The Chronicle has spoken to two former workers who say they were sacked from the $1.6 billion project after raising issues with workplace health and safety.
Another worker who spoke to The Chronicle on the condition of anonymity said he'd seen "a lot of people that raise issues sacked".
He said there was one instance where a worker had an argument with his supervisor about "operating with a crane... while there was a lightning storm around".
"After he left work that day he didn't have a job any more," he said.
One compactor driver with 46 years of experience in the industry said he had been working in tandem with a grader in order to make the edges of worksites safer for vehicles and machinery.
After he was told the grader driver would no longer be assisting him with his work, he told his subcontractor he would make an official complaint to Nexus.
"That afternoon I got a message on my phone saying your services will no longer be required," he said.
Another man with more than two decades experience in the construction industry said that while he was working for a subcontractor for Nexus, people who raised safety issues had their hours cut back.
He said he was sacked after he refused to work with a crane without the driver having a verification of competency.
Construction, Forestry, Mining and Energy Union divisional branch assistant secretary Jade Ingham said the union was "assessing half a dozen new complaints every day" from workers who were sacked for speaking out about health and safety.
Nexus Infrastructure CEO John Hagan said Nexus did not condone any form of workplace harassment, discrimination and unfair dismissal and took reports of such matters very seriously.
"Under no circumstances should employees be terminated for raising safety concerns," Mr Hagan said.
"If an employee feels this is not the case, I personally encourage them to file a formal complaint.
"Our contractor has confirmed to me that they have in place a fair and equitable process for Nexus workers and subcontractors to raise concerns.
"All issues are dealt with promptly, handled confidentially and investigated impartially through their Just Culture approach."