The Eastern Province of Saudi Arabia has witnessed extensive industrialization and urbanization over the past three decades. The wastes produced by such developments would have a serious environmental impact if they were not disposed of properly. The effectiveness of earthen liners or closure caps as hydraulic barriers depends on the composition and construction of the typical local materials used. This investigation was undertaken to evaluate the effect of leaching on some of the properties of a local calcareous soil. Samples were compacted at different moisture contents and subjected to leaching for periods ranging from a few months to over a year in fixed-wall permeameters. The permeation fluid consisted of distilled water mixed with sabkha brine at different proportions. Test results show that the permeability increases with the permeation period as a result of leaching. This is more pronounced in the case of samples compacted on the dry side of optimum compared with those compacted both at optimum and on the wet side of optimum. The coefficient of permeability of the calcareous samples increased by up to 19 times the initial value. The total dissolved solids in the effluent increased initially and then decreased to almost their initial values towards the end of the tests.