ABSTRACT
Undisturbed clayey barriers have a long record of performance with respect to the containment of chemical species often found in a waste disposal site. For example, the 10,000-year salt profile through a freshwater clay deposit overlying a naturally occurring high-salt bedrock is discussed in Chapter 9. The study of this migration profile provides excellent data on the long-term behaviour of clayey barriers. Chapter 9 also discusses a 20-year long investigation of migration of contaminants from a municipal waste disposal site which indicates long-term performance consistent with what one would expect based on short-term laboratory and field data. However, good performance of clay as a
barrier to municipal, industrial and hazardous wastes cannot be assumed a priori. The hydraulic performance will depend on a number of important factors to be discussed in this chapter. These include the method of placement and compaction of the clay and the clay mineralogy. The potential interaction between clay minerals and leachate and its effect on hydraulic conductivity will be examined in Chapter 4.
