Archives

Bringing geomembranes into equilibrium with atmosphere

August 1st, 2021

Q: Some ASTM test methods request that one brings the specimens into equilibrium with the atmosphere prior to the test (some of them determine the conditions: 21±2ºC and 60±10% relative humidity). Considering that we just produce polyethylene geomembranes, and they are not significantly affected by the relative humidity, do you have any suggestions about how […]

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Metal leaching from geosynthetics

August 1st, 2021

Q: Geosynthetics are made from polymers that use metal-based catalysts in their formulations. Do geosynthetics have the potential to leach metals into the environment? A: I think the fair answer to this is yes, but the potential risk is very small due to the long-term stability of the polymers used in geosynthetics and the very […]

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Service life of nonwovens

August 1st, 2021

Q: Where can I find literature on the useful service life of nonwoven geosynthetic fabrics installed in soils? A: One of the best references in this regard is from a manufacturer of nonwoven geotextiles. It is:  SI Geosolutions (now Propex). (1997). Smart Solutions, Technical Note, SM-404. “The durability of polypropylene nonwoven geotextiles for waste containment […]

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Bluff repair in seismically active zone

August 1st, 2021

Q: I am doing a bluff repair on the West Coast in a seismically active zone. Can you direct me to where I can get some design guidance? A: The following references are excellent in regard to your question. National Concrete Masonry Association. (2009). “Guidelines for the design and analysis of mechanically stabilized earth (MSE) […]

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A geotextile filter for an edge drain

August 1st, 2021

Q: I am doing a geotextile filter design for a highway edge drain. All I have from the site is a grain size analysis of the sandy subgrade soil. Can you point me in the right direction? A: First you are going to need to calculate an estimate of hydraulic conductivity for the sandy soil […]

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Design of a CCR composite liner system

August 1st, 2021

Q: We are designing a composite liner system for a coal ash landfill. From the bottom-up, the cross section is subgrade soil, geosynthetic clay liner (GCL), geomembrane, composite drainage layer with nonwoven geotextiles on both sides and then ash from coal combustion residuals (CCR). Do you have an opinion on the design, particularly on 3:1 […]

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Industry standard for wall drainage systems?

June 1st, 2021

Q: I just watched your recorded video of mechanically stabilized earth (MSE) wall inspection. Thank you for the presentation; it was very informative. I do have a follow-up question for you. I was recently the site engineer for a precast panel MSE wall and now have the opportunity to inspect construction of the wall that […]

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Useful service life of nonwoven geosynthetics

June 1st, 2021

Q: Where can I find literature on the useful service life of nonwoven geosynthetic fabrics installed in soils? Thank you. A: Nice to hear from you and thanks for your question in regard to the service life of nonwoven geotextiles.  Below is a reference that I think is very good. In addition, I have exhumed […]

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GCLs in cold temperatures

June 1st, 2021

Q: I am working on supporting a guide (independent) on what to consider when geosynthetic clay liners (GCLs) are installed in minus temperature regions (e.g., –4˚F [–20˚C]). There is not much published on this, especially independently. This is the only thing I found: Designation: D6102-20Standard Guide for Installation of Geosynthetic Clay Liners5.3.8 The GCL should […]

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Geotextile under articulated systems in slope armoring

June 1st, 2021

Q: I have a question about the geotextile placed under articulated systems in slope armoring. Based on my understanding, a drainage layer is recommended between the geotextile and the armoring structure, but, since the armoring structure has some spaces in between the armoring blocks, won’t the particles of the drainage layer be washed out through […]

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