18.2 - Groundwater Quality Monitoring in Landfill Areas

Abstract

To control the efficiency and efficacy of landfill barriers, a groundwater quality assessment and information system should be planned and implemented throughout the different phases of a landfill life span. The core of the information system is a monitoring network for groundwater quality analysis upstream and downstream of the landfilling deposit area and a database to be continuously updated with regard to hydrogeological data, water use in the area, groundwater quality external to the landfill area, and other existing potential contaminating sources. Despite the adoption of measures to prevent the uncontrolled emission of leachate from landfill, diffuse and/or concentrated emissions may occur, either on a short- or long-term basis. This may be manifested particularly with landfills in which technical measures are merely represented by physical barriers (liners, drainage systems). The consequent impact on groundwater quality will depend on the quality of waste, quality of leachate, landfill operation, typology of top cover, unsaturated zone beneath the landfill, aquifer and groundwater characteristics (hydrodynamics, geology, ox or redox conditions), extension of plume, and the natural attenuation in soils and groundwater. This chapter introduces the potential contaminants in landfill leachate, describing the criteria for site conceptual modeling and illustrating the main features of the groundwater monitoring network design. The transport of solutes in groundwater and the management of groundwater quality data are discussed. Finally, the chapter illustrates the use of natural (radioactive, chemical, and microbiological) tracers to evaluate contamination issues around a landfill site.