(a) Any of the prisoners in the county jails located in counties having a population of between twenty-four thousand five hundred (24,500) and twenty-five thousand five hundred (25,500) and between forty-seven thousand five hundred (47,500) and forty-seven thousand six hundred (47,600) inhabitants may be permitted to voluntarily work in any cemetery or on any other public project in those counties.
(b) The prisoners shall be allowed a credit on any fine owed of five dollars ($5.00) for each day they perform such voluntary labor.