GCL shear strength concerns

July 1, 2024  |  Q&A: GMA Techline

Q: We are worried about the midplane shear strength of our GCL in a seismically active zone of our landfill. The GCL is a single component of a double composite liner system. It is backing up the primary geomembrane in the upper composite liner system. Should we be concerned?
Direct shear machine testing

July 1, 2024  |  Q&A: GMA Techline

Q: We just bought a direct shear machine and want to start ASTM D5321 testing. The pneumatic piston applying the vertical loads for normal pressure has a range from a low of 1,124 pounds to a high of 20,000 pounds. Can we use this direct shear box for landfill cover testing?
Avoid geotextile damage from oil spill cleanup

July 1, 2024  |  Q&A: GMA Techline

Q: We are a riverfront landowner with a significant 25-foot (7.6 m) riprap slope protecting our property from erosion and scour. There is a woven monofilament geotextile filter under the riprap to stop the embankment soil from piping into the river. This system has worked well for the past 10 years,…
Liner system selection for leakage and performance

July 1, 2024  |  Q&A: GMA Techline

Q: We recently relined an aeration pond at a POTW with a 45 mil GRI GM-30 barrier. It was successfully lined for 30 years with a 45 mil CSPE (Hypalon®) liner that was, unfortunately, punctured and torn beyond repair by a fallen tree from outside the fence line. The relined surface impoundment curre…
Geosynthetics for marine structures

April 1, 2024  |  Q&A: GMA Techline

Q: Are geosynthetics allowed to be used in marine structures? I am concerned about plastics in the environment and emission of plastic additives and their degradation by-products. 
Geotextile quality issues

April 1, 2024  |  Q&A: GMA Techline

Q: We are performing certified quality auditing (CQA) at a jobsite and having major quality issues with the geotextile delivered to the site. For example, the mass per unit area is low, all mechanical properties are below specification, the permittivity and apparent opening size (AOS) are low. We ar…
Temporary interim covers

April 1, 2024  |  Q&A: GMA Techline

Q: I am writing to inquire if you are aware of any recommendations or guidelines for removal of geosynthetic liners that have been used as temporary interim covers at landfills. We recommend facilities totally take up and remove the temporary cover; however, we have had some recent proposals to run …
Geomembrane testing

April 1, 2024  |  Q&A: GMA Techline

Q: We are a geomembrane manufacturer and have a client who asked us to test an old geomembrane that we sold to them 20 years ago for a surface impoundment. They are also asking us to test a competitor’s geomembrane used at the same site. Can we issue a formal report to a governing agency of result…
Bentonite Cutoff Anchorage

February 1, 2024  |  Q&A: GMA Techline

Q: I have a bentonite cutoff wall containing a positive pressure inside and an overfill situation where the waste being capped will have perched water in the waste mass above the perimeter elevation. Do you have a recommendation for the perimeter connection detail for such a situation?
Geomembrane formulation

February 1, 2024  |  Q&A: GMA Techline

Q: We are specifying HDPE geomembrane for a critical project and noticed that GRI-GM13 only requires endurance testing “per formulation.” What is the definition of formulation and can we obtain Kiwa certification for a geomembrane produced using a known formulation?