Effects of saline coal seam gas water on consistency limits, compaction characteristics and hydraulic conductivities of clays used for liners

Abstract Four kaolinite-dominant clays were moisture-conditioned with coal seam gas (CSG) water (CW) and deionized water (DW) and their consistency limits and compaction characteristics were compared. Further, two of the four clay samples were moisture-conditioned with CW, compacted in compaction mould permeameters and permeated with DW, CW and brine water (BW) under a 100 kPa hydraulic loading, simulating a pond water depth of 10 m in the field. The test results show that CW tended to increase the liquid and plastic limits and decrease the compaction densities of the clay samples. The hydraulic conductivities of the clay samples tended to decrease with decreasing concentration of salt and increasing pH value of the permeating waters. The hydraulic conductivities of the clay samples that were permeated with DW and CW were about one order of magnitude lower than those permeated with BW. At pH values above the isoelectric point of the edges (IEPedge) of the clay particles, the hydraulic conductivities of the clay samples tended to increase with increasing concentration of salt of the permeating water. The changes in the index and hydraulic parameters of the clay samples were attributed to changes in the net interparticle forces and in the associated clay structure.