Trade unions are demanding the contract to build a £100 million incinerator at Baldovie in Dundee does not go overseas.
The new incinerator will convert waste from Dundee City and Angus councils into energy, some of which will be piped into the nearby Michelin factory.
The GMB and Unite unions say they fear the company behind the development, German-owned MVV Environmental Services Ltd, may hire an overseas contractor whose employees are willing to work for less money than Scottish tradesmen.
They claim this practice, called social dumping, occurred during the construction of two other energy-from-waste (EfW) plants built in Scotland.
Neither plant is operated by MVV.
The German company currently operates one UK plant in Plymouth. The contractor used during its construction was Bedfordshire-based firm Kier.
About 300 jobs are expected to be created during the three years it takes to build the new Dundee incinerator.
Gary Cook, Scotland officer for the GMB, and David Lawson, regional officer for Unite, have written to Dundee City Council leader John Alexander about their concerns.
Additionally, they will meet MVV managing direction Paul Carey on January 18 to discuss the issue.
Mr Carey was unavailable for comment.