Geosynthetic clay liner with aquiclude
August 1st, 2022
Q: We are trying to design and construct an aquiclude with a geosynthetic clay liner (GCL). Do you have any experience with this application where a GCL has been used as the impervious barrier between a flowing stream and the underlain geologic formation? A: I have not heard of a GCL being used alone in […]
New GSI test method for resistance of conductive geosynthetics
June 1st, 2022
The Geosynthetic Institute (GSI) has a new test method for resistance measured across positions on conductive geosynthetics. Conductive geosynthetics contain an electrically charged backing (usually a thin layer of polyolefin with letdowns containing 20%–30% carbon black) that allows leaks to be detected in lined systems without the need for a conductive subgrade beneath the liner […]
Geosynthetics for pipe wrapping
February 1st, 2022
Q: I need impervious geosynthetics for pipe wrapping that will be placed within heavy clay. Do you have any suggestions? A: One wraps nonpolymeric pipes for many reasons. Below are some examples: Insulation (sound and thermal)Corrosion protectionWaterproofingImpact resistance Most wraps are tapes or mastics. Polyvinyl chloride (PVC), butyl rubber and bituminous wraps are common. A […]
Geotextile filtration clogging resistance
February 1st, 2022
Q: I have a question about the Filter Criteria in the Federal Highway Administration (FHWA) procedure "Filter Performance and Design for Highway Drains" procedure, specifically the geotextile filtration 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 […]
Sewn versus welded seams
February 1st, 2022
Q: On your GMA Techline website list of sample questions and answers, 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 clay liner (GCL) overlap seams via eight methods. Can you share that study […]
EPDM geomembrane for a water application
February 1st, 2022
Q: We are looking at a life-cycle study for the usefulness of an ethylene propylene diene monomer (EPDM) geomembrane for a water conservation application. Request to kindly share the information for our study. Regards. A: An EPDM geomembrane is going to lie flat on the subgrade soil without wrinkles (no field-induced stress). Therefore, it will […]
Fusion-welded HDPE geomembrane patch
February 1st, 2022
Q: I need to make sure of what the minimum area is for a fusion-welded HDPE geomembrane patch with a 60-mil (1.5-mm) thickness 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)? Thank you […]
Electrical leak detection at depth
February 1st, 2022
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 inspected and […]
ABS geosynthetics product types
February 1st, 2022
Q: Infrequently, I make a note of 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 geosynthetics? A: Thank you for your GMA […]
Reinforced levees to induce seepage path around geogrid layers?
February 1st, 2022
FIGURE 1 Reinforced levee expansion over existing dike using geosynthetics The Geosynthetic Institute (GSI) has been asked many times regarding several applications for different styles of geogrids if reinforced levees will induce a seepage path adjacent to and around geosynthetic layers. At this point, GSI has no case histories where it can quantify such behavior […]