LONG-TERM PERFORMANCE OF GEOSYNTHETIC CLAY LINERS USED IN ACID ROCK DRAINAGE MITIGATION
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- Katsumi Takeshi
- IGS Member, Professor, Graduate School of Global Environmental Studies, Kyoto University, Japan
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- Inui Toru
- JGS Member, Associate Professor, Graduate School of Global Environmental Studies, Kyoto University, Japan
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- Takai Atsushi
- JGS Member, Assistant Professor, Graduate School of Global Environmental Studies, Kyoto University, Japan
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- Ohta Takehiro
- JGS Member, Senior Researcher, Disaster Prevention Technology Division, Railway Technical Research Institute, Japan
Bibliographic Information
- Other Title
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- 酸性廃水に対するジオシンセティッククレイライナーの長期的性能評価
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Abstract
Long-term barrier performance of geosynthetic clay liners (GCLs) when exposed to acid rock drainage (ARD), which is one of the most severe and expensive environmental problems facing the mining and some construction operations, was evaluated. Free swelling, sorption, and a nine-month hydraulic conductivity tests on a needle-punched GCL against an artificial ARD (pH = 3) that contained Al, Fe, Cu, Zn, As, and Pb, were conducted. Free swelling tests showed that a high metal concentration and/or a low pH negatively impacted on osmotic swelling. Sorption test results provided information about the competition among metals, and the Na-bentonite capacity to sorb single metals and metalloids. Nine-month hydraulic conductivity tests demonstrated that pH, EC and permeability changes over time, due to metal sorption/release and precipitation (physical clogging). The hydraulic conductivity remained low during the test duration and was approximately five times lower when GCL was prehydrated with water before ARD permeation (1.1x10^-10 m/s) compared to the case in which prehydration and permeation were done using ARD (5.0x10^-10 m/s). In each case, effluents were evaluated and breakthrough curves were constructed to get information about the GCL attenuation capacity toward metals present in ARD. Considering that bentonite (or GCLs) has the potential to retain heavy metals present in solution, showed relatively low hydraulic conductivity under even extreme conditions, and is available in many parts of the world, GCLs seem to be one possible solution for ARD mitigation.
Journal
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- Geosynthetics Engineering Journal
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Geosynthetics Engineering Journal 26 137-144, 2011
Japan Chapter of International Geosynthetics Society