Improving water storage of reclamation soil covers by fractionation of coarse-textured soil

Abstract

Dobrovolskaya, Y. V., Chau, H. W. and Si, B. C. 2014. Improving water storage of reclamation soil covers by fractionation of coarse-textured soil. Can. J. Soil Sci. 94: 489–501. Mining operations cause considerable land disturbance as well as the accumulation of large amounts of waste rock. Capping waste rock with a soil cover has proven to be a reliable, long-term reclamation technique. This study examines the question of whether it is possible to attain a considerable increase in water storage capacity (WSC) by separating coarse-textured soil into particle size fractions and layering them into a soil cover. Additionally, this study investigated whether preferential flow can be mitigated by increasing the number of layers and extending the interlayer transitions in fine-over-coarse-textured soil systems. Intermittent and constant infiltration experiments were conducted on homogeneous covers composed of natural sand, two-layered covers with abrupt and gradual interlayer transitions as well as on a four-layered cover under initially air-dry and field capacity (FC) conditions. Water storage capacities were determined from a sampling of soil covers’ water content at FC. Infiltration experiments showed that all tested covers under all initial and boundary conditions had limited susceptibility to preferential flow. Increasing the number of layers and extending the interlayer transitions had a stabilizing effect on the wetting front. Water storage capacities and residence time increased with the increased number of layers. Overall, it has been shown that it is possible to improve the WSC of coarse-textured soil by fractionation and layering of it into a relatively fine-over-coarse soil system.