Waste collection staff in Stirling and Clackmannanshire are to walk out over nine days next month, in a dispute over pay.
Trade union UNISON has confirmed strike action will take place between 14th and 22nd August.
The union rejected a 3.2% pay rise from council body COSLA.
They've warned rubbish could "pile up" on streets across the country.
Unite and GMB have also rejected the offer, and will announce planned walk out dates shortly.
Finance Secretary Shona Robison has said the Scottish government is "committed" to further negotiations.
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