The council may waive or relax any requirement of a hazardous substances contravention notice issued by it and, in particular, may extend any period specified in accordance with section 162(5)(b) in the notice.

The powers conferred by subsection (1) may be exercised before or after the notice takes effect.

The council must, immediately after exercising those powers, give notice of the exercise to every person who has been served with a copy of the hazardous substances contravention notice or would, if the notice were re-issued, be served with a copy of it.