If any change in the physical conditions of any lands of a realty improvement, which will materially affect the operation of the water supply system or sewerage facilities covered by any certification issued under this act, shall be made after certification, the certification shall become null and void and a new certification shall be obtained before construction shall proceed. If 50 or more realty improvements are covered by such a voided certificate a copy of the application for a new certificate shall be mailed to the State Department on the date upon which it is submitted to the board.
N.J.S. § 58:11-30