Use of Geosynthetic Clay Liner as a Waterproofing Barrier in Sanitary Landfills (original) (raw)
Related papers
2021
A tremendous increase in the waste is observed specially in metropolitan cities with the increase in population and industrialization. Corresponding to this increase in the produced waste the number of landfill dumping sites are also on an increasing spree in most of the cities. A solution for the development of these dumping sites is provided by geosynthetic clay liners (GCLs) having low hydraulic conductivity and greater structural stability. GCLs are used as a part of liner system to contain the leachate percolation from solid waste management sites. GCLs are made by encapsulating bentonite between geotextiles (either woven or nonwoven), bonded together by needle-punching. Hydraulic conductivity of GCLs is dependent upon the chemical composition of bentonite as well as the chemical composition of leachate. In this study various commercially available GCLs are tested for their hydraulic conductivity for distilled water as well as for synthetically prepared leachates. A flexi wall ...
Characterization of Water Retention Property of Geosynthetic Clay Liner
2016
Geosynthetic clay liner (GCL) is used as hydraulic barrier in municipal solid waste landfill (MSWL) due to the very low hydraulic conductivity of bentonite component of GCL. The GCL is used in MSWL cover liner as an alternative to compacted clay liner. One of main function of the cover liner is to limit the infiltration of rainfall into the MSWL. GCL should be sufficiently hydrated before placement for the effective performance; however, the moisture content of GCL might vary due to the fluctuations in the temperature and rainfall within the landfill area. Hence, the efficiency of the GCL in terms of hydraulic conductivity under varied moisture content need to be established. The performance of GCL under varied moisture condition can be estimated from water retention curve (WRC) of GCL. WRC is a fundamental relationship between suction and its corresponding moisture content. In the present study, total suction of GCL at different moisture content is determined using dew point Potent...
Clay geosynthetic barriers performance in landfill covers
Clay geosynthetic barriers (GBR-Cs) used in landfill covers must ensure lining on the long term. The primary mode of ageing of bentonite GBR-Cs in covers is the coupling of cation exchange and hydrationdesiccation cycles. The objective of this paper is to synthesize the optimal conditions to prevent a loss of performance of GBR-Cs in covers with time, based on a literature review. Various parameters will be discussed. The literature review will put in light the lack of consistent information from study to study. This enforces the need for a list of information to collect in future excavations. Such a list is proposed in the third section of this paper followed by the presentation of results from recent excavations performed by the first author. Formatted Formatted Formatted
Landfill Base Liners: Assessment of Material Equivalency and Impact to Groundwater
Geotechnical and Geological Engineering, 2011
This paper gathered available flow and transport solutions and used them for two composite liners, consisting of geomembrane (GM) overlying either a compacted clay liner (CCL) or a geosynthetic clay liner (GCL). Its aim is to provide a guiding framework for the possible choices of (a) approaches to bottom liner design, (b) respective analytical solutions to flow and transport equations, as well as (c) parameters required for each type of solution. On the basis of the obtained results, the following recommendations are made. When the goal of analysis is to determine material equivalency, leachate flow rate is an adequate key parameter for GM-CCL composite liners. For GM-GCL composite liners, it is necessary to compute contaminant concentration or mass flux, considering (a) transport through defects for inorganic contaminants and (b) diffusion and the contribution of any available attenuation layer for organic contaminants. When the goal of analysis is to assess impact to groundwater, it is advised to calculate both discharge rate and contaminant mass flux regardless of liner type. The critical parameter for the transport calculations is the retardation factor of the contaminant, for the case of CCLs, while the results for GCLs are much less sensitive to this parameter.
Performance of a GCL in a landfill cover after 6 years in service
Six geosynthetic clay liner (GCL) samples were excavated from the cover of a landfill site in the "Nord" Department in France. The objective of this sampling was to analyse if an evolution of the chemical and hydraulic properties of the GCL had occurred after maximum 6 years. This question arised in relation with an important leachate production. The GCL used was a needle punched GCL containing granular sodium activated calcium bentonite, with a minimum mass per unit area equal to 3.5kg/m². Tests performed on the GCL samples consisted in permeability tests according to the French standard NF P 84-705, swell index tests, calcium carbonate content, cation exchange capacity and exchangeable cations determinations. Results obtained on the GCL show a poor hydraulic behaviour in relation with a low confining stress, cation exchange and the presence of cracks in the bentonite. Those results are consistent with previous results from the literature.
International Agrophysics, 2015
A b s t r a c t. This paper presents studies concerning the applicability of two clay materials for the construction of a sustainable landfill liner. The studies consisted in determination of basic characteristics of the materials, eg particle size distribution, bulk density, particle density, total porosity, pore size, mineralogy, specific surface area, nanoparticle size, and Atterberg limits, as well as measurements of their geotechnical and hydraulic parameters, such as in situ saturated hydraulic conductivity, modules of primary and secondary compression, cohesion, and angle of internal friction. Furthermore, the effects of compaction performed by the Proctor method at various water contents on swelling and shrinkage characteristics and saturated hydraulic conductivity were investigated in order to determine the compliance with the national requirements for selection of material for landfill liner construction. The determined characteristics and geotechnical parameters of the tested clay materials allowed qualifying them as suitable for municipal landfill construction. The shrinkage potential of the tested clays observed was rated as moderate to very high. The cyclic drying and rewetting of the clay materials performed resulted in a significant increase in saturated hydraulic conductivity. Thus, the clay sealing layers, as part of a multilayer liner, should be very carefully operated, preventing the drying out of the clay sealing and assuring the possibility of its constant saturation.
The effectiveness of “clay” liners as basal isolation of landfills: a case study
Environmental Earth Sciences, 2005
A sodium bentonite is being used in the basal-isolation of landfills installed on strongly fractured granitic rocks of N Portugal (NW Iberia). To evaluate the performance of this “clay” as the ultimate impermeable basal barrier, a detailed study was carried out of the granite fracture network; the Na-bentonite was tested to characterize its mechanical and geotechnical behavior; geophysical surveys were made to search for landfill leakage and the waters found around the landfill were geochemically characterized. Fractures in the granite are usually open and devoid of mineral infillings or clay materials and, thus, permeability of the granite is very high. Dispersal of contaminants can be further enhanced by the position of the landfill on a high steep-sided ridge. Geophysical and geochemical data show evidence for seepage and dispersion of pollutants, which means that the clay failed as an ultimate isolation barrier against seepage. This investigation shows that this can be due to fracturing of the clay under load and/or to its non-homogeneous saturation and extreme shrinking character upon drying, which are accompanied by the formation of extensive cracking. Observations and experimental results suggest that the use of synthetic “clays” in the safe building of landfill bottom liners needs further research, and extreme care should be taken in preventing that clay water content suffers large variations after saturation, as this process considerably degrades the mechanical behavior and sealing properties of the studied Na-bentonite.
Waste Management & Research, 2012
Compacted clay liners (CCLs) when feasible, are preferred to composite geosynthetic liners. The thickness of CCLs is typically prescribed by each country's environmental protection regulations. However, considering the fact that construction of CCLs represents a significant portion of overall landfill construction costs; a performance based design of liner thickness would be preferable to 'one size fits all' prescriptive standards. In this study researchers analyzed the hydraulic behaviour of a compacted clayey soil in three laboratory pilot scale columns exposed to high strength leachate under simulated landfill conditions. The temperature of the simulated CCL at the surface was maintained at 40 ± 2 °C and a vertical pressure of 250 kPa was applied to the soil through a gravel layer on top of the 50 cm thick CCL where high strength fresh leachate was circulated at heads of 15 and 30 cm simulating the flow over the CCL. Inverse modelling using HYDRUS-1D indicated that the hydraulic conductivity after 180 days was decreased about three orders of magnitude in comparison with the values measured prior to the experiment. A number of scenarios of different leachate heads and persistence time were considered and saturation depth of the CCL was predicted through modelling. Under a typical leachate head of 30 cm, the saturation depth was predicted to be less than 60 cm for a persistence time of 3 years. This approach can be generalized to estimate an effective thickness of a CCL instead of using prescribed values, which may be conservatively overdesigned and thus unduly costly.
The Potential of Marine Clay Used for Landfill Liner: A Geotechnical Study
International Journal of GEOMATE
The increase in excessive solid waste due to the rapid growth of the world's population is considered a severe environmental problem. The landfill leachate will contaminate groundwater, putting all living things at risk. Natural clay is a common liner material used to keep landfill leachate from polluting the environment. This study investigates the geotechnical properties of natural marine clay and its potential to be used as a landfill liner. To investigate the soil properties, the Sungai Besar marine clay (SBMC) was subjected to physico-chemical, morphology and mineralogy properties including particle size distribution, specific gravity, atterberg limits, compaction, permeability, pH, organic content, cation exchange capacity (CEC), specific surface area (SSA), X-Ray Diffraction (XRD) and scanning electron microscope (SEM). Batch Equilibrium Test was conducted to determine the effectiveness of SBMC in adsorbing heavy metals (Pb 2+ , Cu 2+ , Co 2+ , Cd 2+ , Ni 2+ , Zn 2+). Results showed SBMC has a high percentage of fine grain size (silt 73-87% +clay 12-19 %), lower value of specific gravity (2.14-2.29), high liquid limit (79.50-84.00%), plasticity limit (49.18-59.35 %), plasticity index (20.15-34.22 %) and was categorized at very high plasticity in plasticity indexed chart. The SBMC also has maximum dry density value (1.36-1.37 g/cm 3), optimum moisture content, wopt (34.55-37.97 %) and average hydraulic conductivity (6.35 x 10-7-6.88 x 10-7 m/s). The chemical properties of the SBMC1 showed it has a high pH value (6.95-7.42), organic matter (5.31-6.06 %), CEC (91.25-92.32 meq/100g), and SSA value (60.28-62.38 m 2 /g). The XRD results showed that kaolinite, and illite were the most prevalent clay minerals, with quartz as the non-clay mineral. SEM analysis also revealed that kaolinite and microfossils were within the SBMC. The Batch Equilibrium test also showed that SBMC in single solution exhibited higher sorption for Cu (Kd= 0.4499 L/g, R 2 =0.98), followed by Pb (Kd= 0.3701 L/g, R 2 =0.85), Co (Kd= 0.3232 L/g, R 2 = 0. 0.88), Ni (Kd= 0.1483 L/g, R 2 =0.98), Zn (Kd= 0.0711 L/g, R 2 = 0.93) and Cd (Kd= 0.0627 L/g, R 2 = 0.98). Based on physico-chemical, mineralogy and morphology results, SBMC is an excellent choice acting as natural clay-based energy material to be used as an engineered clay liner in a landfill area.