Statistical evaluation of groundwater quality around an uncontrolled landfill: implication for plume migration pathways.

When leachate emanates from an uncontrolled landfill, it poses a threat to the groundwater resources of the surrounding areas. Thus, regular monitoring is essential to protect the groundwater from contamination. In this study, an evaluation is carried out on the quality of groundwater affected by the leachate deriving from an uncontrolled landfill situated in a valley. A nonparametric trend analysis revealed that alkalinity levels were increasing at most monitoring wells, indicating the continuous increase of biodegradation of organic matter. According to a cluster analysis, similar chemical groups developed in a parallel direction to that of groundwater flow. Each group indicates different redox levels and various degrees of landfill leachate effect. This geographical distribution of groups with similar chemical properties is closely associated with local groundwater flow and land surface permeability. However, an evaluation of the effect of recharge flow from the surrounding mountains and of the vertical component of groundwater in the recharge area is essentially required in order to enhance our understanding of redox zonation or distribution of groundwater quality affected by the landfill leachate. [ABSTRACT FROM AUTHOR]