The Problem:
A 375mm diameter asbestos cement sewer pipeline some 148 metres long was blocked. Inspection revealed a collapsed section. An emergency solution was needed because of the risk of further collapse causing major subsidence. The pipeline was some 4 metres deep in sandy, water charged ground, about 100 metres from a canal.

The Solution:
Calaqua (formerly the Water and Sewerage Department of Caloundra Shire Council) worked rapidly to clear the blockage. The blockage was found to be due to a section of the pipeline about 1.5 metres long that had collapsed. The collapse was located under a backyard at about the mid point of the long pipeline.

Calaqua called Interflow who recommended installing a Rib Loc Expanda Pipe liner.

The Project:
Interflow responded quickly to Calaqua’s call for emergency assistance.

While removing the blockage restored service to customers, it did not remove the danger of further collapse. Infiltration from the sandy, water charged ground was washing backfill material into the sewer.

With the 4 metre deep sewer running under the backyards of houses in a built up residential area, any subsidence caused by pipe collapse could have been catastrophic.

All that remained of the collapsed section was a small piece of the invert. The rest of the pipe at that point had disappeared.

Interflow lined the pipeline from the downstream manhole located on a busy road. As the Rib Loc spiral winding process does not require factory pre-manufacture of a liner to the correct dimensions, no lead time was necessary before installation of a 148 metre long liner could commence.

The missing pipe section, and the high level of infiltration, caused no problems for Expanda Pipe installation. Rib Loc Expanda Pipe does not soften during installation, and heating is not required, so a structural liner with a circular cross section and assured material properties was provided.

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