Costain to upgrade Rugby sewage works: design and integration notes for engineers
Reviewed by Tom Sullivan
First reported on The Construction Index
30 Second Briefing
Severn Trent has awarded Costain a £45m design-and-build contract to upgrade the Rugby Newbold sewage treatment works with a new activated sludge plant and biological treatment system, increasing dry weather flow capacity by 28% from 21,600 to 27,598m³/day by 2028 to meet AMP8 WINEP requirements. The scheme includes new pumping stations, four 29m-diameter final settlement tanks, a chemical dosing plant, and expanded inlet works with increased feed and storm capacity. For civil and process designers, key issues will be integrating new biological units with legacy assets while managing higher storm storage and overflow control.
Technical Brief
- Costain’s scope includes full design-and-build of a new activated sludge plant integrated with legacy assets.
- Biological treatment relies on suspended-growth microorganisms to aerobically digest organic contaminants in municipal sewage.
- Four circular final settlement tanks, each 29 m diameter, will provide secondary clarification capacity.
- New pumping stations will reconfigure hydraulic profiles and transfer flows between upgraded inlet, ASP and clarifiers.
- Existing inlet works will be expanded and re-equipped to handle higher peak feed and storm inflows.
- Ancillary upgrades cover on-site facilities and utilities systems, implying modifications to power, control and access infrastructure.
Our Take
A 28% capacity uplift at a Severn Trent wastewater site signals that UK utilities are committing sizeable AMP-period budgets to treatment resilience, which should support a multi‑year pipeline of similar infrastructure work for contractors in the United Kingdom through at least 2028.
For Costain, adding a complex sewage treatment works scheme alongside its HS2 tunnelling role and the £100M M5 junction contract underlines a strategy of balancing regulated utility frameworks with major transport projects to smooth revenue volatility across sectors.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
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