Access to view this particular break was gained by physically entering the line via a 15 metre deep, pump out sump 50 metres upstream of the problem. The timing of access to the line had to be co-ordinated with the rise and fall of the ocean tides, as the amount of infiltration greatly increased during high tide. Previous attempts to seal the infiltration by using putty and expanding foam proved unsuccessful due to the water pressure pushing through the gaps. To ensure the reline of this amount of infiltration was successful, it required a second liner to be installed over the first.

After carrying out the CCTV operations in the pipe the Nuflow team was able to locate the problem as a major infiltration in a 600 mm concrete storm water pipe. Access to the particular problem was gained through a sump pit located upstream of the infiltration.

Alternatives?

An alternative to the relining of this project would be to excavate the pipe and renew the damaged section; this would have involved having to effectively plug the area off that was to be excavated to reduce or even stop the flow of water, in order for an external repair to be carried out or a new piece of pipe installed.

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Result of relining

The project required no excavation. The downtime on this pipe repair was kept to the minimum by utilising a pump to remove the stormwater from the pit upstream of the repair and discharging into the downstream pit, below the repair. A one metre patch liner was used with a slow resin. The entire job, including setup, curing and clean up time was completed in eight hours.