That if at any time it shall appear to the board of directors that any lands that will be affected by the proposed work have been omitted from the assessment, or if any mistake has occurred in the assessment, it shall have power, by an order to be entered on its journal, to cause a supplemental assessment or different supplemental assessments to be made by the same assessors for the supplying of such omissions and the correction of such mistakes. The owners of all lands embraced in or directly affected by any such supplemental assessment shall have notice of the time and place of making the same and of a time and place when and where they shall be entitled to be heard in respect to the same, in the same manner as is provided in respect to the original assessment. Such supplemental assessments, when completed and confirmed by the board of directors, shall from that date be a lien on the lands described in them in like manner as the original assessments and shall be collected in the same manner.