Geocomposite drainage layers

October 1st, 2015

Flammability? Zip ties? MARV? Ponds? GT specs? Questions and answers from the GMA Techline. I wonder about your opinion on the use of a triplanar geocomposite for landfill drainage layer. We have not approved these in our jurisdiction to date. I have a current application where this is proposed to be used (vertical expansion). I […]

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Saturated soil cover on liner question

October 1st, 2015

Questions and answers from the GMA Techline. I need your advice on a reservoir we are designing. It is an irrigation reservoir with a 40-mil HDPE geomembrane liner on a 3:1 slope. The client wants to cover the liner with 1ft of silt loam soil. The water elevation in the reservoir will fluctuate about 15ft […]

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Geotextile data

October 1st, 2015

Flammability? Zip ties? MARV? Ponds? GT specs? Questions and answers from the GMA Techline. I am a student of hydraulic structures and I need some data about transmissivity of geotextiles (ASTM D4716 or ISO/DIS 12958); and also permittivity or cross-plane permeability (ASTM D5493 or every valid standard). My thesis is about transmissivity and permittivity of […]

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Protrusion/particle shape—geotextile cushions

October 1st, 2015

Flammability? Zip ties? MARV? Ponds? GT specs? Questions and answers from the GMT Techline. Our landfill liner project specifications require the use of rounded to subangular gravel to be placed as a leachate drainage layer or leachate collection pipe bedding. The gravel is separated from the geomembrane liner by a nonwoven geotextile cushion. During bidding, […]

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Zip-tie strength

October 1st, 2015

Flammability? Zip ties? MARV? Ponds? GT specs? Questions and answers from the GMA Techline. We had a problem at one of the construction projects where we were providing CQA. It turned out that the installer had two different types (and apparently strengths) of zip ties. There ended up being seam failures in some of the […]

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GRI White Paper #10/Test Method GTI2(A)

October 1st, 2015

Flammability? Zip ties? MARV? Ponds? GT specs? Questions and answers from the GMA Techline. I have reviewed GRI White Paper #10, GRI Test Method GT12(a), ASTM D4354, and ASTM D4759 and have a question. I have reviewed some recent CQA test results of a nonwoven cushion geotextile roll sample and while the average of the […]

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Nonwoven needle-punched GT

October 1st, 2015

We specify that the geotextile under riprap must be nonwoven, needle-punched, Class 1. NCHRP Report 568 (page C-25, Section 7.1) requires that nonwoven geotextile filter under riprap must have a mass density greater than 12osy (ounces per square yard). We have the following questions: What is the cost difference between nonwoven needle-punched, Class 1 12osy […]

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Effluent pond liners

October 1st, 2015

Flammability? Zip ties? MARV? Ponds? GT specs? Questions and answers from the GMA Techline. I’m designing an effluent pond (the geotechnical aspect at least) and have a couple of questions: Do you see any issues with placing a gravel (rounded) subdrain system underneath the pond, sandwiched between a geomembrane (likely textured HDPE) and a geotextile […]

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GCL woven side against geomembrane

October 1st, 2015

Flammability? Zip ties? MARV? Ponds? GT Specs? Questions and answers from the GMA Techline. I seem to recall a webinar or presentation in which the presenter warned against using the woven side of a GCL against a geomembrane due to bentonite squeeze-out and subsequent slippage. Instead, the nonwoven side was recommended against the geomembrane with […]

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HDPE flammability

October 1st, 2015

Flammability? Zip yies? MARV? Ponds? GT specs? Questions and answers from the GMA Techline. I am involved with a landfill permit renewal. A question keeps coming up concerning the flammability potential of HDPE liner. What is that potential and do you know of any liner system fires? Eric | USA Eric, HDPE melts between 110 […]

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