On Saturday afternoon, a small leak occurred in tunnel one (TBM Grace tunnel) of the Forrestfield-Airport Link project, approximately 200m north of Forrestfield Station.
The leak occurred around a cross passage adjacent to Dundas Road, which led to the formation of a sinkhole early on Sunday morning and closure of the road. A cross passage is a throughway to connect the two tunnels and will be used as an emergency exit once the rail line is operational.
The tunnel boring machines have now stopped as a precautionary measure and work is continuing to stop ground water from leaking into tunnel one.
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.
TBM Grace is currently about 3km ahead of this cross passage site and TBM Sandy is located about 2.5km ahead of the site.
Comments attributed to Transport Minister Rita Saffioti:
"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."
PTA agency statement issued Sunday September 23, 2018:
At 1pm on Saturday September 22 a leak developed in a cross-passage between the two Forrestfield-Airport Link tunnels. 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. Safety managers are onsite and measures have been put in place to ensure worker safety.
Media line: (08) 9326 2526 or media@pta.wa.gov.au