Damage to a cross tunnel passage which was flooded by a leak between the two Forrestfield-Airport Link tunnels in Perth, Australia, is under repair.
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 had been continuing to stop ground water from leaking into tunnel one.
Since then the leak has been stopped and repairs and ongoing assessment are underway to the damage to the project’s first tunnel-to-tunnel cross passage.
According to Forrestfield-Airport Link, jet grout was injected into the ground late last year in preparation for the cross passage to be constructed.
In a new update, the company said: “In this instance, a leak occurred during construction allowing groundwater and silt to flow into the cross passage and one of the tunnels. As a result, a sink hole formed at the surface above the cross passage, about 200m north of the Forrestfield Station site where the tunnels follow the alignment of Dundas Road.
“The leak has now been stopped and efforts have shifted to repairing damage caused by the leak, including the reinstatement of Dundas Road.”
An image of the flooded Perth Metro tunnel was posted online shortly after it was reported.
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.