s 16 Section 78X (supplementary provisions)
(1) Section 78X (supplementary provisions) has effect with the following modifications. (2) For subsection (1), substitute— (1) Where it appears to a local authority that two or more different sites, when considered together, are in such a condition, by reason of substances in, on or under the land, that— (a) harm is being caused, or (b) there is a significant possibility of harm being caused, this Part shall apply in relation to each of those sites, whether or not the condition of the land at any of them, when considered alone, appears to the authority to be such that harm is being caused or there is a significant possibility of harm being caused. (3) For subsection (2), substitute— (2) Where it appears to a local authority that any land outside, but adjoining or adjacent to, its area is in such a condition, by reason of substances in, on or under the land, that harm is being caused, or there is a significant possibility of harm being caused within its area— (a) the authority may, in exercising its functions under this Part, treat that land as if it were land situated within its area; and (b) except in this subsection, any reference— (i) to land within the area of a local authority, or (ii) to the local authority in whose area any land is situated, shall be construed accordingly; but this subsection is without prejudice to the functions of the local authority in whose area the land is in fact situated.