Earth-banked Lagoon – Geotechnical Interpretive Report

Renewable Energy Company

Ground and Project Consultants Limited (GPCL) were appointed by Swancote Energy to undertake a preliminary design and geotechnical assessment for a proposed earth-banked slurry lagoon at their site in Swancote. The proposed development comprised the construction of a 15,000 m³ slurry lagoon, intended to support ongoing energy and agricultural operations.

The purpose of the ground investigation and assessment was to determine whether the proposed lagoon could be constructed without a liner, or whether primary containment measures would be required to ensure regulatory compliance. The assessment was undertaken in accordance with Environment Agency (EA) requirements and relevant industry guidance.

GPCL’s scope of work included a ground investigation programme, comprising trial pits, soakaway testing, and associated laboratory testing, followed by a detailed geotechnical assessment of containment options in accordance with CIRIA C759.

Targeted laboratory testing was undertaken to assess whether the underlying soils met the permeability and thickness criteria set out in the guidance. Results of the soakaway testing indicated that the natural ground conditions were not sufficiently low permeability, and that a lined embankment solution would be required.

GPCL subsequently provided design recommendations for the primary containment system, ensuring compliance with EA requirements, and undertook slope stability analyses to confirm the global stability of the proposed lagoon embankments.

This work enabled Swancote Energy to progress the project with a clear, compliant, and technically robust containment strategy.