Abstract
Tests were conducted on eight soils to determine how coal combustion product (CCP) leachates may affect the hydraulic conductivity of compacted soil liners (CSLs) used for CCP disposal facilities. The soils represent a broad range of particle-size distributions, Atterberg limits, and mineralogy, and meet minimum compositional recommendations for CSLs. Hydraulic conductivity tests were conducted with five characteristic CCP leachates from the Electric Power Research Institute (EPRI) database of CCP leachates. The testing confirmed that seven of the soils are suitable for a CSL. Five of the seven suitable soils have hydraulic when permeated with any of the CCP leachates at 28 kPa effective stress (disposal facility with first lift of CCP placed), as do all but one soil when the effective stress is 450 kPa. Larger increases in hydraulic conductivity are associated with soils having lower hydraulic conductivity to deionized water and significant montmorillonite content. Soils exhibiting the smallest increases in hydraulic conductivity have little to no montmorillonite. Hydraulic conductivity to CCP leachate is not related systematically to any of the primary index properties, indicating that mineralogy is a better indicator of sensitivity to CCP leachates than index properties. Increasing the effective stress from 28 to 450 kPa ( to 30 m CCP depth) results in an average reduction hydraulic conductivity of . The average reduction is at 100 kPa and at 250 kPa.
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Acknowledgments
Financial support for this study was provided by the Electric Power Research Institute (EPRI). The findings in this report are those of the authors, and may not reflect the policies or opinions of EPRI. Ken Ladwig and Bruce Hensel of EPRI provided assistance during the study.
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Journal of Geotechnical and Geoenvironmental Engineering
Volume 144 • Issue 4 • April 2018
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Received: Jan 3, 2017
Accepted: Sep 27, 2017
Published online: Jan 30, 2018
Published in print: Apr 1, 2018
Discussion open until: Jun 30, 2018
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