Our Approach
JGL applied its extensive experience in trenchless technology and deep shaft construction to develop a robust delivery strategy tailored to the site constraints. Careful planning was undertaken to manage working space limitations, interface with the existing wastewater treatment works, and mitigate the risks associated with mixed ground conditions.
All temporary works were designed in‑house, ensuring full control over safety, programme and constructability. A clear organisational structure was implemented on site, supported by specialist operatives and dedicated tunnelling equipment from within the Joseph Gallagher Group.
By selecting the most appropriate tunnelling methodology and equipment early in the process, and by maintaining close coordination with the client and main contractor, JGL ensured the works progressed safely and efficiently through each stage of construction.
Key Challenges
Confined Working Areas
The project operated from two compact working compounds, requiring meticulous logistics planning to manage plant movements, materials storage and workforce access without disrupting surrounding operations.
Sensitive Location
The drive shaft was located in a field adjacent to residential properties, while the reception shaft was within a live wastewater treatment works. Strict controls were implemented to manage noise, access and site safety, ensuring minimal disturbance to neighbouring stakeholders.
Complex Ground Conditions
Tunnelling progressed from high‑strength limestone into glacial till consisting of sands, gravels and boulders. This transition demanded careful monitoring, precise machine control and flexible engineering solutions to maintain line and level accuracy throughout the drive.
Added Value
During construction, unexpected boulder sizes were encountered within the glacial till. JGL was able to add value by upsizing the tunnelling machine, selecting a more suitable unit from its in‑house fleet. This proactive approach reduced risk, improved productivity and ensured the continuous progress of the tunnel drive without programme disruption.
