N.Y.C. Admin. Code § 19-142: § 19-142 Workers on excavations.

A person to whom a permit may be issued, to use or open a street, shall be required, before such permit may be issued, to agree that none but competent workers, skilled in the work required of them, shall be employed thereon, and that the prevailing scale of union wages shall be the prevailing wage for similar titles as established by the fiscal officer pursuant to section two hundred twenty of the labor law, paid to those so employed. No permit shall be issued until such agreement shall have been entered into with the department, and all such permits hereafter issued shall include therein a copy of this provision. When permits are issued to utility companies or their contractors, the power to enforce this provision shall be vested with the comptroller of the city of New York consistent with the provisions of section two hundred twenty of the labor law.