GMA Techline

The Geosynthetic Materials Association (GMA) offers the GMA Techline, a resource for technical questions about geosynthetics.

E-mail: gmatechline@ifai.com for fast, free, direct answers to your technical questions. GMA serves as the central resource for information regarding geosynthetics and provides a forum for consistent and accurate information to increase the acceptance, and to promote the correct use, of geosynthetics.

Three of the most difficult questions

June 1, 2016  |  News, Q&A: GMA Techline

From the GMA Techline Q-and-A 1. Mold inside drainage layer? Q: Recently there has been a greater demand for sustainable projects in Southern California and I was glad to see published in Geosynthetics magazine “Geosynthetics: The science that makes green roofs work” (June/July 2014, Vol. 32, No…
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Lining of soil embankment?

June 1, 2016  |  News, Q&A: GMA Techline

Questions and answers from the GMA Techline I have a question concerning lining systems in embankment dams and want to ask for your advice (from your experience only, no need for any calculations). There is a wastewater reservoir built of clay, with a single HDPE geomembrane on top of the clay (i.e.…
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Geotextile question

February 1, 2016  |  News, Q&A: GMA Techline

We have a geotextile AOS requirement of 0.15mm for which we have recommended a 10-ounce geotextile to our client. Because our client has an abundance of 8-ounce geotextile on-site, he would prefer to make use of it in place of the recommended 10-ounce. My question to you is this: Can two layers of 8…
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Reinforcement deformations

February 1, 2016  |  News, Q&A: GMA Techline

You made a presentation in Peru where you talked about a new method to calculate deformations on reinforced embankments. Now I am working on a project where the foundation needs to be, in part, over consolidated tailings. Even though we are putting rockfill embedded on the tailings, our pseudo-stati…
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MQA and GRI specs

February 1, 2016  |  News, Q&A: GMA Techline

There is much inconsistency regarding the definition of a production batch quantity for geomembranes and how this relates to MQA sampling frequencies. What is the intent of the GRI specifications? Maggie | Australia Maggie, Regarding MQC—the factory production of like material—the GRI specificat…
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LLDPE Question

February 1, 2016  |  News, Q&A: GMA Techline

“Burnout” occurred when the double-seam fusion welder got stuck as it welded (a stop at a small crease or at times going up a slope) followed by the welder sitting in one spot for a short time causing a burn hole in the LLDPE. The welder continues from that point onward once the situation is &he…
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Breathable membrane

February 1, 2016  |  News, Q&A: GMA Techline

I am a graduate student pursuing a Ph.D. in environmental engineering. My project involves solving sanitation issues of urban slums in India using breathable membranes. We use a 55-gallon drum lined with this breathable membrane to serve as collection and storage for the fecal matter. We have been p…
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Exposed geomembrane cover

February 1, 2016  |  News, Q&A: GMA Techline

I am evaluating the feasibility of constructing an exposed geomembrane cover on a coal combustion residuals (CCR) fly ash impoundment. The evaluation includes scenarios of: (1) allowing surface water to shed and (2) intentionally impounding water. In reviewing the available literature, I came across…
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Conductive geomembrane

February 1, 2016  |  News, Q&A: GMA Techline

We are developing a conductive liner. I want to know if there is any kind of small-scale test that I can apply in our laboratory as a quality control test. Pacqua | Mexico Pacqua, Great to hear from you and nice to know that you are developing a conductive GM. What is typically done in … <div…
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Spray over HDPE?

February 1, 2016  |  News, Q&A: GMA Techline

Is it possible to spray over an HDPE liner? Can you provide me with spray manufacturers? Abbey | Saudi Arabia Abbey, There is no need to spray on HDPE, and even if you did it wouldn’t stick very easily. Regarding spray manufacturers, just Google “spray applied membranes” and you will get infor…
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