A. The board of county commissioners conducting said hearing or any adjournment thereof shall have the power to review and correct said appraisal and apportionment, and to raise or lower the same as to any lots or tracts of land, as they shall deem just, and shall, by resolution, confirm the same as so revised and corrected by them.

B. At or prior to said hearing, any person, firm or corporation may file objections in writing against the validity or amount of any proposed assessment, specifically setting forth the nature thereof, and shall have full opportunity to be heard thereon. The board of county commissioners shall adjudicate and determine said objections and shall make such order as may be just and proper. Any objections to the regularity of the proceedings with reference to the making of the improvement or the validity or the amount of any assessment, shall be deemed waived unless presented at the time and in the manner herein specified.