Utah Code § 10-8-85: Prison labor and fines.

They may provide by ordinance that any person committed to the county or municipal jail or other place of incarceration as a punishment or in default of the payment of a fine, or fine and costs, shall be required to work for the city at such labor as the person's strength will permit not exceeding eight hours in each working day; and that a judgment that the defendant pay a fine or a fine and costs may also direct that the defendant be imprisoned until the amount thereof is satisfied, specifying the extent of imprisonment which cannot exceed one day for each $2 of such amount.