (standards) for the EU Water Framework Directive.

What aquifers overlie the potential shale gas rocks?

The Aquifers and Shales webpages provide access to national scale maps which show the extent of, and spatial relationships between, the Principal Aquifers of England and Wales and major shale and clay units. This is the product of the Aquifers and shales project, which work was undertaken by BGS with the Environment Agency. We used the BGS Bedrock Fence Diagram (UK3D) and Aquifer Designation Data. The project examined the full extent of each rock type, identified where Principal Aquifers overlie shales and estimated the vertical separation between the different rock types forming the aquifers and those with potential for shale gas.

What percentage of the population use groundwater?

Groundwater supplies water to about 27% of the population across the UK. This proportion varies widely depending on the underlying geology, with the highest proportion of drinking water being supplied by groundwater in the south-east of England (over 70%). In this region the Chalk aquifer is the principal source of groundwater. In the north and west, water supplies come predominantly from surface water but groundwater is still important as it is also used for private domestic supply. The current estimated groundwater usage for public supply by regions: England, 35%; Wales, 2%; and Scotland, 7%.

What is the vertical separation between aquifers and shale gas sources?

The Aquifers and Shales webpages provide access to national scale maps which show the extent of, and spatial relationships between, the Principal Aquifers of England and Wales and major shale and clay units.

Where can I find further information on research on shale gas and groundwater in the UK and globally?

The BGS is currently carrying out the following projects in this area:

Contact

Contact Dr Rob Ward for further information