10.2190/KBUD-RFHT-JYHP-A35E KBUDRFHTJYHPA35E 2 Moisture Flow through Municipal Solid Waste: Patterns and Characteristics 211 231 20020509 20020509 20020509 20020509 KBUDRFHTJYHPA35E.pdf http://baywood.metapress.com/link.asp?target=contribution&id=KBUDRFHTJYHPA35E 3 Chris Zeiss Wade Major University of Alberta, Edmonton Vertical moisture flow through compacted municipal waste layers is more complex than the one-dimensional, uniform Darcian drainage flow through a constant homogeneous medium as modeled in HELP. Channeling and flow along wetting curves produce irregular and more rapid breakthrough times and leakage rates. Tests of compacted municipal waste show distinct channeled flow in two to three streams in cylindrical cells. Furthermore, practical field capacity is substantially lower at 0.136 than the HELP default value of 0.292. Porosity, while similar to the default value of 0.52, varies with compaction ratio from 0.58 to 0.47. As a result, practical unsaturated hydraulic conductivities are 10⁴ to 10⁵ higher at 1.2 · 10^-3 to 1.7 · 10^-2 cm/s than the HELP default of 1.2 · 10^-7 cm/s. As a result, waste default values should be revised in current models, while new leachate generation models need to account for channeled flow. P. Schroeder, R. Peyton, B. McEnroe, and J. Sjostrom, <i>The Hydrologic Evaluation of Landfill Performance (HELP) Model</i>, Office of Solid Waste and Emergency Response, USEPA, Washington, D. C., 1988. G. Campbell, A Simple Method for Determining Unsaturated Conductivity from Moisture Retention Data, <i>Soil Science, 117</i>:6, pp. 311-314, June 1974. R. Brooks and A. Corey, Properties of Porous Media Affecting Fluid Flow, <i>Journal of the Irrigation and Drainage Division, IR2</i>, pp. 61-88, June 1966. A. Bagchi, <i>Design, Construction & Monitoring of Sanitary Landfill</i>, Wiley and Sons, New York, 1990. J. Noble and G. Nair, <i>The Effect of Capillarity on Moisture Profiles in Landfills</i>, 44th Purdue Industrial Waste Conference Proceedings, Lewis, Chelsea, Michigan, pp. 545-554, 1990. J. Noble and A. Arnold, Experimental and Mathematical Modeling of Moisture Transport in Landfills, <i>Chemical Engineering Communications, 1991, 100</i>, pp. 95-111, 1991. D. Wall and C. Zeiss, <i>Municipal Landfill Biodegradation and Settlement</i>, ASCE-Journal of Environmental Engineering (forthcoming). F. Hasselriis, Refuse-Derived Fuel Processing, Butterworth, Boston, Massachusetts, 1984. G. Blight, J. Ball, and J. Blight, Moisture and Suction in Sanitary Landfills in Semiarid Areas, <i>Journal of Environmental Engineering, 118</i>:6, pp. 865-877, November/December 1992. C. Palmer and R. Johnson, <i>Transport and Fate of Contaminants in the Subsurface, Chapter 2, Physical Processes</i>, Center for Environmental Research Information, Cincinnati, EPA/625/4-89/019,148 pp., September 1989. G. Tchobanoglous, H. Theisen, and S. Vigil, <i>Integrated Solid Waste Management</i>, McGraw Hill, New York, 1992. W. Rawls and D. Brakensiek, Estimating Soil Water Retention from Soil Properties, <i>Journal of the Irrigation and Drainage Division, 108</i>, IR2, pp. 166-171, June 1982. A. Freeze and J. Cherry, <i>Groundwater</i>, Prentice Hall, Englewood Cliffs, New Jersey, 1979. I. Oweis and R. Khera, <i>Criteria for Geotechnical Construction of Sanitary Landfills</i>, International Symposium on Environmental Geotechnology, <i>I</i>, H.-Y. Fang (ed.), Envo, 1986. I. Oweis, D. Smith, R. Ellwood, and D. Greene, Hydraulic Characteristics of Municipal Refuse, <i>Journal of Geotechnology Engineering, 116</i>:4, pp. 539-553, April 1990. T. McGhee, <i>Water Supply and Sewerage</i> (sixth Edition), McGraw Hill, New York, 1991.