A four-tower retail and residential development in north-west Sydney is “at threat of collapse” after defects in the load-bearing concrete were identified by the state building commission.

The basement and ground floor of a Macquarie Park development at 23 Halifax Street were found to have “serious damage” and spalling in the concrete, due to “defective workmanship”, the NSW Building Commission said in a work rectification order made public this week.

The Lachlan’s Line precinct was completed in 2019, consisting of four buildings containing a total of 900 apartments, with a retail village on the ground floor.

Spalling refers to deterioration of concrete and threatens the building’s supportive structure.

“This issue compromises structural performance and structural adequacy of the concrete slab,” the document says.

“As a result, it is likely to cause inability of the concrete slab to withstand the car park and ground floor loads.”

The high-rise buildings above ground as well as the retail village on the ground floor, share the basement area.

It is not yet clear how many apartments or businesses or which parts of the development are at risk.

The order was released on Monday, calling on Greenland to “remediate the serious and/or potential serious defects” identified.

“This is a defect … that causes or is likely to cause the basement slab to fail, namely, to fracture and collapse, leading to the destruction of the building … or threat of collapse,” the order says.

The work was “carried out in a manner that could result in a serious defect” in the buildings, the document says.

Greenland has been given eight months to rectify the concerns. The company has been contacted for comment.

‘A bit concerning’

Residents in the precinct told the ABC it was “business as usual” today, while centre management said they were not made aware of the situation prior to the government assessment being made public.

John Dinkha is a barber who has operated out of the Lachlan’s Line since 2020 and said he found out about the defects through his customers.

“I haven’t received any emails, no letters, nothing, not anything,” he said. 

“It’s a bit concerning … the last thing that we need is to lose business here.

“So I’m hoping everything is good … if they can sort it out ASAP would be good.”

Greenland Group was founded in Shanghai, China, in 1992 and operates in nine countries.

It describes itself as a “leader” in ultra-high-rise buildings, specialising in “developing large-scale projects while prioritising quality and efficiency” on its Australian website, which was inaccessible in Wednesday afternoon.

The group has 23 projects under construction or completed internationally, and established its Australian arm in 2013, based in Sydney.

“Greenland Australia has become known as one of the country’s leading developers of residential communities,” its website said.