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Insight into hydraulic conductivity testing of geosynthetic clay liners (GCLs) exhumed after 5 and 7 years in a cover
Published in Canadian Science Publishing
2017
Volume: 54
   
Issue: 8
Pages: 1118 - 1138
Abstract
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). © 2017, Canadian Science Publishing. All rights reserved.
About the journal
JournalCanadian Geotechnical Journal
PublisherCanadian Science Publishing
ISSN00083674
Open AccessYes
Concepts (20)
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    Bentonite
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    Hydraulic conductivity
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    Needles
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    Positive ions
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    CATION EXCHANGES
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    Cover
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    Field studies
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    Geosynthetic clay liners
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    OVERLAPS
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    Geosynthetic materials
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    Clay liner
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    Exhumation
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    Field method
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    Geosynthetics
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    Ion exchange
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    Silty soil
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    Size
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    Sodium
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    Canada
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    ONTARIO [CANADA]