The Slieve Felim Action Group is calling on the Government and Coillte to withdraw the sale of a site to Limerick County Council for what it describes as "an obnoxious megadump".
The action group said in a statement that the land on the scenic Limerick-Tipperary border was bought for forestry and should be used for forestry, the environment and leisure time.
Mr David Thompson, PRO for the group, said Coillte's decision to sell the land was contrary to every point made in a strategic plan for Coillte.
When the former Minister for Agriculture, Mr Ivan Yates, introduced the strategic plan, he made it clear that forestry was not only about timber production, but had to be compatible with environmental aims, enhancing it and encouraging recreational pursuits.
"How can Coillte see a megadump as environment-enhancing and an encouragement to recreational pursuits for enjoyment?" asked Mr Thompson.
He said the proposed dump would destroy the environment, the tourist attractions of the area, wildlife habitats, the Slieve Felim leisure walk, the clean water of the Duglasha river and the natural beauty of the site.
He also claimed that selling the site for a dump would inflict lasting damage to Coillte's public image and would provide its detractors with further and better reasons for public attacks on its prevailing policies and practices.
It would result in a sharp decline in public support with all the inevitable consequences.
Mr Thompson said this viewpoint had been put to Coillte by Prof Laurence Roche, a former president of the International Union of Forest Societies, and he said the Benedictine monks of Glenstal Abbey in Murroe had held vigils on Slieve Felim attended by the public in protest at the landfill proposal.
Limerick County Council has conducted a feasibility study and discussed the contentious issue, which has been passed on to the Environmental Protection Agency for a decision, which is awaited.