5. The substances or articles authorised for deposit at sea are—
(a)iron and steel, copper and aluminium;
(b)stone and rock;
(c)concrete;
(d)sand and gravel;
(e)plastic and synthetic;
(f)material extracted from within the offshore Order limits during construction drilling or seabed preparation for foundation works and cable (including fibre optic cable) sandwave preparation works; and
(g)marine coatings, other chemicals and timber.