Plymouth Central Stormwater UV
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Location: South West
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Sector: Water
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Division: Infrastructure
This large-scale Inlet works and stormwater treatment scheme involved various innovative solutions, including the use of pre-cast concrete units for the flow split and UV Channels, 3D and 4D modelling.
Plymouth Central is the key project in a wider Bathing Waters strategy, delivered under the revised Bathing Waters Directive. The facility became the first of its type in the UK to treat peak unsettled storm discharges of 2000l/s. Prior to on-site commencement, comprehensive 3D and 4D modelling was undertaken to provide all stakeholders with the opportunity to assess the proposed structure and optimum construction sequence.
Collaboration was a key factor in the success of the Bathing Waters Strategy, delivered from an open plan ‘hub’ office.
The new facility increases the volume of stormwater pumped & treated from the Plymouth tunnel system, reducing the load on numerous CSOs, meeting the revised bathing water directive.
The solution Tilbury Douglas implemented saved approximately six weeks on the programme, with a cost-saving of over 15%. At the tender stage, our site teams recognised the potential, and advantages of implementing pre-cast construction and off-site build. This allowed work to be carried out around the UV structure with less labour, resulting in reduced H&S risks and site congestion and more accurate factory tolerances on UV channels. Our approach also enabled time and resources to be focused on the more intricate inlet works and FRC structure. During the planning, value engineering and design stages, we also developed a cost-effective way to re-use existing 1200mm diameter CSO discharge pipework for the new emergency storm tank return line, providing further efficiencies.
Scheme overview
New RC Inlet works to pre-treat FFT, and storm flows – up to a combined flow of 2,700l/s
- 3No. 400l/s (each) FFT Pumps
- 3No. 1000l/s (each) Storm Pumps
- 40mm course screening
- 6mm fine screening
- Vortex grit removal
- 3mm fine screening
- Storm Water UV disinfection installation for flows up to 2000l/s
Flow of 700l/s is pre-treated and pumped to the existing treatment works. The first ‘flush’ of 8000m3 of Stormwater is pumped to existing storm tanks and captured, additional volume is and allowed to gravitate at 2000l/s to a pioneering Ultra-Violet (UV) disinfection process before being discharged via the CSO.