Geosynthetic Clay Liners

From the World's Leading Supplier of GCLs

CETCO GCLs are designed to meet the demands of any project. Our extensive line of bentonite-based and polymer-enhanced GCLs address design challenges such as hydrostatic pressure, shear strength, and chemical compatibility. Our experts can also assist in customizing solutions to meet your unique challenges. 


CETCO offers proven technology for liquid and waste containment applications.



What is a GCL?

A geosynthetic clay liner (GCL) is comprised of two geotextiles that are needlepunched together, encapsulating a layer of sodium bentonite clay between them. GCLs are known for having consistent, very low permeability. They have the unique ability to seal around penetrations, self-heal punctures, and self-seam at the overlaps.


What makes CETCO GCLs unique?

  • Durable needlepunched reinforcement ensure that CETCO GCLs can withstand shear stresses on steep slopes. The high needlepunch density provides higher peak internal shear strengths, without relying on supplemental processing.
  • Granular bentonite creates less dust during installation than powdered bentonite and is less likely to shift through the needlepunch reinforcement process resulting in consistent hydraulic performance.
  • Supergroove™ technology is a groove in the nonwoven fabric that allows the bentonite to migrate out and self-seam at the overlap. This feature eases the installation process by eliminating the need for supplemental bentonite and the additional labor to apply it.
  • Lamination capabilities to provide composite geomembrane-GCL products.

What are the advantages of a GCL over compacted clay?

  • Self-healing and self-seaming - Sodium bentonite is a naturally occurring clay with a high affinity for water. When hydrated, sodium bentonite swells up to 15 times its original volume. This provides the ability to seal around penetrations, self-heal punctures, and self-seam at the overlaps.
  • Better hydraulic performance - GCLs have a total thickness of less than one inch and provide better hydraulic performance than several feet of compacted clay. A fully hydrated GCL typically has a permeability of 5 x 10-9 cm/sec, approximately 20 times lower than a typical compacted clay liner permeability.
  • Resistant to varying weather conditions - GCLs are less likely to be impacted by freeze-thaw or desiccation-rewetting cycles. Freeze-thaw cycles frequently cause compacted clay liners to crack and lead to increased leakage. A geosynthetic clay liner provides consistent performance and is not subject to performance decreases resulting from varying moisture content, density, or clay content, like compacted clay liners.
  • Ease of installation and increased air space - GCLs are an environmentally friendly alternative to clay liners because they require significantly less installation effort than a compacted clay liner. One truckload of GCL is equivalent to 150 truckloads of compacted clay, thereby using up fewer natural resources. When a GCL is used in place of a thicker compacted clay liner it also takes up less air space, which leaves more room for waste.

GCL Selection Process

When designing a GCL, it is imperative that a leachate sample is obtained and submitted for testing as early as possible in the design process to ensure the proper solution is selected.


Step 1
  • Collect sample of leachate or coal ash
Step 2
  • Initial leachate chemical analysis
  • GCL proposed for proxy testing
Step 3
  • GCL proxy testing to validate product selection
  • Write performance-based GCL specification
Step 4
  • Long-term permeability testing
Step 5
  • Finalize GCL product selection