SIPTU has called on the four local authorities in Dublin to honour the agreements with the union to develop waste disposal services in the city.
The demand comes after shop stewards met to discuss the planned outsourcing of waste collection by Dún Laoghaire-Rathdown County Council to the private operator Panda.
The Labour Relations Commission will host talks on the dispute next week.
SIPTU's Paul Smyth said: 'Our members are both angry and concerned that one of the four authorities is attempting to renege on the agreement made two years ago on waste disposal management strategy.
'The attempt by the Dún Laoghaire-Rathdown manager to pull out of the agreement has the capacity to undermine the strategy to safeguard minimum standards and provide some stability to the waste disposal services in the capital.'
Workers in South Dublin, Fingal and Dublin City councils have already voted to take industrial action in support of their colleagues in Dún Laoghaire-Rathdown if the talks fail.
