Frequently Asked Questions

Get the Facts About Geo-Form Geomembrane

Patented Heat Weldable Rubber Lining for Canals, Flumes, and Reservoirs

What is ductility and why is it important in a geomembrane?

According to the Geosynthetic Institute, the “Multi-axial Tensile break” test is the best measure of ductility. This test measures a product's ability to elongate in all directions without breaking.

Geo-Form EPDM Rubber Alloy Lining elongates or stretches in all directions with low force but it is not elastic. It does not recover or shrink back. 

Multiple years of observations of Geo-Form EPDM Rubber Alloy Lining installations has shown this lining to “mold” to the shape of irregular canal subgrades and form around stones or other imperfections in the site preparation. It will also adjust to soil settling or movement over time. 

"Ductility in a geomembrane liner is often a far more important parameter than strength." *

* Dr. Ian D. Peggs, President of I-CORP INTERNATIONAL, Inc., USA, specializing in geosynthetic materials performance.

What is the overall thickness of the material and why is gauge and weight important?

Geo-Form EPDM Rubber Alloy Lining is .100” thick. It has a matte surface finish top and bottom which means there is no asperity thickness. Most HDPE liners that are textured or have spikes will have an asperity thickness of .020”. Therefore Geo-Form EPDM Rubber Alloy Lining is two and one-half times thicker than the average textured  .060" HDPE product.

The specific gravity of Geo-Form EPDM Rubber Alloy Lining is 1.19 while HDPE has a specific gravity of .94. The benefit of a heavy liner is to minimize the risk of uplifting or floating and need for ballast. 

Is a rock or dirt ballast required? Is an underlayment necessary?

Geo-Form EPDM Rubber Alloy Lining does NOT require ballast. It is however recommended at transition points and drops.

Geo-Form EPDM Rubber Alloy Lining does NOT require an underlayment. It can be placed directly over irregular surfaces including broken concrete.

Can Geo-Form EPDM Rubber Alloy Lining be used over broken concrete?

Geo-Form EPDM Rubber Alloy Lining is the perfect solution for worn and cracked concrete. It bridges most cracks without filling.

What are the benefits of a rubber liner? How does rubber compare to HDPE?

HEAVY and RUBBER are two words rarely found in the description of geomembrane lining materials. Most will be thermopastic and often with fiber or filament reinforcement to reduce weight and increase strength. The result is a thin, lightweight, strong material with very little ductility/elongation. 

IMPORTANT NOTE: To determine if the geomembrane liner you are considering has ductility, request the results of the liner material tested to ASTM D5617 (Multi-axial tensile/elongation @ rupture %). This is the test suggested by the Geosynthetic Institute to predict the ductility of a material. 

What is the life expectancy of Geo-Form EPDM Rubber Alloy Lining?

Geo-Form EPDM Rubber Alloy Lining passed a laboratory test performed by Akron Rubber Development Labs for aging and ozone resistance using ASTM D5617 Method A. This is a pass/fail test, not a prediction of life. ARDL stated that any material that passed this test could be expected to last at least 20 years in Arizona sun. Further, the Geosynthetic Institute performs ongoing tests, both laboratory and field studies, of all common polymers used as liners in exposed applications. Recently published results show EPDM at greater than 27 years and PE at 36 years or greater. Because Geo-Form EPDM Rubber Alloy Lining is thicker than materials being studied by GSI, this lining can be expected to last more than 30 years.

How does Geo-Form EPDM Rubber Alloy Lining impact the environment?

Geo-Form EPDM Rubber Alloy Lining is eco-friendly. Made in the USA, Geo-Form EPDM Rubber Alloy Lining is fish-friendly and prohibits weed growth.

Who can install Geo-Form EPDM Rubber Alloy Lining and how is the lining spliced?

Geo-Form EPDM Rubber Alloy Lining uses a unique splicing method that thermally fuses the material making the splices stronger than the liner.

Use your employees to install Geo-Form EPDM Rubber Alloy Lining.

Reduce project costs and provide off-season work for employees.

Are there any additional benefits?
  • Workers learn to make quality welds in minutes.
  • Welding problems are easily seen and quickly corrected.
  • Welding speeds of up to 10 feet per minute.
  • Quality welds can be performed at low temperatures, proven to 10 degrees F.


Because Geo-Form is made of weather and U/V resistant polymers, it's an ideal solution for any lining project where long life expectancy is required.

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  • All Our Liners are Made 100% in the U.S.A.

  • Our Midwest Manufacturing Facility is ISO Certified

  • We Serve Clients All Over the World