Article 81. If the duty-bound party mentioned in article 80 does not act or acts insufficiently, the competent authority orders the person to fulfil his obligations within a specified period of time. If within the time specified the order is not or insufficiently acted upon, the competent authority can in his place ex-officio have the measures mentioned in article 76, 2, implemented, and recover their costs from the duty-bound party in default and the person responsible in accordance with article 16.