Assessment of the Design of an Experimental Cover with Capillary Barrier Effect Using 4 Years of Field Data

Abstract

One important step in the design of inclined covers with capillary barrier effect (CCBE) is the determination of the water diversion length (DL). Numerical simulations can predict the DL more precisely than steady-state analytical solutions. Nevertheless, as simplified methods have always been part of engineering design, the application of analytical solutions with conservative boundary conditions, may allow engineers to make reasonable predictions, particularly during the pre-feasibility stage of a project. In this study, a CCBE was designed, constructed and instrumented at the Saint-Tite-desCaps landfill, Quebec, Canada. This CCBE included a seepage control layer superimposing a sand-gravel capillary barrier. The seepage control layer was made up of deinking by-products (DBP), an industrial byproduct that was previously disposed of as waste. The capillary barrier was designed using an adaptation of the Ross analytical solution and the scenario considered was that of steady-state flow during constant seepage flow applied uniformly at the top of the sandgravel capillary barrier. Although these conditions appear simplistic, they were deemed reasonable because placement of the seepage control layer on the top of the capillary barrier led to very low suctions at the interface, thereby allowing uniform downward seepage rates, limited by the saturated hydraulic conductivity of the DBP. In this paper, a discussion about the behaviour of the cover system based on 4 years of field data from several instruments is presented. The challenge of using DBP, more precisely the settlement of the DBP layer and its impact on k sat , is also assessed. The DL was reassessed considering the new k sat . A discussion on the validity of employing analytical solutions to determine DL is also presented. This paper illustrates how certain variables affect the design of inclined CCBEs that include a highly compressible material as seepage control layer.Keywords Cover with capillary barrier effect (CCBE) Á Diversion length Á Seepage control layer 1 Introduction

Comment on egusphere-2024-1277

“…We adopted a seepage face boundary condition as it is often suggested in studies involving lysimeters to approximate the capillary barrier effect induced by the inclusion of the drainage layer at the bottom of the lysimeters (Scanlon et al, 2002(Scanlon et al, , 2005. The capillary barrier increases water storage in the finer layer situated just above, potentially keeping this finer layer close to saturation (Mancarella and Simeone, 2012;Abdolahzadeh et al, 2011). Our results suggest that a more sophisticated boundary condition is required to more accurately reproduce the temporal variation of soil moisture close to a capillary barrier (Gao et al, 2023;Hübner et al, 2017;Kahale and Cabral, 2024).…”

Design of Microbial Methane Oxidation Systems for Landfills

“…The consequences from reduced diffusivity and conductivity on system performancetherefore on emissions calculations and subsequent reportingcan be calculated using settlement, water content, and suction data. With such data, one can reassess the saturated hydraulic permeability (Abdolahzadeh et al, 2011b), redraw the water retention curve and the k fct , and use the MOT, CALMIM, or other appropriate models to continuously assess the oxidation rate over large areas with greater precision.…”

Capillary Barrier Effect in an Earthen Roof of Historical House

“…In terms of effects of material types, grain size, heterogeneity of the soils, layer thickness, and slope angle or adding transportation layer on the performance and lateral diversion length of the capillary barrier have been investigated in numerous papers [2][3][4][5][6][7][8][9][10][11][12][13][14]. In addition field applications of capillary barriers such as preventing precipitation seepage into the solid waste landfills [14][15][16][17][18][19] or reducing precipitation-induced slope failures [20][21][22][23][24] have been examined by several researchers.…”