5. In section 178 of the principal Act (execution and cost of works required by enforcement notices)—
(a)for “an enforcement notice” in each place where it occurs substitute “a hazardous substances contravention notice”;
(b)for “local planning authority” in each place where it occurs substitute “hazardous substances authority”;
(c)in subsection (2) for “breach of planning control” in both places where it occurs substitute “contravention of hazardous substances control”;
(d)in subsection (4) for “the enforcement notice” substitute “the hazardous substances contravention notice”;
(e)after subsection (6) insert—
“(7) Where different periods are specified for different steps under section 24(5)(b) of the Planning (Hazardous Substances) Act 1990 in relation to a hazardous substances contravention notice, references in this section and in section 179 to the period for compliance with a hazardous substances contravention notice, in relation to any step, are to the period at the end of which the step is required to have been taken.”.