Modeling of Settlement in Saturated and Unsaturated Municipal Landfills
Publication: International Journal of Geomechanics
Volume 6, Issue 4
Abstract
Municipal solid waste (MSW) landfills are not only used to dispose the refuse in most economical way but also utilized as a viable land in today’s waste management strategy. Settlement prediction is an important issue in order to guarantee the integrity of any postclosure structure on landfills. In this study, landfill settlement in saturated and unsaturated landfills is investigated by developing a one-dimensional mathematical model and performing numerical experiments. Under the saturated conditions, the landfill is considered to be completely liquid saturated by preventing gas generation at all times. On the other hand, for the unsaturated case, we assume that a gas mixture comprised of methane and carbon dioxide is generated as a result of microbial decomposition of MSW deposited. The gas generation is assumed to follow a first-order kinetic approach. The liquid phase and gas mixture are considered compressible as well as the solid matrix (landfill body). After the governing equations were discretized using the Galerkin finite-element method, the Gaussian elimination technique is employed for a solution. In saturated landfills, the settlement is mainly caused by the overburden weight of the waste deposited. Further, the mass loss due to waste decomposition contributes for an additional settlement in unsaturated landfills. The predicted settlements are within the range reported in the literature. The model developed can simulate porosity, pressures, saturations, and stress profiles in settling landfills as well as to predict the transient and ultimate settlements in saturated and unsaturated landfills.
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References
Barlaz, M. A., Ham, R. K., and Schaefer, D. M. (1990). “Methane production from municipal refuse: A review of enhancement techniques and microbial dynamics.” Crit Rev. Environ. Control, 19(6), 557–584.
Bear, J. (1972). Dynamics of fluids in porous media, Dover, New York.
Brooks, R. N., and Corey, A. T. (1966). “Properties of porous media affecting fluid flow.” J. Irrig. Drain. Div., 92(2), 61–88.
Campbell, G. S. (1974). “A simple method for determining unsaturated conductivity from moisture retention data.” Soil Sci., 117(6), 311–314.
Cossu, R., Andreottola, G., and Muntoni, A. (1996). “Modeling landfill gas production.” Landfilling of waste: Biogas, T. H. Christensen, R. Cossu, and R. Stegmann, eds., E&FN Spon, London, 237–268.
Demirekler, E., Rowe, R. K., and Unlu, K. (1999). “Modeling leachate production from municipal solid waste landfills.” Proc., 7th Int. Waste Management and Landfill Symp., T. H. Christensen, R. Cossu, and R. Stegmann, eds., Environmental Sanitary Engineering Centre (CISA), Cagliari, Italy, 2, 17–24.
DeWalle, F. B., Hammerberg, E., and Chain, E. S. K. (1978). “Gas production from solid waste in landfills.” J. Environ. Eng. Div. (Am. Soc. Civ. Eng.), 104(3), 415–432.
Durmusoglu, E. (2002). “Municipal landfill settlement with refuse decomposition and gas generation.” Ph.D. dissertation, Texas A&M Univ., College Station, Tex.
Edgers, L., Noble, J. J., and Williams, E. (1992). “A biological model for long term settlement in landfills.” Proc., Mediterranean Conf. on Environmental Geotechnology, M. A. Usmen and Y. B. Acar, eds., Balkema, Rotterdam, The Netherlands, 177–184.
Farquhar, G. J., and Rovers, F. A. (1973). “Gas production during refuse decomposition.” Water, Air, Soil Pollut., 2(10), 483–495.
Findikakis, A. N., and Leckie, J. O. (1979). “Numerical simulation of gas flow in sanitary landfills.” J. Environ. Eng. Div. (Am. Soc. Civ. Eng.), 105(5), 927–945.
Hartz, K. E., Klink, R. E., and Ham, R. K. (1982). “Temperature effects: Methane generation from landfill samples.” J. Environ. Eng. Div. (Am. Soc. Civ. Eng.), 108(4), 629–638.
Kaluarachchi, J. J., and Parker, J. C. (1989). “An efficient finite-element method for modeling multiphase flow.” Water Resour. Res., 25(1), 43–54.
Khalili, N., Khabbaz, M. H., and Valliappan, S. (2000). “An effective stress-based numerical model for hydro-mechanical analysis in unsaturated porous media.” Comput. Mech., 26(2), 174–184.
Korfiatis, G. P., Demetracopoulos, A. C., Bourodimos, E. L., and Nawy, E. G. (1984). “Moisture transport in a solid waste column.” J. Environ. Eng., 110(4), 780–796.
Ling, H. I., Leshchinsky, D., Mohri, Y., and Kawabata, T. (1998). “Estimation of municipal solid waste landfill settlement.” J. Geotech. Geoenviron. Eng., 124(1), 21–28.
Loret, B., and Khalili, N. (2000). “A three-phase model for unsaturated soils.” Int. J. Numer. Analyt. Meth. Geomech., 24(11), 893–927.
Loret, B., and Khalili, N. (2002). “An effective stress elastic-plastic model for unsaturated porous media.” Mech. Mater., 34(2), 97–116.
Lu, C., and Bai, H. (1991). “Leaching from solid waste landfills. I: Modeling.” Environ. Technol., 12(7), 545–558.
Micales, L. A., and Skog, K. E. (1997). “The decomposition of forest products in landfills.” Int. Biodeter. Biodegrad., 39(2–3), 145–158.
Narasimhan, T. N., and Witherspoon, P. A. (1977). “Numerical model for saturated-unsaturated flow in deformable porous media. I. Theory.” Water Resour. Res., 13(3), 657–664.
Narasimhan, T. N., and Witherspoon, P. A. (1978). “Numerical model for saturated-unsaturated flow in deformable porous media. III. Applications.” Water Resour. Res., 14(6), 1017–1034.
Ng, A. K. L., and Small, J. C. (2000). “Use of coupled finite analysis in unsaturated soil problems.” Int. J. Numer. Analyt. Meth. Geomech., 24(1), 73–94.
Pacey, J. G. (1997). “Insights to enhanced landfill gas generation.” Proc., 6th Int. Landfill Symp., T. H. Christensen, R. Cossu, and R. Stegmann, eds., Cagliari, Italy, 1, 359–368.
Park, H. I., and Lee, S. R. (1997). “Long-term settlement behavior of landfills with refuse decomposition.” J. Solid Waste Technol. Manage., 24(4), 159–165.
Parker, J. C., Lenhard, R. J., and Kuppusamy, T. (1987). “A parametric model for constitutive properties governing multiphase flow in porous media.” Water Resour. Res., 23(4), 618–624.
Reddy, J. N. (1993). An introduction to the finite-element method, McGraw-Hill, New York.
Rees, J. F. (1980). “The fate of carbon compounds in the landfill disposal of organic matter.” J. Chem. Technol. Biotechnol., 30(4), 161–175.
Reid, R. C., Prausnitz, J. M., and Poling, B. E. (1987). The properties of gases and liquids, McGraw-Hill, New York.
Schrefler, B. A., and Zhan, X. Y. (1993). “A fully coupled model for water flow and airflow in deformable porous media.” Water Resour. Res., 29(1), 155–167.
Schrefler, B. A., Zhan, X., and Simoni, L. (1995). “A coupled model for water flow, air flow and heat flow in deformable porous media.” Int. J. Numer. Methods Heat Fluid Flow, 5, 531–547.
Senior, E., and Balba, M. T. M. (1990). “Refuse decomposition.” Microbiology of Landfill Sites, E. Senior, ed., CRC, Boca Raton, Fla., 17–57.
Sowers, G. F. (1973). “Settlement of waste disposal fills.” Proc., 8th Int. Conf. on Soil Mechanics and Foundations Engineering, Moscow, 2, 207–210.
Stearns, R. P. (1987). “Settlement and gas control: Two key postclosure concerns.” Waste Age, 18(4), 55–60.
Straub, W. A., and Lynch, D. R. (1982). “Models of landfill leaching: Moisture flow and inorganic strength.” J. Environ. Eng. Div. (Am. Soc. Civ. Eng.), 108(2), 231–250.
Suk, H., Lee, K. K., and Lee, C. H. (2000). “Biologically reactive multispecies transport in sanitary landfill.” J. Environ. Eng., 126(5), 419–427.
Tchobanoglous, G., Theisen, H., and Vigil, S. A. (1993). Integrated solid waste management, McGraw-Hill, New York.
Terzaghi, K. (1943). Theoretical soil mechanics, Wiley, New York.
Wall, D. K., and Zeiss, C. (1995). “Municipal landfill biodegradation and settlement.” J. Environ. Eng., 121(3), 214–224.
Yen, B. C., and Scanlon, B. (1975). “Sanitary landfill settlement rates.” J. Geotech. Eng. Div., Am. Soc. Civ. Eng., 101(5), 475–487.
Yildiz, E. D., Unlu, K., and Rowe, R. K. (2004). “Modeling leachate quality and quantity in municipal solid waste landfills.” Waste Manage. Res., 22(2), 78–92.
Zhou, Y., Rajapakse, R. K. N. D., and Graham, J. (1999). “Coupled fields in a deformable unsaturated medium.” Int. J. Solids Struct., 36(31–32), 4841–4868.
Information & Authors
Information
Published In
International Journal of Geomechanics
Volume 6 • Issue 4 • July 2006
Pages: 269 - 278
Copyright
© 2006 ASCE.
History
Received: Jun 15, 2004
Accepted: Jul 18, 2005
Published online: Jul 1, 2006
Published in print: Jul 2006
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