A strategy for soil

A CGI of the wetland landscape proposed at Langarth Garden Village. © Lavigne Lonsdale.

An award-winning development in Cornwall demonstrates a comprehensive approach to the protection of soils with a pioneering Soil Management Plan.

Birgit Höntzsch Dipl-Ing

Cornwall Council has embarked on the delivery of Langarth Garden Village – a new community just outside Truro, Cornwall, that will provide 3,800 new homes alongside significant green and blue infrastructure. The masterplan recently won the Royal Town Planning Institute (RTPI) ‘Excellence in Plan Making Practice’ category at the National RTPI Awards and has achieved a Building with Nature Design Award.

Cornwall Council champions sustainable development in line with its Climate Change Development Plan Document and, as part of this guidance, the Planning Permission includes a high-level Soil Strategy (available for download from the Cornwall Council Planning Portal).

Langarth Garden Village aims to ensure that the development maximises the reuse of soils and keeps them healthy to support a sustainable future for the community. In addition, soils into landfill must be avoided.

Building on this high-level strategy, the council has developed a Soil Management Plan (SMP) for the Garden Village, setting out principles for the whole site, and additional detail for the first phase of the development. There is a requirement in the SMP for the design of the landscape to seek to minimise carbon loss and maximise opportunities for carbon sequestration within the soils.

Measures suggested are:

– Creation and protection of Soil Protection Zones (SPZs) where the soils and land would not be disturbed

– Minimisation of soil erosion

– Design of habitats that support increased rates of carbon sequestration

– Minimisation of soil handling

– Designing landscape and habitat elements that are permanent (and thus will form a permanent store of carbon)

In practical terms, measures taken at Langarth Garden Village so far include:

– Subsoils from one area of the site that had to be reprofiled have been re-used for construction of a link road and junction where there was a fill deficit

– Topsoil levels in the first phase of parks and infrastructure development have been reviewed, with the aim of increasing depths where possible to retain more soil on-site

– Large wetland areas will be established along the northern site boundary as a component of the drainage strategy, some of which will act as carbon sinks over time

Working with Lancaster University, Cornwall Council is currently contributing to the development of a comprehensive soil policy that will become available as a case study and template for other councils later in 2025.