Water & wastewaterWastewater treatment plant upgrade, inlet works refurbishment, H2S corrosion remediation, screening and grit removal

Hayle STW – Inlet Refurbishment Works

Hayle, Cornwall · 2018 (Case study published, implying completion around this time) [Water Projects Online]

The judgement call

Account-gated at launch

Decision to pursue a "new off-line build" option to minimise interface with existing works and reduce risks [Water Projects Online] - Use of corrosion-resistant materials (PE lined channels, MDPE pipes) due to harsh H2S environment [Water Projects Online] - Extensive trial holes and investigations to locate existing services, using vacuum excavation and air picks [Water Projects Online] - Prefabricated MDPE units and stainless steel tanks for new reception chamber and screens [Water Projects Online]

Key engineering challenges

Remediation of concrete corrosion due to high levels of H2S attack within the existing inlet works [Water Projects Online] - Provision of effective inlet screening and screenings handling from 7 incoming pipelines [Water Projects Online] - Working on a live site, requiring systematic shutdowns and diversions of incoming flows [Water Projects Online] - Complex interfaces and lack of information on existing assets [Water Projects Online]

Project facts

Client / owner: South West Water (SWW)
Lead contractor: Interserve (Main contractor) [Water Projects Online]
Lead designers: Arcadis (Project designer) [Water Projects Online]
Project type: upgrade | refurbishment
Scale: Full flow to treatment is 795 l/s; inlet works can receive 1800 l/s; 7 incoming pipelines; 3 (No.) fine screens (duty/assist/standby); 2 (No.) duty/standby Longwood Engineering 50mm coarse screens [Water Projects Online]
Disciplines: Civil; mechanical; electrical; process; environmental
Standards & frameworks: South West Water technical standards

Sources: Water Projects Online: https://waterprojectsonline.com/case-studies/hayle-inlet-works-2018/ (Accessed: 2026-06-10) - South West Water (DWMP Hayle-Lands End): https://www.southwestwater.co.uk/siteassets/documents/about-us/dwmp/strategic-catchments/hayle-lands-end_l2_dwmp.pdf (Accessed: 2026-06-10)

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