If the work described in any Zoning Permit has not begun within one year from the date of issuance thereof, said permit shall expire. If the work described in any Zoning Permit has not been substantially completed with two and one-half (2½) years of the date of issuance thereof, said permit shall expire and be revoked by the Zoning Inspector. Further work, as described in the canceled permit, shall not proceed unless and until a new Zoning Permit has been obtained or an extension granted.