Engineering plays a critical role in successful tunnel waterproofing. Detailing, sequencing, and constructability must all be considered early to ensure systems perform as intended over the life of the asset. This second instalment of the Bluey checklist has been developed by our engineering team to support design consultants and project teams in applying best practice waterproofing principles across complex underground environments.
11. Check Slab Buoyancy during Pours
During concrete arch pours, formwork can lift due to buoyancy forces, placing significant stress on the membrane system. Protection measures must be engineered to suit the formwork geometry and loading conditions to prevent damage.
12. Design Penetrations Correctly
Pipes and service penetrations are common points of failure if not properly detailed. Engineered solutions, such as preformed trumpet systems, are essential to maintain a watertight seal across a range of penetration sizes.
13. Consider Shotcrete Compatibility
Sheet membrane systems should not be limited to formed concrete applications. Advances in methodology now allow for effective shotcrete application over membranes, supporting improved constructability and reduced rebound when properly designed.
14. Protect the Membrane After Installation
Once installed, particularly in high-traffic areas such as the invert, the membrane must be protected from mechanical damage. Protection systems should be selected based on expected site conditions, including traffic loading and construction sequencing.
15. Optimise Roll Lengths to Reduce Waste
Incorrect roll sizing can lead to unnecessary material waste or increased labour through additional welding. Careful planning of roll lengths helps minimise offcuts, reduce installation time, and control project costs.
16. Use Waterstops for Compartmentalisation
Compartmentalising the membrane system limits the spread of potential leaks and reduces long-term risk. Waterstop layout, spacing, and continuity should align with international best practice to ensure system reliability.
17. Select Appropriate Geotextile Systems
Geotextiles play a critical role in protecting the membrane and managing groundwater flow. Material selection must consider environmental conditions, including chemical exposure, to ensure long-term performance.
18. Design Drainage to Capture all Water flows
Drainage detailing is fundamental to the success of a waterproofing system. Incorrect placement or design can lead to persistent leakage issues. Effective invert drainage is essential to maintaining a dry, serviceable tunnel environment.
19. Consider External Compartmentalisation
External water movement must be managed where required to protect surrounding infrastructure and environments. Proper compartmentalisation can help maintain groundwater conditions and prevent unintended settlement or environmental impact.
20. Use Appropriate Access Systems
Specialist access equipment is often required to achieve safe and efficient installation. Early planning of access solutions improves productivity, reduces installation risk, and supports overall project delivery.. Bluey works alongside project teams to provide the engineering input, systems, and onsite support needed to deliver reliable waterproofing across complex underground environments.
Successful waterproofing relies on more than materials. It requires detailed engineering, careful planning, and experienced delivery.
Bluey invests heavily in training and capability development, including industry-recognised plastics welding programs delivered in partnership with PARTEC in Queensland. Our team continues to support the next generation of installers while maintaining the experience and knowledge built over decades in the tunnelling industry.
