• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.495-504
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• 2000

This study discussed the optimal use of bentonite and cement for the compacted soil liner of landfill. Techniques employed in this optimization included permeability(by KSF 2322) and compressive strength(by KSF 2314). The optimal amount of these materials to the compacted soil liner was determined in accordance with a regulatory guideline of the government: that is, $k=1{\times}10^{-7}cm/sec$. The testing sods were CL(Clayey Soil) and SM(Sandy Soil), which were classified according to LSCS(Unifed Soil Classify System), The results showed that the optimal amounts of bentonite and cement to mix with the compacted CL soil liner were 5% of bentonite and 5% of cement : namely, $k=9.98{\times}10^{-8}cm/sec$ and ${\sigma}_{28}=1275kg/cm^2$. For the compacted SM soil liner. the optimal amount of bentonite was 15%, in conjunction with 5% of cement : namely, $k=9.86{\times}10^{-8}cm/sec$ and ${\sigma}_{28}=18.72kg/cm^2$. It was concluded that the compacted CL or SM soil liner, with containing the optimal amounts of bentonite and cement showed the acceptable permeability and the compressive strength, referring to a regulatory guideline of the government for construction of the landfill.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1315-1323
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• 2010

This paper deals with a case study on a unique slope failure in a liner system of a municipal solid waste containment facility during construction because the sliding interface is not the geomembrane/compacted low permeability soil liner (LPSL) but a soil/soil interface within the LPSL. From the case study, it is concluded that compaction of the LPSL should ensure that each lift is kneaded into the lower lift so a weak interface is not created in the LPSL, and the LPSL moisture content should be controlled so it does not exceed the specified value, .e.g., 3% - 4% wet of optimum, because it can lead to a weak interface in the LPSL. In addition, drainage materials should be placed over the geomembrane from the slope toe to the top to reduce the shear stresses applied to the weakest interface, and equipment should not move laterally across the slope if it is unsupported but along the slope while placing the cover soil from bottom to top.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.497-504
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• 1999

This study presents the physical and engineering characteristics of soil-bentonite admixed liner in I landfill. Main focus was the hydraulic conductivity of compacted soil-bentonite admixed and mechanisms governing low permeable properties of the admixed liner. Laboratory and field tests such as compaction, hydraulic conductivity, density, water content for the soil-bentonite admixed liner were carried out. Quality control criteria for the best construction of the soil-bentonite admixed liner was suggested through laboratory and field test results.

• Environmental Engineering Research
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• v.7 no.3
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• pp.121-127
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• 2002

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1997.05a
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• pp.47-52
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• 1997

The experimental investigations considered in this paper are similar in many respects to those of Lee$^1$, with some key differences. First, there is no layering of the soils in a heterogeneous liner. The only soil investigated is the clay component of the cover liner. This ensures that the clay is exposed to freezing and that frost propagation in the clay can be investigated separate from other processes. Second, a closed system approach to the simulation was adopted. According to Jones$^2$, closed-system freezing occurs when there is no source of water available beyond that originally present in the soil voids. Freezing under such conditions results in very thin or non-existent ice lenses. One of tile objectives of the experiments described in this paper was the moisture migration and the changing of moisture contents of the compacted clay liner in landfill. The closed-system was used to limit tile variables in the experimental simulation to make these calculations more direct, although the final results could be applied to an open system also. As a result, the moisture content decreased about 45%-46% after two freeze/thaw cycles.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.621-628
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• 2003

To prevent the percolation of leachate through the bottom of waste landfills, the liner system of various layers, such as compacted clay, geomembrane, geonet, geotextiles, and geocomposite is designed. Since the friction angle between a geomembrane and other geosynthetics is usually lower than that of the soil alone, the interfaces between soil and geosynthetic or geosynthetic-geosynthetic may become a possible plane of weakness, which leads to potential instability of the system under load of waste at side slopes. In this study, large triaxial tests are carried out with samples of remoulded wastes and direct shear interface friction tests are carried out to understand the frictional properties of geosynthetic-geosynthetic interfaces, which are required for analyzing the safety of side-slope liner systems.

• Journal of the Korean Geosynthetics Society
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• v.7 no.2
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• pp.49-52
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• 2008

Most of waste sludge has generally been disposed in landfill site or dumped in the ocean, which will be banned by the content of its heavy metals according to London Dumping Convention in Korea. Therefore, environmentally friend methods are urgently required for the treatment and disposal of the sewage sludge. Thermal hydrolysis is one of the good treatment methods to solve the sludge problems. In this study, the physical and environmental testing was conducted to evaluate the feasibility of by-product cake from the thermal hydrolysis as liner or cover materials in landfill.

• Journal of Soil and Groundwater Environment
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• v.9 no.2
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• pp.48-53
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• 2004

This study is objected to estimate the variation of the coefficient of leachate according to designs in landfill cover systems. Design (a) is the unsanitary landfill cover system with 50 cm soil. But Design (b), (c) are sanitary cover systems which are composed of soil top layer, drainage layer, barrier liner(Design (b): Geomembrane(1.5 mm) and compacted clay liner(30 cm), Design (c) compacted clay liner(45 cm)), gas venting layer. Quantity of leachate estimates Rational Method generally and depend on the coefficient of leachate, on one of the factors in Rational Method largely. The coefficient of leachate is defined as the leachate production ratio result from incident precipitation. To estimate the variation of the coefficient of leachate, the authors use HELP(Hydrologic Evaluation of Landfill Performance) Simulation and Pilot Test. As a result of HELP Simulation, the coefficient of leachate is 0.36∼0.42 in Design (a) and 0.03∼0.15 in Design (b), (c) according to designs in landfill cover systems and quality of barrier liner placement. These numerical values are similar to 0.13 with the coefficient of leachate in Pilot Test.

• Journal of the Korean Geotechnical Society
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• v.23 no.8
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• pp.97-106
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• 2007

In this study, experiments are conducted to find out the effect of waste leachate on landfill clay liner system. Tensile test, hydrometer analysis and crack pattern test were conducted on sand-bentonite mixtures with different pH values of water. The tensile strength of specimen compacted with pH 9 of water is smaller than that of specimen compacted with for pH 3 and 6 of water. That is, the higher the pH value, the smaller the tensile strength, because a higher pH solution decreases flocculation phenomenon. The percent finer also increased with high pH value in particle size distribution of fine grained soil (<0.075 mm), because the velocity of particles settling decreases. This trend becomes the clearer as the content of bentonite, becomes the larger, because the higher pH value decreases flocculation structure of fine soils. The results of the crack pattern tests also showed the effect of pH values of water.

• Journal of the Korean Geotechnical Society
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• v.15 no.2
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• pp.43-71
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• 1999

This research is an experimental work of developing a construction material using municipal wastewater sludge as liner and cover materials for waste disposal landfill. Weathered granite soil and flyash, produced as a by-product in the power plant, were used as the primary additives to improve geotechnical engineering properties of sludge. For secondary additives, bentonite and cement were mixed with sludge to decrease the permeability and to increase the shear strength, respectively. Various laboratory test required to evaluate the design criteria for liner and cover materials, were carried out by changing the mixing ratio of sludge with the additives. Basic soil properties such as specific gravity, grain size distribution, liquid and plastic limits were measured to analyze their effects on permeability, compaction, compressibility and shear strength properties of mixtures. Laboratory compaction tests were conducted to find the maximum dry densities and the optimum moisture contents of mixtures, and their effectiveness of compaction in field was consequently evaluated. Permeability tests of variable heads with compacted samples, and the stress-controlled consolidation tests with measuring permeabilities of samples during consolidation process were performed to obtain permeability, and to find the compressibility as well as consolidational coefficients of mixtures, respectively. To evaluate the long term stability of sludges, creep tests were also conducted in parallel with permeability tests of variable heads. On the other hand, for the compacted sludge decomposed for a month, permeability tests were carried out to investigate the effect of decomposition of organic matters in sludges on its permeability. Direct shear tests were performed to evaluate the shear strength parameters of mixed sludge with weathered granite, flyash and bentonite. For the mixture of sludge with cement, unconfined compression tests were carried out to find their strength with varying mixing ratio and curing time. On the other hand, CBR tests for compacted specimen were also conducted to evaluate the trafficability of mixtures. Various test results with mixtures were assessed to evaluate whether their properties meet the requirements as liner and cover materials in waste disposal landfill.