Member $299.00 | Non-Member $349.00
IINSTRUCTOR: Robert M. Koerner, Ph.D., P.E.,D.GE, NAE Dist.M.ASCE
Sponsored by ASCE Continuing Education and ASCE's Geo-Institute (GI).
Purpose and Background
Geosynthetic clay liners (GCLs) are very thin layers of bentonite sandwiched between two geotextiles and then needle-punched or stitch-bonded together to form a barrier to liquids and gases. They first appeared in 1986 to absorb leakage through overlying geomembranes in landfill liner systems. Currently, they are being used for both liner and cover systems in myriad environmental, transportation, hydraulic and private development applications. There are approximately twenty manufacturers and the worldwide annual usage is about 150 million square meters. That said, the acceptance and use of GCL's by geotechnical engineers has not progressed nearly as rapidly as it has with other geosynthetic materials like geomembranes, geogrids, etc. Perhaps the main reasons are that compacted clay liners (CCLs) are deeply entrenched in the academic backgrounds of geotechs and also subsequent field experience over the years. This is reflected in current environmental regulations, few of which allow for GCLs to replace or even augment CCLs. This webinar presents the most relevant topics/aspects involving GCLs, including cases of inadequacies in the areas of shear strength and hydraulic conductivity. The webinar also covers the most current GCL testing protocols. In that light, the webinar offers a point-and-counterpoint of GCLs vs. CCLs in both liners and covers. It describes a generic specification with not only suggested limiting test values but also recommendations on quality control and quality assurance.
Primary Topics of Discussion
- Brief History of GCLs
- Cases of Inadequate Shear Strength
- Shear Strength and Peak vs. Residual Decisions
- Tension Peel Strength
- GCL External Interfaces
- Cases of Inadequate Hydraulic Conductivity
- Flow Through GCL Overlaps
- GCL Panel Separation
- GCLs vs. CCLs in Liners and Covers
- The GRI-GCL3 Specification
Learning Outcomes
- Discover the history and manufacturing of GCLs
- Learn about field cases of inadequate shear strength
- Understand testing and critical details of shear testing
- Discuss field cases of inadequate hydraulic conductivity
- Explore testing and critical details of hydraulic conductivity testing
- Become familiar with point-and-counterpoint of GCLs vs. CCLs in both liners and covers
- Emerging GCL opportunities
- Generic specification for GCLs
Webinar Benefits
- Understanding of GCL details; their strengths and weaknesses
- Appreciate the distinctions of using GCL's as liners versus covers
- Learn about current research and testing of GCLs
- Understand the distinctions between GCLs and CCLs in liner and cover systems
- Learn about new GCL opportunities and a generic specification
Intended Audience
- Geotechnical engineers
- Geosynthetic engineers
- Geoenvironmental engineers and regulators
- Hydraulic and coastal engineers
- Private and public industry planners and designers of containment systems
Webinar Outline
- GCL Overview
- Shear strength issues and testing
- Hydraulic conductivity issues and testing
- GCL's vs. CCL's in liner and cover systems
- Emerging GCL's opportunities
- GCL generic specification