This paper presents a multicriteria group decision making method for evaluating the sustainability performance of groundwater remediation technologies. Interval-valued based intuitionistic fuzzy numbers are used to deal with the inherent vagueness and imprecision of the performance evaluation process. An efficient algorithm is developed for producing a closeness coefficient for determining the sustainability performance of the most suitable groundwater remediation technology alternative across all evaluation criteria. An example is presented for demonstrating the applicability of the method.