8(1)If any tidal work is abandoned, the Port Authority may by notice in writing require the nominated undertaker to take such reasonable steps as may be specified in the notice to remove the work and (to such extent as the Port Authority reasonably requires) to restore the site to its former condition.
(2)If any tidal work is in such condition that it is, or is likely to become, a danger to or to interfere with navigation in or the regime of, the river, the Port Authority may by notice in writing require the nominated undertaker to take such reasonable steps as may be specified in the notice—
(a)to repair and restore the work or part of it, or
(b)if the nominated undertaker so elects, to remove the work and (to such extent as the Port Authority reasonably requires) to restore the site to its former condition.
(3)If—
(a)a work which consists of a tidal work and a non-tidal work is abandoned or falls into decay; and
(b)the non-tidal work is in such a condition as to interfere with the right of navigation in the river;
the Port Authority may include the non-tidal work, or any part of it, in any notice under this paragraph.
(4)In this paragraph “tidal work” means so much of any specified work or any other work of which the nominated undertaker is in possession under the powers of this Act as is below the level of mean high water springs and “non-tidal work” means so much of any such work as is above that level.
(5)If after such reasonable period as may be specified in a notice under this paragraph the nominated undertaker has failed to begin taking steps to comply with the requirements of the notice or after beginning has failed to make reasonably expeditious progress towards their implementation, the Port Authority may carry out the works specified in the notice and any expenditure reasonably incurred by it in so doing shall be recoverable from the nominated undertaker.