New $60m Melbourne Water main completed

The first of eight kilometre plus sections, known collectively as the M9, was laid across Merri Creek, Coburg, in February 2009. It replaces a 10.5km main between Preston and North Essendon and its aim is to save water and strengthen security of supply to 50,000 households in Melbourne’s rapidly growing northern and western suburbs, by reducing the risk of leaks and bursts.

Melbourne Water says the new M9 main is more leak resistant than the old pipe because it is made of better quality steel, is cathodically protected and has welded joints rather than horizontal lead joints. As well the new pipe has a consistent minimum cover between the top of the pipe and the finished surface level of 1.2m.

For example there is 3m of cover over the final pipe section due to existing services in the area, that compares with the minimal cover of the old pipe when it was laid 83 to 100 years ago, making it prone in some places to damage from traffic.

Melbourne Water said there was limited use for the old main. But a limited number of sections were lifted, grouted and relaid while others were either recycled for their steel content or left in place. Melbourne Water’s communications director Nicolas McGay, said in response to a question from Earthmover about leaking pipes, that no water system in the world is without leaks or bursts.

“But ours are extremely low and we’re always working to reduce them. Our leak and loss rate target is that measurable transfer losses are less than 1% of total water delivered. We missed this target by 0.1% in 2009/10 chiefly because of operational needs at one of our main service reservoirs in Preston and the need to flush the Winneke-Preston Main. Except for 2009/10 we have consistently met this target since it was established in 2002/03,” he said.

Victorian Water Minister Peter Walsh said the replaced main was more than 100 years old and had reached the end of its service life. He said the replacement of the M9 main constituted $58m of Melbourne Water’s $122m, four-year program to upgrade 20 km of water supply assets.

“The Victorian Coalition Government is committed to making the water supply system more efficient by reducing the loss of non-revenue water. So the city’s water retailers are currently trialing the effectiveness of leakage detection technology in areas with poor infrastructure to help them find and repair leaks faster.”

Melbourne Water’s manager of asset planning Paul Pretto said one of the major challenges of the M9 replacement was undertaking work in densely developed areas.

“With projects like this there is always a degree of inconvenience and we thank the community for their patience and understanding while we completed this essential work,” he said.

Other large-scale water and sewerage projects underway across Melbourne projects include the Melbourne Main Sewer Replacement, the Northern Sewerage Project and the Easter Treatment Plant tertiary upgrade.