Gaining ground: Tracking soil changes
Chris Stapleton introduces a proposed new methodology for tracking the effects of development on soil
Soil functions are vital to terrestrial ecosystems; in my November 2019 Transform article (bit.ly/3djAEaA) I set out the most important land and soil inputs for environmental impact assessments (EIAs), as we move towards a terrestrial ecosystem services approach.
If the focus of protecting land and soil is beginning to encompass the provision of a wider range of terrestrial ecosystem services than the production of biomass (food, fibres etc) from agricultural land, how can this be done within EIAs? Here, I set out one approach with reference to the content of environmental statements (ES).
Impacts and mitigation
The important impacts of development are land take and the permanent or temporary displacement of soils. Site boundaries and scheme designs can be adjusted to ensure that the smallest area of land is lost or disturbed, while layouts can be configured to locate hard development on less valued land and soils, and to maintain the physical viability of residual agricultural land.
Soils displaced should be quantified and conserved for sustainable residual end uses. For temporarily displaced soils this can be achieved by putting them back where they came from. Finding a suitable location for the sustainable reuse of permanently displaced soils is a greater challenge.
Changes to EIAs and ES
ES generally have a section or chapter on agriculture, setting out the Agricultural Land Classification grades of land taken by development. However, proposals for the conservation and sustainable use of displaced soils are often overlooked.
The shift in focus to a terrestrial ecosystems approach for the protection of a wider range of soil functions than the production of biomass should be reflected in a more generic ES chapter entitled Land and Soils. This would help us to concentrate on the most important impacts and mitigation measures. It would recognise the significance of land take and soil displacement in ecosystem services terms, particularly with regard to land use changes from agriculture to hard and soft development.
A Land and Soil chapter would set out the areas of agricultural land (in hectares) transferred to different types of hard and soft development, together with an account of what was done with the soils displaced. There would also be a commentary on the maintenance of soil functions for the provision of terrestrial ecosystem services. For example, opportunities for the use of permanently displaced soils to establish groundcover on brownfield land intentionally included within a proposed development site could be more clearly presented as a sustainability gain.
Proposed methodology
My online article sets out a worked example of the proposed methodology. Environmental specialists within EIA teams would contribute towards this analysis and commentary to determine the balance of sustainability achieved with regard to soil functions and land use changes. The methodology combines a degree of quantification commensurate with our understanding of the various EIA topics, together with objective analysis by specialists. In particular, and for the biodiversity soil function, there would be scope for ecologists to determine any biodiversity net gain and offsetting.
Find the longer version of this article, including a worked example of the method proposed at: bit.ly/2Z10Wdz
Chris Stapleton is a member of the Royal Town Planning Institute and IEMA.