4Meaning of contaminated land

4 Meaning of contaminated land (1) In this Act: contaminated, in relation to land, means the presence in, on or under the land, or a building or structure on the land, of a substance at a concentration above the concentration at which the substance is normally present in, on or under land, or a building or structure on land, in the same locality, if the presence causes, or is likely to cause either or both of the following: (a) a risk of harm to human health; (b) a risk of environmental harm. (2) For subsection (1), land may be contaminated even if it became contaminated partly or entirely by the migration of contaminants into, onto or under the land from other land. (3) However, land is not contaminated only because in any surface water standing or running on the land a substance is present in a concentration above the concentration at which the substance is normally present in, on or under land, or a building or structure on land, in the same locality.