legal action is being taken by residents in Sandymount and Ringsend against Dublin City Council (DCC) over the Poolbeg incinerator.
A meeting on Wednesday night was attended by 100 community leaders from Ringsend, Fairview, Marino, Irishtown and Sandymount.
"The message was quite clear, that we are determined to stop the incinerator at Ringsend going ahead," said chairwoman of the Combined Residents Against Incineration group, Frances Corr.
"We are going to take legal action very shortly. We think we have a very strong challenge."
The city authority has already spent millions of euro on the project.
The group, which Ms Corr has chaired for the past 17 years, will also march to the Dail for the first time.
Hundreds of residents are expected to join the march later this month.
"We're going to march from Ringsend church to the Dail on Wednesday, October 22 at 5pm," Ms Corr told the Herald.
"Anyone who is in work can join us outside the Dail from 6pm.
"It's our first march on the Dail and it's happening there because we believe that is where the power lies."
A DCC spokesman said the council had no comment to make on the matter.
Works are expected to begin on the incinerator site in the coming weeks.
Ms Corr said she has spent so many years campaigning against the incinerator is because she "loves Dublin".
"I am born and bred here. "I love the city. My family goes back generations in Dublin," she said. "I want to see proper planning and sustainable development."
Last month, DCC chief executive Owen Keegan told councillors in a report that the waste project is needed and makes commercial sense.
It is expected it would process 550,000 tonnes of waste every year.
Private US energy company Covanta is due to arrive at the Poolbeg Generating Station in the coming days with construction beginning shortly afterwards.
DCC previously confirmed this move, and said a project agreement had been signed with Covanta.
The European Commission ruled last May that the project was not in breach of state aid rules.
That decision meant the incinerator was cleared for construction.
Planning permission for the project had originally been granted in 2007, but it has been beset by a number of delays and other problems.