The provisions of this article shall not apply to any of the following activities:
(1) The extraction of coal by a landowner for his own noncommercial use from land owned or leased by him;
(2) For surface mining operations affecting two acres or less, the regulatory authority may waive certain requirements of this article where those requirements will not affect the reclamation of the affected lands;
(3) The extraction of coal as an incidental part of federal, state or local government-financed highway or other construction under regulations established by the regulatory authority;
(4) The extraction of coal incidental to the extraction of other minerals where coal does not exceed sixteen and two-thirds percent of the tonnage of minerals removed for commercial use or sale pursuant to regulations established by the regulatory authority.