Beneath our feet: The hidden failures in Melbourne’s sewer tunnels

When the firm Steve Hastings worked for discovered hundreds of collapsed bricks inside the labyrinthine tunnels of Melbourne’s largest sewer, he expected swift action from the city’s water authority.

The sewer, after all, carries 191 million litres of raw sewage daily, from the inner city to Werribee, and is a vital, costly artery performing a function most citizens hope they can take for granted.

“Melbourne Water didn’t want to know,” says Steve Hastings, once the CFO of surveying company UAM Tec, which found serious issues with projects. Credit: Simon Schluter

When Hastings’ firm told Melbourne Water about the substantial brick pile during the $206 million Hobsons Bay Main Drain repair project, he says that a swift response was not the reaction.

“They didn’t want to know,” says the former chief financial officer of surveying company UAM Tec, hired by Melbourne Water in 2022 for its high-definition underground video and laser scanning.

UAM Tec and Melbourne Water are now locked in a legal dispute that has resulted in the contractor making a complaint to the corruption watchdog and sparked questions in parliament amid concerns that essential urban infrastructure is not being maintained appropriately.

As the dispute has rumbled on, internal documents have emerged showing Melbourne Water staff have doubts about its knowledge of the state of significant pipes and tunnels beneath the city’s streets.

A 2023 brick collapse inside the Hobsons Bay Main Drain, a sewer carrying a third of Melbourne’s sewage under the Yarra River to Werribee.Credit: UAM Tec

When UAM Tec reported the brick collapse in 2023, Hastings says Melbourne Water didn’t demand urgent repairs. Instead, it let construction firm John Holland — the building contractor leading the repair works — sack UAM Tec.

Melbourne Water confirmed to this masthead this month that the bricks remained in the tunnel but is fighting UAM Tec’s claims it has been mistreated.

The collapse is one of two major tunnel projects that concerned UAM Tec.

The company was hired on a long-term basis, says former Melbourne Water infrastructure general manager Eamonn Kelly, only to be removed from all work for the authority after just 18 months.

“We lost our contract due to what we found – and they did not want us to find anything else,” says Hastings.

UAM Tec is now seeking millions in payments from the water authority for years of future work it says Melbourne Water commissioned before dumping them.

It has also referred the water company to Victoria’s Independent Broad-based Anti-corruption Commission, saying in its submission that the Hobsons Bay brick collapse “represented a clear and present danger to the tunnel’s structural integrity. Despite this, [we were] informed that we would not receive further work”.

The opposition has demanded in state parliament that Water Minister Gayle Tierney take immediate action to investigate the issue.

Melbourne Water disputes UAM Tec’s accusations, saying builder John Holland dealt with the brick collapse in the tunnel sufficiently at the time. Planning is now under way to eventually go back and repair the tunnel where the collapse happened. The authority has also said it has acted in line with its contractual obligations to UAM Tec.

“Melbourne Water is currently involved in a dispute with a supplier. Melbourne Water maintains its position that it is not liable for any of the claims made against it,” a spokesman for the authority said.

Some of the bricks in the Hobsons Bay Main Drain in 2023 after the flushing attempt.Credit: UAMTEC

The spokesman said the tunnels at the centre of the dispute, which run from Port Melbourne under the Yarra River to Spotswood and then ultimately to Werribee, did not pose a safety or operational risk, and that the authority undertook “regular maintenance on its assets and uses a range of products and services to find the best solutions”.

After the brick discovery, builder John Holland attempted to “flush” the bricks and rubble by redirecting sewage into the passage to clear it. Photos, supplied to The Age, taken after the flushing show this failed.

The water authority last year had $853 million worth of capital works under way on the city’s waterways and sewers.

Internal Melbourne Water emails obtained by The Age show the authority’s employees are concerned about the accuracy of the information the authority holds on its own systems.

One senior project manager said in an email that “most of Melbourne Water’s [sewer] drawings are not readable any more” because of “bad scans of 100-year-old drawings not covering all information [such as] missing manholes [or] missing upgrades/rehabilitation completed in the past”.

Another email from within Melbourne Water’s Major Capital Delivery department shows that on just three projects, there were $10 million worth of unforeseen costs because the water authority had an inadequate picture of what was below the ground when it tendered repair works.

Melbourne Water hired UAM Tec on a $5 million contract to survey many of the city’s drains and sewers and, over a longer period, potentially develop its technology for sale to other city authorities.

In another project involved in the dispute, the surveying firm found major faults in a stormwater drain under Hawthorn being re-lined so the tunnel could last another 50 years.

UAM Tec was hired to verify the quality of work being done by contractor Aqua Metro Services.

Core samples taken at the Hawthorn drain, showing the concrete reinforcement had been applied too thinly.Credit: UAM Tec

The main drain under Hawthorn’s Church Street used GeoKrete, a “wonder” concrete that Aqua Metro was – according to a UAM Tec report given to Melbourne Water – meant to spray in a coating 40 millimetres thick over 100-year-old brickwork to reinforce it.

The survey found GeoKrete was sprayed over the brickwork as thin as 14mm in places, with photos showing the reinforcing concrete also blocking some inlet drains and “weep holes”, which allow groundwater accumulating behind a drain wall to enter the tunnel, preventing pressure buildup.

Heat mapping produced by UAM Tec showed 57 per cent of the GeoKrete sprayed in the tunnel was not at the correct thickness and later core samples confirmed it was sprayed too thin.

A report by UAM Tec given to Melbourne Water warned brick walls “with insufficient liner thickness may be more susceptible to wear, corrosion, and potential failure, undermining the overall effectiveness of the reinforcement”.

Instead of being credited for finding faults, UAM Tec was removed from all Melbourne Water projects.

Melbourne Water confirmed Aqua Metro would return to repair the drain at no cost to taxpayers.

Aqua Metro director Marcus Wade said his company had “gone back and done a small amount of work. We definitely haven’t gone back and done a lot of work”.

Wade said later in an emailed statement that GeoKrete was widely used in Europe and the United States.

UAM Tec has received support in its legal battle against Melbourne Water from Eamonn Kelly, who from 2015 to 2022 was the general manager at Melbourne Water in charge of hundreds of millions of dollars in large sewerage and water projects.

He said Melbourne Water signed up UAM Tec for the long term and that not continuing to use them broke its promise outside of the agreed terms.

Kelly has previously received high praise from Melbourne Water which, in 2022, described him as an “innovator” who “leads by example and influences change for the better across the industry”.

Kelly said the firm’s sewer monitoring technology could potentially save the water authority tens of millions of dollars by checking both ongoing construction and existing sewers.

Kelly has previously done consulting work for the company, and Melbourne Water has argued he is not a reliable witness because future possible work with the firm gives him a vested financial interest.

The state opposition’s Upper House leader, David Davis, raised the matter in parliament this month, asking Water Minister Gayle Tierney whether she supported Melbourne Water in the dispute.

“There are massive problems in the drains, and who do you sack? Not the contractor firm that has done the work but the whistleblower,” he told parliament.

“Will the minister please investigate what has gone on here? The company that blew the whistle is the one that is being shot, and we need to understand why the minister and the officials are supporting the people who have done the wrong thing.”

Tierney declined to comment, citing the ongoing legal stoush when asked if she was concerned and to express confidence in Melbourne Water’s management of the city’s sewers and stormwater system.

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