Guidance
PEAT SURVEY GUIDANCE
1.
What is this guidance for?
1.1. Proposals for developments (including land use changes) on land where peat is the
main soil type include wind farms, hydro-schemes, transmission infrastructure, surface
coal mines, buildings, road widening/construction and forestry. In view of the
importance of Scottish peatlands for carbon storage and the habitats they support,
guidance on conducting site surveys for developments on peat has been prepared to
enable the potential loss and disturbance of peat to be estimated and minimized.
1.2. This guidance provides key, generic principles for surveying peatland for a wide range
of applications such as:
1.2.1.
1.2.2.
1.2.3.
1.2.4.
1.2.5.
1.2.6.
Peat landslide risk assessments
Carbon savings & losses evaluation
Waste minimization & management plans
Site design and layout
Drainage planning and hydrological assessment
Post-construction habitat management/site restoration.
1.3. It should be noted that this guidance does not relate to surveys of carbon rich soils
other than peat and peaty soils. It should also be noted that other surveys of peatland
may be required in order to assess impact on sensitivities such as groundwater
dependent terrestrial ecosystems or Annex 1 habitats on peat.
1.4. The intensity and detail of survey effort required for different types of developments will
vary. However, the principles and approach described in this guidance are equally
applicable in order to estimate the likely disturbance or loss of peat in many cases.
1.5. Experience from wind farm developments indicates that initial peat site surveys as a
minimum should comprise:
A low resolution survey on a 100m by 100m grid basis across the whole development site
which provides information on peat depth variability, identifies areas where deep peat is
present and also identifies steep slopes (greater than 100), which need to be avoided. On
slopes between 20 and 100 the Landslide Risk Assessment1 will inform whether these areas
should also be avoided.
A detailed survey on a 10m by 10m grid basis around the centre of each proposed turbine
base or other infrastructure. A detailed survey at 50m intervals along proposed track/road
locations using 10m right angled offsets.
2.
What is peat?
2.1. The term peat is used for organic material derived from dead plants, accumulated under
wet/waterlogged (mainly anaerobic) conditions. This material can be characterised as
fibrous or amorphous, depending on the decomposition stage of the organic material.
2.2. Peat is also the name given to a specific soil type, defined in Scotland by the amount
and depth of organic material present in the soil. It is important to have a clear
1
Peat Landslide Hazard and Risk Assessments: Best Practice Guide for Proposed Electricity
Generation Developments Scottish Government. 2007
1
definition of peat, deep peat and organo-mineral soils (sometimes known as peaty soils)
in order to define whether a site being considered for development is indeed classified
as a site on peat.
2.3. In this guidance, the Joint Nature Conservation Committee (JNCC) report 445 Towards
an Assessment of the State of UK Peatlands2 definitions for Scotland are used:
2.3.1. Peaty (or organo-mineral) soil: a soil with a surface organic layer less than
0.5m deep;
2.3.2. Peat: a soil with a surface organic layer greater than 0.5m deep which has an
organic matter content of more than 60%;
2.3.3. Deep peat: a peat soil with a surface organic layer greater than 1.0m deep.
2.4. It should be noted that ‘peaty soil’ (or ‘organo-mineral soil’), ‘peat’ and ‘deep peat’ are
classified differently in other parts of the world (including the rest of the UK) and
therefore these terms may have different meanings outwith a Scottish context. Use of
the JNCC report 445 definitions for Scotland enables consistency across Scotland in
the approach for all types of developments and ensures that the same criteria for
avoiding ‘sensitive areas’ are always applied.
Peat is defined as soil that has an organic surface horizon over 0.5m deep1. Published soil
maps3 generally indicate if a site proposed for development is likely to contain peat, but peat
may occur locally outwith areas shown on these maps. Many sites consist of a complex mix
of peat and soils with shallower organic surface horizons. A first step screening exercise
should be carried out to confirm if the soil type ‘peat’ is present. This will ensure peat site
surveys, landslide risk assessments and carbon assessments are undertaken on sites that
currently require them.
3.
The requirement for information on peat depth and peat characteristic
3.1.
Developers need to be aware of the potential carbon and waste implications, potential
impacts on habitats and water quality, and the risk of landslide due to building activity
on peat. There is increased scrutiny of carbon emissions from the land use sector in
Scotland as part of a wider policy aspiration to reduce total greenhouse gas
emissions.
3.2.
Consistent and accurate site information is required when obtaining planning
permission for any development on peat. Good site information on the depth and
condition of the peat will:
3.2.1. Enable the total impacts on the peat resource, such as potential volumes lost
and disturbed, to be determined
3.2.2. Reduce both construction and financial risks, especially those related to
landslides and mass movements
3.2.3. Inform better planning assessments and Environmental Impact Assessments
3.2.4. Save time later in the process (e.g. pre-construction /
construction/restoration/decommissioning)
3.2.5. Provide more robust carbon assessments and waste management plans
3.2.6. Enhance a developer’s ability to reduce peat disturbance and loss
3.2.7. Aid effective peat management and restoration
2
JNCC report 445 published in 2011 http://ipbes.unepwcmc004.vm.brightbox.net/system/assessment/187/references/files/542/original/jncc445_web.pdf?13642171
80.
3
Soil Survey Scotland 1984. Organization and Methods. Handbook 8. Macaulay Institute for Soil
Research.
2
3.2.8. Reduce the likelihood of pollution of watercourses via run-off and erosion.
3.3.
Data collated from developments on peat can also provide valuable information on the
extent of potential peat loss and disturbance at a national level4.
3.4.
The requirements for a site survey should be discussed with the relevant authority
charged with determining the application for permission, under legislation such as the
Electricity Act or Town & Country Planning Acts to ensure it will provide sufficiently
detailed site information.
3.5.
These guidelines are intended to ensure that approaches to site surveys on peat are
conducted in a consistent and transparent manner regardless of the nature of the
proposed development and as screening tool for developers to determine if a
proposed site does in fact contain the soil type ‘peat’.
4.
Principles
4.1.
This guidance does not prescribe the use of one particular technique or technology. It
does not seek to stifle innovation or the use of novel techniques and equipment. It is
up to developers and their consultants to choose appropriate methods for the site in
question, balancing costs and risks with the need for good quality data. This guidance
does recommend the use of the Soil Survey of Scotland Scottish Peat Survey
methods5 and terminology for conducting an appropriate site survey to determine peat
stock and condition at a site.
4.2.
A site survey should provide:
4.2.1. A representative evaluation of peat depth and condition across the whole site
along with some statistical measure of variability.
4.2.2. Details of peatland characteristics such as surface vegetation cover density,
vegetation type, artificial drainage features, signs of historic and current erosion
and peat stability on slopes.
4.2.3. Sufficient detail to inform the design and layout of infrastructure including
identification of sensitive areas.
4.2.4. Details of peat depth, bulk density and carbon content on areas where
development is planned.
4.2.5. An indication of the maximum potential volume of peat likely to be affected by
extraction, disturbance and drainage, including areas where the peat layer is less
than 0.5m thick. This also includes calculations of surface areas where excavation
has exposed peat e.g. steep batters, and where restoration will be difficult.
4.2.6. A level of survey tailored to the development within the proposal boundary,
focusing on areas of greatest potential impact with less scrutiny of areas remote
from infrastructure development.
4.2.7. Sufficient information to inform the future effective restoration of the site postdevelopment.
5.
5.1.
Process
A peat survey or 'site investigation', as it is often referred to, normally consists of 3
stages:
5.1.1. A desk study to determine if peat is likely to be present on a site using existing
soil survey and/or geological survey maps complemented by aerial photos.
4
5
Scottish Soils Framework. Scottish Government 2010
Soil Survey of Scotland Scottish Peat Surveys, 1964 Volume 1 HMSO, Edinburgh .
3
Where available detailed 1:63,360 scale soil maps should be used, in other
areas only national 1:250,000 scale soil maps will be available and should be
used6. The methodology for identification on "carbon-rich soil mapping units"
can be used7. A site visit will confirm the presence of peat, after which a peat
survey can be designed (see section 6).
5.1.2. A low resolution 'first pass' to identify the broad extent and depth of peat
across the site. This will identify areas that require more detailed survey prior
to outline design and infrastructure location. This is likely to require a depth
measurement at least every 100m across the area proposed for development.
Areas of the application site which are unlikely to be developed (due to other
constraints) do not need to be surveyed in any greater density.
5.1.3. A more detailed survey of peat depth and peat characteristics. This should
focus on likely infrastructure locations particularly on sensitive areas which
should be avoided where possible subject to site specific considerations.
These areas need to be clearly marked on the outline design of the
development. This is likely to require a depth measurement and site
description every 10-50m on and around areas where infrastructure will be
located. During this survey, it is important to record whether the peat is fibrous
or amorphous - based on field observation and core results - as this has an
impact on future storage and potential best re-use of this material. Site details
such as slope and drainage patterns (e.g. bog pools) plus any erosion features
(e.g. gullies, rills or 'hags') should also be noted and spatially referenced.
Ecology expertise is also required in order to survey and assess vegetation
across the site as part of the Habitat Survey.
6.
6.1.
Techniques, Equipment & Field Methods
A variety of resources and equipment are required for peat surveying, these include:
6.1.1. Existing soil survey/geological survey maps, aerial photographs and satellite
images. These are a key starting point for any survey indicating the presence of
peat, vegetation patterns, topography, surface drainage and any erosion
features such as gullies or 'hags' (Section 5.1.1).
6.1.2. Results from the low resolution ‘first pass’ (100m by 100m grid; section 5.1.2)
are required as background for the more detailed survey (10-50m grid; section
5.1.3).
6.1.3. A hand held GPS device. This is used to record and locate sampling points and
markers to identify the grid pattern being applied across the site.
6.1.4. A camera for taking photographs on site.
6.1.5. Peat probes (sometimes referred to as depthing rods). These are required to
measure peat depth and should be capable of measuring total peat depth. They
should be used to measure peat depth accurately, including in areas where this
is less than 0.5m.
6.1.6. Soil augers or Russian peat samplers/cores, capable of extracting peat samples
for carbon analysis, bulk density measurements and degree of decomposition
assessments. This should be capable of reaching total peat depth, and
extension rods should be used where required. Note: on forested sites augers
need to be sufficiently robust to allow cutting through tree roots. A minimum of 4
on-site sampling locations are required. Selected samples should be representative
of peat in areas where development is planned. The results can be checked against
nationally derived estimates of bulk density and total carbon content (provided in
section 8) to ensure accuracy.
6.1.7. Labeled air and water tight containers for storage of peat samples.
6
7
http://www.huttonsoils.com/maporderform.php?category=1
SNH. Identification of carbon-rich soil mapping units http://www.snh.gov.uk/docs/A602512.pdf
4
6.1.8. A sampling protocol based on quadrats for the description and characterisation
of vegetation8, 9 should be used to provide a representative survey across the
site to assess the overall site condition, typically undertaken by ecologists for the
Habitat Survey.
6.1.9. Disturbance of intact peat and surface vegetation during sampling should be
minimized where possible, paying particular attention to vehicular access to the
site / sampling locations.
7.
Presenting the information
7.1.
Survey-derived information should be presented on a map (or maps) at an appropriate
scale covering the whole site (including new or upgraded access tracks leading
to/from the development site), with the proposed development overlaid. Maps should
be produced for peat depth (preferably using contours), vegetation cover as part of the
Habitat Survey and other important site information (such as existing grips, tracks,
gullies or bog pools) noted during the survey.
7.2.
Data on peat depth, the carbon content and bulk density of peat, dominant vegetation
cover plus some measure of the variability of peat depth across the site should be
presented in a suitable format such as a table or spreadsheet.
7.3.
The plans of the proposed development should then be superimposed over any maps
of peat depth to show the link between the intended location of infrastructures and
how impacts on deep peat and peatland habitats have been minimised.
8.
Definitions and units
Acrotelm
Amorphous peat
Basin peat
Blanket peat
Carbon content
Catotelm
The surface layer of a peatland within which all living
vegetation exists, although the rooting zone may
penetrate the underlying catotelm. Acrotelm is an aerobic
soil zone which can be periodically inundated and has
high hydraulic conductivity due to large pore spaces
within the fibrous plant material. The total thickness is
usually less than 30cm but may be up to 50cm.. Acrotelm
peat is typically more structurally coherent than catotelm
peat and more suitable for on-site re-use in development
projects.
Peat containing no identifiable plant remnants, often
associated with the lower ‘catotelm’ layer of peat soils.
Amorphous peat is typically within H6-H10 values of the
Von Post scale.
Peat soil that has formed due to waterlogging as a result
of water accumulation in excess of evapotranspiration
due to runoff from surrounding land and/or groundwater
Peat soil that has formed due to waterlogging as a result
of rainfall locally exceeding evapotranspiration
Concentration of carbon in a peat soil sample, normally
determined as a percentage of total dry mass of the peat.
Layer of peat which sits below the acrotelm and is anoxic
due to complete saturation by a permanently high water
8
Rodwell, J.S. (ed.) 1991. British Plant Communities. Volume 2. Mires and heath. Cambridge
University Press
9
JNCC 2010. Handbook for Phase 1 habitat survey – a technique for environmental audit
5
Deep peat
DOC
Dry bulk density
Erosion features
Fibrous peat
Generic values dry bulk density
(g/cm3) for basin and blanket
peat10
Generic values for % carbon
content for basin peat11
Generic values for % carbon
content for blanket peat8
Peat
Peat auger
Peat condition
Peaty soil or organo-mineral soil
Peatland
POC
Sensitive areas
table. The anaerobic conditions inhibit and drastically
slow decomposition processes resulting in the build up of
peat. The structure of the catotelm is highly variable;
fibrous near the surface and increasingly amorphous with
depth. The oldest and most decomposed peat material
no longer contains any identifiable plant structures.
Catotelm peat may be structurally unstable, particularly
after excavation, and its high moisture content may mean
that it is not suitable for on-site re-use in development
projects.
Soil with a surface organic horizon > 1.0 m deep, as
defined by JNCC report 445.
Dissolved organic carbon. Organic carbon dissolved in
water draining peatland.
Mass of soil solids (dry soil) divided by total volume of
soil; determined using an undisturbed peat core
In peat, these include hags (isolated mounds of
vegetated peat left raised above the surrounding peat by
erosion) and gullies (permanent or seasonal channels cut
through peat by water erosion)
Peat that contains identifiable plant remnants, often
associated with the upper ‘acrotelm’ layer of peat soils.
Fibrous peat is typically within H1-H5 values of the Von
Post scale.
Minimum: 0.072. Maximum: 0.293. Mean: 0.132
Minimum: 32.61. Maximum: 59.12. Mean: 50.00
Minimum: 19.57. Maximum: 64.28. Mean: 53.23
Soil with a surface organic horizon 0.5 – 1.0 m deep, as
defined by JNCC report 445.
Device for taking samples of peat soils. Various designs
exist, some of which collect an undisturbed sample
suitable for bulk density analysis
This refers to whether the peat is intact, eroded, drained
or otherwise affected by management practice.
Soil with a surface organic horizon < 0.5 m deep, as
defined by JNCC report 445.
Wetlands with a thick water-logged organic soil layer
(peat) made up of dead and decaying plant material.
Peatlands include moors, bogs, lowland raised bogs,
mires, peat swamp forests and permafrost tundra.
Particulate organic carbon. Organic carbon present in
suspended material in water draining peatland.
Sensitive areas constitute areas which are to be avoided
where possible due to the scale of associated
10
The James Hutton Institute. Unpublished data from the National Soil Inventory of Scotland (20072009) and are for amorphous, well decomposed peat. For more fibrous peats (fibrous and semifibrous), the bulk density will be lower.
11
The James Hutton Institute. Data from the Scottish Soils Knowledge and Information Base (SSKIB)/
Soils Indicators For Scottish Soils (SIFSS) and are summary information for all peat profiles held within
the Scottish Soils Database.
6
Undisturbed sample/ undisturbed
core
environmental impact. The elements to consider when
identifying a sensitive area include: the presence of
unmodified peat, deep peat, steep slopes at risk of
slide/failure and active erosion features.
A sample of peat taken without compaction during
sampling, preserving its volume as found in the field.
Used to analyze peat for bulk density
Acknowledgements
Scottish Natural Heritage
Scottish Environment Protection Agency
The James Hutton Institute
References
1. Peat Landslide Hazard and Risk Assessments: Best Practice Guide for Proposed
Electricity Generation Developments Scottish Government. 2007.
2. JNCC report 445 Towards an assessment of the state of UK Peatlands. April 2011.
3. Soil Survey of Scotland. 1984. Organization and Methods. Handbook 8. Macaulay Institute
for Soil Research.
4. Scottish Soils Framework. Scottish Government 2010.
5. Soil Survey of Scotland Scottish Peat Surveys, 1964 Volume 1 HMSO, Edinburgh.
6. Macaulay Maps. http://www.huttonsoils.com/maporderform.php?category=1.
7. SNH. Identification of carbon-rich soil mapping units. November 2012.
8. Rodwell, J.S. (ed.) 1991. British Plant Communities. Volume 2. Mires and heath.
Cambridge University Press.
9. JNCC 2010. Handbook for Phase 1 habitat survey – a technique for environmental audit.
10. The James Hutton Institute. Unpublished data from the National Soil Inventory of Scotland
(2007-2009).
11. The James Hutton Institute. The Scottish Soils Knowledge and Information Base (SSKIB)/
Soils Indicators for Scottish Soils (SIFSS).
7