GCL and HDPE questions

June 1, 2012  |  Q&A: GMA Techline

From the GMA Techline RE: Two questions Does a geosynthetic clay liner (GCL) form whales from gas or water pressure, the same way as with a flexible membrane liner (FML), or does gas or water under pressure pass upward through a GCL? When a high-density polyethylene (HDPE) pipe crushes—say, du…
MSW landfill cap anchor trench design

June 1, 2012  |  Q&A: GMA Techline

From the GMA Techline RE: MSW landfill cap anchor trench design I have been asked by a project manager with my company to design an anchor trench for a municipal solid-waste (MSW) landfill that is being capped using a 40-mil LLDPE (linear low-density polyethylene) geomembrane. Having read through De…
Questions and answers from the GMA Techline

June 1, 2012  |  Q&A: GMA Techline

Wall connections? Friction values? Anchor trenches? —the Techline answers all GMA techline answers from Bob Koerner The Geosynthetic Materials Association (GMA) offers the GMA Techline, a resource for technical questions about geosynthetics. E-mail: gmatechline@ifai.com for fast, free, direct answ…
Draping and spraying

October 1, 2011  |  Q&A: GMA Techline

From the GMA Techline RE: Draping and spraying I am looking for a geosynthetic fabric webbing or netting that can be draped and then sprayed with concrete. (Ted | California) Reply: I suspect you are talking about shotcrete of gunite and my answer is accordingly. Fabric-wise, you are probably best w…
Extrusion welds

October 1, 2011  |  Q&A: GMA Techline

GMA techline answers from Bob Koerner RE: Welds Are destructs typically conducted on extrusion welds? Our flexible membrane liner (FML) spec doesn’t specifically address this. It does explicitly list a destruct frequency of every 500 linear feet of seam length. Does “seam” refer to…
HDPE & LLDPE rates

June 1, 2011  |  News, Q&A: GMA Techline

From the GMA Techline RE: HDPE & LLDPE rates I have always been under the impression that in using field tensiometers on jobsites that the rates for HDPE and LLDPE are different —HDPE at 2in./min. and LLDPE at 20in./min. However, I don’t have any documentation to back this up. Can yo…
Grid zone backfill

June 1, 2011  |  Q&A: GMA Techline

From the GMA Techline RE: Backfill I know you indicated sand was the ideal grid zone backfill. I suppose crushed limestone has a high installation damage reduction factor due to its angular nature. But what about a rounded river gravel? We’re running out of ash as we near completion of an MSE …
The 15 most difficult GMA Techline questions from the 3rd 500 Q’s-and A’s

February 1, 2011  |  News, Q&A: GMA Techline

From the GMA Techline Note: This is an appendix to the article, “GMA Techline’s 3rd 500 Q’s-and-A’s.” Question 1 Q: I am trying to find a way to predict the size and shape of a gas bubble that might form under a geosynthetic liner in a pond lining system—specifically, the relatio…
GMA Techline’s 3rd 500 Q’s-and-A’s

February 1, 2011  |  News, Q&A: GMA Techline

From the GMA Techline Introduction The GMA Techline was initiated in September 2004, as a free worldwide service to answer questions involving the many aspects of geosynthetic materials. From the outset there were no constraints placed on the questioner or their questions. GMA contracted with the Ge…
GG3-87

October 1, 2010  |  News, Q&A: GMA Techline

From the GMA Techline RE: GG3-87 I was wondering if guideline GG3-87 is still in use. If it is, could I get a copy? Thank you. (Jason | Kentucky) Reply: Good question and, as with many other GRI Standards, we have given the GRI method to ASTM, which now has a replacement. The replacement for &hellip…