Effect of Compaction on Soil Physical Properties of Differently Textured Landfill Liner Materials (original) (raw)
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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.
Environmental Earth Sciences, 2012
In current geoenvironmental practice, design engineers usually require that soil liners in waste landfills be compacted within a specified range of water content and dry unit weight. This specification is based primarily on the need to achieve a minimum dry unit weight for factors controlling the performance of compacted soil liners most especially the hydraulic conductivity, k. In this study, lateritic soil treated with up to 10% bentonite, prepared at various compaction states (dry of optimum, optimum and wet of optimum moisture content) was compacted with four compactive efforts (i.e., the reduced British Standard Light, British Standard Light, West African Standard, and British Standard Heavy) to simulate the range of compaction energies expected in the field. Prepared soil mixtures were permeated with water and specimens that yielded the permissible limit of k B 1 9 10-9 m/s were enclosed in an envelope (known as the acceptable zone) on the water content-dry unit weight curve. It was observed that compaction conditions resulting in moisture content slightly wet of optimum led to the lowest values of k and that the shapes and boundaries of the acceptable zones gradually increased in extent, shifting to wet side of optimum moisture content as the bentonite content increased to 10%. This approach provides good control over the quality of compacted soils and has great potential for field application.
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.
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.
Effect of Compaction on Soil Hydraulic Parameters of Vegetative Landfill Covers
Geomaterials, 2012
Parameters of water retention and air capacity are important factors for the evaluation of soil material that will be used for vegetative covers or evapotranspiration (ET) covers of landfills. These values are often measured in the laboratory (usually on disturbed samples), but are also estimated from texture, organic matter content and dry bulk density. The standard basis for the estimation in Germany is the German Soil Classification Handbook (KA5). This estimation implicitly assumes that the data in the KA5 compiled from naturally developed soils are also valid for artificially compacted materials. In the present study, 25 materials were evaluated in the laboratory for the available water capacity, air capacity and permanent wilting point at 85%, 90% and 95% of Proctor density. The data were compared with parameter estimations from the KA5 and the program ROSETTA. Both estimation methods show significant deviations from the measured values; specifically, the change in the available water capacity in compressed samples is not estimated correctly. A possible explanation is a change in pore structure at different compaction levels of build in soil material in comparison with naturally developed soils of different bulk densities.
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.
Laboratory and field testing for utilization of an excavated soil as landfill liner material
Waste Management, 2006
This study investigates the feasibility of using a silty soil excavated in highway construction as landfill liner material. The tests were conducted both at laboratory and in situ scales, and the soil was tested in pure and lime treated forms. Different levels of compaction energy were used. For the field study, a test pad was constructed and in situ hydraulic conductivity experiments were conducted by sealed double ring infiltrometers (SDRI). Laboratory testing revealed that while lime treatment improved the shear strength, it resulted in higher hydraulic conductivity values compared to pure soil. It was observed that leachate permeation did not change the hydraulic conductivity of the pure and lime treated samples. Laboratory hydraulic conductivities were on the order of 10 À9 m/s and met the 1.0E À 08 m/s criterion in the Turkish regulations, which is one order of magnitude higher than the value allowed in most developed countries. SDRI testing, which lasted for 6 mo, indicated that lime treatment increased the hydraulic conductivity of pure soil significantly in the field scale tests. In situ hydraulic conductivities were on the order of 1E À 08 and 1E À 07 m/s, and exceeded the allowable value in the Turkish regulations. Undisturbed samples collected from the test pad were not representative of field hydraulic conductivities. Contrary to laboratory findings, higher compaction efforts did not result in lower hydraulic conductivities in field scales. The study verified the importance of in situ hydraulic conductivity testing in compacted liners.
Volumetric shrinkage of compacted soil liner for sustainable waste landfill
Chemical engineering transactions, 2018
One of the main principal sources that contributes to the release of leachates in the environment is the municipal solid waste in landfill facilities. To mitigate the negative effects of leachate, landfill liner is constructed to provide a protective barrier that will not allow the leachate to pass through the compacted soil, which may cause groundwater contamination. Due to seasonal variation in tropical regions, compacted or natural soil liners tend to lose moisture when dry. This result to volumetric shrinkage, which causes cracks that affect the engineering properties and performance of the soils. Groundwater can easily be affected by leachate permeating through these cracks in soils because of desiccation induced by volume change. This paper aims to evaluate the effect of fines content at various gradation and moulding water content on volumetric shrinkage property of compacted laterite soil; and to compare the results with the regulatory standard for compliance to mitigate the...
Geosciences, 2018
The effects of compaction on soil shrinkage behavior need to be considered for engineering long-term durable mineral liners of landfill capping systems. For this purpose, a new three-dimensional laser scanning device was coupled with a mathematical-empirical model to simultaneously determine the shrinkage behavior of a boulder marl (bm) and a marsh clay (mc). Therefore, both materials were precompacted in 200 soil cores (100 cm 3) on the basis of the Proctor test results with five different degrees of compaction (bm1-bm5; mc1-mc5). Thus, the shrinkage behavior, intensity, and tendency were determined during a standardized drying experiment. The volume shrinkage index was used to describe the pore size dependent shrinkage tendency and was classified as high to very high (11.3-17.7%) for the marsh clay and medium (5.3-9.2%) for the boulder marl. Additionally, only the boulder marl (bm2), compacted up to 88% of Proctor density, could be installed as landfill bottom liner in drier locations if the local matric potentials did not exceed the previously highest observed drying range (i.e. values below −300 hPa), to avoid crack formation and generation.