ABSTRACT
Since their introduction as barrier materials in waste containment systems in the USA in 1986 and in transportation related waterproofing systems in Germany at about the same time, geosynthetic clay liners (GCLs) have been installed in a variety of applications. Perhaps the major applications have been as leachate containment barriers beneath landfills and surface impoundments, and as infiltration water barriers in landfill covers. When one considers that the traditional barrier material in these applications is a natural clay mineral sealing layer or compacted clay liner (CCL), it is only logical that the two materials should be compared and contrasted to one another in such a way so as to assess technical equivalency. This paper provides a suggested methodology for providing such an assessment. It is based primarily on technical issues and results in a framework that can possibly be used for assessment of both landfill liner and cover barrier materials. It should be possible to use the same methodology for other than landfill applications where a choice is being considered for substituting a GCL for a CCL.
In this assessment it is seen that except for issues of puncture resistance and product thinning due to abutting objects and uneven subgrades (both of which can be avoided by proper design and CQC/CQA procedures), GCLs can often be used on an equivalent basis as CCLs. However, site specific conditions like long term slope stability may provide unique situations calling for specific products or alternate designs.
Needed to further this assessment of GCLs to CCLs is a continued dialogue with respect to technical issues, close monitoring of GCL installations, and involvement of regulatory agencies in the decision making process.
