Southport Wastewater Treatment Works

Murphy is delivering a major upgrade at Southport Wastewater Treatment Works as part of United Utilities’ Enterprise delivery model, which unites seven design and construction partners with United Utilities in a fully integrated delivery team.

The scheme will increase stormwater storage capacity at the site, helping to improve water quality by reducing the frequency of storm overflow operations during periods of heavy rainfall. The project is being delivered in two phases. Phase One focuses on the construction and commissioning of 4,500m³ of additional stormwater storage, while Phase Two will increase treatment throughput through the introduction of a new side-stream treatment process.

Phase One achieved a significant milestone with the completion of the new storm tank and associated pipework installation in early 2026. The project team is now progressing the final mechanical, electrical, instrumentation, control and automation (MEICA) connections required to fully integrate the tank into the existing storm system. The project remains on track to meet the regulatory deadline for bringing the additional storm storage capacity into operation by the end of September 2026.

Phase Two is advancing at pace and is scheduled for completion in late 2029. This phase will significantly enhance the site’s ability to treat increased volumes of wastewater during periods of heavy rainfall. By increasing treatment capacity, storm storage can be returned to service more quickly following rainfall events, creating additional resilience and reducing the need for further on-site storage infrastructure.

A key element of the treatment upgrade is the construction of a new Sequencing Batch Reactor (SBR), a proven technology previously designed and successfully delivered by Process Engineering on projects in Ireland. Construction of the steel reinforced concrete base slab and walls is progressing well, supported by more than 400 piles installed by Ground Engineering. As the civil structures near completion, our Process Engineering team will commence PMEICA installation activities to ensure a smooth transition between construction and commissioning phases.

Subsequent works will include the construction of a new inlet structure to screen and remove grit from incoming flows prior to treatment within the SBR. Additional scope includes the installation of SBR blowers, a new Motor Control Centre (MCC), and enhanced sludge handling and thickening facilities. The final stage of the project will deliver a new ultraviolet (UV) treatment plant, designed to treat combined flows from both the new SBR and the existing treatment assets, ensuring compliance with increasingly stringent Environment Agency requirements.

The Southport upgrade demonstrates the strength of the One Murphy approach, bringing together expertise from our teams in Infrastructure and Process Engineering, with support from our Plant, Applied Engineering, Ground Engineering, Technical Services, and Ireland teams to deliver a coordinated and efficient solution for United Utilities and the local community.

Key Benefits

• Increased stormwater storage capacity of 4,500m³.
• Increase treatment capacity of 360l/s and site resilience.
• Reduced operation of storm overflows during heavy rainfall events.
• Improved water quality and environmental performance.
• Compliance with future regulatory and Environment Agency requirements.
• Successful integration of expertise across multiple Murphy business units through the One Murphy delivery model.

For more information on our work as part of United Utilities’ Enterprise delivery model, visit here.