Methane gas geomembrane permeability

April 1, 2022  |  Q&A: GMA Techline

Q: What is the least permeable geomembrane to methane gas? Regarding the permeability of geomembranes to methane gas, could you send me some technical guidelines?
Scratch impact on HDPE liners

April 1, 2022  |  Q&A: GMA Techline

Q: I have a project where multiple and extensive scratches were created on the high-density polyethylene (HDPE) liner for a reservoir due to poor construction practices. (See the following Figures 2–4.)
Sand fines overlying geocomposite

April 1, 2022  |  Q&A: GMA Techline

Q: We are working at a site with a permitted landfill cell with a leachate collection system that includes a drainage geocomposite with 12 inches (305 mm) of leachate collection sand overlying it. My question has to do with the percentage of fines in sand on a geocomposite. Our leachate collection p…
Electrical leak detection at depth

February 1, 2022  |  Q&A: GMA Techline

Q: I am taking the opportunity to ask a question about the electrical leak detection (ELD) test for geomembranes: We have the area covered with silt from the past rainy season, and it is estimated to be about 5 feet (1.5 m) deep worst-case scenario. The liners in this area were not properly inspect…
ABS geosynthetics product types

February 1, 2022  |  Q&A: GMA Techline

Q: Infrequently, I note geosynthetic products manufactured using acrylonitrile butadiene styrene (ABS) (e.g., geogrid, binding line, a few molded specialty products). Can you provide a summary of most of the geosynthetic product types using ABS, as well as the general benefits and limitations of ABS…
Geotextile filtration clogging resistance

February 1, 2022  |  Q&A: GMA Techline

Q: I have a question about the Filter Criteria in the Federal Highway Administration (FHWA) Filter Design procedure, specifically the clogging resistance equation 2-10. This seems to require a particularly large pore size; for example, if the D15 of the soil was for 70 microns, the minimum O95 of th…
Sewn versus welded seams

February 1, 2022  |  Q&A: GMA Techline

Q: On your website list of sample questions and answers (https://geosynthetics.ifai.com/programs/gma-techline), a question is asked about a recommendation for sewn versus welded seams for geotextiles. Bob Koerner answered this question by stating that you have done a study for joining geosynthetic c…
EPDM geomembrane for a water application

February 1, 2022  |  Q&A: GMA Techline

Q: We are looking at a life-cycle study for the usefulness of an ethylene propylene diene monomer (EPDM) based geosynthetic liner for a water conservation application. Request to kindly share the information for our study. Regards.
Geosynthetics for pipe wrapping

February 1, 2022  |  Q&A: GMA Techline

Q: I need an impervious geosynthetic to wrap a pipe that will be placed within a heavy clay. Do you have any suggestions?
Fusion-welded HDPE geomembrane patch

February 1, 2022  |  Q&A: GMA Techline

Q: I need to make sure of what the minimum area is for an HDPE geomembrane with a 60-mil (1.5-mm) thickness patch that should be fusion welded instead of extrusion welded. Also, when does one need to replace a panel that is damaged (i.e., the percent of damage allowed to be repaired)?