Abstract
AbstractA cover system is a crucial component of engineered landfills, to minimize water percolation into the underlying waste. Capillary barriers are an alternative cover system, which has been widely used in the arid and semiarid regions as no cohesive, low‐permeability materials are used. However, the performance of capillary barriers in tropical climate has been unsatisfactory (breakthrough observed). In recent years, synthetic water‐repellent granular materials have drawn increasing attention due to their distinctive hydraulic behavior (inhibited water infiltration and high water entry pressure), suggesting they may also be used to improve the performance of cover systems. In this study, flume tests were conducted with inclined model slopes under artificial rainfall. By monitoring the surface runoff, lateral diversion, and basal percolation and conducting water balance analysis, the performance of monolithic cover, conventional capillary barrier, and water‐repellent cover systems were evaluated. The study revealed that (a) the barrier effect and diversion capacity were significantly strengthened by induced water repellency, providing a promising solution to extend the application of capillary barrier covers; and (b) cover systems can be formed using one raw material to decrease the construction cost, by using synthetic water‐repellent soil as the underlying layer.
Highlights
A landfill cover system, or capping system, is a crucial component of engineered municipal or hazardous waste landfills, which is designed to prevent access or exposure to waste, minimize water percolation into the underlying waste, and control landfill gas emissions (EPD, 2019; USEPA, 2011)
Data collected from 10 field sites at the time of construction and 2–4 yr after construction indicated that the saturated hydraulic conductivity can increase by 10,000 times (Benson, Sawangsuriya, Trzebiatowski, & Albright, 2007), and Rayhani et al (2007) reported a 12–34 times increase in hydraulic conductivity that was attributed to cracking
The water-repellent layer is composed of dry, granular material, which can deform without impairing water repellency
Summary
A landfill cover system, or capping system, is a crucial component of engineered municipal or hazardous waste landfills, which is designed to prevent access or exposure to waste, minimize water percolation into the underlying waste, and control landfill gas emissions (EPD, 2019; USEPA, 2011). A variety of landfill cover systems have been developed worldwide, including resistive cover systems and alternative cover systems. The resistive cover systems appear technically efficient, questions regarding their high construction cost and long-term performance have been reported (Rayhani, Yanful, & Fakher, 2007; Sadek, Ghanimeh, & El-Fadel, 2007). Evapotranspiration (ET) cover systems, including monolithic covers and capillary barrier covers, have been proposed and implemented as technically feasible alternative capping systems with easy construction and low cost (Bareither, Foley, & Benson, 2016; Barnswell & Dwyer, 2012). The ET covers serve not as a barrier, but as a reservoir that stores water during rainfall events
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