Compression of tire aggregates in leachate collection systems

Tire-derived aggregates (TDA) have previously been applied in leachate collection and drainage systems (LCDSs). However, these systems are subjected to large overburden pressures, which may compress a tire medium and change its properties, thereby affecting its performance. In this study, properties of three types of commercially-available TDA sourced from processors in Alberta, Canada were investigated under conditions expected in a landfill, along with the implications of these properties on hydraulic performance of LCDSs. A large test apparatus was used to compress the materials by up to 330 kPa. Samples tested were highly compressible, with strains of about 50% under 150–240 kPa loads (corresponding to landfill heights of 12–18·5 m under typical compaction). Vertical hydraulic conductivity decreased with compression, but remained above the Alberta threshold of 10⁻⁴ m/s. No significant differences among media types were demonstrated. A criterion for determining the initial thickness of a drainage layer required to maintain a thickness of at least 300 mm over a landfill's lifetime. At least 600 mm of TDA would need to be placed to account for 50% compression.