Examining Screening-Level Multimedia Models Through a Comparison Framework for Landfill Management

Two models for evaluating transport and fate of benzene were studied and compared in this paper. A fugacity model and an analytical environmental multimedia model (AEMM) were used to reconcile fate and mass transfer of benzene observed in a landfill site. The comparison of two models were based on average concentrations and partition behavior of benzene among three different phases i.e., air, soil, and groundwater. In the study of fugacity method about 99.6 % of the total benzene flux was distributed into air from landfill source. According to AEMM the diffusion gas flux was also predominant mechanism for benzene released from landfill and advection of gas and liquid was second dominant transport mechanism at steady-state conditions. Overall study of fugacity modeling (Level I and II) confirms the fate and transport mechanism of benzene released from landfill by comparing it with AEMM. However, the values of predicted concentrations, advection, and diffusion flux of benzene using fugacity model were different from AEMM results due to variation in input parameters. In comparison with experimental observations, fugacity model showed more error difference as compared to AEMM as fugacity model is treated as a single unit box model. This study confirms that fugacity model is a screening level tool to be used in conjunction with detailed remediation followed by AEMM that can be evolved as strategic decision-making stage.