GCLs and hydraulic equivalence

June 1, 2009  |  Products

By Timothy D. Stark Q: Are GCLs hydraulically equivalent to a compacted low permeability soil liner? A: A good, but difficult, question. GCLs are hydraulically equivalent to low permeability soil liner in terms of advective flow. However, GCLs are not hydraulically equivalent to low permeability soi…
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The effects of heat on Subtitle D composite liner systems

June 1, 2009  |  Products

By Timothy D. Stark Q: What effect does heat have on a Subtitle D composite liner system? A: Heat can have many detrimental effects on a Subtitle D composite liner system. For example, heat can adversely affect the compacted low permeability soil liner by reducing its moisture content, leading to an…
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Design strength for GCLs

June 1, 2009  |  Products

By Timothy D. Stark Q: What design strength should be used for GCLs? A: If the GCL is not encapsulated between two geomembranes, the slope design should/must assume that the GCL will be fully hydrated at a low normal stress (e.g., 5–10 psi for a liner system). If the GCL will be encapsulated b…
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Fixing an exposed landfill cover

June 1, 2009  |  Products

By Timothy D. Stark Q: The following photo shows a landfill cover with a gray material exposed. Is this good? If not, what should be done? A: A close-up of the gray material indicates that it is the geomembrane that is part of the final cover system for this landfill. This is not good and … <…
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Prefabricated bituminous geomembrane: A candidate for exposed geomembrane caps

April 1, 2009  |  Products

By Ian Peggs Landfill caps prevent incident precipitation from becoming leachate that has to be treated, contain landfill gas that can be used to generate electricity, and prevent odors that annoy neighbors. Typically, geomembrane caps are covered with soil and vegetation for appearance and for the …
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Geocomposite drainage

April 1, 2009  |  Products

From the GMA Techline Subject: Geocomposite drainage — Canadian landfills apparently have not been allowed to use geocomposite drainage materials in lieu of 2 feet of gravel because they have to prove it will not clog for a period of up to 100 years. Have you studied this in the various geocom…
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CETCO introduces new geosynthetic clay liner product

October 1, 2008  |  Products

CETCO has introduced a new geosynthetic clay liner product that combines the benefits of its needlepunched GCLs with the pricing of its adhesive GCLs, according to a company press release. Bentomat 200R is manufactured with a 3.5oz-per-yd2 nonwoven polypropylene cap fabric that is needlepunched into…
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Cheaper products

October 1, 2008  |  Products

From the GMA Techline Subject: Cheaper? — We are looking for a manufacturer of geosynthetic bags, tubes, and structures that are small and cheap. (Don, California) Reply: “Cheap” I don’t do very well! That said, if you are looking for a vendor other than the usual manufacture…
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Alkalinity

October 1, 2008  |  Products

GMA techline answers from Bob Koerner Subject: Alkalinity — I am working on a site where there is limestone bedrock. There may be some blasting required that could generate blasted rock fill. Is there a concern with using limestone rockfill with HDPE or polyester-coated geogrids? (Mike, Virgin…
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Seams on a sideslope

October 1, 2008  |  Products

From the GMA Techline Subject: Seams on a sideslope — I am currently reviewing a design for a piggybacked cell that is an extension of a cell that was built 4 years ago. The issue that I am most troubled by is that the 2 cells meet halfway up the slope of an existing landfill. … <div><a…
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