A hearing has begun into an equal pay claim which could cost Birmingham City Council millions of pounds.
The case, being brought by 4,200 women workers, could leave the council with a £400m bill, with each claimant seeking up to £100,000 in compensation.
According to solicitor Paul Doran, who is representing the women, bonuses and overtime mean that those in traditionally male dominated jobs such as rubbish collecting and road sweeping could earn four times as much as women on the same salary grade.
The claimants are primarily employed in female-dominated roles such as care, cleaning and catering.
Doran told the Birmingham Mail that the women would be bringing test claims for equal pay based on 49 different job groups within the council.
Birmingham City Council introduced a single status agreement in 2008, aimed at removing salary differences between men and women.