In the suburb of Balgownie, near the Illawarra Escarpment State Recreation area, flood waters rushing down a steep, rock strewn gully caused serious erosion of its banks. Concerns were raised for a road at the head of the gully, as well as nearby houses.

Also causing concern was a 225mm diameter vitrified clay sewer main buried in the banks of the gully. About 12 months previously the main had been structurally lined by Interflow with Rib Loc Expanda Pipe.

After the storms had cleared, Sydney Water engineers found that a section of the sewer main had been exposed as the bank eroded. After clearing the debris they found that, while the vitrified clay pipe had been smashed and the pieces washed away by the flood waters, the Expanda Pipe was intact and the main was still water tight.

They found the section of Expanda Pipe operating as an above ground pipeline, completely unsupported over a length of approximately 2.5 metres. Large rocks, fallen trees and pieces of broken vitrified clay pipe surrounded it.

The flood, which had unleashed sufficient force to wash away a large section of the gully, move large rocks, uproot trees and smash the vitrified clay pipe, had left the Expanda Pipe completely undamaged.

Laboratory tests confirm Expanda Pipe provides a strong structural liner. The storms at Wollongong have demonstrated that it is also remarkably capable of withstanding the destructive forces of nature.