S.C. Code Ann. § 49-19-2620

When the work set out in the Plan of Reclamation of any drainage district is found insufficient to reclaim in whole or in part any or all of the lands of the district the board of supervisors may formulate new or amended plans containing new canals, ditches, levees or other works and additional assessments may be made in conformity with the provisions of SECTIONS 49-19-960 to 49-19-1010 in proportion to the increased benefits accruing to the lands because of the additional works.