10.2190/JW1M-A901-L1X9-T15F JW1MA901L1X9T15F 3 Mechanisms and Patterns of Leachate Flow in Municipal Solid Waste Landfills 247 270 20020509 20020509 20020509 20020509 JW1MA901L1X9T15F.pdf http://baywood.metapress.com/link.asp?target=contribution&id=JW1MA901L1X9T15F 3 Chris Zeiss Mark Uguccioni University of Alberta Vertical moisture flow through municipal solid waste landfills has been represented primarily as one-dimensional Darcian flow in homogeneous media, though channeling of flow through large pores in the waste has been shown to be an important flow mechanism at high loading rates. Channeling of flow through test cells containing compacted municipal solid waste appears to be a significant flow mechanism even at low infiltration rates (0.17 mm/hr) and after steady-state conditions (infiltration = discharge) have been reached. Practical field capacity is significantly lower at 0.0996 than the HELP model field capacity of 0.294, while the average experimental porosity is identical to the HELP default value (0.52). Experimental unsaturated hydraulic conductivity values are one to two orders of magnitude higher than the HELP default value at field capacity (1.2 × 10^-7 cm/s), however, these values appear to be influenced by the experimental loading rate. In order to better understand the mechanisms and patterns of moisture flow in solid waste, more detailed information on the channels such as nature of flow in the channels and the spatial distribution of the channels is needed. Also, to more accurately represent the physical system, any new leachate generation models should account for both Darcian and channeled flow. C. Zeiss and W. Major, Moisture Flow Through Municipal Solid Waste: Patterns and Characteristics, <i>Journal of Environmental Systems, 22</i>:3, pp. 211-231, 1993. 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. R. Brooks and A. Corey, Properties of Porous Media Affecting Fluid Flow, <i>Journal of the Irrigation and Drainage Division, IR2</i>, ASCE, pp. 61-81, June 1966. G. Campbell, A Simple Method for Determining Unsaturated Hydraulic Conductivity from Moisture Retention Data, <i>Soil Science, 117</i>:6, pp. 311-314, 1974. E. R. Perrier and A. C. Gibson, <i>Hydrologic Simulation on Solid Waste Disposal Sites</i>, EPA-SW-868, U. S. EPA, Cincinnati, Ohio, 1980. J. C. S. Lu, R. D. Morrison, and R. J. Stearns, <i>Leachate Production and Management from Municipal Landfills: Summary and Assessment</i>, Municipal Solid Waste: Land Disposal, proceedings of the Seventh Annual Research Symposium, U. S.-EPA-600/9-81-1323, 1981. K. Beven and P. German, Macropores and Water Flow in Soils, <i>Water Resources Research, 18</i>:5, pp. 1311-1323, 1982. G. P. Korfiatis, A. C. Demetracopoulos, E. L. Bourodimos, and E. G. Nawy, Moisture Transport in a Solid Waste Column, <i>Journal of Environmental Engineering, ASCE, 110</i>:4, pp. 780-796, 1984. A. Bagchi, <i>Design, Construction & Monitoring of Sanitary Landfill</i>, J. Wiley and Sons, New York, 1990. J. Noble and A. Arnold, Experimental and Mathematical Modeling of Moisture Transport in Landfills, <i>Chemical Engineering Communications, 100</i>, pp. 95-111, 1991. G. Blight, J. Ball, and J. Blight, Moisture and Suction in Sanitary Landfills in Semiarid Areas, <i>Journal of Environmental Engineering, ASCI, 118</i>:6, pp. 865-877, 1992. D. Wall and C. Zeiss, Municipal Landfill Biodegradation and Settlement, <i>Journal of Environmental Engineering, ASCE</i>, forthcoming. F. Hasselriis, <i>Refuse-Derived Fuel Processing</i>, Butterworth, Boston, Massachusetts, 1984.