8.—(1) Where a relevant authority gives notice approving the plan and section subject to modifications, or disapproving the plan and section, it shall state its reasons for doing so.
(2) If a relevant authority duly gives notice—
(a)objecting to the plan and section in form, or
(b)approving them subject to modifications to which the undertaker does not agree, or
(c)disapproving them,
then, unless the notice is withdrawn, the undertaker may refer the matter to arbitration.
(3) If the notice is withdrawn, the plan and section as submitted shall be deemed to have been settled by agreement between the relevant authority and the undertaker.