April 1, 2021
In this April/May issue of Geosynthetics magazine, our feature authors tackle three very different uses of geosynthetics with in-depth examination, testing and even a new design method. In the introduction to their article, “Modular Geosynthetics Construction,” E. Silva, T. D. Stark and Duff Simbeck discuss the benefits of a specific manufacturing process for geomembranes. They …
Q: We are having issues related to obstructions in the reinforced zone of our mechanically stabilized earth (MSE) retaining walls. In the first case, there is a rock outcrop that is limiting the length of the geogrid reinforcement. In the second case, we have a drop-down inlet structure to divert stormwater, which is in the …
Q: We are using Robert Koerner’s Designing with Geosynthetics to calculate the required thickness of a geomembrane. See Figure 1 and Equation 1 from the book for details. Can you point us in the right direction with the mobilization distance, x? A: Yes, please see Figure 2 for high-density polyethylene (HDPE). It shows ASTM D6706 …
Q: We are a large liner installation firm that has been asked to install a geomembrane liner from low gradient to high gradient. Is this the new normal? A: This is not normal, and we suggest you strongly object to this recommendation. There are many stakeholders in regard to panel layout (i.e., installer, general contractor, …
Q: Our liner system is a double composite and along a western tie-in. We need to extrusion-weld the secondary 60-mil (1.5-mm) HDPE (new cell) to an existing secondary 40-mil (1-mm) HDPE (old cell), and the state is continuing to have issues with the fact that we are using the 40-mil (1-mm) GRI-GM19 peel specification as …
Q: We are interested in using a geotextile as an “unbonded concrete interlayer” over existing concrete pavement to float the new slab over deteriorated pavement, instead of a thin asphalt layer. Do you have any guidance for us in this regard? A: Over the past several years, 16-ounce-per-square-yard (542-g/m2) nonwoven needlepunched geotextiles have been used …
By E. Silva, T. D. Stark and Duff Simbeck Modular construction is a process in which a building or other item is constructed primarily off-site; under controlled factory conditions; and using the same design, materials, equipment, testing and construction quality control and assurance (CQC/CQA) techniques as a field-constructed facility—but usually in about one-half the time …
By Pietro Rimoldi and Nicola Brusa Rapid and extreme climate change is putting our planet under stress. As a consequence, in mountain and hilly regions, infrastructure and people are more often threatened by quick and unpredictable rockfall events. Falling boulders can have extremely high speeds, exceeding 11 mph (5 m/s) and up to 67 mph …
By James E. Sprague and C. Joel Sprague Sediment retention devices (SRDs) include silt fences, wattles, filter logs, compost socks and various types of stormwater inlet protectors. They are a widely used best management practice (BMP) to provide sediment filtration from stormwater runoff while allowing water passage. However, SRD performance varies greatly in flow rate …
By Bryan Gee What’s in a name? For those of us who work in the geosynthetics industry, this question may be more important than you think. A recent call with a high-level federal policy maker brought this home to me. With no prior knowledge of our industry, this person did not understand what geosynthetic materials …
