Namhoon Lee*, Tetsuya Kusuda**, Takayuki Shimaoka*** and Masataka Hanashima***

*Div. of Engineering, Graduate School, Kyushu University
**Dept. of Civil Engineering Hydraulics and Soil Mechanics, Kyushu University
***Dept. of Civil Engineering, Fukuoka University

+ Correspondence should be addressed to Masataka Hanashima:
Dept. of Civil Engineering, Fukuoka University
(8-19-1, Nanakuma, Jonan-ku, Fukuoka 814-01 Japan)

Abstract

Chlorine transport as conservative matter through unsaturated solid waste landfills was analyzed by experimental work using four large scale simulated lysimeters; a mathematical model on this was formulated and the experimental results were used to calibrate and verify it. The hydraulic properties for moisture flow, and the parameters for solute transport, were determined from additional small scale experiments. Simulated leachate discharge rate in a moisture flow model, which assumed that unsaturated hydraulic conductivity is dependent on the volume fraction of mobile phase in liquid phase, showed reasonable agreement with the observed one. It was also shown that a Modified Two Phase Flow Model, incoporating hydraulic dispersion of solute in mobile phase, as well as solute exchange occurring between mobile and stagnant phases in the liquid phase, could express solute transport through a solid waste layer successfully. Results from the simulation of chlorine transport through a solid waste layer show that the exchange term has a similar function to the leaching term, working between dissoluble phase and mobile phase.

Key words: solid waste landfills, unsaturated moisture flow, solute transport, conservative matter, numerical model