A massive stockpile of used tyres at two sites in Brisbane's south has been described as a disaster waiting to happen, with the Queensland Government saying it is powerless to act against the rogue company operating the sites.

Key points: Tyremil Group is controlled by former building industry figure Tony Di Carlo

Tyremil Group is controlled by former building industry figure Tony Di Carlo Insiders say the 'recycling' plants are little more than dumps

Insiders say the 'recycling' plants are little more than dumps Many past employees of Mr Di Carlo describe being abused by him after leaving the business

An estimated 800,000 tyres have been stockpiled at Tyremil Group's two sites in Rocklea and Kingston, with the company claiming to operate a cutting-edge, zero-emissions recycling plant capable of transforming scrap tyres into steel, gas and diesel.

But former company insiders have told 7.30 that no recycling plant exists and the company is little more than a dumping ground for used tyres.

7.30 is also aware of a government investigation into 85 shipping containers full of used tyres which have been dumped at another location at the Brisbane Port by a company associated with Tyremil.

Company overseen by Tony Di Carlo

Mr Di Carlo was disqualified by ASIC from managing companies in September 2012. ( Supplied )

The Tyremil Group is controlled by former building industry figure Tony Di Carlo, although his name does not appear on company documents lodged with corporate regulator ASIC.

His mother is listed as the sole director and shareholder of the company.

Mr Di Carlo was disqualified by ASIC from managing companies in September 2012 for two-and-a-half years.

In 2014, during his disqualification period, Mr Di Carlo moved into the Queensland tyre recycling business after he became mixed up in a multi-million dollar debt dispute involving underworld figure George Alex and standover man turned Islamic State fighter Khaled Sharrouf.

Mr Di Carlo bought into an existing tyre recycling business in the Brisbane suburb of Kingston and rebranded the business as Tyremil, a company first registered in NSW in 2009.

Satellite images show that soon after Mr Di Carlo became involved in the Kingston business the site was overflowing with scrap tyres.

Short of space, a Tyremil company called Grindle Services rented a new site in a semi-industrial part of Rocklea and began to stockpile hundreds of thousands of tyres and tyre crumb on the property.

An internal government document obtained by 7.30 revealed that shortly after moving into the Rocklea property, Mr Di Carlo's operation triggered a complaint from a neighbouring property about a dust nuisance.

The Department of Environment and Heritage Protection investigated the complaint and fined Grindle Services $11,780 for breaching its conditions of operation.

In May this year Grindle Services was placed into liquidation by court order owing creditors more than $70,000. The fine remains unpaid.

'The firies tried to close him down'

A former associate described Mr Di Carlo as an "aggressive verbal bully". ( Four Corners )

Two months before Grindle Services was liquidated, an early morning fire was discovered by a truck driver delivering waste to a neighbouring property.

This led to an investigation which found a fire at the site had the potential to cause "serious or material environmental harm".

As a result Mr Di Carlo was issued an emergency direction to minimise the damage and the Queensland Fire Service ordered that no further tyres were to be accepted at the site.

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"The firies tried to close him down two or three times now, and he just seems to work a way around it and open up again," said one former worker who spoke on the condition of anonymity due to concerns for his safety.

"The instructions we got were, 'it's my f***ing business and I'll run it how I see fit'."

Across Australia, recyclers are paid to take used tyres from retailers. Industry insiders have told the ABC that the Tyremil operation was undercutting other recyclers.

Fire 'could close airport, blanket city in toxic smoke'

Dave West from the Boomerang Alliance, an environmental group which has monitored Tyremil since it began operating in Queensland, said that if the March fire had taken hold it would have caused an environmental disaster capable of closing down nearby Archerfield Airport and blanketing much of south east Queensland with a blanket of thick, toxic smoke.

"We're talking about evacuating people, potentially closing the airport," Mr West said.

"This government is overdue to recognise that this is not an environmental issue, it's a public safety issue, and dicking around for 18 months is not acceptable."

Former employee received abuse, threats

7.30 has spoken to more than 20 former workers and associates of Tony Di Carlo. None of the them were prepared to speak on the record about their experience, and the vast majority described being abused and threatened by Mr Di Carlo after they left the business.

Sorry, this video has expired A voice message from Di Carlo to a former employee

One former employee received a call from Mr Di Carlo shortly after the 7.30 investigation began.

"It's Tony Di Carlo. Remember one thing mate, you want to f*** me over with Tyremil and ABC," Mr Di Carlo said in a voicemail left with the former worker.

"I hope you guys don't put any false statements, cause not only will I break your f***ing legs right? But I'll sue you for any damage to Tyremil if you put any false statements in."

After the ABC asked Mr Di Carlo's lawyers about the fact the Australian Tax Office was chasing his Tyremil Group for $448,000, another former associate received a call from Mr Di Carlo which was recorded on voicemail.

"You're f**king with the wrong bloke. I just had a letter from the ABC and you're the only one who had the information about the ATO you dog f***ing c***. You think you're a tough little c***, come and f***ing see me. I'm going to gut ya."

7.30 understands that both of those calls are now the subject of police inquiries.

Di Carlo showed 'paranoid and aggressive behaviour'

Court records also reveal that Mr Di Carlo is known for his temper.

Last year he was accused of pulling a 20-centimetre knife during a road rage incident in Brisbane. A police intelligence report obtained by 7:30 warns officers that Mr Di Carlo "exhibits paranoid and aggressive behaviour," and that he "may present a risk."

In a statement provided by his lawyer, Mr Di Carlo denied ever having threatened a person with a knife.

The report reveals that police once visited Mr Di Carlo at his home and "he appeared to be confused and paranoid and was carrying a pocket knife."

A section of the police intelligence report on Tony Di Carlo. ( Supplied )

One former associate of Mr Di Carlo believes his threatening manner is the reason why authorities have not closed him down.

"He's an aggressive verbal bully," the former associate said.

Former government blamed for inability to act

Several former workers who spoke to 7.30 said they were owed thousands in unpaid entitlements from Grindle Services and Ace Recycling, however they are unlikely to ever be paid what they are owed because both companies are in liquidation owing creditors more than a million dollars.

Queensland's Environment Minister Steven Miles blamed changes made by the previous Newman government for his department's inability to close Mr Di Carlo down.

"The previous government took away the requirement that he would need a licence for these kinds of ventures," Mr Miles said.

"What that's done is attract rogue operators who aren't interested in value recovery, they are not interested in recycling. They are there to make a quick buck."

Mr Miles said that the State Government was consulting with the tyre recycling industry and he planned to introduce new regulations for tyre recycler later this year.

Mr Di Carlo's lawyer said that Tyremil was working to ensure that the companies two sites became compliant.