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Perth airport tunnel construction grinds to a halt after water leak causes sinkhole

ABC News, 25 September 2018
A water leak, which has led to the creation of a sinkhole, is continuing to delay the construction of Perth’s new $1.8 billion airport tunnel.Tunnelling for the new Forrestfield-Airport Link project was brought to an abrupt halt on Saturday afternoon. The sinkhole appeared on Sunday morning, forcing the closure of Dundas Road.


WA Transport Minister Rita Saffioti said on Monday that the leak was caused by activity from the creation of a “tunnel cross passage”, a throughway that connects the tunnels to be used as an emergency exit when the rail line opens.

“It is a complex part of this project, and as I understand one of the most complex parts of building any tunnel — getting that cross passage constructed,” Ms Saffioti said.

“There was checking done to make sure there was no water coming through, and as a result of that construction, something happened and they created a water flow.

“So this shouldn’t have happened, it should be water tight and that’s an issue that we need to review going forward.

“There will be a review into the method used to create future cross passages, and surveys are now being undertaken of the ground and the two tunnels in the vicinity of this particular cross passage.”

The two boring machines, called TBM Grace and Sandy, are being used to dig the eight-kilometre tunnel from Forrestfield to Bayswater. But they have both been stopped until engineers find a way to stop the leak.

Speaking on Tuesday, the Minister said the water flows were now minimal.

“Of course it’s positive, but I’d like to see the water stop altogether and make sure the whole area is stabilised and moving forward,” she said.

“This has got implications for in particular how the TBMs will be able to move forward.

“Safety and quality is absolute priority and that’s going to be the message I send to everybody involved in the project.”

Safety concerns raised by union

The Construction, Forestry, Maritime, Mining and Energy Union (CFMEU) said up to 15 members had quit the project amid safety concerns on site.

It said there had been two near-fatal events, and two previous failures of the pipes inside the tunnel leading to flooding and a serious spill of tens of thousands of litres of untreated and potentially toxic water.

The union said the basic working conditions, including toilet and other core facilities, have been described as third-world.

CFMEU assistant secretary Graham Pallot said the union had not been given access to the tunnel.

“Our workers on this project are considerably concerned, there’s been a high turnover of people left after the last incident, we’re expecting turnover yet again,” he said.

“And that means we’re going to get replacements with more and more inexperienced workers again.”

Ms Saffioti could not say with certainty when work would resume, but that worker safety was the priority.

“This is a contract that we need to finish, we’ve got two TBMs in the ground and everyone has got to work together, but of course it’s a project we inherited,” Ms Saffioti said.

“We want to continue working with the contractor (Salini-Impregilo – NRW Joint Venture) and highlight that workers safety is our number one priority, and the whole team is working together.”

Opposition spokesman Dean Nalder said the flooding was concerning.
“It’s really important that the Government… takes accountability for it, and can assure people they’re going to fix it up so these things don’t continue to occur,” he said.

Mr Nalder said the project went through a proper due diligence process when the Liberals were in government.
“It went through all those independent processes before it came to me, as minister and to cabinet,” he said.

“Mistakes occur on projects, but it’s not so much the mistake that occurs, it’s how you actually handle it, and we need open transparency and full accountability from the Government.”

Ms Saffioti asked the Public Transport Authority to review the timeline of the project, which is due to be completed in 2020.

Earlier this year, both boring machines were forced to stop work for about two months, because of a number of ground disturbances detected in the area.

https://www.abc.net.au/news/2018-09-24/wa-airport-link-sinkhole-floods-tunnel/10298606

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