R Kerry Rowe, chair, department of civil and environmental engineering, University of Western Ontario, London, Canada. This paper was first published in GE’s August 1997 edition.
The mechanisms of contaminant transport are discussed in the context of evaluating the range of suitability of different “standard” designs for barrier systems which involve a composite (geomembrane over clay) liner. The advantages and disadvantages of hydraulic control of contaminant are discussed. The factors that control the impact of a waste disposal facility on groundwater quality are highlighted. Finally, the adoption of design versus performance standards is discussed. It is concluded that some existing design standards do not appear to be adequate in some circumstances while they may be grossly over designed in other cases. It is argued that appropriate performance standards provide flexibility and allow for the selection of the most cost effective and environmentally sound design for a given situation.