23.—(1) Not less than 56 days before the commencement of any works authorised by this Order that are near to, or will or may affect, any apparatus the removal of which has not been required by TfL under paragraph 21(2) or otherwise, TfL must submit to National Grid a plan.
(2) In relation to specified works, or any works that (wherever situated) impose any load directly upon any apparatus, the plan to be submitted to National Grid under sub-paragraph (1) must show—
(a)the exact position of the works;
(b)the level at which these are proposed to be constructed or renewed;
(c)the manner of their construction or renewal including details of excavation and positioning of plant;
(d)the position of all apparatus;
(e)by way of detailed drawings, every alteration proposed to be made to or close to any such apparatus; and
(f)details of any ground monitoring scheme if required.
(3) TfL must not commence any works to which sub-paragraph (2) applies until National Grid has given written approval of the plan so submitted.
(4) Any approval of National Grid required under sub-paragraph (3)—
(a)may be given subject to reasonable conditions for any purpose mentioned in sub-paragraph (5) or (7); and
(b)must not be unreasonably withheld.
(5) In relation to a work to which sub-paragraph (1) and (2) applies, National Grid may require such modifications to be made to the plan as may be reasonably necessary for the purpose of securing its system against interference or risk of damage or for the purpose of providing or securing proper and convenient means of access to any apparatus.
(6) Works executed under sub-paragraph (1) or (2) must be executed only in accordance with the plan, submitted under sub-paragraph (1) or (2), as amended from time to time by agreement between TfL and National Grid and in accordance with such reasonable requirements as may be made in accordance with sub-paragraphs (4), (5), (7) or (8) by National Grid for the alteration or otherwise for the protection of the apparatus, or for securing access to it, and National Grid is entitled to watch and inspect the execution of those works.
(7) Where National Grid requires protective works to be carried out either themselves or by TfL (whether of a temporary or permanent nature) such protective works, inclusive of any measures or schemes required and approved as part of the plan approved pursuant to this paragraph, must be carried out to National Grid's satisfaction prior to the commencement of any work to which sub-paragraph (1) or (2) applies and National Grid must give 56 days' notice of such works from the date of submission of a plan in line with sub-paragraph (1) or (2) (except in an emergency).
(8) If National Grid in accordance with sub-paragraph (5) or (7) and in consequence of the works proposed by TfL, reasonably requires the removal of any apparatus and gives written notice to TfL of that requirement, paragraphs 16 to 18 and 21 to 22 apply as if the removal of the apparatus had been required by TfL under paragraph 21(2).
(9) Nothing in this paragraph precludes TfL from submitting at any time or from time to time, but in no case less than 56 days before commencing the execution of any works, a new plan, instead of the plan previously submitted, and having done so the provisions of this paragraph apply to and in respect of the new plan.
(10) TfL is not required to comply with sub-paragraph (1) where it needs to carry out emergency works as defined in the 1991 Act but in that case it must give to National Grid notice as soon as is reasonably practicable and a plan of those works and must—
(a)comply with sub-paragraph (5), (6) and (7) insofar as is reasonably practicable in the circumstances; and
(b)comply with sub-paragraph (11) at all times.
(11) At all times when carrying out any works authorised under this Order comply with National Grid's policies for safe working in proximity to gas apparatus enshrined in Specification for safe working in the vicinity of National Grid, High pressure Gas pipelines and associated installation requirements for third parties T/SP/SSW22 and the Health and Safety Executive's guidance note “Avoiding Danger from underground services HSG47”.
(12) As soon as reasonably practicable after any ground subsidence event, TfL must implement an appropriate ground mitigation scheme.