Ten-peer reviewed papers give you the latest information on geosynthetic clay liner (GCL) technology. Topics address the ability of the current ASTM standards to assess GCLs, and how they can be improved to better meet the needs of the industry; compatibility and longevity testing of GCLs; and new testing methods to advance the understanding of GCLs and their components. Sections cover: Assessment of Clay Component-examines various aspects of testing the clay component and what knowledge these test results generate for the user. Durability of Clay Component-provides a better understanding of liquid/soil interactions with the bentonite and their possible effects on the durability of the clay component of the GCL. Evaluation of Current and Proposed GCL Standards-discusses ASTM standards D 5889 Practice for Quality Control of Geosynthetic Clay Liners; D 6495 Guide for Acceptance Testing of Geosynthetic Clay Liners; and D6243 Test Method for Determining the Internal and Interface Shear Resistance of Geosynthetic Clay Liner by the Direct Shear Method Movement of Compounds through the GCLs-details investigations on the behavior of GCLs subject to thermal gradients in a containment application; effect of freeze-thaw on the permeation of arctic diesel fuel through GCLs STP 1456 is a valuable resource for regulators, engineers, and researchers.