Sounds simple enough doesn’t it? But add that the joint is over one metre in diameter, six metres underground, tidally influenced and immediately under a concrete flood levee and things quickly get complicated. This is the scenario that the Launceston City Council of Tasmania recently faced.

The asset in question was a storm water pipe laid from the pump station to the low tide level at the river. Previous open-trench repair attempts had failed, leaving Undergroud Asset Services (UGAS) with a seemingly improbable job, as no trenchless spot repair of this size had ever been attempted in Tasmania, and as far as is understood, the rest of Australia.

For this project, UGAS used KRE Engineering Services to supply trenchless equipment and materials required. KRE organised the 1000/1200 mm Inflatable Packer to be flown in especially for the job, and also provided the appropriate PatchBox kits for the in-situ pipe repair, all of which were delivered on site and on schedule, ready for job commencement.

PatchBox is an innovative method of pipe repair supplied by KRE, which utilises the highest quality materials available to suit underground conditions, and provides a long-term repair solution with both structural integrity and a watertight seal.

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Works were scheduled around the low tide when infiltration was at its lowest, leaving UGAS with a tight schedule to complete the works in. Fortunately, the KRE Waterglass Resin provides extra security, allowing PatchBox to cure in minimum time, even when fully submerged, and provides an excellent bond to pipe walls in heavily hydrated environments.

The site was prepared and all the materials required for the repair were supplied in the PatchBox. Application was straightforward: the fibreglass mat was rolled out and impregnated with KRE Waterglass Resin. The packer was wrapped in protective polyethylene sheeting and the impregnated glass-mat securely wrapped around the protected inflatable packer. Due to the flexible nature of the packer, allowing it to bend up to 90 degrees during insertion, the restricted entry of the pipeline posed no problems.

Two patches were placed within the pipeline, allowing sufficient overlapping at the defective joint. Both patches went according to plan, and the entire job was completed within a ten-hour time frame.

The trenchless method offered an effective means of repair to the damaged pipe, which could be performed without any disruption to services, customers or the general public. The repair method was both cost-efficient and time effective, to the great satisfaction of the Launceston City Council who could not afford to have their storm water pumps offline for too long.