6.—(1) In carrying out or maintaining the authorised development, the undertaker may—
(a)deviate the works laterally within the extent of the limits of deviation for those works shown on the works plans;
(b)deviate the pipeline works vertically upwards to a limit of not less than 1.2 metres below the surface of the ground (except where ground conditions make compliance with this upwards limit impracticable in which case the upwards limit is 0.452 metres below the surface of the ground);
(c)in respect of those sections of the pipeline works which may be constructed and installed using trenchless installation techniques, deviate the pipeline works vertically downwards to such extent as may be found necessary or convenient subject to a maximum depth of 35m;
(d)deviate works other than the pipeline vertically—
(i)upwards or above ground level to the height limits set for those works in Schedule 2 (requirements); and
(ii)downwards to any extent as may be found necessary or convenient.
(2) The maximum limits of vertical deviation specified in paragraph (1)(b) do not apply within Work No 43E.
(3) The maximum limits of vertical deviation specified in paragraphs (1)(b), (c) and (d) do not apply where it is demonstrated by the undertaker to the Secretary of State’s satisfaction and the Secretary of State, following consultation with the relevant planning authority, certifies accordingly that a deviation in excess of these limits would not give rise to any materially new or materially different environmental effects to those identified in the environmental statement.