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CIPP liners show flexibility in deteriorated stormwater pipes

While the majority of the Australian gravity pipeline rehabilitation market is focused on sewer pipes, it is generally stormwater pipes that are found to be in the worst structural condition. Missing sections, large joint displacements, bends, and poor connections are all common defects due to poorer construction standards when compared to sewer mains.

These defects can often make it difficult or impossible to rehabilitate the pipe without costly civil repairs.

However, Insituform Pacific has successfully completed a number of difficult stormwater rehabilitation projects in Australia over the past two years using its CIPP lining technology. These projects have been completed without the need for civil repairs and the associated community disruption. These projects have been carried out in 225 mm – 750 mm pipes in urban environments, as well as for under-road culvert crossings. One particular culvert in Singleton, New South Wales was able to be lined without prior repairs even though it had an intermediate increase in size from 525 mm –
600 mm.

There are two key factors that allow Insituform’s CIPP liners to be installed in such difficult conditions:

1. The liners are installed into the pipe in a flexible state and are therefore able to negotiate quite severe defects and bends. The liners are then cured within the pipe resulting in a tight fit structural liner within the pipe.

2. The liners are inverted into pipes under pressure. Therefore, as soon as the liner passes through/over a defect, the pipe is internally supported, which reduces the risk of any further pipe sections or soil being dislodged by the liner and falling into the pipe.

A number of clients in New South Wales and Queensland have benefited from the lining systems and achieved results that were previously thought impossible.

The pictures opposite show one such case from a 300 mm stormwater pipe recently lined at Sydney’s famous Bondi Beach. The pipe was over 100 metres in length and had a number of major defects including vertical and horizontal bends, large joint displacements and protruding junctions, not to mention its extremely poor structural condition.

After robotic trimming of protrusions and cleaning, the pipe was easily lined within a few hours without any civil repairs or disruption to residents.

Insituform said this project was an excellent demonstration of the benefits of trenchless pipeline rehabilitation technology, particularly CIPP liners, when it comes to severely deteriorated stormwater pipes.

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