“…It is related to characteristics of contaminant transport and fate in subsurface and behavioral patterns of an individual or a population exposed to the pollutant [ Maxwell et al , 1998; Phan et al , 2010]. Site‐specific risk assessment is thus essential based on the modeling results of contaminant transport and fate simulation [ Ma , 2002; Maqsood et al , 2005; Chen and Ma , 2006; Lee et al , 2009]. Simulation‐based risk assessment requires extensive data and information which are inherently associated with multiple forms of uncertainties [ Bogen and Spear , 1987; Hoffman and Hammonds , 1994; Labieniec et al , 1997; Bennett et al , 1998; Carrington and Bolger , 1998; Daniels et al , 2000; Ma , 2002; Tam and Byer , 2002; Li , 2003; Kentel and Aral , 2004, 2005; Lopez et al , 2008].…”