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GMA Techline

August 1, 2017

Liner repair? Pullout tests? Sewn seams? Shear strength of sludges? Geomembrane liner repair Q: I have a facility that has submitted liner repair documentation for the repair of a high-density polyethylene (HDPE) liner for a leachate/stormwater pond at an industrial landfill site. The repairs were performed using either a patch or, for indentations and small …

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Questions and answers from the GMA Techline

February 1, 2017

Spraying? Shear Strength? Hydraulics? [A more] non-permeable GT? Q: I have received an inquiry for a non-permeable geotextile, which is UV-resistant and will be installed on a long slope for erosion control. Could you kindly recommend a product that would meet these requirements or a solution for this application? Your assistance with this is much …

A tribute to Robert Landreth

Former head of the EPA’s National Risk Management Research Laboratory (NRMRL) An unsung hero of the geoenvironmental and geosynthetics fields is a retired former research director at the U. S. Environmental Protection Agency (EPA), Mr. Robert E. Landreth. It was Bob Landreth’s vision and tenacity in advocating for research funds that made possible pioneering research …

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Questions and answers from the GMA Techline

August 1, 2016

Geosynthetic filter failure Q: I am interested in your upcoming webinar on geosynthetic filters and was hoping to get a little clarification on the content. I’m most interested in how geotextile fabrics are used with riprap but I also understand these fabrics are perhaps more commonly associated with roadway construction. How much does this webinar …

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Recycled materials reinforcement?

June 1, 2016

Questions and answers from the GMA Techline We are soliciting information on the use of recycled materials in the reinforced zone of MSE walls. I recall you as the keeper of many case histories. Do you have any success or failure stories about such recycled content in a reinforced zone? I’m mindful of chemical attack …

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Weld or sew?

Questions and answers from the GMA Techline We have a liner contractor who would like to wedge-weld geotextile rather than sew it. The material is simply a cushion layer below the 40-mil geomembrane and the contractor is concerned the sewn seams will affect wedge welding of the above geomembrane. Do you have a recommendation on …

We’re losing the battle

The above title is not about military, political, or social issues; it is about the knowledge base of graduating students and other new employees entering the field of geosynthetics. In both situations (i.e., graduating students and other new employees), entry level men and women have little or no idea of the plethora of available geosynthetic …

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Strength test?

Questions and answers from the GMA Techline Something that has always puzzled me while performing the CQA for liners is the strength test for a weld using the extrusion gun. I always thought that if the weld does not pass for elongation, that has more to do with the sheet than how well the weld …

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Three of the most difficult questions

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. 3). I am curious if there are any …

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Lining of soil embankment?

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., a kind of …