Abberton Reservoir Scheme
The largest reservoir improvement scheme in the UK
To meet water resource requirements in the future, Essex & Suffolk Water implemented a scheme to increase the storage capacity at their existing reservoir at Abberton, from 26 to 41 billion litres of water. The scheme was designed to minimise impact on the environment and improve amenity and ecological habitats. The reservoir is one of the most important in Britain for wildfowl, therefore it was essential that the environment was protected before, during and after construction. MWH, now part of Stantec, supported Essex & Suffolk Water, working closely with Natural England, Essex Wildlife Trust and the RSPB to develop enhancements to the design for the benefit of wildlife.
Throughout the duration of the project, MWH used best practice processes and procedures to the highest professional standards and ensured that value was given to environmental sensitivity and sustainable engineering.The design for raising the existing dam required careful consideration of a number of factors. For example, the earth filled, clay core design took into account the fact that the largest recorded earthquake in the UK was centered just a few miles from the dam. The dam was also subject to a slip event during its original construction, posing additional challenge to the designers. Finite Element Analysis techniques were therefore used for back-analysis of the historic slip to ensure the causes had been understood, and to verify the new design.
Storage capacity was increased by raising the reservoir top water level by 3.2m to provide an additional 15,000Ml of raw water storage, an increase of 58%. Engineering focused on the need to maintain water production, retain existing key assets, and minimise disturbance of the reservoir that was to remain fully operational during construction activities. The infrastructure improvements around the reservoir include a replacement off-take pumping station, re-engineered valve tower, pipelines and discharge channels, an outlet tunnel at the main dam and the re-routing of 2km of existing public highway around the enlarged reservoir perimeter.