In regions dominated by high carbonate aggregates, landfill owners are faced with using alternative materials for leachate collection systems.
ES&C lightweight aggregates essentially contain no carbonates and may provide a suitable alternative. TXI performed an engineering evaluation of ES&C aggregates to assess their suitability for leachate collection systems. The permeabilities of the aggregates under 50 psi exceeded the typical minimum regulatory value (0.01 cm/sec) by one or two orders of magnitude. The aggregate showed no deterioration after being immersed in municipal solid waste leachate for more than 60 days. Interface friction angles between the dry aggregates and smooth HDPE geomembrane at 7kPa (1 psi) normal stress ranged from 23' to 27'.
The evaluation concluded that ES&C aggregates are viable and competent materials for use in leachate collection systems in municipal solid waste landfills. In addition, ES&C's high permeability greatly enhances the drainage capabilities of the leachate collection system to reduce the probability of head rise in the landfill. While the high angle of internal friction promotes its interlocking capability, it provides a more stable interface with the liner/cover systems on slopes.