Dartford-Thurrock Crossing Act 1988

12 (1) If—

(a) within the period beginning with the commencement of the construction of the bridge and ending ten years from the completion of that construction, any part of the river becomes subjected to silting or scouring which is wholly or partly caused by a tidal work; or

(b) within the period of ten years beginning with the commencement of the carrying out of any tidal work in connection with the maintenance or improvement of the bridge any part of the river becomes subjected to silting or scouring which is wholly or partly caused by that tidal work;

and within that period the Port Authority give notice to the Secretary of State that in their opinion that silting or scouring should be removed or, as the case may be, made good in the interests of persons using the river or for the protection of other works in the river, the Secretary of State shall pay to the Port Authority any additional expense reasonably incurred by them in dredging the river to remove the silting or, as the case may be, in making good the scouring in so far as, in either case, it is attributable to a tidal work.

(2) If any part of the river becomes subjected to silting or scouring within a period specified in sub-paragraph (1) above, and that siltation is removed, or, as the case may be, that scouring is made good, in circumstances in which the Secretary of State is liable to make any payment to the Port Authority under that sub-paragraph, the provisions of that sub-paragraph shall apply to any recurrence of such silting or scouring within the remainder of the period ending twenty years from the completion of the construction of the bridge, or, as the case may be, the commencement of the tidal work in connection with the maintenance or improvement of the bridge, as they apply to silting or scouring to which that part of the river is subjected within the period specified in sub-paragraph (1).

(3) On application made by the Port Authority to the Secretary of State, he shall make payments to them on account of any sum payable under sub-paragraph (1) or (2) above, by one or more interim payments of such amounts, at such times, as may be reasonably required by the Port Authority for defraying expenditure incurred by the Port Authority from time to time in removing the silting or making good the scouring.

(4) The Secretary of State shall pay to the Port Authority any costs reasonably incurred by them in order to ascertain whether silting or scouring has occurred in respect of which liability may arise under sub-paragraph (1) or (2) above, not being costs which the Port Authority would have incurred for other reasons.