Damage to an underwater dual water trunk main at Jindalee, sustained during the 2011 flood and compounded by subsequent river flows, was recently repaired using innovative engineering solutions.

Built in the 1950s, the main, known as the Jindalee River Crossing, is unique because it was laid in the river bed when most other crossings are on bridges or in tunnels.

It is believed a shipping container rolling along the riverbed during the 2011 flood initially damaged the pipeline. Since that time, water supply to Mount Ommaney and Jindalee has been maintained using an Seqwater-owned crossing from Mt Crosby, however the repair was essential to ensure a reliable and secure water network for customers into the future.

Innovative team work was required to overcome many challenges during the repair task, which was undertaken by QUU’s Civil Maintenance Delivery team with the support of a diving contractor.

“Our initial repair attempts using gibault joints (clamps used to join sections of pipe) were unable to withstand further flooding, so we needed a more robust welding solution,” said Manager Major Contracts and Budget, Daniel Faccio, who led the project.

“To manage the harsh environment, which included working underwater with poor visibility, tidal movements, high currents, shifting silt and a changing riverbed, a purpose-built ‘habitat’ for the divers was created from an inverted shipping container,” explained Daniel.

“Demonstrating QUU’s careful attention to safety, we requested the diving contractor use electronic shark repellent to mitigate the risk of sharks in the river,” said Daniel. “It was the “first time the contractor had been asked to do so.”

Other unique aspects of the repair included using underwater CCTV vision, and pumping clear water into the ‘habitat’ to stabilise the work environment and ensure quality control around the welding.

Three divers did rotating welding shifts about 10 metres below the surface of the Brisbane River upstream from the Centenary Bridge, with the two replacement pipe insertions being about one metre long and 550mm in diameter. Of the dual main, only one of the pipes has been repaired, as a replacement main is due to be constructed by the end of 2015.

See the Urban Utilities article here.