Browsing by Author "Kawamoto, K"

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item: Conference-Full-text
Characterization of geotechnical properties as affected by sediment environment in Kanto lowland clays in Japan
(2013-11-11) Tsuboi, H; Yanase, Y; Hamamoto, S; Kawamoto, K; Takemura, T; Oda, M
The purpose of this study is to investigate effects of sedimentary environment (freshwater and marine deposits) on geotechnical properties for Kanto lowland clays. Freshwater and marine sediments were used to perform standard consolidation tests, undrained triaxial compression tests, and unconfined compression test. Pore-water compositions were also measured for the sediments. As results, higher compression index, higher sensitivity, and lower shear strength ratio were observed for the marine sediments as compared to those for the freshwater sediments. In addition, the measurements of pore-water compositions revealed that the sensitivity values were well related to the proportion of monovalent cations, especially for the sediments with plastic index of less than 30.
item: Conference-Full-text
Characterization of landfill leach ate from municipal solid wastes landfills in Sri Lanka
(2013-11-13) Sewwandi, BGN; Takahiro, K; Kawamoto, K; Hamamoto, S; Asamoto, S; Sato, H
Open dumping of municipal solid waste (MSW) is the most common way of handling solid waste in Sri Lanka due to high cost involved with advanced technologies for landfilling, lack of technical capacity, lack of know-how to manage landfill sites, and so on. Landfill leachate generated from the MSW landfill sites must be treated before dispose into the environment as it creates many social and environmental problems. Characterization of landfill leachate is important to identify the most critical pollutants present in the leachate and thereby to introduce suitable and applicable treatment technologies such as in-situ permeable reactive barrier technologies for contaminant remediation. Therefore, the objective of this research is to characterize landfill leachate collected from several MSW landfills in Sri Lanka. The leachate samples were collected from 12 landfill sites located in Matale, Hambantota, Kataragama, Bandaragama, Kolonnawa, Gampola, Gohagoda, Wennappuwa, Rathnapura, Negombo, Galle, and Matara. For the collected samples, general water quality parameters (pH, EC, DO, ORP, and SS), organic pollutants (BOD5, COD, TOC, IC, TN, TP), typical anions and cations (Cl-, SO42-, NH4+, K+, Mg2+, Ca2+, etc), and heavy metals (Cr, Mn, Fe, Se, Pb, etc) were measured. The results showed that most of the pollutants (F-, Cl-, PO43-, NH4+, Fe, Se, Pb, BOD5, and COD) exceeded the maximum tolerance limits in Sri Lankan Standards. It was found that the BOD5/COD ratio ranged from 0.01 to 0.6 for the most samples and the highest value of 0.6 was observed in the Kolonnawa sample. Measured EC values for all samples were high and varied ranging from 4.5 to 38.3 mS/cm, indicating the biological treatment system alone would not be effective in reducing the pollutants especially for heavy metals. The results of this study will be used in developing site specific remediation technologies in landfill leachate treatment.
item: Conference-Full-text
Compressibility of Japanese landfilled/buried waste samples: measurement of compaction curves and consolidation test for compacted waste samples at different compaction levels
(2013-11-13) Nandika, HLD; Hamamoto, S; Koide, T; Kawamoto, K; Endo, K
Compressibility characteristics of landfilling and buried waste samples are highly heterogeneous, depending on various waste compositions, degree of organic matters, decomposition, and so on. Measured data presented in this paper are the results from laboratory tests for different types of landfilling and buried waste such as incineration ash, industrial waste (plastics, rubbers, etc.) and un-burnable domestic waste (glasses, ceramics, etc.) and buried industrial solid waste fully mixed with soil from an industrial waste landfill at Saitama Prefecture in Japan, respectively. Prior to the compaction and consolidation tests, each sample was dried and the waste composition and particle size distribution were determined. Standard proctor compaction tests were carried out to discuss the compaction properties. For the buried industrial solid waste fully mixed with soil (two sample fractions: < 2 mm and < 9.5 mm) and incineration ash samples, optimized water contents (wopt) which gave the maximum dry bulk densities can be measured similar to typical soil samples. On the other hand, for the industrial and domestic waste samples mainly composed of plastics and glasses, the values of wopt could not be clearly observed and measured dry bulk densities were not controlled by the initial water content of samples. Consolidation tests for compacted samples at different compaction levels were carried out by using a specially designed oedometer in the laboratory. Based on the results from consolidation tests, the compressibility characteristics will be discussed based on the consolidation indices such as compression and consolidation coefficient, and their dependency of waste composition and fraction and surrounding environment (e.g., temperature).
item: Conference-Full-text
Consolidation characracteristics for Sri Lankan and Japanese clays: void index in relation to stress states and sedimentation environment
(2013-11-19) Yanase, Y; Tsuboi, H; Hamamoto, S; Kawamoto, K; Takemura, T; Kurukulasuriya, LC; Oda, M
It is well known that cementation/aging and sedimentation environment affect significantly a compressibility of natural clays. In this study, one-dimensional consolidation curves (e-log p) have been measured using a standard oedometer test for several Sri Lankan and Japanese clays with different sedimentation environment (i.e., freshwater and marine sediments). The void index proposed by Burland (1990) was used to analyze the measured cosnsolidation curves. As a result, void index of marine sediments is higher than that of freshwater sediments and drastically decrease after consolidation yield stress. On the other hand, void index of Sri Lankan clays is quite low and gently narrow as increase consolidation stress. That indicates the Burland’s void index well characterized the effects of sedimentation enviroments on the consolidation characteristics of clays.
item: Conference-Full-text
Detection of benzene in landfill leachate from Gohagoda dumpsite and its removal using municipal solid waste derived biochar
(2016-01-04) Jayawardhana, Y; Kumarathilaka, P; Weerasundara, L; Mowjood, M; Herath, G; Kawamoto, K; Nagamori, M; Vithanage, M
Numerous landfill associated volatile organic compounds (VOCs) are emerging concern due to their potential risk of health. Benzene is one of the most common VOCs in landfill leachate. Biochar has bulged as a universal sorbent for the removal of contaminants from water and soil. Hence, this study examines the potential of biochar derived from municipal solid waste (MSW-BC) on adsorption of benzene so that MSW can be recycled to treat its own pollutants. Landfill leachate was collected from five sampling points at Gohagoda MSW dumpsite and analyzed for benzene. In order to evaluate the potential of MSW-BC for removal of benzene from water, the equilibrium adsorption was procured by using headspace GCMS. The effects of pH, contact time and sorbent (1-10 g/L), sorbate (30-300 μg/L) concentration were investigated using a batch sorption technique. Benzene was detected in landfill leachate, approximately 20 μg/L. The batch experiments indicated that benzene adsorption was dependent solution pH and percentage removal became higher above pH 7 and highest adsorption 42.7 μg/g was observed within 24 hours at pH 9. Maximum saturated sorption capacity of MSW-BC for benzene was 87.0 μg/g. Preliminary experiment data suggest a potential of MSW-BC to be utilized as a material for VOC remediation from MSW dumpsites.
item: Conference-Full-text
Effects of moisture content and shrinkage on soil-thermal properties for peat soils in Japan
(2013-11-19) Hamamoto, S; Dissanayaka, S; Kawamoto, K; Komatsu, T
Wetland is known as a source of atmospheric methane, typically produced by microbiological and chemical processes under anaerobic conditions. Soil temperature in the wetlands is a key factor to control the processes. Peat soils can be found in many types of wetlands. Peat soils contain high organic matter content and thus shows unique physical properties such as high total porosity and shrinkage. This study aims to study the heat transport of peat soils at variably saturated conditions and effects of volume shrinkage on thermal properties of peat soils. Study area of this research is Bibai marsh, Hokkaido in Japan. Undisturbed peat samples were obtained from two different peat profiles at different depths. In general, the thermal conductivity (TC) and the heat capacity (HC) of peat soils linearly increased with increasing volumetric water content, and simple two-phase (solid and water phases) models for TC and HC could generally express TC and HC behaviors, respectively, for most of peat soils. In addition, the observed volume-shrinkage of the peat soils under dry conditions did not affect the TC and HC behaviors for the studied samples.
item: Conference-Full-text
Flux measurements of greenhouse gases from an abandoned open dumping site of solid waste in Sri Lanka
(2013-11-13) Nagamori, M; Koide, T; Wijewardane, NK; Watanabe, Y; Isobe, Y; Mowjood, MIM; Ishigaki, T; Kawamoto, K
The investigation of greenhouse gas emission from a waste dumping site in Sri Lanka was conducted. The investigated site in this study is an abandoned waste dump site located at a hilly river bank in the Central Province of Sri Lanka (N 7º 09', E 80º 35'), consisting of two different sections with waste ages of around 0.5 year (New-section) and 7 years (Old-section). A simplified method for determination of methane gas flux using laser methane detector was considered to be effective to grasp the magnitude of methane flux. It was shown that the points those exhibited high value of methane gas flux also showed low EC-value compared with those of the other surround points. Furthermore, the low hardness of these points indicated that large amount of methane gas flux was caused by high permeability of surface as some stumps had been grown or as boundary between buried waste and ground line had been loosened. Measured fluxes for methane, carbon dioxide, and nitrous oxide in New-section ranged in <0.04-1800, 4.9-1800, and <0.0001-0.35 mL m-2 min-1, respectively. Little amount of methane gas was emitted from surface in Old-section. Relatively high fluxes of nitrous oxide were observed in some plots at middle and bottom for both sections, suggesting that nitrification was stimulated by aerobic condition due to the penetration of air from the slope of dumped waste.
item: Conference-Full-text
Gas and Heat transport in variably-compacted landfill cover at variably-saturated condition
(2013-11-11) Hamamoto, S; Kawamoto, K; Komatsu, T
Understandings of gas and heat transport in the landfill covers are essential for enhancing the landfill site stabilization and reducing the greenhouse and toxic gas emissions. Gas diffusion and thermal conduction are main mechanisms for gas and heat transport in soils. Gas diffusion coefficient and thermal conductivity govern gas diffusion and thermal conduction, respectively. In this study, we developed a unified predictive model for gas diffusion coefficient and thermal conductivity considering soil compaction level. Numerical simulations of gas (methane, carbon dioxide, and oxygen) and heat transport in a landfill cover were performed using the developed predictive model. Increase of compaction level enhanced not only heat transport in the landfill cover but also methane gas emissions due to reduced methane gas oxidation nearby soil surface.
item: Article-Abstract
Gas exchangeable properties of "Maharagama" open dump cover soil
Ranasinghe, RHK; Nawagamuwa, UP; Wickramarachchi, PNK; Kawamoto, K
In Sri Lanka, normal practice is to dump waste in low lands and cover with a good compacted soil without providing gas venting facilities. This can be found at 'Mahargama' dumpsite too. Once municipal solid waste is placed in landfills, complex sequence of biologically, chemically and physically mediated events occur relating to hazardous gaseous and liquid landfill emissions. Hence, cover soil of landfills/ open dumps plays a major role in emission of landfill gases, because gases are released to atmosphere with high pressure, through cover soil. Therefore, studying gas transport parameters of cover soil are of paramount importance in evaluating its future gas emission. Soil gas diffusion coefficient (Dp)and Air Permeability (ka) govern transport and emission of gases through soil. In this study, these parameters were measured in repacked samples at different water matric potentials. Methane concentrations were measured in site and a methane concentration contour map was produced to identify the gas emission from landfill. According to the observed data, the Maharagama cover soil can be expressed as a less gas exchangeable material (but a good capping soil). In the future methane emission can be increased through the loose compacted points and this can become hotspots. Further, formation of cracks around the ground area will also be possible.
item: Article-Abstract
Gas transport parameters for compacted reddish - brown soil in Sri Lankan landfill final cover
Wickramarachchi, P; Ranasinghe, K; Hamamoto, S; Kawamoto, K; Nawagamuwa, UP; Moldrup, P; Komatsu, T
Gas exchange through (he compacted final cover soil at landfill sites plays a vital role for emission, fate, and transport of toxic landfill f,ases. This study involved measuring the soil-gas diffusivity tDp/Du, the ratio of gas diffusion coefficients in soil and free air) and air permeability (k,J for differently compacted soil samples (reddish-brown soil) from the final cover at the Maharagama landfill in Sri Lanka. The samples were prepared by either standard Proctor compaction or hand compaction to dry bulk densities of 1.60-1.94 g cm='. Existing and modified models for predicting Dp/ Do and k" were tested against the measured data. The simple, single-parameter Buckingham model predicted measured Dp/ Do values across compaction levels equally well or better than a dry bulk density (DBD) dependent model and a soilwater retention (SWR) dependent model. The measured ku values for differently compacted samples were highly affected by the compactionlevel and the sample moisture preparation method. Also, for air permeability, a single-parameter Buckingham-type k" model was most accurate in predicting k" in the differently compacted soil samples. Equivalent air-filled pore diameters
item: Conference-Full-text
Heat and gas transport characteristics in differently-decomposed peaty soils at variably-saturated conditions
(2013-11-12) Dissanayaka, SH; Hamamoto, S; Kawamoto, K; Komatsu, T
Knowledge of heat and gas transport properties of the peat soils is important to simulate greenhouse gas behaviour and changes of soil-temperature in the wetlands. In this study, the heat and gas transport properties for differently-decomposed and variably saturated peat soils were measured in order to investigate the general analogies and differences between transport properties of the peat soils. As results, changes in liquid-phase tortuosity under different moisture conditions and volume shrinkage under dry conditions did not significantly affect the thermal conductivity, showing linear increase of thermal conductivity with moisture content. On the other hand, marked effects of soil-water blockage and volume shrinkage on the soil-gas diffusion coefficient under wet and dry conditions, respectively, were observed.
item: Conference-Full-text
Investigation of landfill suitability based on semi quantitative risk matrix and GIS
(2013-11-13) Balasooriya, BMRS; Vithanage, M; Mowjood, MIM; Kawamoto, K; Komai, T; Zhang, M; Herath, GBB; Hara, J
Open dumping is the most widely practiced method in Sri Lanka to dispose municipal solid waste (MSW) because it is the cheapest and easiest method compared to other methods available to manage MSW.Currently, there are no guidelines available for a proper selection of landfill dump site which may minimize the environmental, social and economic problems in the country. Site selection for landfill sites is an important aspect from both environmental conservation and social/economical point of view. Data was collected from the Udapalatha area for analyzing. Considering priority of all criteria in comparison with others, a specific risk rate was decided to each criterion according to their total influence on the whole process of decision making. Suitable landfill site was analyzed by using the Geographic Information System (GIS) together with risk assessment. To identify appropriate landfill areas in the study area, five input map layers including surface water bodies, distance from transportation routes, distance from urban areas, land use/land cover, and elevation were used in the mapping. Based on these data a risk assessment wascarried out with a semi-quantitative matrix. The findings obtained from this study could be used for preliminary information to develop criteria for new landfill site selection. Finally, suitable low-risk regions in the area have been proposed for solid waste landfill disposal.
item: Conference-Full-text
Landfill gases at an abandoned open dump: a case study at Udapalatha/Gampola site in the Central Province of Sri Lanka
(2013-11-13) Koide, T; Nagamori, M; Wijewardane, NK; Watababe, Y; Isobe, Y; Mowjood, MIM; Kawamoto, K
There are very limited studies on landfill gas on uncontrolled open dumps in developing countries. In this study, landfill gas samples at 1 m depth from an abandoned open dump (AOD) in the Central Province of Sri Lanka (N 7º 09', E 80º 35') were collected and the typical landfill gas composition such as O2, N2, CH4, CO2, H2, H2S, and N2O were measured. Buried waste samples at 1 m depth were also taken from the site and organic carbon and nitrogen contents in the residue (< 2 mm) were measured. The samples were taken from some marked plots inside the dump with waste ages of around 0.5 and 7 years (AOD0.5 and AOD7) and outside intact (AODint). Measured CH4 concentration for AOD0.5 and AOD7 ranged in 19–58 % and 0–12 %, respectively, suggesting that the dumped waste at 1 m depth was in the process to be the ‘stabilization phase’ at least 7 years after dumping. This is likely to be a much shorter time period to reach the phase after dumping than those in mid-latitude regions (typically in several decades). The carbon contents in the waste residue in AOD0.5 and AOD7 were 151±67 and 29±7 mg g-1, respectively, implying that high waste decomposition and leaching of organic compounds might have been enhanced due to high temperature and precipitation at the site. A further study for the landfill gas and waste quality in the deeper layer is required to judge whether whole of the dumpsite had reached the stabilization phase rapidly.
item: Conference-Full-text
Locally available expansive soils as a liner material for municipal landfills
(2013-11-13) Wanigarathna, D; Kurukulasuriya, C; Hamamoto, S; Kawamoto, K
The bottom liners in the municipal landfill sites are expected to prevent the migration of pollutants (leachate) to the groundwater. Different types of liner materials are being used in the construction of liners of municipal landfills over the world. Compared to the liner materials such as Geosynthetic Clay Liners (GCL) and High Density Polyethythene (HDPE), Compacted Clay Liners (CCL) are more economical, if materials are locally available. Different types of clay have been experimented for their suitability as liner materials in many countries. An expansive soil however, having a high plasticity index can be expected to absorb more volume of water emanating from the leachate and as a result it can withstand longer dry periods before cracks develop. Further, even if cracks do develop during a prolonged dry period, the cracks may self heal with the subsequent exposure to a rainy period as the shrink-swell behavior of expansive soils is reversible. Therefore, in this study, the suitability of a locally available expansive soils in which the major clay mineral is montmorillonite was investigated for use in landfill liners. For this purpose expansive soils obtained from Digana and Moragahakanda areas of Sri Lanka were chosen as candidate soils. The Rowe Cell apparatus was used to measure the hydraulic conductivity of the consolidated soil sample using de-aired water as the permeant liquid. The results showed that for all the test specimens hydraulic conductivity was less than 1x 10-9 m/s conforming to the requirements of maximum hydraulic conductivity recommended for liner materials. Similar tests were performed on expansive soils obtained from Moragahakanda amended by the addition of 5% bentonite (Sodium Bentonite). Addition of bentonite resulted in a decrease of hydraulic conductivity by a significant amount. Therefore, it can be concluded that subjected to the satisfaction of durability criteria the expansive soils of Digana and Moragahakanda are suitable as liner materials and have the potential to be incorporated into a relatively thin liner by amending with bentonite.
item: Article-Abstract
Measurement of gas transport parameters for final cover soil at Maharagama landfill in Sri Lanka
Wickramarachchi, PN; Ranasinghe, RHK; Nawagamuwa, UP; Kawamoto, K
To make a proper evaluation and better understanding of gas component movement inside a landfill site, investigation of the different parameters related to gas flow is important. In this study, air permeability (ka) and gas diffusivity (DP/Do; where Do is the gas diffusion coefficient in free air) were measured as a function of soil air content (D} in final cover soil at Maharagama landfill in Sri Lanka. The ka and D, were measured at different gravimetric water content in some samples and another set of samples were treated under different pF conditions (pF= log (-'¥) where '¥ is the soil water matric potential in H2O a) and water blockage parameter (.i..) were calculated accordingly.
item: Conference-Full-text
Preliminary solid waste management (SWM) data survey and assessment of town, treatment site and disposal site conditions; case study southern province of Sri Lanka
(2013-11-13) Edirisinghe, DD; Priyankara, NH; Dayanthi, KCN; Alagiyawanna, AMN; Mangalika, L; Ijima, S; Kawamoto, K
In case of southern province of Sri Lanka, Solid Waste Management (SWM) can be an aggravated problem in future with respect to the present development activities in the area. To find a sustainable solution for this problem is very important to aware about present situation of SWM in the province. But there is no SWM data survey has been carried out in the province recently. Therefore under this research work a preliminary SWM data survey has been conducted in all 49 Local Authorities (LA) in Southern province. Research work was basically carried out at LA level since LA is the responsible administration body for solid waste management within its territory. Further town condition, waste treatment and disposal site conditions of each local authority were visited and assessed according to an accepted assessment criteria. Total daily waste collection in the province is 231.65 tons and it is only a 20% of total daily waste generation in the province. Composting is the most adopted waste treatment method in the province as 19 LAs out of 49 have already established composting facilities. Waste disposal is the major problem for most of the LAs as it contributes to create many socio-environmental issues. When consider waste disposal methods in southern province, 29 LAs have adopted open dumping while other LAs are burying. According to the assessment it was found that SWM in 96 percent of LAs is not up the acceptable level. The findings and results of the study have been presented in this research paper in detail.
item: Conference-Full-text
Solid waste generation, characteristics and management within the households in Sri Lankan urban areas
(2013-11-13) Wijerathna, DMCB; Lee, K; Koide, T; Jinadasa, KBSN; Kawamoto, K; Iijima, S; Herath, GBB; Kalpage, CS; Mangalika, L
Municipal Solid Wastes are becoming a multidimensional threat to the Sri Lankan environment. Especially the solutions are needed to reduce the amount of the environmental problem caused by haphazard solid wastes disposal done by the local governments and the public Even though the country’s Solid Waste Management (SWM) strategy is aimed to reduce the amount of final disposal by introducing reuse trends, proper collection methods, source segregation and improved recovery of recyclables still needed to be established. But there should be the knowledge of the amount of waste generation and their composition to guide for the appropriate solutions which the methods can be implemented. Solid Wastes generation from the urban households would cause many problems than in the rural. The consumption rates and the patterns are different from each High, Middle and Low income levels in the urban areas and as well as from the urban areas to the rural areas, so that the waste generation pattern also different from each other. This study discusses the consumption of consumer goods and the solid wastes generation at Gampola UC area, Sri Lanka. Data were obtained through a Waste Amount and Composition Survey which was done throughout 7 consecutive days of a particular week in August, 2012 with consideration of different income levels of the households and a Non-Collection area from the UC limits. Household wastes consisted of kitchen wastes, garden wastes, paper & cardboard, plastics, textiles, rubber & leather, metal, glass, ceramics, hazardous wastes and E- wastes, the proportion of each waste was approximately 61.5%, 8.92%, 3.02%, 3.25%, 0.71%, 0.25%, 0.58%, 0.97%, 0.04%, 0.23% and 1.26%, respectively. The waste generation rates for High, Middle, Low levels and Non-Collection areas are respectively 0.44, 0.31, 0.27 and 0.55 kg/pers/day. It has indicated that there is a relationship between the household income and the total waste generation.
item: Conference-Full-text
Spatial variation in landfill gas composition under different precipitation condition and waste age in Sri Lanka
(2013-11-13) Koide, T; Nagamori, M; Watanabe, Y; Isobe, Y; Wijewardane, NK; Herath, GBB; Mowjood, MIM; Kawamoto, K
A study was conducted to assess the effect of precipitation and age of waste on the stabilization of the dumped waste. Landfill gas samples at 1-m depth were collected from 13 waste landfill sites in Sri Lanka with different annual precipitation ranging from 1,000 to 4,000 mm and waste age ranging from 1 to 120 months. Typical landfill gases O2, N2, CH4 and CO2 were measured quantitatively by a gas chromatograph. Buried waste samples at 1-m depth were also taken from all locations to determine organic carbon contents in the residue (< 2 mm). With the age of wastes, the measured O2 and N2 concentration (ranged in 1 - 20% and 2 - 80% respectively) in collected landfill gas samples were increased and the CH4 and CO2 concentration (ranged in 0-60% and 1-68%, respectively) decreased, implying the buried wastes are getting stabilized within 120 months after dumped (typically in several decades in mid-latitude regions). However, the correlations between measured gas concentrations and the annual precipitations at the sampling site show no definite results. Organic carbon contents in the waste residues (ranged in 24-236 mg g-1) were not fully related to the waste age and the precipitation amount, while significant time-dependent decreases of the organic carbon contents can be observed in some investigated landfill sites. Further studies are needed with continuous monitoring of rainfall with gas emission.
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Study on gas transport and water retention In landfill cover solI : a Sri Lankan case study
Ranasinghe, RHK; Nawagamuwa, UP; Wickramarachchi, PN; Kawamoto, K; Komatsu, T
In Sri Lanka, engineered landfills are not usually available and the common procedure is to cover the waste with a good cover soil without providing gas venting facilities. Hazardous gaseous and liquid landfill emissions are major problems of landfills. Hence cover soil of the landfill plays a major role in emission of landfill gases, because once the solid waste is covered with soil these gases are released to atmosphere with high pressure, through this cover soil. Therefore, studying the cover soil parameters are paramount importance in evaluating its future gas diffusion. The Soil gas diffusion coefficient (Dp) and permeability (ka) govern the transport and emission gases in the unsaturated zone. In this study, "V>ll'I'.0'" diffusivity (DplDo, Do is gas diffusion coefficient in free air) and k, was measured for the soil ofMaharagama landifill final cover soil at different soil water matric potentials
item: Conference-Extended-Abstract
Study on gas transport and water retention in maharagama land fill cover soil
(2009) Ranasinghe, RHK; Nawagamuwa, UP; Kawamoto, K
In Sri Lanka there are few controlled landfills available and usual procedure is covering the waste layer with a good toil as a final cover. The Soil gas diffusion coefficient (Dp) and Air Permeability (Kcl) govern the transport and mission of gases in unsaturated zone. In this study, Dp and Ka in soil which was used to construct Maharagama yandfdl site cover filling at different soil water matric potential were measured. With the soil air content, it is found hat, Dp monotonically increases and Ka gradually increases.