Leachate generated from landfill material flows through soil gravitationally downward and. continues to flow until it encounters groundwater, posing the thread of pollution. So selection of liner material having a low permeability and testing method are required. The study was performed to find bentonite content of soil-bentonite mixtures for using as liner and cover of waste landfills. This paper includes results of consolidation tests and permeability tests and evaluates suitability and properties of soil-bentonite mixtures as impervious materials.