Challenge
Washout of fines created voids beneath a live wastewater outfall pipe, causing joint settlement, water loss, and environmental risk — requiring rapid stabilisation without excavation or operational disruption.
Solution
Geobear injected geopolymer to 2.2m depth, filling voids and re-supporting pipe joints in three shifts, eliminating water loss with no excavation or disruption to wastewater operations.
Total delivery programme
Geopolymer installed
Versus traditional grouting
A Tier 1 contractor managing wastewater infrastructure in Co. Dublin identified a critical issue affecting a live outfall pipe. A drain survey confirmed that washout of fines had created voids beneath and around the pipe.
As the ground support deteriorated, the pipe began to sink at the joints, leading to ongoing water loss. Given the pipe’s operational importance within the wastewater network, the risk was both environmental and operational.
A fast, controlled remediation solution was required to prevent further settlement and eliminate leakage without disrupting surrounding infrastructure.
The remediation strategy needed to:
Fill voids formed by washout of fines
Re-support the pipe at the joints
Eliminate water loss
Avoid excavation and protect adjacent infrastructure
Minimise disruption to active wastewater operations
Traditional cementitious grouting was considered, with a quoted cost of approximately €115,000. However, this approach would have required a longer programme, greater site disruption, and a higher material volume, increasing both cost and carbon impact.
A faster, lower-footprint alternative was required.
Geobear proposed targeted geopolymer injection to a treatment depth of 2.2 metres beneath and around the outfall pipe.
Using a two-person crew and a single truck, approximately 2,048 kg of geopolymer resin was injected over three shifts. The expanding material filled the voids caused by the washout, densified surrounding soils, and re-established uniform support at the pipe joints.
The non-invasive approach required no excavation, no road closures, and no interruption to wastewater operations. Geobear acted as principal contractor, delivering a controlled and efficient stabilisation programme.
The voids were successfully filled and the pipe re-supported at the joints, eliminating ongoing water loss. The works were completed in just three shifts — days rather than weeks.
Compared to the traditional grouting alternative, the Geobear solution delivered an approximate 47% cost saving.
With no excavation and minimal plant, the solution significantly reduced disruption and environmental impact, protecting the asset while maintaining full operational continuity.
Get in touch with our expert team today and discover how Geobear can extend the life of your critical infrastructure assets.
