Research and analysis

Monitoring at shale gas sites: developing environmental quality baselines - summary

Published 17 December 2021

Applies to England

1. Chief Scientist’s Group report summary

This project applied statistical methods to environmental monitoring data from 2 shale gas sites in England to investigate how best to measure and describe the quality of the environment before activities associated with a shale gas site take place.

1.1 Why was this project needed?

Activities at shale gas sites have the potential to release pollutants into the environment. Understanding the initial air quality, surface water quality and groundwater quality at a shale gas site is an important part of managing the pollutant risk from these activities.

Environmental quality measurements are made before activities take place to provide an environmental baseline. If the environmental baseline has been adequately described, later monitoring results can be used to help investigate whether or not the site activities are changing the quality of the environment.

Not all variations in environmental quality are due to site activities. Some may result from seasonal variations, or emissions from other sources. Statistical techniques can be used to identify these variations in air and water quality so that they are not falsely attributed to site activities.

1.2 What did the project involve?

A previous Environment Agency report provided guidelines on the use of statistical techniques for checking whether monitoring data at shale gas sites was sufficient to describe environmental baselines and for investigating whether activities had caused a change in environmental quality.

In this project, the statistical guidelines were applied to environmental monitoring data from the Preston New Road and Kirby Misperton shale gas sites. Because these are among the first shale gas sites in England, a substantial amount of monitoring had been carried out by the British Geological Survey, the Environment Agency and the site operators.

The monitoring data covered several phases of activity, including:

1. Before onshore oil and gas activities began
2. Site preparation activities
3. Drilling, including waste disposal
4. Hydraulic fracturing
5. Gas extraction and flow-back of water from the well.

The hydraulic fracturing and gas extraction phases were only relevant to Preston New Road as these activities did not take place at Kirby Misperton.

For Preston New Road, the guidelines were to be used to see if the air quality had changed significantly between different phases of activity. However not all of the air quality monitoring measurements were available for this project. This meant that the project could not fully investigate changes in air quality before and after shale gas activities began at Preston New Road.

1.3 What were the findings?

For both sites, the environmental monitoring measurements were found to be sufficient to describe baseline air, surface water and groundwater quality. Baseline statistics were developed and illustrated with graphs and other diagrams.

The project found that one year of measurements is likely to be enough to characterise baseline conditions for air quality and should also be the starting point for designing baseline water quality surveys.

Although the simplest definition of a baseline period is the time before any activities begin at a site, this project found that a simple breakdown into “baseline” and “operational” phases may not adequately reflect real-world complexities in the development of a site. For example, a fully informed baseline would identify existing trends (are things already changing and for better or worse?), impacts of other local changes, how mitigation measures for one issue may affect others (sound barriers at 9m tall affect air flow and so air quality).

1.4 Recommendations

The study recommends that site operators and regulators should identify and agree the priority substances to be measured before investing in detailed baseline monitoring. The study also gives recommendations on what statistical analyses to use for air quality and water quality environmental baselines.

Further analysis would help to establish the minimum requirements for data capture and quality, and the number and position of monitoring locations. This would ensure that changes in air and water quality due to shale gas operations could be identified accurately when compared with baselines.

1.5 Publication details

This summary relates to information from project reported in detail in the following output:

• Report: SC170018/R
• Title: Monitoring at shale gas sites: developing environmental quality baselines

Environment Agency project manager: Mark Bourn, Chief Scientist’s Group

Research contractor: Ricardo Energy and Environment.

This project was commissioned by the Environment Agency’s Chief Scientist’s Group, which provides scientific knowledge, tools and techniques to enable us to protect and manage the environment as effectively as possible.

Enquiries: research@environment-agency.gov.uk.

© Environment Agency