20.—(1) The promoter shall upon completion of any part of any permanent specified work remove as soon as practicable any temporary works and materials for temporary works constructed or placed in, on, over or under a waterway in connection with that part of the work.
(2) All temporary works shall be removed to the reasonable satisfaction of the engineer, and in the construction, maintenance and removal of such works the promoter shall not cause avoidable detriment.