The Poolbeg incinerator is already "oversubscribed" for waste disposal and will operate at full capacity, according to Dublin City Council.
The incinerator, which is being built at an estimated cost of €500 million, is due to open next year.
In a written reply to Independent Councillor Ruairi McGinley, council officials said two contracts have already been signed accounting for 60% of the incinerator's capacity.
Discussions are also continuing with other waste collectors for the remaining capacity.
One long-standing criticism of the project was that there would not be enough black bin waste for the 600,000 tonne facility.
But Dublin City Council, which is leading the project on behalf of all the local authorities in Dublin, has pointed out that 500,000 tonnes of waste is being exported nationally every year for incineration abroad.
The Poolbeg incinerator is being developed by the private partner US firm Covanta and will take waste from nine counties in Leinster.
Meanwhile the council’s executive manager has said the 3% to be given as community gain - to fund local community projects - has increased from €8m to €10.38m.
He rejected claims that the amount should be €15m as a percentage of overall capital costs.
