Advection and Retardation of Non-polar Contaminants in Compacted Clay Barrier Material with Organoclay Amendment

Abstract

Compacted clay liners (CCLs) are widely used as hydraulic barriers in landfills, underground storage tanks, vertical cutoff walls and surface impoundments. Most commonly, the breakthrough of contaminant flows in CCLs takes a long time due to the reduced advection rate; however, the attenuation of non-polar fluid or organic contaminants in CCLs is relatively low because of the non-reactive nature of most CCL materials. Surfactant-modified bentonites are promising barrier amendments as they are coated with organic surfactant and are capable of uptaking the non-polar species from the aqueous phase. In this study, laboratory tests were carried out to evaluate the swelling, permeability and contaminant retention of compacted silty clay amended with an organoclay (hexadecyltrimethylammonium (HDTMA) modified bentonite) against both gasoline and organic solution. The swelling properties and the hydraulic conductivities of compacted soils with varying liquids were evaluated and the transport of naphthalene, a representative of polycyclic aromatic hydrocarbons (PAHs) and a possible component of NAPLs, in organobentonite-amended silty clay was examined through batch sorption and column tests. The results indicated that the addition of 10% HDTMA bentonite to compacted silty clay slightly increased the permeability of the mixture to water. However, higher swelling tendency and lower permeability to gasoline were also observed. With 5% of HDTMA bentonite amendment, the compacted silty clay soil had a much stronger retardation capacity for naphthalene.

Department(s)

Civil, Architectural and Environmental Engineering

Keywords and Phrases

Amendment; Clay barrier; Compacted clay liners; Hydraulic conductivity; Organobentonite; Reactive geo-material; Retardation; Swelling

International Standard Serial Number (ISSN)

0169-1317

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2024 Elsevier, All rights reserved.

Publication Date

15 Jun 2017

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