In a secret recording, Mr Allman can be heard telling the department's regional director for the south-west region, Matt Dunkley, that he had "destroyed" evidence.
Mr Dunkley asked Mr Allman whether he had "deleted that s---" and "got rid of it all" to keep himself "squeaky clean" when he knew an investigation into misconduct at the department was under way.
"You have f------ cleared up all your mess, haven't you, mate? You're – you're squeaky clean now?" he can be heard asking Mr Allman.
Mr Allman, who was sacked last year after it emerged that he threw documents into a bin at a Bunnings hardware store, told Mr Dunkley he had destroyed evidence.
Mr Dunkley was a member of the department's integrity committee, which was set up in the wake of IBAC's investigation.
Following Tuesday's evidence, the department confirmed Mr Dunkley had been removed from that committee and had also been suspended as regional director of the south-west region.
Mr Allman admitted that on May 25, 2009, he bought 12,300 shares in CSG Limited, the company that won the Ultranet contract, for less than $10,000. He did this just two days before ASIC publicly announced the contract.
Mr Allman also admitted he advised his "best friend" Ian Morrison to buy the shares after the announcement.
He conceded to IBAC that he lied to KPMG interviewers when they investigated the share purchase, telling them he had received a tip that CSG Limited was a "good bet", just months before the Ultranet contract was signed.
Yet he told IBAC that he thought to buy the shares after overhearing one of Mr Fraser's conversations on a hands-free call when they were driving in a car, in late 2008.
Mr Allman denied that he was involved in several Ultranet-related activities at the department from 2004-2006, despite department documentation suggesting otherwise.
IBAC heard Mr Allman was fined $2500 by the financial watchdog.
The commission is investigating how contracts for the Ultranet project were awarded and tendered, and whether education department purchased shares in the company that won the lucrative contract.
Oh, by the way....Matt Dunkley ( MBE or something or other) is my Regional Director.
An investigation into the Department of Education and Training’s $180 million Ultranet project is progressing to the next stage, guided by information uncovered during recent anti-corruption hearings.
IBAC CEO Alistair Maclean said the Operation Dunham public examinations, which concluded today, were a vital part of the investigation of alleged corruption in the education sector.
“Not only are they an invaluable investigative tool but they have also assisted in informing the public sector and the community on the risks and impacts of corruption more broadly,” Mr Maclean said.
“As a result of these hearings, many people have contacted us with new information, which will help in the next stages of our investigation.
“The investigation is ongoing, so I encourage people with information to come forward.”
During the hearings, 39 witnesses were called and 273 exhibits tabled.
A public report for Operation Dunham will be released in 2016, containing findings and recommendations for further action and improvements.
The public report for Operation Ord, IBAC’s first investigation into the Department of Education and Training, will be released shortly.
Operation Dunham is just one of IBAC’s active investigations. To report concerns about public sector corruption, go to www.ibac.vic.gov.au