5.—(1) Subject to sub-paragraph (2), an application for a permit to operate an existing Part A installation or Part A mobile plant shall not be made before the beginning of the relevant period for that installation or mobile plant without the consent of SEPA.
(2) Where an operator of an existing Part A installation proposes to make a substantial change in the operation of the installation the operator may make an application before the beginning of the relevant period for a permit to operate that part of the installation that will be affected by the substantial change.