(1)For the purpose of the construction, maintenance or improvement of the new bridge, the Secretary of State may deepen, widen, dredge, scour, cleanse, alter or improve the bed of the river Severn or blast any rock in it.
(2)The power conferred by subsection (1) above shall not be exercised in relation to any part of the river which is—
(a)outside the limits within which the Gloucester Harbour Trustees have authority at the passing of this Act, or
(b)upstream of the relevant inward limit.
(3)The Secretary of State shall not exercise the power conferred by subsection (1) above—
(a)within the area bounded by planes passing vertically along the length of lines drawn forty metres laterally distant from the longitudinal centre line of the Severn Tunnel, or
(b)by blasting within the area bounded by planes passing vertically along the length of lines drawn one hundred metres laterally distant from that centre line,
without the consent of the British Railways Board; and where the Secretary of State requests the consent of the Board for the purposes of this subsection it shall not be unreasonably withheld or delayed.
(4)The Secretary of State may use, appropriate or sell or otherwise dispose of anything removed in exercise of the power conferred by subsection (1) above.