Upgrading our Swalecliffe site to reduce storm overflows
We've optimised our Swalecliffe Wastewater Treatment Works to increase available storage, reducing storm overflows by 36%. This optimisation cost around 90% less than building a new storm tank, and was much less carbon intensive so better for the environment.
The problem at Swalecliffe
The storm tanks at Swalecliffe Wastewater Treatment Works (WWTW) were not being used to full capacity, and as a result the site was using its long sea outfall around 100 times a year. To prevent this, we wanted to find a way to use this storage while staying within the permits and guidelines set by our regulators.
Optimising the site to manage more stormwater
We worked with the Environment Agency to get new permits and design a complex engineering solution to completely overhaul the way the site worked. We installed new chambers and pipework which enabled us to redirect 450 litres of storm water per second during heavy rainfall and store it in the 1,800 cubic metres of extra storage capacity.
The installation of the new chambers and pipework cost a total of £750,000, as opposed to the millions that would be needed to build a new storm tank. This optimisation of existing assets means that building of new structures was avoided, saving time, cost, and carbon.
The results
The work was completed in August 2023 and immediately started preventing storm overflow releases from the long sea outfall at Tankerton Beach.
We’ve seen a consistent 36% reduction in storm overflows as a result of the optimisation and will continue to monitor the results.
Future work
We're investing over £25 million on upgrades to the Swalecliffe Wastewater Treatment works, including the replacement of the storm overflow pipe. By using optimisation over building new structures, we’re able to make the investment go much further.
More investment is planned in the local area to reduce and slow the amount of surface water entering the system in the longer term. We’re using mainly nature-based solutions to achieve this, with a strong focus on maintaining and boosting community green spaces and local biodiversity.
Look at our Clean Rivers and Seas Plan to see all our planned storm overflow investments on an easy-to-use interactive map.