Multicriteria decision analysis to assess options for managing contaminated sediments: Application to Southern Busan Harbor, South Korea.

Many years of untreated effluent discharge from residential areas, a shipyard, a marina, and a large fish market resulted in substantial contamination of bottom sediment in Southern Busan Harbor, South Korea. Contaminants in these sediments include heavy metals and organic compounds. Newly introduced regulations for ocean disposal of dredged material in South Korea pose significant challenges, because the previous practice of offshore disposal of contaminated dredged material was no longer possible after August 2008. The South Korean government has mandated that such sediments be assessed in a way that identifies the most appropriate dredged material management alternative, addressing environmental, social, and cost objectives. An approach using multicriteria decision analysis (MCDA) in combination with comparative risk assessment was used as a systematic and transparent framework for prioritizing several dredged sediment management alternatives. We illustrate how MCDA can recognize the multiple goals of contaminated sediment management. Values used in weighting decision criteria were derived from surveys of stakeholders who were sediment management professionals, business owners, or government decision makers. The results of the analysis showed that land reclamation was the preferred alternative among cement-lock, sediment washing, 3 contained aquatic disposal alternatives (one in combination with a hopper dredge), geotextile tubes, solidification, and land reclamation after solidification treatment. Land reclamation was the preferred alternative, which performed well across all MCDA objectives, because of the availability of a near-shore confined disposal facility within a reasonable distance from the dredging area.