About the
project
Odessa Street Flushing Valve Decommissioning
Greater London
Wastewater Engineering / Survey & Inspection
RWP provided comprehensive survey and inspection services to support the decommissioning of 12 redundant flushing valve assets along the Thames, made obsolete by the commissioning of the Thames Tideway Tunnel.
The disciplines involved in this project were:
- Wastewater Engineering
- Civil Inspection
- Confined Space Entry
- 3D and Topographical Surveying
May 2020 - May 2022
The Thames Tideway Tunnel replaced the legacy sewer system that was operating beyond capacity, having been designed for 2 million people but serving over 9 million. The existing flushing valves, originally directing excess storm water into the Thames, were no longer needed and were allowing river water to enter the sewer system during high tide.
RWP was engaged to survey and assess all 12 flushing valve sites, carrying out confined space entry inspections, visual inspections, CCTV surveys and 3D/topographical surveys. The work required careful coordination with the IAB (Infrastructure Access Body) for chamber access and safe systems of work.
Working hours were restricted to low-tide periods due to proximity to the Thames, and tanker operations were required to clean the system before survey works could proceed. RWP coordinated the sequencing of all 12 sites to optimise the programme.
Key Challenges
- Route crossing a carriageway, private land, railway and nature reserve.
- Tunnelling within a flood plain and beneath the water table.
- Network Rail crossing requiring specialist coordination.
- Structural inspection of River Ray culvert at depth.
- Multiple stakeholders across the extended route.
Project Phases
- Desktop study to identify assets for decommissioning.
- Survey planning with Thames Water and contractors.
- IAB approval and RAMS development for each site.
- Survey works across all 12 flushing valve sites.
- Decommissioning plan preparation and reporting.
Achievements
- Early designer involvement enabled efficient sequencing across 12 sites.
- Strong collaboration with Thames Water, contractors and the IAB.
- All survey works completed on schedule.
- Comprehensive evidence base for decommissioning plans.
- Knowledge gained transferable to future flushing valve sites.
Conclusion
- Tidally-constrained works require meticulous programme planning.
- Good relationships with access bodies accelerate approvals.
- Sequencing multiple sites creates efficiency gains.
The Odessa Street Flushing Valve Decommissioning showcases RWP’s survey and inspection capabilities within complex, tidally-constrained environments. The project contributed to the optimisation of Thames Water’s Tideway infrastructure by enabling the removal of redundant assets causing inefficiency in the sewer network.
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