Interactions of Per- and Polyfluoralkyl Substances (PFAS) with Landfill Liners

This review synthesises the available published research on interactions of per- and polyfluoroalkyl substances (PFAS) with landfill liners, with the view to inform on the expected behaviour of these persistent environmental pollutants in landfills. The review addresses the nature and significant types of PFAS compounds that are destined for landfills, as well as their by-product. It discusses the known and anticipated interactions with separate landfill liner components, namely geomembranes, geosynthetic clay liners and compacted clay liners. Various water-soluble PFAS are shown to advectively transport through geosynthetic clay liners (GCL) and showcase the limitations of relying on mineral liners alone to retain PFAS. Addition of activated carbon, while increasing saturated hydraulic conductivity, significantly increases PFAS retention by the GCL and reduced PFAS flux to manageable concentrations. An assessment of the relative risk for environmental exposure of different types of PFAS from landfills through interaction with those liner components is achieved with reference to published case studies of PFAS detection in and around landfills from Australia and around the World.

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Behavior of Geosynthetic Clay Liners due to the Migration of Heavy Metal

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.989-994.433 ◽

2014 ◽

Vol 989-994 ◽

pp. 433-436 ◽

Cited By ~ 1

Author(s):

Jing Jing Fan

Keyword(s):

Heavy Metal ◽

Low Cost ◽

Compacted Clay ◽

Geosynthetic Clay Liners ◽

Clay Liners ◽

Composite Liner ◽

Landfill Liner ◽

Low Leakage ◽

Liner System ◽

Underlying Soil

To protect the underlying soil and groundwater from landfills, the landfills are commonly lined with layered liner systems. Geosynthetic clay liners (GCL) have been increasingly used in the landfill liner systems to substitude the traditional compacted clay liners (CCL) because of their low cost, easily construction behavior and low leakage rate. To study the behavior of the GM+GCL liner system used in China due to the migration of Pb2+, we introduce in detail GM+GCL liner systems proposed by the Chinese specification. Then one dimensional finite layer model is used to investigate the anti-pollution behavior of the CM+GCL composite liner systems, with the focuses on the heavy metal Pb2+. It could be concluded that the main migration way through the GM+GCL composite liner system is that the transport of Pb2+through a GM+GCL composite liner system of a landfill cover takes place primarily through the holes in the GM. The findings provide useful reference for preventing, controlling and treating groundwater pollution in the GM+GCL liner system technically and scientifically.

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Statistical analyses of compacted clay landfill liners. Part 1: model development

Canadian Journal of Civil Engineering ◽

10.1139/l94-093 ◽

1994 ◽

Vol 21 (5) ◽

pp. 872-882 ◽

Cited By ~ 7

Author(s):

Scott B. Donald ◽

Edward A. McBean

Keyword(s):

Hydraulic Conductivity ◽

Geometric Mean ◽

Model Development ◽

Statistical Analyses ◽

Compacted Clay ◽

Clay Liners ◽

Landfill Liner ◽

Landfill Liners ◽

Clay Liner ◽

Spatial Correlation Structure

The acceptance of compacted clay liners, from a management point of view, has been a source of major concern because of the uncertainty associated with the hydrogeologic properties of the clay. By examining the flux of leachate through the compacted clay liner of a typical engineered landfill, where the hydraulic conductivity of the clay is represented by a stochastic process, an acceptance protocol suitable for compacted clay landfill liners is derived. Determination of the equivalent hydraulic conductivity of the clay liner is accomplished by comparing the flux of leachate through a homogeneous representation of the clay with the flux obtained by Monte Carlo analyses. Acceptance criteria are subsequently developed based on a statistical technique which calculates the confidence limits about a percentile of a probability distribution as well as about the mean of the distribution. For the landfill configuration simulated, the results indicate that the hydraulic conductivity of a compacted clay landfill liner follows a lognormal distribution and exhibits virtually no spatial correlation structure. In addition, for liners exhibiting a geometric mean conductivity of 10−7 cm/s and a standard deviation of 0.3, the geometric mean value is a conservative estimate of the hydraulic conductivity of the clay, provided the liner is constructed in a series of four 150 mm lifts. Key words: clay liners, hydraulic conductivity, statistical analyses, latin hypercube, equivalent hydraulic conductivity.

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Kaolin based protective barrier in municipal landfills against adverse chemo-mechanical loadings

Scientific Reports ◽

10.1038/s41598-021-89787-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Partha Das ◽

Tadikonda Venkata Bharat

Keyword(s):

Ionic Strength ◽

High Ionic Strength ◽

The Self ◽

Design Parameters ◽

Layered System ◽

Geosynthetic Clay Liners ◽

Clay Liners ◽

Landfill Liner ◽

First Time ◽

Applied Stresses

AbstractIn this work, we assess the self-sealing and swelling ability of the compacted granular bentonite (GB) under an inorganic salt environment and induced overburden stresses from the landfill waste. The laboratory permeation tests with high ionic strength salt solutions reveal that the GB fails to seal and exhibits a significant mechanical collapse under different applied stresses. The applicability of GB in the form of geosynthetic clay liners as the bottom liner facilities in landfills that produce high ionic strength salt leachates, therefore, remains a serious concern. We propose an additional barrier system based on kaolin, for the first time, to address this problem. The proposed kaolin-GB layered system performs satisfactorily in terms of its sealing and swelling ability even in adverse saline conditions and low overburden stresses. The kaolin improves the osmotic efficiency of the self and also helps the underlying GB layer to seal the inter-granular voids. The estimated design parameters by through-diffusion test suggest that the kaolin-GB layered system effectively attenuates the permeant flux and suitable as a landfill liner.

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Geosynthetic Clay Liners (GCLs)

4th International Pipeline Conference, Parts A and B ◽

10.1115/ipc2002-27012 ◽

2002 ◽

Author(s):

Bruno Herlin ◽

Kent von Maubeuge

Keyword(s):

Cost Savings ◽

Low Permeability ◽

Compacted Clay ◽

Geosynthetic Clay Liners ◽

Clay Liners ◽

Research Level ◽

The World ◽

Fuel Storage ◽

Technical Properties ◽

Nonwoven Geotextile

Geosynthetic Clay Liner’s (GCLs) are an established sealing product in the geoenvironmental industry. They are used in landfill applications as caps and base liners, secondary containment for fuel storage facilities, as well as within various other containment structures such as dams, canals, rivers, and lakes. Rolled out like a carpet to provide a durable impermeable liner, Geosynthetic Clay Liners consist of a layer of high swelling sodium bentonite sandwiched between two geotextiles. Manufactured around the world in different techniques, the Canadian manufactured GCL, is mechanically bonded by needlepunching from one nonwoven geotextile through the bentonite to the other nonwoven or woven geotextile. The low hydraulic conductivity of the GCLs are used mainly as a replacement to thick, difficult to build compacted clay liners to provide a barrier to liquids and gases, offering both a technical and economical advantage. GCLs, with an average thickness of 7mm, offer a volume advantage over Compacted Clay Liners. They are more capable of withstanding freeze-thaw and wet-dry cycles; offer substantial construction cost savings in reduced on-site QC/QA and a quicker installation. Furthermore, GCLs offer equivalent or lower rates of release of fluids and chemicals than Compacted Clay Liners (CCLs). Bentonite is a clay mineral with expansive characteristics and low permeability, where montmorillonite is the chief mineral. Montmorillonite, swells when contacted with water approximately 900% by volume or 700% by weight. When hydrated under confinement, the bentonite swells to form a low permeability clay liner, the equivalent hydraulic protection of several feet of compacted clay. A relatively new engineering material for some, geosynthetic clay liners have been used extensively over the past two decades, and are finding increasing use in every sector of the environmental industry. This paper will review the technical properties of these materials, their documentation at the research level, their integrity as a sealing barrier and recent field applications in the pipeline industry. Further, because these materials are factory produced, their properties are predictable, assisting the engineer to design with a high confidence level. Technical properties and economical benefits are sure to further increase GCL installations around the world to protect our environment and more importantly our groundwater.

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The role of organic attenuation in saturated clay barrier system

Water Science & Technology ◽

10.2166/wst.1996.0161 ◽

1996 ◽

Vol 33 (8) ◽

pp. 145-151 ◽

Cited By ~ 1

Author(s):

Irene M. C. Lo

Keyword(s):

Hydraulic Conductivity ◽

Concentration Gradient ◽

Organic Contaminants ◽

Molecular Diffusion ◽

Pollution Prevention ◽

Fickian Diffusion ◽

Compacted Clay ◽

Landfill Liner ◽

Landfill Liners ◽

Saturated Clay

A review of literature finds that advection, diffusion, and retardation are the main processes that govern the migration of organic contaminants through compacted clay landfill liners. However, much emphasis is placed on the hydraulic conductivity in the specification for landfill liner design. It is misunderstood that if the hydraulic conductivity of the clay is low, then the liner must provide an adequate barrier for groundwater pollution prevention. Unfortunately, even the advection is minimal, contaminants can migrate through clay by simple Fickian diffusion at a rate that can be significant. The process of diffusion is mainly dependent on the concentration gradient between the leachate and the groundwater. If a clay lining system is installed, the only way to reduce the effect of diffusion is to reduce the concentration gradient by pollutant retardation. In this paper, the relative importance of molecular diffusion and advection, and the effect of pollutant retardation on the advective and diffusive transport are discussed using a conceptual-mathematical model. Based on a review of organic contaminant attenuation by clay liners, a guideline on the development of a high organic attenuation engineered barrier as a second line of defence for containment sites is proposed.

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An evaluation of geosynthetic clay liners to minimize geomembrane leakage caused by protrusions in subgrades and compacted clay liners

Clay Geosynthetic Barriers ◽

10.1201/9781003078777-8 ◽

2021 ◽

pp. 61-69

Author(s):

D. Narejo ◽

G. Corcoran ◽

R. Zunker

Keyword(s):

Compacted Clay ◽

Geosynthetic Clay Liners ◽

Clay Liners

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Uma abordagem geral dos principais fatores influenciadores no desempenho de geocompostos argilosos

Holos Environment ◽

10.14295/holos.v20i2.12377 ◽

2020 ◽

Vol 20 (2) ◽

pp. 251

Author(s):

Gustavo Dias Miguel ◽

Mozara Benetti ◽

Karla Salvagni Heineck

Keyword(s):

Compacted Clay ◽

Geosynthetic Clay Liners ◽

Clay Liners

Geocompostos argilosos para barreira impermeabilizante (GCL, do inglês: Geosynthetic clay liners) apresentaram-se como uma alternativa a Camadas de Argila Compactada (CCL, do inglês: Compacted Clay Liners). Um produto manufaturado apresenta benefícios em comparação àqueles que se utilizam apenas de produtos naturais. Entretanto, um manejo inadequado destes produtos pode fazer com que estes se tornem inaptos a sua utilização. Se tornando, na verdade, um inconveniente onde aplicado. Assim sendo, algumas considerações básicas devem serem levadas em conta quando de sua utilização. Com isto, aspectos como principais benefícios, resultados de pesquisas, particularidades de sua utilização que prolonguem ou afetem a vida útil e desempenho, são discutidas no presente trabalho. Ao final, é realizada uma breve comparação entre as duas técnicas correlatas, GCLs e CCLs, ambas utilizadas como barreiras impermeabilizantes.

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