The Hearing Examiner has the authority to revoke or modify any permit or approval which was issued pursuant to the Examiner's review. Prior to such revocation or modification, a public hearing shall be held by the Examiner and procedures concerning notice, reporting, and appeals shall be the same 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.