The petition may be amended at any time before final action on the petition. At the time set for hearing on the petition, the board shall hear and determine the sufficiency of the petition as to form and substance and all objections filed against the abandonment and dissolution of such district. If the board finds that such district is free from indebtedness and that the necessity for the continued maintenance thereof no longer exists or that the expense of the continued maintenance of such district is not commensurate with the benefits derived therefrom, the board shall enter an order abandoning and dissolving such district, which order shall be filed with the county auditor of the county or counties in which such district is situated and noted on the drainage record.