The Tideway Tunnel, a monumental undertaking, is set to revolutionize London’s sewer infrastructure by constructing a 25 km (16 mi) tunnel under the River Thames. This visionary project aims to mitigate the pollution stemming from the overflow of the city’s existing sewer system. Here’s a comprehensive overview of this ground-breaking initiative:
Capital Cost and Funding:
- The estimated capital cost stands at £4.3 billion, exclusive of financing, operations, and maintenance expenses. This figure may fluctuate due to factors such as design refinements, project scope adjustments, and the influence of the COVID-19 pandemic.
- Bazalgette Tunnel Limited, also known as Tideway, a newly established utility company under the regulatory purview of Ofwat, the water services regulator for England and Wales, is the driving force behind the financing of this project. Tideway earned the role through a competitive tender process, securing the project based on the most competitive cost of capital.
- Funding for the Tideway Tunnel is garnered through an additional charge imposed on Thames Water customers, anticipated to range between £19 and £25 annually by the mid-2020s. The exact charge will be contingent on the final Regulated Capital Value (RCV) assigned to the project.
Construction Timeline and Phases:
- Commenced in 2016, the project is slated for completion by early 2025, advancing through three principal phases: west, central, and east. Each phase is executed by a distinct consortium of contractors.
Tunnel Specifications:
- The tunnel boasts an impressive internal diameter of 7.2 m (24 ft), spanning from -30 m (-98 ft) at Acton in west London to -70 m (-230 ft) at Abbey Mills in east London, where it seamlessly interfaces with the Lee Tunnel, directing flow to Beckton Sewage Treatment Works. The tunnel’s primary role is intercepting 34 combined sewer overflows (CSOs) along the Thames, curbing their discharge into the river.
- A fleet of six Tunnel Boring Machines (TBMs), each named after a remarkable woman who left an indelible mark on London’s history, spearheads the excavation. These TBMs navigate diverse geological terrains, including clay, chalk, gravel, and sand.
- The tunnel’s lining consists of concrete segments, meticulously crafted at a factory in Avonmouth. These segments embark on a sustainable journey, transported by barges along the Thames, effectively reducing the environmental footprint and alleviating traffic congestion linked to the project.
Operational Oversight:
- Thames Water assumes responsibility for the tunnel’s daily operation as an integral part of London’s sewerage network. Meanwhile, Tideway takes charge of its operation and maintenance.
Environmental Impact and Community Benefits:
- The Tideway Tunnel promises to enhance the Thames’ water quality and ecology, marking a significant step toward a cleaner, healthier river ecosystem. Furthermore, the project’s development brings forth new public spaces and amenities along the riverfront, enriching London’s urban landscape.
Join us on this transformative journey as we delve deep into the Tideway Tunnel project, forging a path toward a cleaner, greener, and more vibrant London.