|R S Ward1, P L Smedley1, G Allen2, B J Baptie1, M R Cave1, Z Daraktchieva3, R Fisher5, D Hawthorn1, D G Jones1, A Lewis4, D Lowry5, R Luckett1, B P Marchant1, R M Purvis4 and S Wilde4. 2018. Environmental baseline monitoring: phase III final report (2017–2018). British Geological Survey Internal Report, OR/18/026.
With contributions from:
High-quality environmental baseline monitoring data are being collected in areas around two proposed shale gas sites near Kirby Misperton, North Yorkshire and Little Plumpton, Lancashire. Monitoring has now been on-going for over two years and has produced an internationally unique data set that will allow any future changes that arise from industrial activities at either or both shale gas sites to be detected and characterised, as well as providing a significant resource for future research. The monitoring includes: water quality, air quality, seismicity, ground motion, soil gas and radon in air.
This report presents the results of monitoring in the Vale of Pickering, within which the Kirby Misperton shale gas site (KM8) is located, for the period April 2017–March 2018. It also includes the results of atmospheric composition measurements made near the Little Plumpton (Preston New Road) site. Earlier results and other monitoring in Lancashire are reported elsewhere and can be accessed from the British Geological Survey’s website[note 1].
As well as providing valuable insight into the importance of establishing robust information on the conditions before shale gas operations start, it also highlights the challenges in establishing effective monitoring and producing reliable results. For groundwater, this includes the importance of: developing and flushing newly installed boreholes; the spatial variation in water quality and; the selection of monitoring and measuring techniques. Having two years of data has allowed comparison between years. The preliminary analysis reported here has shown that sample populations were not significantly different between the two years. This is directly relevant to the duration of monitoring required by legislation, with the evidence supporting a baseline monitoring period of at least 12 months before any site operations start.
The seismic monitoring network installed for measuring background seismicity has operated successfully throughout the reporting period. All but one station show levels of data completeness over 90% which represents a high-quality dataset. There has been no significant change in recorded noise levels at any of the stations in the network. This combined with instrument performance means the network is capable of detecting seismic events with magnitudes of 0.5 ML or less around Kirby Misperton.
The monitoring has detected successfully a number of earthquakes around both the Vale of Pickering and the Fylde peninsula. However, all of these are at some distance from the shale gas sites. The Vale of Pickering network has also detected a number of other seismic events that have been attributed to quarry blasts. The magnitudes of these events range from 0.7 ML to 1.6 ML.
We have also developed and applied a new magnitude scale to correct for overestimation of magnitudes at small epicentral distances. This results in a significant reduction of the magnitudes of quarry blasts in the Vale of Pickering by over 0.5 magnitude units in some cases. The variance in the magnitude estimates is also slightly reduced. This issue is critical for correct estimation of the magnitudes of any earthquakes that might be induced by hydraulic fracturing.
The greenhouse gas monitoring continues to reinforce the conclusion that a baseline at one location is not applicable to other locations. However, the consistency of the baseline measurements (and baseline variability within each year) at both sites clearly suggests that 12 months of baseline monitoring is sufficient to establish a meaningful climatology to compare with analogous climatologies during the operational lifetime of the shale gas sites. Twelve months of data allow differentiation of local and long-range sources of greenhouse gases. At both sites, local (<10 km) sources dominate the contribution to statistically elevated concentration observations.
We conclude that: the consistency of the baseline statistics year-to-year at each site separately, strongly validates the utility of these statistics in future comparative work; repeatability and similarity in both mean and statistical variability at each individual site across both annual periods suggests that 12 months of monitoring is sufficient to characterise the baseline at future sites usefully and; the large differences between the baselines at both sites, due to influence of local sources, demonstrate that careful thought and further work may be required to assess the spatial scale over which baselines can be usefully applicable.
The baseline distribution of air pollutants measured at the Lancashire site has been broadly similar in 2017 to previous years, but there have been substantial changes observed at Kirby Misperton. There was a noticeable increase in NOx from Autumn 2017 as the site was prepared for hydraulic fracturing operations to begin. The high level of vehicle movements and operation of equipment during this period led to enhanced local NOx emissions. The equipment was removed after operations were suspended and the NOx concentrations returned to broadly the same concentrations seen previously during the baseline period. This highlights the importance of measuring the whole shale-gas operational cycle for air quality as the preparative operations can have a substantial impact on air pollution.
In the Vale of Pickering, 133 households volunteered to have detectors for measuring indoor radon concentrations. The results were consistent with the usual log-normal distribution for indoor radon and reflected the locations of the monitoring with respect to whether they were in Radon Affected Areas or not, i.e. radon levels above 200 Bq/m3 were measured in homes in Malton which confirmed the PHE/BGS classification of this location as a Radon Affected Area.
Outdoor radon was also measured. There is no indication of elevated outdoor radon concentrations in either the Pickering or Malton Radon Affected Areas, or elsewhere. Results from an active monitor and passive detectors, placed on the Kirby Misperton well site were in good agreement with the average outdoor radon concentrations for the area around Kirby Misperton. The active monitoring showed significant short-term variations over time. However the annual average was consistent, whichever of the techniques was used.
Seasonal variability in baseline soil gas and flux values continues to be observed as well as shorter-term diurnal changes and event-driven variations, for example related to the passage of weather systems. The longer-time-series data and the preliminary geostatistical appraisal of selected data suggest that any emissions related to shale gas operations will be easiest to detect in the autumn when baseline biological activity is lower and the soil remains dry. Saturation of the ground in the winter months precludes free gas measurements.
A further component of the study is to characterise ground motion (subsidence and/or uplift) in the study areas using satellite data. The objective being to determine what the current situation is, so that any changes that might be caused by hydraulic fracturing, if it takes place, can be identified. The baseline conditions have previously been reported (Ward et al, 2018) and as now hydraulic fracturing has yet taken place, no further analysis has been carried out during this reporting period.
Other reports in this series:
Smedley, P L, Ward, R S, Allen, G, Baptie, B, Daraktchieva, Z, Jones, D G, Jordan, C J, Purvis, R M, and Cigna, F. 2015. Site selection strategy for environmental monitoring in connection with shale-gas exploration, Vale of Pickering, Yorkshire and Fylde, Lancashire. BGS Report, OR/15/067.
Ward, R S, Allen, G, Baptie, B J, Daraktchievea, Z, Jones, D G, Jordan, C J, Purvis, R M, Smedley, P L. 2016. Environmental baseline monitoring — Vale of Pickering: Phase I – Final Report (2015/16). BGS Report, OR/16/002.
Ward, R S, Smedley, P L, Allen, G, Baptie, B J, Daraktchieva, Z, Horleston, A, Jones, D G, Jordan, C J, Lewis, A, Lowry, D, Purvis, R M, Rivett, M O. 2017. Environmental Baseline Monitoring Project. Phase II, Final Report. BGS Report, OR/17/049.