(1)  The general manager, by notice in writing served on the owner or occupier of land, may require the owner or occupier to rehabilitate land from which soil, rock, sand or material has been extracted at any time after the commencement of this Act.

(2)  The general manager, by notice in writing, may undertake not to make a requirement under subsection (1) in respect of any soil, rock, sand or material extracted before the date of that notice.