An image of a flooded cross tunnel passage and a video of the sinkhole, between the two Forrestfield Airport Link tunnels in Perth, Australia, have been posted on social media.
Currently under the construction, a leak was discovered in a cross tunnel passage between the twin-bored tunnels on Saturday 22 September. A sinkhole developed immediately above the site.
At the time the TBMs were stopped and work has been continuing to stop ground water from leaking into tunnel one, said a statement from Government of Western Australia.
Forrestfield tunnel leak
Source: Facebook: CFMEU WA
The statement said: ”While that work is ongoing, a survey of the ground along Dundas Road and tunnel connecting to the cross passage is also underway.
”Due to the leak there has been some movement of approximately 10 tunnel rings near the point of the cross passage. Additional internal bracing is now in place as work continues to stop the leak and resolve the sinkhole damage.
Transport Minister Rita Saffioti added: “The State Government is monitoring this very closely and working with Salini-Impregilo - NRW Joint Venture. We are hopeful a resolution can be found in the very near future.
“My number one priority is to ensure work is carried out safely.
“I have asked the Public Transport Authority to review the timeline of the project, to ensure worker safety is paramount.
“In addition, 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.”
Watch the ABC News video of the sinkhole here.
In a statement over the weekend Forrestfield-Airport Link said: “Immediate efforts were made to stop the leak, and this continued throughout the night.
“Despite these efforts, groundwater and silt is still flowing into the cross passage and one of the tunnels. A sinkhole developed immediately above the site, on Dundas Road about 200m north of the Forrestfield Station site. Dundas Road has been closed to traffic while work takes place to fix the leak and repair the road.”
Both tunnel-boring machines, which are more than 2km further on from this cross-passage, have been stopped while the repair work takes place. No one was hurt in the incident.
Earlier this year, both boring machines were stopped for about eight weeks due to ground disturbances detected in the area.
The AUS$1.86bn (£1.03bn) Forrestfield-Airport Link is jointly funded by the Australian and Western Australian governments and will deliver a new rail service to the eastern suburbs of Perth – with three new stations at Redcliffe, Airport Central and Forrestfield.
The line will spur off the existing Midland Line near Bayswater Station and run to Forrestfield through twin-bored tunnels. In April 2016 the Public Transport Authority awarded the design, construct and maintenance contract to Salini Impregilo and NRW Joint Venture. The project is due to be completed in 2020.