Paragraph 27 I1

any tidal work is abandoned or out of repair or is in such other position that it is or is likely to become a danger to or (save as this Order may permit) interfere with navigation or other public rights in the river; and

the Port Authority by written notice require the undertaker to repair the tidal work or (if the undertaker no longer requires the work) to abate and remove the tidal work or any part of it and restore the site to its former condition; and

the undertaker fails to comply with the notice within 28 days after the receipt of it;