The contaminant introduced into the soil-rock-groundwater system will spread within the system only if a transport mechanism is available, for example, aflowing liquid. As soon as the contaminant reaches the subsurface water in the unsaturated or saturated zone, various processes (physical, geochemical and bio- chemical) determine its fate [14]. The physical processes include advection, dis- persion, evaporation, filtration, and degassing while those of geochemical are ac- id-base reactions, adsorption-desorption, ion exchange, oxidation-reduction, pre- cipitation-dissolution, retardation and complexation. The biochemical processes include amongst others transpiration, bacterial respiration, decay and cell syn- thesis (Figure 4). The movement of a chemical pollutant within an aquifer is described by the “transport equation” (Equation (1)):