Volumetric shrinkage of compacted soil liner for sustainable waste landfill (original) (raw)
Related papers
Shrinkage behaviour of landfill clay liner materials in dry zone
Japanese Geotechnical Society Special Publication, 2016
Due to formation of shrinkage cracks in landfill clay liners in dry zone of Sri Lanka leads to infiltration of leachate into ground during the rainy season. Therefore, in this research study, shrinkage behaviour of expansive soil available in dry zone of Sri Lanka, which is used to develop compacted clay liners, were evaluated using laboratory desiccation plate tests. Circular desiccation plates with different thicknesses were used for the experiments. A series of tests have been carried out with unamended soil and soil amended with different percentages of bentonite. Further, shrinkage behaviour was studied by amending oleic acid and coconut coir fibers into the soil. Digital image processing technique has been used to determine the Crack Intensity Factor (CIF). Crack initiation time under different configuration was recorded. Based on visual observations, it can be seen that all samples produce predominantly orthogonal crack patterns leading to sub division of crack area in to smaller cells. Higher desiccation rate was observed for smaller thickness of soil specimen. In addition, higher CIF was recorded for the bentonite amended soil. It was noted that shrinkage cracks can be controlled by amending soil with coconut coir fibers.
2020
The primary objective of hydraulic barriers in containment facilities is to prevent migration of leachate directly into the underlying subsurface during both the active disposal period and the post-closure period. Liner system is, therefore, one of the most important elements of a modern sanitary landfill. In order to achieve an effective soil lining system, a minimum criterion of 30% fines content is required to fulfil the hydraulic conductivity requirement of ≤ 1 × 10-9 m/s as specified by most regulatory agencies and researchers. Studies reveal that at this percentage, laterite soils are vulnerable to leachate permeation, which will contaminate the groundwater. Therefore, this research aims to determine the effects of gradation on engineering properties of laterite soil with respect to hydraulic conductivity, volumetric shrinkage strain, and unconfined compressive strength. In order to satisfy the regulatory requirements of soil liner, tests were carried out on natural soil (30% ...
Compaction Characteristics of a Fine-Grained Soil Potential for Landfill Liner Application
International Journal of GEOMATE, 2020
Increasing population growth and urbanization results in increased demand for waste disposal processes and facilities that can protect public health and the environment. In the Philippines, there is a great demand to construct sanitary landfills (SLF) with only 387 local government units (LGUs) or equivalent to 23.86% compliant to date with Republic Act 9003 which mandates all LGUs to use the sanitary landfill. The compaction characteristics of a locally abundant fine-grained soil at different compaction energy levels were investigated as part of a broader study in the suitability of the soil as a landfill liner material. Compaction is essential in the preparation of a well-compacted soil liner in a sanitary landfill to avoid or minimize the migration of leachate and thereby reduce the risk of groundwater pollution. The physical properties are determined through a series of laboratory tests which covers the grain-size distribution, specific gravity, Atterberg limits, soil classification, XRD and SEM-EDX. Correlations to estimate the compaction characteristics at any rational compaction energy (E) are developed. The maximum dry unit weight values at different compactive efforts were used to determine void ratios which were then utilized to compute for the saturated hydraulic conductivity using numerical model for hydraulic conductivity for the same soil type. The resulting hydraulic conductivity ranges from 2.30 x 10-7 to 1.20 x 10-7 cm/sec well above the required value in the Philippines as per RA 9003 and its IRR for the intended Category I and II SLFs application.
Effect of Compaction on Soil Physical Properties of Differently Textured Landfill Liner Materials
Geosciences, 2018
Mineral landfill liners require legally-fixed standards including a sufficiently-high available water capacity (AWC) and relatively low saturated hydraulic conductivity values (Ks). For testing locally available and potentially suitable materials with respect to these requirements, the soil hydraulic properties of boulder marl (bm) and marsh clay (mc) were investigated considering a defined compaction according to Proctor densities. Both materials were pre-compacted in 20 soil cores (100 cm3) each on the basis of the Proctor test results at five degrees of compaction (bm1–bm5; mc1–mc5) ranging between 1.67–2.07 g/cm3 for bm and 1.09–1.34 g/cm3 for mc. Additionally, unimodal and bimodal models were used to fit the soil water retention curve near saturation and changes in the pore size distribution (PSD). The structural peak of the PSD in the fraction of pore volume between −30 and −60 hPa was more pronounced on the dry side (bm1–2, mc1–2) than on the wet side of the Proctor curve (bm...
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.
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.
Effect of compaction on soil physical properties and some plant growth
1997
Mineral landfill liners require legally-fixed standards including a sufficiently-high available water capacity (AWC) and relatively low saturated hydraulic conductivity values (Ks). For testing locally available and potentially suitable materials with respect to these requirements, the soil hydraulic properties of boulder marl (bm) and marsh clay (mc) were investigated considering a defined compaction according to Proctor densities. Both materials were pre-compacted in 20 soil cores (100 cm 3) each on the basis of the Proctor test results at five degrees of compaction (bm1-bm5; mc1-mc5) ranging between 1.67-2.07 g/cm 3 for bm and 1.09-1.34 g/cm 3 for mc. Additionally, unimodal and bimodal models were used to fit the soil water retention curve near saturation and changes in the pore size distribution (PSD). The structural peak of the PSD in the fraction of pore volume between −30 and −60 hPa was more pronounced on the dry side (bm1-2, mc1-2) than on the wet side of the Proctor curve (bm4-5, mc4-5). Therefore, the loss in structural pores can be attributed to an increasing dry bulk density for bm and an increasing gravimetric moisture content during Proctor test for mc. While the mc fulfils the legal standards with AWC values between 0.244-0.271 cm 3 /cm 3 , the Ks values for bm between 1.6 × 10 −6 m/s and 3.8 × 10 −7 m/s and for mc between 7.4 × 10 −7 m/s and 1.2 × 10 −7 m/s were up to two orders of magnitude higher than required. These results suggest that the suitability of both materials as landfill liner is restricted.
IRJET- Desiccation Potential of Compacted Soils for Landfill Liners
IRJET, 2021
Desiccation is the phenomenon by which moist soil undergoes reduction in volume due to rise in temperature to attain a thermal equilibrium. Reduction in volume induces cracks on the soil surface which further propagates downwards. Crack induced failure of topsoil of various earthen structures is most commonly seen in arid and semi-arid climatic regions. Crack induced failure of earthen structures such as landfill liners and covers, earthen roads, agricultural fields, earthen dams are most commonly found. Desiccation induced cracks formed on the surface encourage the rain water infiltration to higher extents and results in adverse conditions. The phenomenon of desiccation is more likely to be affected by the amount of clay content, moisture content, soil density, foreign matter, rate of change in temperature. During compaction, water is added to soil for lubrication purpose. Compacting soils at optimum moisture content yields maximum dry density. However, this moisture content may result in volumetric shrinkage of soil mass. Hence balancing the right amount of moisture content to satisfy both the maximum density and minimum shrinkage requirement is a critical task in geotechnical engineering applications particularly in Landfill liners. To reduce the shrinkage or desiccation cracks, optimum moisture content was reduced by 5% for locally available soil and volumetric shrinkage was found at 8.1%. Permeability of model clay liner was found at 2.85 x 10-5 cm/s which was considerably higher for landfill liner. To reduce the volumetric shrinkage further, optimum moisture content was reduced by 10% which resulted in shrinkage of 4%. To reduce the permeability, about 6% of bentonite clay was added and tests revealed that liner was almost impermeable.
The paper discusses the effect of municipal solid waste (MSW) leachate on the strength of compacted tropical soil for landfill liner. The leachate was obtained from an open dump site in Bauchi, Bauchi state Nigeria. The Mineralogy and chemical compositions of the soil were determined by means of X-ray Diffraction (XRD) and X-ray fluorescence (XRF) respectively. Tests specimens for unconfined compressive strength (UCS) was compacted at water contents of -2, 0, and +2% relative to the optimum moisture contents derived from three compactive efforts, namely; British Standard Light (BSL), West African Standard (WAS) and British Standard Heavy (BSH). UCS tests were carried out on specimens permeated with MSW leachate for period of 7, 21, 42, 84, and 120 days respectively. Results of the study showed that UCS of the compacted specimens generally decreased with increase in permeating periods for BSH, WAS and BSL compactive efforts respectively. The reduction in strength was due to the increase in clay size particles which lowered the frictional resistance between the solid particles at their contact points. UCS values greater than 200 kN/m2 (minimum required for a material to be used in waste containment applications) where recorded for permeating periods up to 42 days for BSH and 21 days for WAS compactive efforts.
Unsaturated Performance Comparison of Compacted Clay Landfill Liners
Advances in Unsaturated Geotechnics, 2000
rests were conducted to determine the variation in volumetric ,vater content and pore \\ater suction for a variety of compacted clay soils used in the construction of landfill liners. The fit of the experimental data to an existing parametric model was imestigated for two different fitting techniques. The first technique involvcs the use of the rl.?tention curve computer program (RETC) developed for the U.S. EPA. The second technique employs the Solver subroutine included in Microsoft Excel. The parametric models resulting from either technique correlated well to the experimental data, HO\\evcr. the individual curve fit parameters varied significantly. The effect of these variations on the unsaturated behavior of compacted clay liners \\as e\aluatl.?d using the Hydrologic Evaluation of Landfill Performance (HELP) model. The curve fit parameters resulting from both the RETC and the Solver techniques were used as input to the HELP routine for simulation of variably saturated now through a covcr liner. There were no significant differences in the volume of leakage or rate of leakage predicted using the input from the t\,;o curve-fitting techniques. However. there was significant soil-dependent variation in the HELP output. Examination of the HELP output provides information regarding variation in the volumetric water content of the cover liner soil. This information can be used to predict pore water suction variations and susceptibility to desiccation cracking.