Emergency teams of cleaners, escorted by police officers, will begin cleaning the streets of Madrid on Saturday after talks to end a strike failed.
The walk out is now in its 12th day and rubbish is piling up in the capital’s streets and parks.
Both sides failed to reach a deal within a 48-hour deadline set by the city’s mayor.
The unions have slammed attempts by private contractors to lay off more than 1000 workers and cut wages by 40 percent. The companies have since offered to reduce redundancies to 296 but unions have rejected this.
Mayor Ana Botella has faced criticism over her handling of the dispute. She is angry that private contractors have failed to maintain a minimum level of services agreed with City Hall.