An artist's impression of the incinerator due to be built at Saltend
When the region's two councils first put forward plans to burn non-recyclable household waste almost 10 years ago, the expected cost of constructing a facility was about £30m.
The latest estimate – which is three times the cost of Hull's KC Stadium – has infuriated anti-incinerator campaigners.
Barry Robinson, a leading member of the Hull and Holderness Opposing the Incinerator (Hoti) group, said: "This huge cost is just the latest reason why this monstrosity should not be built.
"We should also be asking why the councils are proposing to pay a waste company to burn our rubbish when, at the same time, we are recycling more than ever."
Both East Riding Council and Hull City Council are currently locked into a 25-year contract with the Waste Recycling Group (WRG) firm to manage the disposal of region's household rubbish.
The contract includes provision for a 240-ton capacity incinerator.
When it was signed in 1999, it was originally envisaged the two councils would foot the bill.
But since then costs have soared as a series of delays have hit the project.
After a potential site in Hull was rejected in 2003 after a costly public inquiry, an alternative at Saltend was identified two years later.
Although planning permission was subsequently granted for the site, the facility's operating licence was withdrawn by the Environment Agency earlier this year after a legal challenge by campaigners.
WRG is still in the process of resubmitting a licence application pending a review of its own procedures by the Environment Agency.
Had the Hull site gone ahead, the incinerator would have already been up and running.
But with all the delays there is still no scheduled opening date.
The original contract also now prevents the councils from seeking Whitehall funding through a Private Finance Initiative (PFI) – the Government's favoured option for new incinerator developments – as it pre-dates current PFI funding rules.
With the latest cost estimate influencing moves by both councils to renegotiate the contract, senior councillors are also examining a joint PFI bid, having submitted an expression of interest earlier this year.
Senior East Riding councillors on the authority's cabinet met yesterday to hear an update on discussions around the joint waste contract.
Because of commercial confidentiality, members of the public and the media were excluded from that part of a meeting.
However, a statement released afterwards said: "The cabinet of East Riding Council today considered a report on the progression of the joint waste contract between the council and Hull City Council with the Waste Recycling Group.
"It would be inappropriate to make any comment at this time in advance of the meeting of Hull City Council's cabinet later this month when the item will be discussed."