GMA Techline

February 1, 2018

Determining quantity of recycled HDPE in a geonet Q: I have a question about high-density polyethylene (HDPE) geonets. Is it possible, by thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC) analysis, to determine the quantity of recycled HDPE present in a geonet? I have a geonet that, I think, is made with virgin and recycled …

GMA Techline

October 1, 2017

Welding HDPE to PVC and more Q: I would appreciate any input you have on these questions: Can a high-density polyethylene (HDPE) geomembrane (GM) be welded to a PVC geomembrane? I am looking to connect a geomembrane to a building foundation. Based on some research, I have found the following options: bolt the geomembrane to …

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 …

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 …

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 …

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 …

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 …

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 …

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 …

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 …