Long-term hydraulic conductivity of a geosynthetic clay liner permeated with inorganic salt solutions

Ho Young Jo, Craig H. Benson, Charles D. Shackelford, Jae Myung Lee, Tuncer B. Edil

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160 Citations (Scopus)

Abstract

Hydraulic conductivity tests were conducted on a geosynthetic clay liner (GCL) for more than 2.5 years and as many as 686 pore volumes of flow (PVF) using single-species salt solutions (NaCl, KCl, or CaCl2) to (1) evaluate how the long-term hydraulic conductivity (KL) is affected by cation concentration and valence and (2) demonstrate the relevance and importance of termination criteria when measuring hydraulic conductivity of GCLs to salt solutions. Permeation with CaCl2 solutions resulted in an increase in the hydraulic conductivity of 1 order of magnitude or more. The rate at which these changes occurred depended on concentration, with slower changes (years and hundreds of PVF) occurring for weaker solutions. In contrast, permeation with 100 mM NaCl or KCl solutions or de-ionized (DI) water resulted in no appreciable change in hydraulic conductivity, regardless of the duration of permeation or number of pore volumes of flow. Hydraulic conductivities determined in accordance with ASTM D 5084 and D 6766 (K5084 and K6766) equaled KL when the permeant solution contained NaCl, KCl, or was a strong (≥50 mM) CaCl2 solution. In contrast, when the permeant liquid was a weak (≤20 mM) CaCl2 solution, K6766 and K5084 were 2-13 times lower than KL. Closer agreement between K6766 and KL (3 X) was obtained for weak CaCl2 solutions when the electrical conductivity ratio criterion was tightened to ±5%. Hydraulic conductivities obtained after comparable influent and effluent concentrations of the permeant salt (±10%) were approximately 2X lower than KL for weak CaCl2 solutions. Hydraulic conductivities equal to KL were obtained from the tests permeated with weak CaCl2 solutions only when Na was no longer eluted at detectable levels.

Original languageEnglish
Pages (from-to)405-417
Number of pages13
JournalJournal of Geotechnical and Geoenvironmental Engineering
Volume131
Issue number4
DOIs
Publication statusPublished - 2005 Apr 1

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Keywords

  • Bentonite
  • Chemical equilibrium
  • Compatibility
  • Geosynthetics
  • Hydraulic conductivity
  • Inorganic chemicals

ASJC Scopus subject areas

  • Environmental Science(all)
  • Geotechnical Engineering and Engineering Geology

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