18.—(1) Subject to sub-paragraph (2), in the event that no gas is stored within any of the cavities within a period of 10 years following the completion of all solution mining works comprising part of the authorised development, a scheme detailing the appropriate measures for decommissioning of the authorised development must be submitted to the relevant planning authority for approval.
(2) Not later than ten years after the start of use of the authorised development a scheme detailing the appropriate measures for decommissioning of the pipe bridge and diffuser forming part of Work No.10 must be submitted to the relevant planning authority for approval.
(3) A scheme approved under sub-paragraph 17(1) or 17(2) must be implemented in full within 24 months of its approval by the relevant planning authority.