The deal, which enabled the company to work around the clock and complete the project five months early, reportedly saved it up to A$100 million.
The union branch was also given hundreds of thousands of dollars by a global chemical manufacturer, Huntsman, to employ a worker whose duties included "stopping trouble" and helping to close down a factory without industrial unrest, according to the Australian.
The implication is that the AWU bolstered its fortunes, and the clout of its leaders within the labour movement, at the expense of workers - an accusation explicitly levelled by Prime Minister Tony Abbott this week.
Shorten has denied any impropriety, and said he would respond in detail when he testifies before a royal commission into trade union corruption. His lawyer Leon Zwier said Shorten had asked the commission to fast-track his appearance to July during Parliament's winter break, rather than have it in August or September as scheduled.
But history is also haunting Shorten in the shape of The Killing Season, a three-part ABC TV documentary investigating the troubled Rudd and Gillard Labor era. This week's episode alleged that Mark Arbib, a key Labor factional player, told Gillard that "you couldn't trust Bill Shorten". Arbib has denied the claim.
Now Shorten, who played a pivotal role in the knifing of both Rudd and Gillard, is facing a possible mutiny himself, or so some are claiming. Labor MPs complain he is obsessed with the 24-hour news cycle and disregards the advice of senior colleagues, according to Dennis Shanahan, a columnist with the Australian. The MPs see a "frightening parallel [with Rudd]" and fear Shorten is "doing a Kevin", he wrote yesterday.
This week, Shorten abruptly abandoned his pursuit of the Government over payments to an asylum-seeker boat crew, after it emerged that Labor governments repeatedly paid money to "disrupt" people smuggler operations.
He also faced criticism of his refusal to back pension cuts for people with assets of more than A$1.15 million. The Greens' decision to support the Government left Labor completely isolated on the issue.
The documentary's title refers to the time of year when both Rudd and Gillard were toppled - this time of year, just before the parliamentary winter break After Rudd returned to power in June 2013, he changed the party's rules to give grassroots Labor members an equal say with parliamentarians in electing leaders.
Australian columnist Peter Van Onselen yesterday quoted a Labor frontbencher as telling him that, had that not happened, "Bill could have become a victim of the killing season himself".