Liverpool Bay Carbon Capture Storage M56

Project Optimisation Outcomes

Predictable programme performance

A steady production rate of around 20 m per day provided excellent programme certainty, helping the client maintain confidence in deliverables and overall project schedule.

Safety and assurance under live motorway conditions

Working beneath an operational motorway demanded rigorous monitoring and precise control of tunnelling parameters. This ensured zero settlement and uninterrupted traffic flow - an essential requirement for the client.

Integrated design expertise 

With both Temporary and Permanent Works design completed by the JGL Design Team, the project benefitted from a fully coordinated engineering approach, enhancing safety, constructability, and delivery efficiency.

Project Highlights

• Microtunnelling crossing completed beneath the M56 under live traffic conditions
• No disruption to traffic or road operations during the works
• Tunnel length of approximately 97.5 metres
• Tunnelling carried out through weak to medium sandstone
• Average advance rate of around 20 metres per day achieved
• Jacking pressures maintained between 50–100 bar
• Accurate line and level maintained throughout the drive

Technical Overview

• No. of Shafts 2
• Shaft Diameter - 10.5 m
• Shaft Construction - Secant piled
• Launch pit - 10.7m - Secant piled shaft
• Reception pit - 9.2 m - Secant piled shaft
• Tunnel size - ID 1500 mm – Length 97.5
• Tunnel lining precast concrete pipe
• TBM Machine Model, Size & No. etc. MTBM - AVN 1500
• Completed Drive Length - 97.5m
• Diameter of tunnel / pipe - 1500 mm
• No. of crossings 1
• Ground Conditions Sandstone – weak to medium
• Concrete Poured m3 - Secant piled approx. by Subcon: 1300m3 JGL Works: 65m3
• Muck Away - 2208.4m3

In‑House Engineering & Delivery

• Design of Temporary Works – JGL Design Team
• Design of Permanent Works – JGL Design Team
• Microtunnelling – JGL Design Team

Live Motorway Conditions

The microtunnelling works were carried out beneath the M56 under live traffic conditions, and the crossing was completed with no impact on the operation of the road above.

The TRS08 microtunnelling works presented several environmental and geotechnical challenges that required proactive engineering solutions. One of the most significant constraints was the absence of a water discharge licence from the client. This meant that traditional dewatering methods could not be used, prompting the team to develop an alternative strategy that would both stabilise the excavation and comply fully with environmental restrictions. A secant‑piled shaft design was adopted, creating an effectively sealed structure that minimised groundwater ingress. This approach proved highly successful, keeping the shaft dry throughout excavation and eliminating the need for any uncontrolled water discharge.

In addition, the presence of artesian water in the sandstone strata required careful management to maintain stability beneath the live M56 motorway. The team implemented controlled face pressures, continual geotechnical monitoring, and disciplined TBM operation to avoid ground movement.

By integrating real-time feedback with experienced operator control, the team safely navigated the variable rock conditions without affecting the motorway above. These combined efforts ensured that the project remained safe, compliant, and uninterrupted despite the demanding conditions.

Outcome

The crossing was delivered safely, efficiently, and within budget, meeting all technical requirements. The microtunnel advanced smoothly at an average rate of around 20 metres per day and maintained accurate line and level throughout the drive. The works were completed under live M56 traffic with no disruption to road operations. The secant‑piled shafts performed effectively, providing a dry and stable working environment and avoiding unnecessary water discharge. Coordinated plant support and strong collaboration between design and site teams contributed to a predictable, well‑managed programme. The TRS08 crossing demonstrated JGL’s capability to deliver complex trenchless works beneath critical infrastructure.