The provisions of this subtitle do not apply to activities of the State Highway Administration, any county roads department in the State, any legally constituted public governing entities such as municipal corporations, or to activities of any person acting under contract with any of these public agencies or entities, on highway rights-of-way or borrow pits owned, operated, or maintained solely in connection with the construction, repair, and maintenance of the public roads systems of the State or other public facilities. This exemption does not become effective until the public agencies or entities have adopted reclamation standards applying to the activities and the standards are approved by the Department. The provisions of this subtitle do not apply to mining on federal lands when performed under a valid permit from the appropriate federal agency having jurisdiction over the land. Any or all of the provisions of this subtitle do not apply in any county if the Secretary determines that the county laws are as restrictive as the provisions of this subtitle with respect to regulating surface mining, reclamation and revegetation procedures, abandoned areas, and bonding requirements.