The GMA Techline
April 1st, 2020
Moderated by George R. Koerner and Y. “Grace” Hsuan Welding Rod Q: This question is in regard to the welding rod intended for welding of geomembranes (both high-density polyethylene [HDPE] and linear low-density polyethylene [LLDPE]). Are there any GRI GM13- or GM17-based requirements for welding rods or are there any white papers or specifications? I […]
Large-scale studies to evaluate the resilient modulus of geocell-reinforced pavement
April 1st, 2019
The 2017 ASCE report card (ASCE 2017) on civil infrastructure assigned grade “D” for America’s roads, and this rating necessitates the adoption of more sustainable and resilient approaches in design and construction of transport infrastructures such as highway embankments and pavements. Reclaimed asphalt pavement (RAP) material has been considered as one of the sustainable options […]
The GMA Techline
April 1st, 2019
Vegetation causing gases under geomembrane? Q: I have a site where we are installing a high-density polyethylene (HDPE) liner in an existing pond. Because of some residual heavy metals in the top layer of soil, I would like to strip off the top 3–6 inches (7.6–15.2 cm) of soil and vegetation. Alternatively, we could mow and […]
A leachate pond geomembrane after 25 years of service
February 1st, 2019
This article reports on the evaluation of an exposed geomembrane liner in a landfill leachate pond after being in service for 25 years. The evaluation was performed in two campaigns: in August 2014 and in May 2018. The purpose of the evaluation was to determine the condition of the geomembrane and to provide a recommendation […]
EPT introduces new string-reinforced LLDPE geomembrane
December 13th, 2018
To meet the growing demand for linear low density polyethylene (LLDPE) by geomembrane fabricators and installers, Engineered Polymer Technologies (EPT) has announced a new string-reinforced LLDPE fabric. LLDPE has been in increasing demand due to its superior flexibility and better layflat versus high density polyethylene (HDPE). EPT has specially formulated its LLDPE fabric for high […]
The GMA Techline
October 1st, 2018
Toxicity of nonwovens? Q: Are there any comprehensive tests (or a general synopsis) of the environmental toxicity of leachate from nonwoven polypropylene fabrics when aged in a freshwater or saltwater solution? Regulatory and municipal bodies in Europe and New Zealand are requesting more info about products that are used in riparian and coastal environments. A: […]
Minnesota Pollution Control Agency updates geosynthetic liner guidelines for stormwater management
August 30th, 2018
The Minnesota Pollution Control Agency (Minnesota PCA) revised and released new geosynthetic liner guidelines for stormwater management in August. The guidelines specify where liners are required and where liners are recommended, liner specifications (e.g., HDPE, GCL, PVC), and how to select an appropriate liner. “Liners are designed to limit infiltration of water from a stormwater […]
Don’t be afraid of making horizontal geomembrane seams on side slopes
August 1st, 2018
Over the years, there have been many discussions raising concerns about having geomembrane field seams located horizontally on side slopes. By not allowing such seams, it usually results in many short roll lengths that become either unused or difficult to tailor into the flat area of the project. Stated differently, the installation costs increase accordingly. […]
The GMA Techline answers all
August 1st, 2018
UV Weathering of Geotextiles Q: My firm is providing construction quality assurance services for a landfill cell expansion. We are having an issue with our contractor and are going to be in a position of having 8 ounces/square yard (271 g/m2) of nonwoven geotextile exposed for a period of time, which exceeds the seven-day limit […]
Presto releases geocell ballast research
June 1st, 2018
Presto Geosystems, manufacturer of the high-density polyurethane (HDPE) GEOWEB® geocell base stabilization system, has released results from railroad-track research performed to quantify the reinforcement benefit of GEOWEB-confined ballast as compared to unconfined ballast. The company said the research was a cooperative effort under the direction of Ben Leshchinsky, Ph.D., P.E., of Oregon State University, and […]