Up to 100 Waterford City Council workers are engaged in unofficial industrial action over the council's use of outside contract staff without consultation with the union.
Wheelie-bin collections, roadworks and waterworks are all being affected as a result of the action.
Management have issued a letter to staff to return to work without delay.
Failure to do so will be considered gross misconduct in breach of the city council's grievance and disciplinary procedures.
Today's action comes after 50 staff staged a sit-in at the city’s Bolton Street depot yesterday.
Workers from a number of departments were involved in the action before staff from other sections joined the protest this morning.
Meetings have been taking place between union officials and council management. Ballots for strike action had been taken two weeks ago on the issue of contract workers.
