Julia Tindale, from RPS, discusses the increasingly important issue of how peat is examined as a resource in environmental impact assessments (EIAs)
There is no fixed methodology for the assessment of peat as a resource through the EIA process. However, over the last five years there has been increasing concern expressed about the potential effects of development on peat resources, in particular wind farm development.
In 2011, the Joint Nature Conservation Committee (which includes Scottish Natural Heritage, Natural England, the Northern Ireland Environment Agency and the then Countryside Commission for Wales (CCW)) produced a report entitled Towards an assessment of the state of the UK peatlands, which provided an overview of the extent and nature of the peat resource across the UK.
In addition, CCW produced guidance for assessing the impact of wind farm development on peatlands in 2010, and the Scottish Environmental Protection Agency and Scottish Renewables published guidance on the assessment of peat volumes for developments during 2012.
The requirements of statutory bodies with regard to peat assessment have, therefore, evolved in tandem with their emerging guidance. This has created challenges for developers on sites where the guidance has been introduced during the application process, when the environmental assessment is largely complete.
In some cases developers have had to play catch up, carrying out retrospective peat survey work and then adjusting elements of the development to try to minimise impacts on peat resources.
However, for newly emerging sites there are a number of common threads that run through the guidance that has been produced and that should be taken into account in EIA.
The first consideration is that the location and nature of peat resources should be taken into account early on in the design process wherever possible. The key premise should be to avoid peat resources if at all possible. If avoidance is not possible, then the effects should be reduced wherever feasible and opportunities to mitigate any effects should be considered.
Guidance recommends that a typical soil resource assessment methodology should be adopted for this work. This includes a desktop study of all relevant data, including soils and geological mapping, together with aerial photography of the site.
On many sites, this combination of information can help to identify areas likely to comprise deep peat resources (more than 1m deep) where impacts could be significant, and this may help to inform the design process.
In some cases, more site-specific survey work may be available. For example, where wind farms are proposed in forested areas, Forestry Commission soils maps may have been produced prior to planting which can provide the most recent and spatially detailed soils data.
If the desktop study indicates that soil types likely to comprise peaty horizons are present onsite, this should be followed by a site reconnaissance survey.
Reconnaissance surveys include a limited site soil survey targeted in the areas indicated by the results of the desktop study. Such surveys can use photographic recordings of soil observations, including soil pits, and can be used together with information from other specialists, including ecologists and hydrologists, to provide additional information to refine the design of the proposal and its potential effects on peatland.
Detailed site assessment work is carried out once the design for the project is fully developed and the potential effect on peat resources has been limited as far as possible. The survey should comprise peat probing or auger borings to provide soil data at regular intervals. This will identify the depth and nature of peat materials that may be directly affected by the project.
It is advisable to consult the appropriate statutory body at this stage, providing a summary of the findings of the desktop study and initial site survey, and to agree a methodology for the detailed survey work that is proposed. If concerns are raised about the density and location of sampling proposed, or the information to be recorded, this is best discussed and resolved before visiting the site.
If the detailed site assessment identifies volumes of peat that will be affected by the project, and there is no scope for final scheme adjustments to avoid or reduce the effects on these resources, appropriate mitigation measures should be designed. These measures are likely to include appropriate soil-handling techniques for moving the peat and the consideration of appropriate storage and restoration locations. If possible, there should be further consultation with the statutory authority to discuss the most appropriate soil-handling methodology for the site.
In summary, consideration of peat resources should, if possible, be integrated into development design as an early a stage as possible. Although it is possible to introduce mitigation measures at a later stage, recent experience on wind farm sites indicates that statutory authorities may require additional peat assessment work to be undertaken where they do not consider sufficient effort has been made to avoid or reduce the effects on those resources.
This article was written as a contribution to the EIA Quality Mark’s commitment to improving EIA practice.
Julia Tindale is a technical director at RPS Oxford
