Discussion of “Hydraulic Conductivity of Two Prototype Clay Liners” by Steven R. Day and David E. Daniel (August, 1985, Vol. 111, No. 8)

: Landfill liners are underlying materials with low permeability whose main function is to mitigate the infiltration of toxic contents into ground water lying beneath. Landfill liners are primarily made of bentonite clay. Bentonite has a very low hydraulic conductivity, that might not be readily accessible, unlike kaolin which is found to have a lower hydraulic conductivity compared to that of bentonite and can be extensively obtained from numerous different sources. Explored, for the purposes of the present research paper, were various ratios of bentonite and kaolin and their hydraulic conductivity, in particular ratios of 90:10 kaolin to bentonite, 80:20 kaolin to bentonite, 70:30 kaolin to bentonite, 60:40 kaolin to bentonite and 50:50 kaolin to bentonite in an effort to achieve an acceptable barrier suitable as a liner / where tap water and ammonium solution were used as permeants. It was concluded that the ratios not lower than 20% bentonite (80:20, 70:30, 60:40 and 50:50) all had their hydraulic conductivity value reduced compared to the 100% kaolin.

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Prediction of Field Hydraulic Conductivity of Clay Liners Using an Artificial Neural Network and Support Vector Machine

International Journal of Geomechanics ◽

10.1061/(asce)gm.1943-5622.0000129 ◽

2012 ◽

Vol 12 (5) ◽

pp. 606-611 ◽

Cited By ~ 30

Author(s):

Sarat Kumar Das ◽

Pijush Samui ◽

Akshaya Kumar Sabat

Keyword(s):

Neural Network ◽

Artificial Neural Network ◽

Support Vector Machine ◽

Hydraulic Conductivity ◽

Support Vector ◽

Clay Liners ◽

Artificial Neural

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Insight into hydraulic conductivity testing of geosynthetic clay liners (GCLs) exhumed after 5 and 7 years in a cover

Canadian Geotechnical Journal ◽

10.1139/cgj-2016-0473 ◽

2017 ◽

Vol 54 (8) ◽

pp. 1118-1138 ◽

Cited By ~ 22

Author(s):

R.K. Rowe ◽

R.W.I. Brachman ◽

M.S. Hosney ◽

W.A. Take ◽

D.N. Arnepalli

Keyword(s):

Hydraulic Conductivity ◽

Unit Area ◽

Divalent Cations ◽

Hydraulic Gradient ◽

Silty Sand ◽

Geosynthetic Clay Liners ◽

Clay Liners ◽

Percentage Area ◽

Bundle Size ◽

Insight Into

Four geosynthetic clay liners (GCLs) serving as single liners were exhumed from below 0.7 m of silty sand on a 3:1 (horizontal:vertical) north-facing slope at the QUELTS site in Godfrey, Ontario, after 5 and 7 years. The 300 mm GCL overlaps with 0.4 kg/m supplemental bentonite were all physically intact. The exchangeable bound sodium was completely replaced with divalent cations. The GCL with the smallest needle-punched bundle size (average of 0.7 mm) and percentage area covered by bundles (4%) maintained low hydraulic conductivity (k) when tested under 0.07–1.2 m head with 10 mmol/L CaCl2 solution as the permeant. For GCLs with larger bundles (1.1–1.6 mm) and higher percentage area covered by bundles (9%–14%), k was low when the head was low (0.07 m). Once the applied head increased, k increased by 1–4 orders of magnitude depending on the (i) hydraulic gradient, (ii) size and number of the needle-punched bundles, and (iii) structure and mass of the bentonite per unit area. The results suggest that the GCLs can perform effectively as a single hydraulic barrier in covers providing that the head above the GCL is kept low (e.g., by a suitable drainage layer above the GCL).

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