Long term performance efficiency of MLCS under climatic condition

Long term performance efficiency of MLCS under climatic condition Submitted toDr. Sreedeep S.Associate prof.IIT Guwahati Submitted by Krishan Dev 154104040M.Tech

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Acknowledgement Dr. Sreedeep S.Associate prof.IIT Guwahati

Janarul shaikh P.hd Scholar IIT guwahati

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3Contents

Basics of Landfill coverBasics of Climate changeLiterature ReviewNumerical modelling in HYDRUSExperimental lab modelConclusions Future scope OutcomeReferences

to separate waste from environmentto maximize runoffto give suitable surface for vegetation aesthetic view.

Function of landfill cover Landfill Cover ? design criteria ?Design conditions ?Local climate Soil type Regulations

intrusionRoot penetrationErosioncloggingSeismic eventsbiological processes short-duration severe storm Freeze/thawdesiccation

Components of cover 4

Cover is nothing but it is a cap or engineered containment which separate the environment and the various wastste 4

To minimize Percolationharmful leachate migration of contaminantspollution of the groundwaterblowing of litter or dust emission of landfill gaspotential for fire hazard

Objectives of landfill cover

(Koerner & Daniel, 1997) (US EPA, 1991)

(US DOE, 2000)5

......Literature review......

Field monitoring of Cover SystemMellies & Gurtung (2004) Field tests in large lysimeterDrainage geo-composite and the Ca-GCL proved to be performance effective elements within cover system.Melchoir et al. (2010) Large-scale lysimeter(Tensiometers, neutron probes and TDR Sensors)Evapotranspiration can be increased significantly by planting busheslimited the potential leakage through barrier layers.Mellies & Schweizer(2011) Large-scale lysimeter(FDR probes; Delta Devices)K of CCL or GCL may increase substantially, if there is no long-lasting protection against desiccation (thick soil cover or a GM)

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Cover System under climate change Chang et al. (1999) HELPUntil 100 years the infiltration flux for cover design was negligible even under doubling of the precipitation Considering degradation after 100 years, the infiltration flux significantly increased to the design criteria.Khire et al. (2000) UNSAT-HSimulations indicated that thickness and hydraulic properties of the surface layer significantly affect the WB of capillary barriers.

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Numerical Modeling Considering Different Climatic ConditionsChang et al. (1999) Water balance methodUntil 100 years the infiltration flux for cover design was negligible even under doubling of the precipitation Considering degradation after 100 years, the infiltration flux significantly increased to the design criteria.Khire et al. (1997) HELP and UNSAT-H Captured seasonal variations in overland flow, evapotranspiration, soil water storage, and percolation. Percolation is slightly over predicted by HELP and under predicted by UNSAT-H.Luellen & Brydges (2005) HELP Model and Leakage Equations Observed uncertainties about the effects of degradation mechanisms on long-term cap performance.

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Climate change Reason consequences effect on cover Energy from sun Absorption ReflectionTilt of earth Orbital shape of earthGreen house gasesVolcanic eruptionEarths rotationfeedback

Change in rainfallFlood Heat wavesDroughtChange in marine Temperature

Desiccation Unwanted plantErosion PermeabilityFreeze/thaw

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Long term monitoring of weather like weather of a month year century.9

Numerical Modelling in Hydrus (2D/3D)

Data Input SimulationData Output

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Useful SWCC Model

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Concept of Water Balance

Percolation starts if S > ScS = soil water storageSc =soil water storage capacity

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Water balance is framework for simplifying, describing & quantifying the hydrological budget of water, which is specific to an area and time interval. 12

Flow of Water in Porous Soil MediaSaturated Soil MediaDarcy, 185613

Flow of Water in Porous Soil MediaUnsaturated Soil MediaRichards , 193114

Properties RSBBSSRBSpecific Gravity (G)2.632.882.682.70Hygroscopic Water Content (%)5.4511.672.547.32Grain Size Distribution (%)Gravel ( > 4.75 mm)0.16NANA0.12Coarse sand (2.00 mm 4.75 mm)22.00NA2015.4Medium sand (0.425 mm 2.00 mm)33.64NA4223.53Fine sand (0.075 mm 0.425 mm)28.044.43820.85Silt (0.002 mm 0.075 mm)9.8338.77NA18.51Clay ( < 0.002mm)6.4956.83NA21.59Liquid limit (%)40.50295NA115Plastic limit (%)22.6040NA27Shrinkage limit (%)20.7710.5NA17Plasticity Index (%)17.9255NA88Classification MLCHSPMLSpecific Surface Area (m2/gm)55348NA142Optimum Moisture Content (%)17381923Maximum Dry Density (g/cm3)1.731.261.771.6Saturated Hydraulic Conductivity (m/s)2.9E-82.3E-124.23E-62.7E-9Linear Shrinkage (%)1.833.22NA2.25Free Swell Index (%)10686NA212Organic Content (%)0.480.22NA0.40Cation Exchange Capacity (meq/100gm)1048NA21

Basic Characterization of the Materials Used in the Study

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Layer HomoDimensionThickness (m)1.150Length (m)1.5Width (m)0.5MaterialRS% of Sand83.7% of Silt9.8% of Clay6.5Predicted v Genuchtens Parameters0.040.40.17047n1.30770.250I0.50.40.40.170470.2500.305

NUMERICAL

MODELlING17

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19RESULTsVariation of VWC With depthVariation of suction with depth

20Variation of VWC and suction with time

Layer PLDLBLDimensionThickness (m)0.4500.3000.400Length (m)0.30.30.3Width (m)0.30.30.3MaterialRSSSRB% of Sand83.710059.7% of Silt9.8018.5% of Clay6.5021.6Predicted v Genuchtens Parameters0.040.020.070.40.360.4650.170470.839560.01195n1.30771.686091.294460.250365.4720.00173I0.50.50.50.40.360.4650.40.360.4650.170470.839560.011950.250365.4720.001730.3050.070.36

Numerical Modelling

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23Variation of VWC with depthVariation of suction with depthRESULTs

24RESULTsNUMERICAL EXPERIMENTAL

25RESULTsNUMERICAL EXPERIMENTAL

26CONCLUSIONSsame trend as VWC increases suction decreases.

Suction and VWC Fluctuating is lesser at the lower part. After a certain depth effect of climate become invisible and they become constant. At all the nodal point suction and VWC varies between two extreme values and corresponding suction which is input by user as material properties. The extreme value of VWC and suction depends upon the soil profile, its particle arrangement and texture. That is why they differ layer to layer.Results of the model depend upon the fitted parameters of SWCC, initial wetting and drying curve and hysteresis.

During the rainfall season the permeability ,water content and percolation tends toward the saturation value in upper zone as well as in the lower zone of cover therefore it is in critical condition during these periods

27CONCLUSIONSVariation in lab cylindrical model and numerical model is may be because of mixing, handling, not uniform initial pressure condition, leakage of water along periphery. Not fully saturation in real model shows air entrapment.

Outcome from the study can be used to......

develop the proper design guidelines and performance monitoring system for MLC suitable for Indian tropical Climate.

understand factors affecting suitable design and performance efficacy of different soil cover by the impact of the climate change.

study the suitable configuration and material of each component layer of the multi layer cover (MLC) for its longer sustenance against adverse future climatic conditions.

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FUTURE SCOPESNumerical modelling with catastrophic rainfall events to access the worst condition in future.Numerical modelling by considering the degradation phenomena.Numerical modelling with erosion.Prediction next 100 year climatic data using GCM model.Comparison of the results obtained in numerical studies with field monitoring. Probabilistic sensitivity of different evaporation method on cover design. Validation of the work with using another code VADOSE/W.

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Bashir, R., Sharma, J., and Stefaniak, H., (2015). Effect of hysteresis of soil-water characteristic curves on infiltration under different climatic conditions. Can. Geotech. J.52 : 112 (2015) dx.doi.org/10.1139/cgj-2015-0004Khire, M.V., Benson, C.H., and Bosscher, P.J., (2000). Capillary barriers: design variables and water balance, Journal of Geotechnical and Geoenvironmental Engineering, Vol. 126, No. 8,695-708.Benson, C.H., Albright, W.H., Roesler, A.C., and Abichou, T. (2002). Evaluation of final cover performance: field data from the Alternative Cover Assessment Program (ACAP) , Wm 02 Conference, February 24-28, 2002, Tucson, Az.Khire, M.V., Benson, C.H., and Bosscher, P.J.,(1997). Water balance modeling of earthen final covers Journal of Geotechnical and Geoenvironmental Engineering, Vol. 123, No.8, August, 1997Mellies, U.H., and Gartung, E.,(2004). Long-term observation of alternative landfill capping systems field tests on a landfill in Bavaria. Land Contamination & Reclamation, 12 (1), 2004 2004 EPP Publications LtdLuellen, J.R., and Jason M. Brydges, J.M.,(2005). Long-term hydraulic performance evaluation for a multilayer closure cap. Practice Periodical of Hazardous, Toxic, and Radioactive Waste Management, Vol. 9, No. 4, October 1, 2005Melchior, S.,Sokollek, V., Berger, K., Vielhaber, B., and Steinert, B.,(2010). Results from 18 Years of In Situ Performance Testing of Landfill Cover Systems in Germany Journal of Environmental Engineering, Vol. 136, No. 8, August 1, 2010Mellies, W.U.H., and Schweizer, A.,(2011). Long-term performance of landfill covers results of lysimeter test fields in Bavaria (Germany). Waste Management & Research 29(1) 5968Chang, K., Park, J.W., Yoon, J.H., Choi, H.J., and Kim, C.L., (2000). Water Balance Evaluation of Final Closer Cover for Near Surface Radio Active Disposal Facility. Journal Of Korean Nuclear Society, Vol. 32, No.3,Pp. 274-282, June 2000

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31THANK YOU !