Clegg Associates were appointed to provide the design, detail and project management for the construction of an anaerobic digester in Codford, Wiltshire. These digesters work by breaking down food waste and producing a biogas, in this case methane, and a bio-fertiliser. The digester on this project was designed to receive 45,000 tonnes of food waste per year, creating methane gas from two 21.5m diameter digesters. The gas is burned in two Combined Heat and Power (CHP) plants to provide electricity, with the bio-fertiliser being used as manure on nearby fields.
We were responsible for the design and detailed drawings for all structural elements on this project. The site was situated on chalk so the foundations had to be designed to allow for fissures and swallow holes whilst supporting 4000 tonnes of liquid for each digester. A bund was created around the digesters comprising of a ground bearing concrete slab and sealed walls to contain any spillages that could occur, preventing contamination of the water table. The reception building was constructed from a galvanized steel frame and a concrete retained bay was designed to store the incoming food waste. We also designed a lagoon into which the bio-fertiliser is pumped, ready for collection and spreading onto nearby fields.