Interface Transmissivity Measurement in Multicomponent Geosynthetic Clay Liners PDF Download
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Author: K. P. von Maubeuge
Publisher:
ISBN:
Category : Advective flow
Languages : en
Pages : 15
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Book Description
Three different multicomponent geosynthetic clay liners (GCLs) from different manufacturers are tested in a transmissivity cell with a new testing procedure to quantify the flow rate and the interface transmissivity between the coating or attached film presenting a hole and the upper geotextile of the GCL. The testing device was previously used in studies aiming to evaluate the interface transmissivity between a damaged geomembrane (GM) and a regular GCL. Different results are obtained regarding the evolution with the time of the flow rate ranging from 1.73 x 10-11 m3/s to 2.18 x 10-10 m3/s at steady state, which is on average in the range of flow rate results obtained with a GM-GCL composite liner. Additional tests performed by adding a GM on top give lower values of flow rates. This shows the importance of the film or coating rigidity for decreasing flow rate and insuring a better quality contact at the interface.
Author: K. P. von Maubeuge
Publisher:
ISBN:
Category : Advective flow
Languages : en
Pages : 15
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Book Description
Three different multicomponent geosynthetic clay liners (GCLs) from different manufacturers are tested in a transmissivity cell with a new testing procedure to quantify the flow rate and the interface transmissivity between the coating or attached film presenting a hole and the upper geotextile of the GCL. The testing device was previously used in studies aiming to evaluate the interface transmissivity between a damaged geomembrane (GM) and a regular GCL. Different results are obtained regarding the evolution with the time of the flow rate ranging from 1.73 x 10-11 m3/s to 2.18 x 10-10 m3/s at steady state, which is on average in the range of flow rate results obtained with a GM-GCL composite liner. Additional tests performed by adding a GM on top give lower values of flow rates. This shows the importance of the film or coating rigidity for decreasing flow rate and insuring a better quality contact at the interface.
Author: K. P. von Maubeuge
Publisher:
ISBN:
Category : Flow rate
Languages : en
Pages : 12
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Book Description
A procedure was developed that combines measuring devices from NF EN 14150 for flow rate measurement through geomembranes and a rigid wall permeameter from NF P84-705. The new procedure aims at measuring flow rates through geosynthetic clay liners (GCLs) in order to measure flow rates through multi-component GCLs. The resulting testing device allows one to measure very small variations in volume with time while applying constant hydraulic pressures. The pressure difference applied on both sides of the multi-component GCL specimens varied between 25 kPa and 100 kPa, with the latter value being equal to the one applied across geomembranes in NF EN 14150. Three different multi-component GCLs from two different manufacturers were tested in order to determine the ability of the testing equipment to quantify the flow rate through multi-component GCLs. The flow rate measurement was performed after a hydration phase under very low hydraulic head and with a 10 kPa normal load on the specimens in accordance with NF P84-705. Details regarding the experimental conditions that could lead to the development of a standard for the measurement of flow rates through multi-component GCLs are given. Results obtained tend to show that flow rates are 1 order of magnitude larger than the ones usually measured for virgin geomembranes (i.e., 10-5 m3/m2/d).
Author: Kent P. von Maubeuge
Publisher:
ISBN:
Category : Coating barrier
Languages : en
Pages : 11
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Book Description
Multi-component geosynthetic clay liners (GCLs) are a new variation of GCLs or GBR-Cs (Geosynthethic Clay Barriers--CEN and ISO definition) and are fast growing in the current sealing applications. During the manufacturing process, the "classic" geosynthetic clay liners are combined with either an adhered film, coating, or membrane that can decrease the hydraulic conductivity of the product but can also add other features. ASTM D5887 [2009, "Standard Test Method for Measurement of Index Flux through Saturated Geosynthetic Clay Liner Specimens Using a Flexible Wall Permeameter," Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA] is the standard test method for hydraulic testing/testing the index flux through saturated geosynthetic clay liner specimens using a flexible wall permeameter. It gives guidance for testing procedures and apparatus but it is noted in the standard that it may not be applicable to GCL products with geomembrane backing(s). In this paper, results will be shown of the testing of the different multi-component geosynthetic clay liners using exactly the ASTM D5887 procedure. Further modifications will be discussed to allow testing according to this method and suggestions for a new method will be presented.
Author: Larry W. Well
Publisher: ASTM International
ISBN: 0803124716
Category : Geosynthetics
Languages : en
Pages : 270
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Book Description
An engineering perspective on the liners, which are used as barriers for containing liquid and in conjunction with geomembranes in landfills and capping systems. Explore aspects of testing for shear strength and long-term creep, issues and methods of testing for hydraulic conductivity, and specifica
Author: Robert E. Mackey
Publisher: ASTM International
ISBN: 0803134843
Category : Clay
Languages : en
Pages : 161
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Book Description
Soon after the inception of ASTM D35.04 Subcommittee on Geosynthetic Clay Liners, the first symposium on Testing and Acceptance Criteria for Geosynthetic Clay Liners (GCLs), STP 1308, was held on 29 January 1996, in Atlanta, Georgia. The intention of the symposium was to bring together the current knowledge and understanding regarding this relatively new product used in containment systems. Since that symposium, numerous GCL standards have been developed along with a greater appreciation of the product's capabilities and limitations. ASTM D35 determined it was time to assess the current state of GCL technology to better address possible revisions of the present ASTM GCL standards and determine what new standards will be required in the future.
Author: Zehong Yuan
Publisher:
ISBN:
Category : Boundary effect
Languages : en
Pages : 10
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Book Description
The internal shear strength of geosynthetic clay liners (GCLs) can be evaluated through direct shear testing in accordance with ASTM D6243 under a specific set of boundary conditions for a given normal stress. In order to prevent slippage at the GCL-gripping system interface and ensure an internal shear failure of the GCL, a gripping surface made of spikes 1 to 2mm tall mounted on a rigid substrate is recommended in the standard method and has been commonly used. It is recognized that certain boundary effects exist as a result of the aggressive gripping system. To improve the hydraulic performance and/or protect the bentonite core, a multi-component GCL is designed to have a thin membrane or film laminated or glued to one of the carrier geotextiles. It is necessary to investigate the boundary effect on the multi-component GCL internal shear strength tests, because the film- or membrane-geotextile interface is more prone to interference from the rough gripping surface recommended by the current standard. A series of internal shear strength tests were conducted on the same multi-component GCL product under different gripping conditions. It was found that tests using the aggressive gripping system yield a significantly higher peak shear strength of the multi-component GCL and a lower residual shear strength at large displacements.
Author: Madalena C. P. Barroso
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Composite liners are used to limit the contamination migration from landfills. Their successful performance is closely related with the geomembrane as it provides the primary barrier to diffusive and advective transport of contaminants. Critical issues on the performance of the geomembranes are the seams between geomembrane panels and the inevitable defects resulting, for instance, from inadequate installation activities. In landfills, where high density polyethylene geomembranes are usually used, seams are typically made by the thermal-hot dual wedge method. A literature review on quality control of the seams showed that, in situ, fluid-tightness of seams is evaluated in qualitative terms (pass/failure criteria), despite their importance to ensure appropriate performance of the geomembranes as barriers. In addition, a synthesis of studies on geomembrane defects indicated that defects varying in density from 0.7 to 15.3 per hectare can be found in landfills. Defects represent preferential flow paths for leachate. Various authors have developed analytical solutions and empirical equations for predicting the flow rate through composite liners due to defects in the geomembrane. The validity of these methods for composite liners comprising a geomembrane over a geosynthetic clay liner (GCL) over a compacted clay liner (CCL) has never been studied from an experimental point of view. To address the problem of fluid migration through the geomembrane seams, an attempt is made to provide a test method, herein termed as "gas permeation pouch test", for assessing the quality of the thermal-hot dual wedge seams. This test consists of pressurising the air channel formed by the double seam with a gas to a specific pressure and, then, measuring the decrease in pressure over time. From the pressure decrease, both the gas permeation coefficients, in steady state conditions, and the time constant, in unsteady state conditions, can be estimated. Experiments were carried out both in laboratory and in field conditions to study the suitability of this test to assess the quality of the seams in situ. The results obtained suggest that it is possible to assess the quality of the geomembrane seams from a non-destructive test conducted in situ by determining the time constant. To address the problem of fluid migration through geomembrane defects, composite liners comprising a geomembrane with a circular hole over a GCL over a CCL were simulated in tests at three scales. Flow rates at the interface between the geomembrane and the GCL were measured. Correspondent interface transmissivity was estimated based on final flow rates and observation of the wetted area. A parametric study was performed to evaluate the influence of the prehydration of the GCL, the hydraulic head on top of the liner and the confining stress over the liner system, on the flow rate through composite liners due to defects in the geomembrane, as well as to check the feasibility of an extrapolation of the results obtained on small-scale tests to field conditions. It was found that the transmissivity does not seem to be affected by the prehydration of the GCLs when low confining stresses were used. It also does not seem to be influenced by the increase in confining stress when non-prehydrated GCLs are used. Finally, the transmissivity does not seem to be significantly affected by the increase in hydraulic head. The results also suggest that predictions on flow rates though composite liners due to defects in the geomembrane, which are based on transmissivity values obtained in small scale tests, are conservative. Lastly, based on the transmissivities obtained in this study, empirical equations for predicting the flow rate through composite liners consisting of a geomembrane over a GCL over a CCL are proposed. Flow rates calculated using these equations are in better agreement with the flow rates measured experimentally than the empirical equations reported in literature. The new empirical equations provide design engineers with simple and accurate tools for calculating the flow rates through the above mentioned type of composite liners.
Author: Mohamed Said Hussein Hosney
Publisher:
ISBN:
Category :
Languages : en
Pages : 1730
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Book Description
The use of geosynthetic clay liners (GCLs) as (i) covers for arsenic-rich gold mine tailings and landfills, (ii) subsurface barrier for migration of hydrocarbons in the Arctic, and (iii) basal liner for sewage treatment lagoons were examined. After 4 years in field and laboratory experiments, it was found that best cover configuration above gold mine tailings might include a layer of GCL product with polymer-enhanced bentonite and a geofilm-coated carrier geotextile serving above the tailings under [greater than or equal to] 0.7 m overburden. However, acceptable performance could be achieved with using a standard GCL with untreated bentonite provided that there is a minimum of 0.7 m of cover soil above the GCL. When GCL samples were exhumed from experimental landfill test cover with complete replacement of sodium in the bentonite with divalent cations in the adjacent soil, it was observed that the (i) hydraulic head across the GCLs, (ii) size of the needle-punched bundles, and (iii) structure of the bentonite can all significantly affect the value of the inferred in-situ hydraulic conductivity measured at the laboratory. The higher the hydraulic head and the larger the size of the needle-punched bundles, the higher the likelihood of internal erosion/structural change of bentonite at bundles that will cause a preferential flow for liquids to occur. A key practical implication was that GCLs can perform effectively as a single hydraulic barrier in covers provided that the water head above the GCL kept low. The hydraulic performance of a GCL in the Arctic was most affected by the location within the soil profile relative to the typical groundwater level with the highest increase in the hydraulic conductivity (by 1-4 orders of magnitude) for GCL below the water table. However, because the head required for jet fuel to pass through the GCL was higher than that present under field conditions, there was no evidence of jet fuel leakage through the barrier system. The leakage through GCLs below concrete lined sewage treatment lagoons was within acceptable limits, in large part, due to the low interface transmissivity between GCLs and the overlying poured concrete.
Author: Kent von Maubeuge
Publisher: ASTM International
ISBN: 9780803175488
Category : Clay
Languages : en
Pages : 154
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Book Description
"Peer-reviewed papers that were presented at a symposium held June 29, 2012 in San Diego, CA"
Author: DE. Daniel
Publisher:
ISBN:
Category : Bentonite
Languages : en
Pages : 12
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Book Description
An important property of geosynthetic clay liners (GCLs) is hydraulic conductivity. The authors describe and evaluate a new device, a GCL flowbox, that offers several advantages over large tanks or flexible-wall permeameters. The GCL flowbox can be used to test large-scale intact specimens, overlapped specimens with a full-width seam, and specimens subjected to environmental stresses such as freeze-thaw. A transparent, acrylic GCL flowbox was developed for testing at low normal stresses, and a metal version was developed for applying higher normal stresses. Results from the GCL flowbox compared favorably to results obtained with tanks and flexible-wall permeameters. It is concluded that the GCL flowbox provides a convenient and reliable testing methodology for verifying the hydraulic conductivity of both intact specimens and overlapped GCL panels.
