Down to earth
As we move towards a soil and land quality approach that takes more account of terrestrial ecosystems, Chris Stapleton considers how EIAs should deal with these resources
Land and soils are often considered the same thing, but there are important differences. Land is a more complex concept, and because these terms are practically indivisible it is more helpful to consider the relationship between them than to seek separate definitions. ‘Land and soils’ (facing page) sets out an integrated definition.
Within Environmental Impact Assessments (EIAs), ‘land quality’ has two meanings. Firstly, and outside of urban settings and brownfield sites, land is likely to be agricultural with natural undisturbed soils. Within our planning system, the focus of land and soil protection has been on the productive value of agricultural land, with reference to the five-grade Agricultural Land Classification (ALC) system. In England and Wales this has involved the protection of our ‘best and most versatile land’ – grades 1 and 2 and subgrade 3a.
Secondly, land quality is concerned with the degree to which land and soils have been degraded by disturbance and contamination arising from human activities, and with remedial measures.
I am concerned with the first type of land quality, which is beginning to encompass the provision of a wider range of terrestrial ecosystem services than biomass production
from agricultural land. The concept of sustainable development has raised the need to protect land and soils for for a wider range of environmental objectives, and this should be reflected in EIAs.
Land and soils are perhaps the most direct environmental receptors of development impacts. Land take, and the displacement of soils by development, are the primary impacts – particularly in the change from agriculture to urban uses.
While it is not possible to mitigate the loss of agricultural land to a development, it is possible to mitigate the displacement of soils. Land with natural soils may be lost to hard development (built structures and manufactured impermeable surfaces), but for sustainable development the soils displaced must be conserved for beneficial use.
Where a significant impact on land or soils is anticipated, ALC and soil surveys should be carried out as part of the EIA baseline studies. The field survey should also include an assessment of the volumes and types of topsoil and subsoil available within the study area, to facilitate their separate stripping and their use in land restoration.
“Within our planning system, the focus of land and soil protection has been on its productive value”
It is necessary to ensure that the smallest possible area is lost and avoid highly valued or sensitive land and soil resources. Site boundaries and the corridors of land affected by linear developments can be adjusted during project design to achieve this. Layouts can be configured to locate hard development on less valued land and soils, and to maintain the physical viability of residual agricultural land.
The restoration of land to its original quality is the main mitigation objective, and this can be achieved through the conservation and sustainable reuse of temporarily displaced soil resources that are put back where they came from.
Finding a suitable location (preferably within the red line of a development site for effective development control) and beneficial reuse for permanently displaced soils, in a way that retains their natural functions, is more of a challenge. Good project design and well-managed construction operations must ensure that topsoils and subsoils are handled separately from the bulk movement of other excavated materials, in order to conform to good practice guidelines for soil handling.
Soil stripping, storage and subsequent reinstatement operations for land restoration can damage soil structure. This is due to the use of inappropriate methods and machinery, and the moving of soil when it is too wet and plastic. Good practice is to use excavators to strip and reinstate topsoils and subsoils successively in parallel strips, the width of the strip being determined by the reach of the excavators. This maximises the volumes of topsoil and subsoil separately stripped and minimises the mixing of topsoils and subsoils. It reduces damage to soil structures, retains drainage in reinstated soils and allows for varying stripping depths in a controlled manner as the parallel strips cross the boundaries of different soil types.
Using bulldozers to strip soils may be quicker and cheaper, but it causes more damage to the soil. It is difficult to control on a construction site, and often results in loss of soil function.
Changes to Environmental Statements
EIAs and Environmental Statements (ES) focus on agricultural land and soils, and these inputs are covered in an ES section or chapter setting out the areas of ALC grades of land taken by the proposed development, together with soil handling proposals for the conservation and reinstatement of displaced soils.
Perhaps the shift in focus from agricultural land to the protection of a wider range of soil functions should now be reflected in a more generic ES section or chapter simply entitled ‘Land and Soils’. This could help us to more fully understand the significance of land take in ecosystem services terms as changes of land use from one category to another. This section or chapter could set out the areas of agricultural land (in hectares) transferred to different types of hard and soft development within a scheme, together with an account of what has been done with the soils displaced.
Land take is superimposed on patterns of land ownership or tenure, and the loss of land from a farm holding might also be accompanied by a consequential restructuring of ownership and tenure. These impacts on agriculture can be addressed in existing ES sections and chapters on social and economic impacts.
These changes within the EIA process would help to facilitate a more sustainable approach in determining the effects of development on land and soils.
Land and soils
People think of land in terms of what they can do with it. Economists consider land to be one of the basic factors of production, along with labour and capital. From the human perspective, land is an area or location where we can live and carry out activities for subsistence or wealth-creating employment, leisure activities and other lifestyle choices. Its value is partly determined by its physical properties. Land also has social and economic dimensions, influenced by the different potential uses of land (including urban development) and also by its location in relation to settlements. Historically, land ownership has been ‘route one’ to wealth and power.
Where soil occurs, it is the topmost layer of the land and it is a component of terrestrial ecosystems, providing a medium for the transmission of carbon, water, nutrients and the growth of plants. People rely on ecosystem services provided by land and soil for biomass production, including food, fibres, and timber, and these services are central to social, economic and environmental sustainability.
Taken from Methods of Environmental and Social Impact Assessment, Oxford Brookes, 2018
Chris Stapleton is a member of the Royal Town Planning Institute and IEMA.