Coventry Sewer Diversion

About This Project

The Gulson Road Sewer Diversion Project in Coventry, completed in 2019, enabled the redevelopment of a brownfield site into an eight-storey, 460-room student accommodation complex as part of Coventry University’s expansion. To facilitate construction, a major Severn Trent trunk sewer—measuring 1050mm x 700mm and carrying up to 900 litres per second during storm events—had to be diverted. Severn Trent appointed nmcn PLC (now Galliford Try) as the design and build contractor, supported by Active Tunnelling Ltd, COWI, and other specialist partners. Initial investigations ruled out open-cut methods due to urban constraints, leading to a complex tunnelling solution involving a 7m-deep, 3.66m-diameter shaft and a new tunnelled connection into the existing 3.05m Sherbourne Valley Tunnel. A critical component was constructing an 11m-long timber heading beneath a live carriageway, requiring extensive planning, stakeholder engagement, and Highways Authority approval. The project faced geotechnical challenges, including unforeseen weak mudstone layers that led to redesigning the tunnelling methodology into a safer, open-faced shielded pipe jack approach. Safety remained paramount throughout, with innovations such as a temporary tunnel flow-sealing plate, 3D SLAM scanning for as-built data, and advanced confined-space safety measures. The project also supported Severn Trent graduate training and adopted collaborative planning to coordinate with ongoing site development. The diversion was successfully completed without any lost-time incidents and received the 2019 West Midlands Small Project Merit Award from the Institution of Civil Engineers.