Dublin city councillors are being urged to reject a proposal to sell one of the local authority's recycling plants.
Trade union Fórsa says a review on bringing waste collections back under the council's remit should be concluded before a decision is made about the centre in Ballymount.
National secretary Peter Nolan says it makes no sense to allow the sale to go ahead as things stand.
"The council are committed to reviewing the prospects of bringing the services back under council control.
"It seems absolutely crazy to sell off facilities that would be necessary should they decide to get back into providing the service directly."