ABSTRACT
This chapter is concerned with the important physical and chemical properties of the contaminants and the subsurface environment. It presents a practical and applied discussion of potential migration pathways, upper limits of contamination based on equilibrium assumptions, and fundamental mass transport processes that govern the fate of a chemical in the subsurface. The chapter focuses on the behavior of dense nonaqueous-phase liquid (DNAPL) than light nonaqueous-phase liquid, due primarily to the greater propensity of DNAPLs to contaminate groundwater systems. An understanding of DNAPL transport in the subsurface begins with an understanding of the capillary phenomena associated with multiphase fluid flow. In a porous medium the residual contamination takes the form of isolated droplets and/or globules of pure-phase DNAPL held in the soil interstices by capillary forces. Virtually no information exists regarding DNAPL residual saturation in fractured rock, owing to the virtual impossibility of simulating fractured rock behavior in the laboratory and the difficulty of conducting field studies in fractured rock.
