Deteriorating sewer trunk main to be replaced


A $1.9m project starts next month to replace the deteriorating sewer trunk main which takes 50 per cent of Ashburton's domestic and commercial waste water to the local treatment plant at Wilkins Road.

Built in 1949 with reinforced concrete pipes, the 1.5km long Ashburton Borough catchment sewer has reached the end of its lifespan and is struggling to cope with the volume of wastewater currently running through it.

The sewer line starts in Dobson Street, goes down William Street and then runs parallel to the Ashburton River until the end of Trevor's Road where it meets with the current grit chamber.

Service and Delivery Chair Councillor Stuart Wilson says the replacement of the concrete pipeline was necessary with ongoing concerns about wastewater leakage and the structural integrity of the exposed and raised sections of pipeline.

"Replacing the existing trunk main with a larger pipeline allows for future development, as well as eliminating the ongoing maintenance necessary to keep it in service.

"The old pipeline has reached its capacity and isn't in great condition after 66 years," he says.

The contract has been awarded to Ashburton Contracting Limited (ACL).

The new pipes are made out of polyethylene and will be 700mm in diameter, replacing the existing 450mm pipeline.

Operations and Projects Manager Viv Eyberg says the larger pipes will double the capacity the pipeline can handle which means, based on current Ashburton's growth rate, it should cope for at least 60 years.

Mr Eyberg says unlike the concrete pipes which were laid above ground, these ones will be below ground which will help extend their lifespan and keep them protected from the elements and accidental damage.

In 2003 and 2008 Council began investigations into the sewer pipeline to look at the quality of the pipes and the volume of waste passing through them. This information helped inform the replacement project.

Services will not be affected while the work is being carried out.

Page reviewed: 21 May 2015 9:37am