(1)The hazardous substances authority may by order revoke a hazardous substances consent or modify it to such extent as they consider expedient if it appears to them, having regard to any material consideration, that it is expedient to revoke or modify it.
(2)The hazardous substances authority may also by order revoke a hazardous substances consent if it appears to them—
(a)that there has been a material change of use of land to which a hazardous substances consent relates; or
(b)that planning permission has been granted for development the carrying out of which would involve a material change of use of such land and the development to which the permission relates has been commenced; or
(c)in the case of a hazardous substances consent which relates only to one substance, that that substance has not for at least five years been present on, over or under the land to which the consent relates in a quantity equal to or exceeding the controlled quantity; or
(d)in the case of a hazardous substances consent which relates to a number of substances, that none of those substances has for at least five years been so present.
(3)An order made by virtue of subsection (2)(a) or (b) in the case of a consent relating to more than one substance may revoke it entirely or only so far as it relates to a specified substance.
(4)An order under this section shall specify the grounds on which it is made.