【Paper】
Effectiveness of Daily Cover Soil on Solid Waste Landfill Stabilization
Naoko Hori*, Takayuki Shimaoka**, Kentaro Miyawaki**
Syogo Sakita** and Masataka Hanashima***
* Department of Urban and Environmental Engineering, Graduate School of Engineering, Kyushu University
** Department of Civil Engineering, Kyushu University
*** Fukuoka Research Center for Recycling Systems
† Correspondence should be addressed to Takayuki Shimaoka:
Department of Civil Engineering, Kyushu University
（6-10-1 Hakozaki, Higasi-ku, Fukuoka, 812-8581 Japan）

Abstract
Obtaining land for new landfill sites in Japan is now exceedingly difficult. For this reason, various alternative cover materials that decrease the necessary volume of cover are being developed in order to prolong the effective life of existing landfill sites. It is necessary to know the impact of these cover materials on waste stabilization and the characteristics of leachate quantity and quality. In this research, a long-term experiment was conducted using three large two-dimensional lysimeters with no cover, soil cover, and an alternative cover（used paper）.
As a result of this experiment, it was found that a soil cover layer caused channeling in the water movement and soluble pollution was not uniformly washed out. It was also found that stabilization of the landfill waste was delayed because the supply of oxygen needed for decomposition of the organic pollution elements was insufficient. In the case of the alternative cover material, permeability and ventilation were better than that of the soil cover and the waste stabilization was accelerated.

Key words: daily cover soil, alternative cover material, used paper, leachate, landfilled waste stabilization