Clay Heave and Sulphates, Swindon
Introduction:
The site was zoned in terms of volume change potential and a detailed assessment of foundation and floor slab options for each plot was completed. Careful investigation of the soil sulphate and hydrogeological conditions allowed significant cost savings to be made in foundation concrete. The assessment was submitted to, and approved by, the NHBC allowing development to proceed. Exact positions of services along the roads leading to the development were also established.
Key skills:
Investigation of utilities in busy A-road
Tailored site investigation
Assessment of desiccation and volume change potential
Careful assessment of soil sulphate and pyrite levels
Details:

A major housing development was proposed on Kimmeridge Clay soils near Swindon. Heavy clays such as the Kimmeridge Clay can contain a number of geotechnical hazards including a high potential for volume change within the zone of influence of existing and proposed high water demand trees, and high sulphate/pyrite content.
Services Provided for Clay Heave and Sulphates:
- Desk study review.
- Trial pitting and shallow boreholes.
- Assessment of shallow groundwater conditions.
- Investigation of existing utilities along busy A-road.
- Detailed assessment of desiccation of shallow soils.
- Recommendations to mitigate volume change risks and foundation concrete.