干旱区生态环境知识资源中心

Alternative cover systems for landfills such as evapotranspirative covers and capillary barriers are commonly presented as an interesting technical and low cost solution for final cover design. However, due to the main role of the cyclic infiltration-evapotranspiration process on the long-term performance of this kind of covers, these solutions are normally restricted to arid or semi-arid climate regions. In discussing the potential use of the induced soil-water repellency technique (ISWR) in improving the performance of alternative cover systems, we present the differences introduced into the hydraulic characteristics of a sandy soil treated to become water repellent. The concept of water-entry level and water repellency grade are presented. Comparing the performance results of continuous infiltration tests carried out on scaled models of a traditional capillary barrier and an alternative ISWR barrier, it can be observed that the ISWR barrier presents a substantially better long-term performance, capable of keeping the moisture out of the bottom of the cover system for the entire time lag. It can be concluded that the ISWR technique shows a good potential for being used efficiently in landfill final cover designs, ensuring high level long-term performance standards even in a sub-tropical climate region.