4. For the purposes of these Regulations, premises for the time being used for depositing refuse from a single mine, being premises exclusively occupied by the owner of that mine, shall be deemed to form part of that mine, and premises for the time being used for depositing refuse from two or more mines, being premises occupied by the owner of one of those mines (either exclusively or jointly with the owner of the other or any of the others) shall be deemed to form part of such one of those mines as the Executive may direct.