Soil Resource Survey

Our brief

Lithos were commissioned by a national builder to prepare a Soil Resource Survey prior to redevelopment of the site with housing.

Site history and characteristics

The site comprises undulating agricultural fields with no history of development, and as such comprises a significant volume of Topsoil, a fundamental and ultimately finite resource.  The ground investigation identified clay Topsoil to c.300mm thickness overlying a predominantly clay subsoil, locally weathered to sand where underlying bedrock was shallow.

What we did

Prior to attending site, Lithos reviewed available plans published by the British Geological Survey (BGS) and The Soil Survey of England & Wales to determine the nature of the shallow soils from which the Topsoil and Subsoil have been derived and to confirm the soil classification for the site.

A suitably qualified Lithos engineer visited the site to excavate 18 sampling pits on a rectilinear grid  through a combination of hand digging and augering to a maximum 1.0m depth.  Logging and sampling of the Topsoil and Subsoil was undertaken in accordance with the Soils Survey Handbook (Third Edition), with photographs taken of the soil profile.  A visual assessment of sharps (glass, ceramic etc) and visible contaminants (plastic, cloth, timber etc) across the surface of the site was made by the engineer.  Testing to determine the suitability of the soils for re-use in garden and landscaped areas was undertaken in accordance with BS3882:2015 (Specification for Topsoil) and BS8601:2013 (Specification for Subsoil).

The outcome

Results of the inspections and the laboratory testing were presented to the developer to assist them, and their landscape architect, in determining the most feasible landscaping solutions for the site.  Where soil parameters did not meet the criteria for a multipurpose topsoil as set out in BS3882, appropriate treatment options were presented to reduce/eliminate the need for soil disposal and import, therefore saving time and money.  Once Topsoil and Subsoil resources were characterised in the Soil Resource Survey these could be incorporated into the Soil Management Plan, detailing how the resources will be managed.  This allowed the developer to effectively manage the soil resources on site, and discharge planning conditions associated with protection and re-use of soils.