Nobutoshi Tanaka* and Toshihiko Matsuo*

*Department of Environmental and Sanitary Engineering, Faculty of Engineering, Hokkaido University

+ Correspondence should be addressed to Nobutoshi Tanaka:
Faculty of Engineering, Hokkaido University
(8, Nishi, Kita13jyo, Kita-ku, Sapporo-city, Hokkaido 060 Japan)

Abstract

Unsaturated water flow is a fundamental problem to elucidate transport phenomena in sanitary landfill layers, but few studies on it have been done. It is expected that the theory of unsaturated water flow in soil layers can be also applied to solid waste layers. First, parameters such as suction head and unsaturated hydraulic conductivity were determined as a function of volumetric water content, for an incineration residue and an artificial refuse. A medium sand was used as a control. Secondly, using the same layers, many data of outflow rate were observed for several experiments of step-like starts of precipitation, stoppage of precipitation, and random pulse-like precipitations. Based on these experiments, the characteristics of unsaturated water flow in solid waste layers was discussed. In addition, it is shown that the above-determined parameters, and the theory of unsaturated soil layers, that is Richards' Eq., can simulate these observed outflow rate patterns with comparatively good coincidence; they can be applied to solid waste layers, using a time scale of a number of days.

Key words: sanitary landfill layer, unsaturated water flow, unsaturated hydraulic conductivity, incineration residue, artificial refuse