Shale Gas & Water in the UK

Hydraulic Fracturing and its Impact on the UK's Water-Energy Nexus

Shale gas exploitation in the UK has made the headlines for the right and wrong reasons. Should the "fracking" industry fully develop in the country, what impact will it have on water resources, treatment and the environment? An independent review from CIWEM looks at the potential impacts.

By Laura Grant

Compared to other fossil fuels the overall water use intensity of shale gas is low. Claims by some opponents that the shale gas industry represents a threat to the security of public water supplies are alarmist.

This is according to CIWEM's report that calls for water and sewerage companies to become statutory consultees in the shale gas planning process regardless of whether they continue to provide and treat water for the industry. They must be engaged with early and provided with the right information to meet their duties.

Assessment of risks to the water environment

The impacts of shale gas extraction on groundwater are likely to be local, dependent on whether the geographical location of any productive areas of geology coincides with areas of particular water resource pressure and/or near to groundwater resources or sensitive aquatic environments. These will need to be thoroughly assessed during the planning stage to ensure they are protected.

If shale gas is to be developed safely, ensuring due regard for protection of the wider environment, exploration should not be permitted in areas where there is a genuine risk to valuable drinking water resources located in groundwater.

Groundwater including any local aquifers should be carefully delineated by the operator as part of the well design and fracturing risk assessment process. The mapping of the relationship between potential shale gas source rocks and principal aquifers should be used to assess applications with strong enforcement by the Environment Agency through planning or permitting controls to protect groundwater.

This would help to minimise the risks from the mobilisation of solutes or methane in areas of natural faults or in areas of shallow shale plays.

Contamination of aquifers from mobilisation of solutes and methane is unlikely where shale plays exist at depth in the UK. The British Geological Survey believes such contamination is unlikely to occur if shale gas exploitation is restricted to depths greater than 1500m.

Where the source rocks are shallower there could be a greater risk and companies will have to ensure that fracture sequences are monitored using performance standards. Fracturing operations should be examined as part of the well examination arrangements.

Loss of well integrity has been recognised as one of the pathways of contamination to groundwater quality and must be seriously considered by all appropriate regulators with construction closely monitored to ensure that best practice is followed.

CIWEM calls for seismic monitoring, in line with UKOOG guidelines, to be used to assess any potential impact on well integrity. This would be with the HSE undertaking an active role in visiting sites for verification inspections of monitoring operations and take enforcement action where it is found to be inadequate.

Contamination of soil, surface or groundwater from spills of returned waters is a considerable hazard. Risk assessments need to consider all potential sources of pollution, potential pathways and receptors. Evidence from the US suggests that the maintenance of well integrity, including post operations, and appropriate storage and management of fracking fluids and wastes are important factors in controlling risks.

For example, Massachusetts Institute of Technology reviewed 10,000 wells and found that of 43 pollution incidents related to natural gas operations, 50% were related to the contamination of groundwater due to drilling operations and 33% due to surface spills of stored fracking fluids and flowback water.

Water reuse

Returned waters from the hydraulic fracturing process require treatment as they may be highly saline and include naturally occurring radioactive materials. The nature of the substances concerned mean that the water may not be of an appropriate chemical composition to be sent to a typical public wastewater treatment works and may require specialist industrial treatment or pre-treatment in order to enable this.

At the exploration stage there seems to be enough capacity to treat returned waters as public treatment works are able to cope with a range of contaminants and there are a number of industrial wastewater treatment works in the UK.

However, returned waters are likely to be highly saline. To be able to treat by dilution a public treatment plant that discharges to an estuary may be needed. There are other technologies available but these entail greater energy consumption and cost. It is certain that if the industry grows, and wastewater volumes increase, water treatment capacity will need to expand to support it.

Reuse of flow back and produced water arguably represents the most sustainable process and given that there is common ground between the industry and regulator, they should work closely together to identify optimum solutions.

Research and development is needed in water treatment and decontamination technologies that exhibit reduced energy consumption, as well as into onsite and mobile treatment solutions that reduce the risks of transporting waste.

Assessing the impact

Accurate baseline environmental monitoring is essential to assess the impact of shale gas extraction on the environment and any implications for public health and should begin immediately.

Good data, measurement, and transparency by the industry are vital to environmental protection and public trust. Given the relative abundance of monitoring data in the UK, it may be comparatively well placed to develop a baseline in a comprehensive and cost effective manner.

CIWEM welcomes the BGS study currently underway into assessing baseline levels of methane in groundwater. Other programmes of study will need to be established in the vicinity of shale gas operations for both deep and shallow aquifers for radio-nuclides and other contaminants.

Public engagement

Despite the extensive media coverage of the issue in recent years and the often vociferous nature of opposition from a growing number of local pressure groups, ‘fracking' for shale gas, even at this very early exploration stage, is embryonic in the UK. So the question is not only what might the impacts be but will an industry develop at all?

While there has been much speculation on both sides of the shale gas discussion as to whether an industry might be viable, without further assessment neither the government nor the industry have the information to make a meaningful estimate of recoverable reserves at the current time.

Discrepancies evident between the projections made by opponents and proponents underline the requirement for clear scientific evidence and transparency to be at the centre of the debate.

It is important that there is clarity, robustness and openness in the messages coming from the senior parliamentarians on all these aspects. The polarised and politicised media debate does not help in this respect.

CIWEM's report recommends that government departments and agencies should actively promote informed understanding among stakeholders using clear scientific evidence, transparency and consistent messages, across a range of media and forums. Government ministers should ensure that their messages on shale gas are consistent with those of the Department for Energy and Climate Change.

Aside from the risks to the water environment, there are also risks from release of fugitive methane emissions, localised air pollution, landscape and visual amenity intrusion and the potential consequences of induced seismicity.

These are not dealt with in detail in CIWEM's report but will require a robust regulatory regime to protect the environment and to improve general public confidence in what is presently a highly controversial process. Not only this, but it is vital that should an industry develop that there are adequate resources for regulators for enforcement and monitoring.

Laura Grant is policy adviser at CIWEM (Chartered Institute of Water & Environmental Management). Shale Gas and Water is available from www.ciwem.org/shalegas