DUBLIN City Manager Owen Keegan has said it would be "entirely appropriate" for an independent investigation to be carried out into the disastrous Poolbeg Project.
Mr Keegan revealed that the overall bill saddled on the taxpayer is estimated to be at €108m.
He was highly critical of the handling of the Incinerator project, adding: "Nobody is more concerned about the cost than I am".
And Mr Keegan admitted that he doesn't know whether the project will proceed at all because of an ongoing EU investigation.
Members of the Oireachtas Environment Committee were left stunned after being told the details of the expenditure on the Dublin 4 project.
Fianna Fáil senator Averil Power likened the project to the disastrous e-voting system.
"It's throwing good money after bad," she said.
Mr Tierney, who is the new Irish Water chief, spent six years as City Manager and had a direct role in decision making in relation to the project.
Not a single brick has been laid, despite the huge sums spent on consultancy, land, engineering services and site management.
Mr Keegan did not apportion blame to any named former official but said he believed there were "serious weaknesses" in the management of the project.
Under questioning from Labour TD Kevin Humphreys, Mr Keegan admitted that some €12m has been spent on a heating project in Dublin which is interrelated to the incinerator.
He confirmed that the heating project was dependent on the incinerator being given approval.
This means that the overall bill for both related projects is over €108m.
Significantly, Mr Keegan said he would welcome an independent investigation inrto Poolbeg. "It would be entirely appropriate," he said.