Thames Water awards upgrade contract to Kier Infrastructure

The contract is intended to deliver a higher quality of treated effluent and support compliance with new requirements. The project includes extensive treatment and infrastructure upgrades across the works, comprising new inlet screening and storm separation assets, a new storm tank and river outfall, upgrades to existing primary settlement tanks, and the conversion of three storm tanks into primary settlement tanks. The scheme also includes new activated sludge treatment capacity, eight new final settlement tanks, additional sludge thickening, new tertiary solids removal plants, chemical dosing systems to support phosphorus removal, electrical and power network upgrades, SCADA enhancements, standby generation, and the demolition of redundant assets. The upgrade will ensure a higher quality of treated effluent, reducing phosphorus levels entering the river to below an average of 0.25 mg/l. Storm tank capacity will also be increased, reducing the need for untreated sewage discharges during storm conditions. Thames Water expects the site to meet all government targets for storm overflows between 2035 and 2040. The standstill period for the contract ended on 26 February 2026. The works are scheduled to run from 1 April 2026 until 29 March 2030.