Hydraulic Conductivity and Swell of Nonprehydrated Geosynthetic Clay Liners Permeated with Multispecies Inorganic Solutions

Kolstad, Dale C.; Benson, Craig H.; Edil, Tuncer B.

doi:10.1061/(asce)1090-0241(2004)130:12(1236)

Cited by 206 publications

(82 citation statements)

References 36 publications

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“…Results from Kolstad et al (2004a) tend to show that a GCL containing a bentonite with a SI greater than 15 mL/2g in a given liquid generally exhibits a hydraulic conductivity lower than 5 x 10 -11 m/s to the same liquid. In contrast, a GCL with a SI lower than 15 mL/2g in a given liquid may exhibited greater hydraulic conductivity.…”

Section: The Filter Press Testsmentioning

confidence: 99%

“…The resulting ratio of monovalent-to-divalent cations, or RMD (Eq.1), of the SL was 0.43 mM 1/2 , where RMD (mM 1/2 ) is defined as per Kolstad et al (2004a) …”

Section: / 46mentioning

confidence: 99%

“…As far as possible, the tests were not terminated before the following criteria were achieved (Shackelford et al, 1999;ASTM, 2002;Kolstad et al, 2004a;Jo et al, 2005;Benson et al, 2008;Katsumi et al, 2008b): (1) a steady hydraulic conductivity; (2) a ratio of incremental outflow to inflow (referred to herein as the "flow ratio") of approximately unity;…”

Section: Oedopermeameter Testsmentioning

confidence: 99%

“…Kolstad et al (2004a) conducted their tests beyond 15 to 20 PVF until each of the four termination criteria previously noted were achieved. The number of PVF for the oedopermeameter tests presented in this paper ranged from 6 to 40.…”

Section: Oedopermeameter Testsmentioning

confidence: 99%

“…Each stage lasted at least one month after application of the stress, which occurred within a few minutes. At the beginning of the 25-kPa stage, a hydraulic head was applied to the sample, starting with 0.3 m maintained for approximately one week, then 0.6 m for one week, and finally 1.2 m. The hydraulic head was kept at 1.2 m during the last two confining pressure stages.As far as possible, the tests were not terminated before the following criteria were achieved (Shackelford et al, 1999; ASTM, 2002;Kolstad et al, 2004a;Jo et al, 2005;Benson et al, 2008;Katsumi et al, 2008b): (1) a steady hydraulic conductivity; (2) a ratio of incremental outflow to inflow (referred to herein as the "flow ratio") of approximately unity;(3) a minimum of two pore volumes of flow (PVF) passed through the specimen; and (4) ratios of effluent-to-influent electrical conductivity (EC) and pH (herein referred to as the 11 / 46 "EC ratio" and "pH ratio") within 1.0 ±0.1. In addition, some authors (e.g., Jo et al 2005) recommend comparing the concentration of specific chemical species between the influent (i.e., permeant liquid) and effluent (e.g., ±10%).…”

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confidence: 99%

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Impact of a synthetic leachate on permittivity of GCLs measured by filter press and oedopermeameter tests

Rosin-Paumier

Touze-Foltz

Pantet

2011

Geotextiles and Geomembranes

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Geosynthetic clay liners (GCLs) are used in landfill liner applications due primarily to their low hydraulic conductivity to water. The low hydraulic conductivity of GCLs comes from the structure of the clay in the bentonite. However, the interaction between clay and aggressive liquids may alter the structure of the clay and, thus, result in an increase in the hydraulic conductivity of the GCL. This paper presents the results of a project aimed at evaluating the impact of a synthetic leachate on the structure of four different bentonites used in the manufacturing of GCLs. The preparation of bentonite dispersions increased the interaction between the bentonites and the various liquids. The hydraulic properties of the dispersions also were tested using filter press tests to obtain flow curves. Results of these tests were correlated with the cationic concentration, electrical conductivity and pH of the 2 / 46 dispersions, swell indexes of the bentonite extracted from the GCLs, and permittivities of the intact GCLs determined in oedopermeameter tests. The results showed that one bentonite was more sensitive to the synthetic leachate than the other bentonites. For example, the permittivities of the more sensitive bentonite based on the oedopermeameter tests and filter press tests were respectively 2.11x10 -8 s -1 and 5.6x10 -8 s -1 , whereas the permittivities for other bentonites, including a natural sodium bentonite and two sodium activated calcium bentonites, were respectively 5.7 to 6.5x10 -9 s -1 and 3.2 to 3.5x10 -8 s -1 . The filter press test served as a quick and easy-to-use test to compare the performance of the various bentonites in containing a given liquid. However, the oedopermeameter test or direct permeation test is preferable to filter press tests or fluid loss tests for evaluating the long-term impact of a liquid on a bentonite.Keywords: bentonite, cation exchange, permittivity, synthetic leachate. INTRODUCTIONGeosynthetic clay liners (GCLs) generally consist of a layer of granular or powdered bentonite sandwiched between two geotextiles, linked by needle punching or stitch bonding.Bentonite has been widely studied, and consists of a mixture of minerals, with the predominant mineral being smectite (van Olphen, 1977;Patterson and Murray, 1983).However, the quality of bentonites used in GCLs for landfill applications may vary widely.The smectite mineral imparts to the bentonite its swelling properties and its low hydraulic conductivity. For landfill bottom liner applications in France, sodium bentonite is recommended for use in GCLs, meaning that sodium ions are the predominant exchangeable cations of the bentonite (MEEDDAT, 2008). The existence of sodium as the exchangeable cation may be the result of natural geological processes, as typically the case for Wyoming 3 / 46 sodium bentonites, or the result of an activation process whereby naturally occurring calcium bentonite is mixed with soda ash to force sodium-for-calcium cation exchange. These latter bentonites are often called sodium-activ...

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Section: The Filter Press Testsmentioning

confidence: 99%

“…The resulting ratio of monovalent-to-divalent cations, or RMD (Eq.1), of the SL was 0.43 mM 1/2 , where RMD (mM 1/2 ) is defined as per Kolstad et al (2004a) …”

Section: / 46mentioning

confidence: 99%