Contractors are pouring concrete into a sinkhole in a bid to prevent the collapse of a two-storey building in suburban Sydney, as the NSW government is forced to defend a major road tunnelling project.
A Fire and Rescue NSW spokesman said more concrete would be poured into the sinkhole over the weekend after a section of ground subsided on Friday, causing the building to sag in the middle and appear unstable.
Emergency services are attempting to shore up a building in Rockdale to prevent further structural collapse.Credit: Sam Mooy
The 10-metre-wide hole opened up at an office block in an industrial park in Rockdale, in Sydney’s south, on Friday morning, at a site above the M6 tunnel construction.
Excavation work was occurring inside the tunnel at the time of collapse, the Australian Workers Union said.
Construction on part of the $3 billion M6 motorway project was brought to a sudden halt, with workers forced to evacuate tunnels due to falling debris.
No one was working in the part of the office block that partially collapsed into the sinkhole, but about 10 people were evacuated from another part of the building.
A sinkhole appeared under a Rockdale office building on Friday.Credit: Nine
Firefighters have also set up laser monitoring equipment and drones to detect any further movement in the building on West Botany Street.
The spokesman said no further structural collapse had occurred, and the laser detectors had only detected “very, very minor movement” in the building at this stage.
“Our priority at this stage is to shore up that building to prevent further structural collapse,” he said.
Firefighters will enter the office block once it has been declared safe to determine the extent of damage and develop a plan to shore up the building, he said.
On Saturday afternoon, Assistant Superintendent Belinda Hooker of Fire and Rescue NSW said that more concrete would be poured into the sinkhole over the weekend under the guidance of engineers.
A Transport for NSW spokesman said the extent and cause of the subsidence were under investigation.
“Our focus now is to remediate the subsidence and safely progress works on the south-bound tunnel,” he said.
The tunnel mishap follows construction delays reported last year on the Snowy 2.0 pumped hydro project when a massive tunnel-boring machine got stuck in soft rock beneath Kosciuszko National Park.
The spokesman said no other sites on the M6 project had been affected by the subsidence in Rockdale.
The first stage of the M6 toll road linking Kogarah to the WestConnex motorway at Arncliffe is due to be opened to traffic by the end of 2025 – about a year later than originally planned.
Seventy per cent of tunnel excavations for the new motorway have been completed, he said.
“Each major project has unique challenges with respect to geology,” he said. “Our engineering and safety controls provide the best tunnelling methodology for the predicted geology.”
Opposition transport spokeswoman Natalie Ward said the safety of the workers and nearby communities needed to be the priority right now.
“Hopefully, the project can resume work soon, once it is safe to do,” she said.