Unconventional oil and gas policy: SEA

7 Soil

What are the environmental effects of unconventional oil and gas development on soil?

7.1 The environmental effects of unconventional oil and gas development on soil are identified as:

• Ground contamination caused by:
  • flowback fluids associated with hydraulic fracturing;
  • leaks from surface installations (e.g. tanks and pipework);
  • saline intrusion.
• Soil sealing resulting from construction of the well pad and access roads;
• Greenhouse gas emissions associated with land-use change (the greenhouse gas emissions are assessed under climatic factors).

How do these effects relate to the current pressures and trends?

7.2 The most important pressures affecting soil are climate change and changes in land use and land management practices.^[175] According to the most recent State of Soil Report^[176] it is acknowledged that there is a lack of systematic Scottish soil data and significant gaps remain in relation to the potential threats that unconventional oil and gas developments could impose on Scotland’s soils. Gaps include:

• data on the extent and nature of soil contamination is limited;
• there is no systemic data collection to capture the extent and the quality of land being sealed;
• relatively little is known about the state and trend of Scotland’s soil biodiversity except for a few protected soil-dwelling species.

7.3 There is some evidence that some contaminant inputs and their impacts are reducing, for example from atmospheric acid deposition. However, many other potential soil contaminants such as organic chemicals are not routinely measured. This, alongside changes in land management practices has the potential to impact on soil biodiversity.

7.4 The distribution of best and most versatile agricultural land is illustrated in Figure 7a and 7b, and the distribution of high carbon soils is illustrated in Figure 8a and 8b, Appendix 1. These show there are areas of both of these important soil types distributed across the Midland Valley, within the areas of potential unconventional oil and gas development. Best and most versatile land is important in relation to agricultural production and high carbon soils are important carbon sinks and are also important for biodiversity.

What current regulatory processes control these effects?

7.5 There is legislation in place to control certain impacts of unconventional oil and gas developments on the wider water environment, which result in secondary effects on soil. These include the Water Environment (Controlled Activities) (Scotland) Regulations 2011 and Pollution Prevention, Control (Scotland) Regulations 2012^[177] and Environmental Liability (Scotland) Regulations 2009^[178]. Scotland’s regulatory framework comprises regulation to mitigate the risks of surface spills of fracturing fluid i.e. caused by accidental release. It is important to note that these controls would reduce, but not fully eliminate, such risks.

7.6 Furthermore, the Town and Country Planning (Environmental Impact Assessment) (Scotland) Regulations 2017^[179] relate to the assessment of the impact of certain public and private projects on the environment through the planning system.^[180] This would require consideration of impacts on soil quality where unconventional oil and gas developments are of a size and scale to require EIA.

7.7 The Management of Extractive Waste (Scotland) Regulations 2010^[181] requires that extractive waste will be managed without using processes or methods which could adversely impact upon soil quality.

7.8 Authorisation by SEPA under the Radioactive Substances Act 1993^[182] (RSA) is required if activities include the disposal of water, sediments or scales returning to the surface which contain naturally occurring radioactive materials and are above a certain threshold defined in the Act. If granted by SEPA, the RSA authorisation puts conditions and limitations on the accumulation and disposal of the produced and flowback waters and solids produced.

7.9 Workplace exposure to harmful substances is regulated under the Control of Substances Hazardous to Health Regulations 2002 (COSHH)^[183] by HSE. Under COSHH, assessment and control of the hazard posed by fluids containing chemicals that may be harmful to worker health is required, therefore it may also, indirectly, contribute to providing some protection measures against soil contamination.

7.10 In the event of land contamination, remediation can be required by SEPA under the environmental permitting system. If remediation does not otherwise occur it is regulated by the Environmental Protection Act 1990^[184] Part IIA and the Contaminated Land (Scotland) Regulations 2000^[185]. Local authorities are responsible for identifying and securing remediation of contaminated land.

7.11 Due to the existing regulatory regime, the environmental impacts of ground contamination from flowback waters should be minimal, unless there is illegal disposal of fluid. There is regulation to mitigate the risk of surface spills of fracturing fluids, and therefore the environmental impacts of soil contamination from these should be minimal. However, the proximity of potential unconventional oil and gas development sites to sensitive receptors means that the potential impacts of these limited effects could be more significant.

7.12 The planning system controls development and the protection of soils and reduction in carbon emissions is embedded in the national policy framework. Nevertheless, were UOG to go ahead, negative effects could occur.

What stages of unconventional oil and gas development result in these effects, what is the nature and significance of these effects?

Ground contamination

Business as usual – shale oil and gas extraction

7.13 Ground contamination from flowback fluids can occur during the exploration, appraisal and production stages of unconventional oil and gas development, which together could occur over a period of approximately 20 - 30 years for an individual development.

7.14 Surface leaks from decommissioned wells can occur during the decommissioning and abandonment stage of development, which may occur over a period of 2 – 5 years for an individual development

7.15 Surface spills from surface installations can occur during the exploration, appraisal and production stages of development, which may only occur over a period of approximately 20 years for an individual development.

7.16 Should ground contamination or surface spills occur, it is judged that the nature of these effects would be temporary, the scale and duration of these impacts is uncertain, depending on the nature of the contamination, the extent of contamination, and the sensitivity of the receiving environment. Contamination of soils which affects water supply for consumption or farmland soils could impact on human health, and all emissions into the wider environment could impact on biodiversity, flora and fauna (covered under the section on ‘biodiversity, flora and fauna’).

7.17 The scale of these effects is likely to be greatest under the KPMG high production scenario, which has the highest number of pads and greatest number of wells developed per pad. This larger number of developments increases the risk of ground contamination and surface spills. There is regulation to mitigate the risk of accidental release of hazardous materials and therefore a minor negative but uncertain effect is identified. These effects are likely to be lower for the central and low KPMG scenarios.

Business as usual - CBM

7.18 The nature and timescale of impacts on soil from ground contamination arising from CBM are similar to those described above. The scale of effect is limited to impacts arising from the development of two pads and 30 wells. Impacts on soil will reflect the sensitivity of the receiving environment, and in light of the regulatory controls the effects on soil quality are judged to be negligible but uncertain.

Pilot project

7.19 The significance of effects of ground contamination related to a pilot project will depend upon the sensitivity of the receiving environment. Impacts on soil quality for each the three potential pilot locations could impact on soil biodiversity and functionality. Similar to CBM, the scale of effects is limited to the area of a single pad and an unknown number of wells. Therefore the effects on soil quality of all three pilot locations are judged to be negligible but uncertain.

Preferred policy position

7.20 The preferred policy position means that potential soil contamination associated with unconventional oil and gas development in Scotland would be avoided.

7.21 This is considered to be a minor positive effect.

Soil sealing

Business as usual - shale oil and gas extraction

7.22 Soil sealing occurs during exploration, the development of the pad, and production, where further wells may be developed with additional surface infrastructure. The effect of soil sealing from an individual unconventional oil and gas development will be for the duration of approximately 20 - 30 years, but will be temporary, as the majority of surface infrastructure is removed during decommissioning, and the site restored to original condition. However the extent to which the soil returns to its original function is uncertain. Soil sealing also impacts on flood risk, and this is covered under the section on ‘Water’.

7.23 For each of the KPMG shale oil and gas extraction scenarios the scale of effect from each scenario is greatest under the high production scenario, where the highest number of pads would be developed, leading to soil sealing over a larger area. This would result in the sealing of approximately 24ha^[186] for the high scenario, 16ha for the central scenario and 8ha for the low scenario^[187]. All of the areas indicated are excluding any additional land area required for access roads, pipes etc. and are therefore presented as conservative estimates.

7.24 Even under the KPMG high scenario, the area of land lost to soil sealing is insignificant compared to the areas of land being brought forward for other types of development within the relevant local plan areas. The potential location in areas of existing flood risk means that effects of soil sealing under all of the KPMG scenarios is judged to be minor negative uncertain.

Business as usual - CBM

7.25 The nature of the effect of soil sealing is similar for both shale oil and gas extraction and CBM. The scale of the effect for CBM reflects the potential development of two pads of a total area of approximately 1.6ha.

7.26 The overall scale of effect on soil sealing for CBM is identified as negligible.

Pilot project

7.27 Reflecting the above conclusions, the scale of soil sealing from an individual pad for a pilot project, in any of the three potential locations is judged to be negligible.

Preferred policy position

7.28 The preferred policy position means that potential soil sealing associated with unconventional oil and gas development in Scotland would be avoided.

7.29 This is considered to be a minor positive effect.

Cumulative, synergistic and secondary effects

Business as usual – shale oil and gas extraction

7.30 There is some degree of uncertainty over the extent of current threats to soil. The range of impacts on soil arising from shale oil and gas extraction includes minor negative effects from ground contamination and significant negative but uncertain effects of greenhouse gas emissions from land use change (assessed under climatic factors). These are not identified to have cumulative effects on the soil resource due to their different impact pathways in terms of soil quality and the contribution of soil to greenhouse gas emissions.

Business as usual - CBM

7.31 No cumulative effects are identified reflecting the negligible effects identified for all impacts on soil from the development of CBM.

Pilot project

7.32 No cumulative effects are identified reflecting the negligible effects identified for all impacts on soil from the development of a pilot in the three theoretical locations.

Preferred policy position

7.33 The environmental impact of the Scottish Government’s preferred policy position on the development of unconventional oil and gas in Scotland is relative to the baseline which assumes the development of unconventional oil and gas. The timeframe for the avoidance of these additional effects is approximately the next 40 years. The avoidance of these effects is judged to be permanent within the context of the SEA. The scale of avoidance of effects reflects the geographic area identified as prospective for shale oil and gas, across the Central Belt of Scotland.

7.34 The effect is judged to be minor positive in relation to soil quality, reflecting the avoidance of any adverse effects on soil from unconventional oil and gas development.

7.35 In conclusion, although the soils of the Central Belt of Scotland will continue to face existing pressures, the preferred policy position means that additional pressures on the soil resource which would result from unconventional oil and gas development are avoided. This includes the potential impact on high carbon soils, soil sealing in flood risk areas and the proximity of the area of potential development to sensitive receptors (see Water, Population and Human Health, Biodiversity flora and fauna). The effect is judged to be minor positive in relation to soil quality, reflecting the avoidance of any adverse effects on soil from unconventional oil and gas development.

Scope for further mitigation

7.36 The assessment results are based on the application of existing regulatory controls. The evidence base includes information on a number of processes which could be implemented to reduce the scale of impact on soils. These could reduce the overall potential scale of effect from unconventional oil and gas development, and therefore the associated scale of effect avoided as a consequence of the preferred policy position.

7.37 The applicability and practicality of many of these additional measures will be determined at a site specific level so it is not possible to draw firm conclusions as to the extent to which they would mitigate predicted effects successfully.

7.38 Potential measures include:

7.39 Ground contamination – many of the water mitigation measures could help to protect soils, and reduce or avoid ground contamination. These include the use of geotextiles and geo-synthetics, the use of biodegradable fracking fluids, the (optimised) treatment of flowback and produced water through mobile units or at central facilities, and the use of advanced monitoring technologies (e.g. DTS and DAS). Other mitigatory measures include careful soil stripping, storage, and restoration in accordance with best practice. Furthermore, contingency planning to deal with accidental spillages and contamination of soil is likely to significantly reduce the potential impacts on soil quality and quantity associated with unconventional oil and gas developments.

7.40 Greenhouse gas emissions associated with land use change – avoiding development on high carbon soils is likely to have positive effects in terms of reducing greenhouse gas emissions associated with land use change.

7.41 Soil sealing resulting from construction of the well pad and access road – mitigating the effects of soil sealing can be achieved by using permeable materials that reduce water runoff and allow more rain water to infiltrate through the underlying soils. This could help to lower water treatment costs and reduces the risk of flooding and water erosion. Furthermore, impacts on soil quality could be reduced or potentially avoided if the works would be undertaken in suitable weather conditions to prevent soil damage i.e. avoiding periods of high rainfall.

Table 7.1: Summary of effects on soils

Environmental impact	Alternative	Potential scale of development	Timescale when effect may occur	Duration of effect	Predicted effect taking account of existing regulation	Key areas of uncertainty
Ground contamination	Business as usual– shale oil and gas extraction	Major	Short to long term	Temporary	A minor negative effect is identified. These effects are likely to be lower for the central and low KPMG scenarios.	There is regulation to mitigate the risk of accidental release of hazardous materials, however there is a risk of ground contamination and surface spills. A larger number of developments increases the risk of ground contamination and surface spills.
	Business as usual– coal bed methane extraction	Minor	Short to long term	Temporary	A negligible effect is identified reflecting that the scale of effects is limited to the development of two pads and 30 wells.	There is regulation to mitigate the risk of accidental release of hazardous materials, however there is a risk of ground contamination and surface spills.
	Pilot project	Minor	Short to long term	Temporary	A negligible effect is identified reflecting that the scale of effects is limited to the area of a single pad and an unknown number of wells
	Preferred policy position	None	Short to long term	Permanent	A minor positive effect is identified reflecting the avoidance of minor negative effects.
Soil sealing	Business as usual– shale oil and gas extraction	Major	Short to long term	Temporary	A minor negative effect is identified reflecting that the area of land lost to soil sealing is insignificant compared to the areas of land being brought forward for other types of development within the relevant local plan areas.	The potential location in areas of existing flood risk means there is uncertainty over impacts on soil sealing.
	Business as usual– coal bed methane extraction	Minor	Short to long term	Temporary	A negligible effect is identified reflecting the scale of development.
	Pilot project	Minor	Short to long term	Temporary	A negligible effect is identified reflecting the scale of development.
	Preferred policy position	None	Short to long term	Permanent	A minor positive effect is identified reflecting the avoidance of minor negative effects.
Cumulative	Business as usual– shale oil and gas extraction	Major	Short to long term	Temporary	None due to the different impact pathways in terms of soil quality and the contribution of soil to greenhouse gas emissions.	There is uncertainty over the extent of current threats to soil.
	Business as usual– coal bed methane extraction	Minor	Short to long term	Temporary	None due to negligible effects identified for all impacts on soil from the development of CBM.
	Pilot project	Minor	Short to long term	Temporary	None due to the negligible effects identified for all impacts on soil from the development of a pilot in the three theoretical locations.
	Preferred policy position	None	Short to long term	Permanent	None reflecting the avoidance of no identified cumulative effects.