not exceeding [ F68 400 ] [ F68 level 5 on the standard scale ] and a further fine not exceeding 50 for each day on which the failure continues after conviction for the offence and before the authority which served the notice has begun to exercise its powers in pursuance of the following paragraph; and (b) the said authority may do what that person was required by the notice to do and may recover from him any expenses reasonably incurred by the authority in doing it. (5) If it appears to such an authority as is mentioned in subsection (1) of this section that waste has been deposited as there mentioned and that --  (a) in order to remove or prevent pollution of water or danger to public health it is necessary forthwith to remove the waste or to take other steps with a view to eliminating or reducing the consequences of the deposit of it or necessary forthwith to remove the waste and to take such other steps; or (b) there is no occupier of the land in question; or (c) the occupier of the land neither made nor knowingly permitted the deposit of the waste, the authority may remove the waste from the land or take such other steps as aforesaid or, as the case may require, may remove it and take such other steps. (6) Where an authority exercises in respect of any land a power conferred on it by the preceding subsection it shall be