The Director or designee has the authority to revoke or modify any permit or approval which was issued pursuant to the Director or designee's review. Prior to such revocation or modification, the Director or designee shall follow procedures concerning notice and appeals as required for the initial consideration thereof, provided that when any permit or approval is not exercised within the time specified in such permit or approval or if no date is specified, within two years from the approval date of said permit or approval, the permit or approval shall automatically become null and void and no public hearing shall be required on the matter.