Kier has been awarded a £15.8m early contractor involvement (ECI) contract under Southern Water’s strategic delivery partner framework for asset management period 8 (AMP8).
It is Kier’s first project under the framework.
The contract covers early-stage design and planning for nitrogen reduction works at Portswood wastewater treatment works and the installation of UV disinfection at Thornham wastewater treatment works, where capacity upgrades are also being developed.
At Portswood, near Southampton, Kier is developing solutions to meet a new total nitrogen discharge consent of 9mg/litre by 2030, in line with the Water Industry National Environment Programme.

The site is heavily constrained, requiring innovative, space-efficient approaches. Current proposals include repurposing existing infrastructure and expanding the activated sludge and tertiary treatment facilities.
At Thornham, near Havant, the scope includes installing a UV disinfection system to improve shellfish water quality by 2027, alongside longer-term upgrades to increase treatment capacity to support population growth. Options under consideration include converting the plant to an activated sludge process and building new assets south of the existing site.
Southern Water capital delivery director Simon Tomlinson said: “Together, these upgrades will help Southern Water continue to deliver safe, high-quality wastewater services for its customers, strengthening resilience, supporting regulatory compliance, and enhancing environmental performance across its network.â€
Rob Campbell, operations director, water for Kier Natural Resources, Nuclear & Networks, said: "These are two technically complex schemes on constrained sites, and we’re bringing our expertise to shape the right long-term solutions. This early collaboration sets the tone for how we’ll work together throughout AMP8, aligned, agile and focused on delivering real value for communities and the environment."
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