Multi-objective optimal design of sewerage rehabilitation for the Sam Son sewerage system, Thanh Hoa province

Abstract

    The rehabilitation of a sewerage system is to maintain its initial designed capacity. Implementingmulti-objective optimal rehabilitation plans results in both increase in benefit and mitigation ofnegative environmental impact.This paper proposed a multi objective optimal model to determinethe optimal rehabilitation plans of Sam Son sewerage system, Thanh Hoa province. NSGA-II wasutilized to define Pareto solution sets which were trade off solutions among three objectivesincluding minimum rehabilitation cost, maximum service life and minimum traffic impact. As aresult, rehabilitation cost contours in relation to service lifes and traffic disruption were establishedto determine optimal rehabilitation plans.Three trade off plans including the plan A with theminimum rehabilitation cost (12,5 billion VND), the plan B with the maximum service life (78years) and the plan C with minimum traffic disruption (0 veheicle/hr) were analyzed in more detailto facilitate decision makers. Using the multi objective optimal design helped to quantify socialcosts of rehabilitation costs.