20. Every authorised person who takes possession of a derelict tank under the provisions of this Act shall maintain the same in proper condition, and if, in the opinion of the Collector, he fails to do so the provisions of sections 5 and 6 shall be applicable as if the maintenance of the tank in proper condition were an improvement specified in the notice under section 3 or the Collector may, if he thinks fit, arrange for the maintenance of the tank in proper condition and recover the cost thereof from the authorised person.