Capillary Barrier Effect from Underlying Coarser Soil Layer

Stormont, John C.; Anderson, Clifford E.

doi:10.1061/(asce)1090-0241(1999)125:8(641)

Cited by 182 publications

(112 citation statements)

References 13 publications

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“…The upper two-layer CCBE was no longer functional after this ponding duration. This phenomenon has been demonstrated by researchers for two-layer CCBEs under one-dimensional conditions [22][23][24]. After 24 hours of ponding (>1000 year rainfall), a hydrostatic condition seems to develop above the clay layer.…”

Section: Distribution Of Hydraulic Head Profilesmentioning

confidence: 71%

Feasibility study of a new unsaturated three-layer landfill cover system

Coo

Chen

et al. 2016

E3S Web Conf.

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Abstract.As an improvement of the two-layer cover with capillary barrier effect (CCBE) (i.e. fine-grained soil overlying a coarse-grained soil), a new three-layer landfill cover system is proposed and investigated for humid climate. This new system is to add a fine-grained soil (i.e., clay) underneath a two-layer CCBE (i.e., a silt overlying a gravelly sand layer). The feasibility of this proposed cover system was investigated by conducting a one-dimensional water infiltration test. In addition, transient seepage simulations were carried out to back-analyse the test results and investigate the importance of hydraulic properties of the CCBE on the proposed cover. Based on the infiltration experiment and numerical back-analysis, it is found that no percolation was observed after 48 hours of ponding, which is equivalent to a rainfall return period of greater than 1000 years. However, the upper two-layer CCBE is only effective for a rainfall return period of about 35 years. This implies that the proposed bottom clay layer is needed for humid climate. Numerical parametric simulations reveal that increasing the saturated permeability of the upper finegrained soil by two orders of magnitude (1.4x10 -6 m/s to 2.1x10 -4 m/s), the wetting front is still within the clay layer after 12 hours of constant water ponding (>1000 year rainfall) and no percolation occurred.

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Section: Distribution Of Hydraulic Head Profilesmentioning

confidence: 71%

Feasibility study of a new unsaturated three-layer landfill cover system

Coo

Chen

et al. 2016

E3S Web Conf.

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“…As noticed during the experiments, runoff did not enter the lower sand layer until the head was built up sufficiently to overcome the capillary tension between layers (Stormont and Anderson, 1999). Afterwards, infiltrating runoff flowed quickly through the bottom sand layer.…”

Section: Tss Removal During Repetitive Experimentsmentioning

confidence: 79%

“…For the effect of media configuration, Hillel (1998) compared the flow of water in four different media (including homogeneous and layered media) and concluded that preferential flow occurred in the layered profile with a fine-textured layer overlying a coarse-textured layer. In addition, a capillary barrier was also noticed between two layers in which the medium with a lower hydraulic conductivity overlaid another medium (Stormont and Anderson, 1999). In this case, water did not enter the lower layer until the head was built up sufficiently to overcome the capillary tension between layers.…”

Section: Water Flow In Bioretention Mediamentioning

confidence: 99%

Engineering Bioretention for Treatment of Urban Storm Water Runoff

Hsieh¹,

Davis²

2002

proc water environ fed

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Bioretention, a "Low Impact Development" urban storm water best management practice, was developed in the early 1990's. Although bioretention has been used at many areas in the United States, the impact of this technology on ground and surface water quality as well as the optimal design of bioretention media for pollutant removal, have not been systematically investigated. The objectives of this study were to investigate the effectiveness of this technology for storm water runoff treatment and finally to give recommendations for future design. The methods used included developing pollutant removal performance curves for a variety of bioretention media mixes and evaluating the effectiveness of existing bioretention facilities. Synthetic runoff, which contained oil and grease (O/G), suspended solids (SS), lead (Pb), phosphorus (P), nitrate, and ammonium, was employed in laboratory experiments and 6 on-site bioretention evaluations. Two more on-site experiments were conducted during a rainfall event to compare with laboratory investigations.Overall, all bioretention columns and on-site facilities demonstrated excellent removal for O/G and Pb. TSS removal was good in columns, but washing out of media particles was noted in field facilities, mostly from new installations. For nutrients treatment during a 6-hr experiment, the removal efficiency of Total P ranged widely and appears to be related not only to chemical properties of the media, but also to the flow behavior of runoff through the media. Results from batch P sorption tests on six media, three continuous column studies, and two repetitive 6-hr bioretention columns with total 28 repetitions showed that the medium with a higher P sorption capacity can retain more P from the infiltrating runoff after a high P loading. However, the sorption data alone is not adequate to predict the P retention through a bioretention column for a short-term experiment due to the complicated processes occurring between the runoff and media.Unless special provision were made, all media employed in this study were ineffective in removing nitrate and ammonium. The removal efficiency of both pollutants was improved by increasing the water holding capacity of the media and enhancing the development of nitrification and denitrification processes in the bioretention column.

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“…Since it is the mechanism of capillary tension that is responsible for a limitation of vertical seepage, this effect is referred to as the capillary barrier (Stormont and Anderson, 1999;Ross, 1990). Given a horizontal interface, the wetting front will temporarily pause.…”

Section: Discussionmentioning

confidence: 99%

Impacts of a capillary barrier on infiltration and subsurface stormflow in layered slope deposits monitored with 3-D ERT and hydrometric measurements

Hübner¹,

Günther

Heller³

et al. 2017

Hydrol. Earth Syst. Sci.

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Abstract. Identifying principles of water movement in the shallow subsurface is crucial for adequate process-based hydrological models. Hillslopes are the essential interface for water movement in catchments. The shallow subsurface on slopes typically consists of different layers with varying characteristics. The aim of this study was to draw conclusions about the infiltration behaviour, to identify water flow pathways and derive some general interpretations for the validity of the water movement on a hillslope with periglacial slope deposits (cover beds), where the layers differ in their sedimentological and hydrological properties. Especially the described varying influence of the basal layer (LB) as an impeding layer on the one hand and as a remarkable pathway for rapid subsurface stormflow on the other. We used a time lapse 3-D electrical resistivity tomography (ERT) approach combined with punctual hydrometric data to trace the spreading and the progression of an irrigation plume in layered slope deposits during two irrigation experiments. This multitechnical approach enables us to connect the high spatial resolution of the 3-D ERT with the high temporal resolution of the hydrometric devices. Infiltration through the uppermost layer was dominated by preferential flow, whereas the water flow in the deeper layers was mainly matrix flow. Subsurface stormflow due to impeding characteristic of the underlying layer occurs in form of "organic layer interflow" and at the interface to the first basal layer (LB1). However, the main driving factor for subsurface stormflow is the formation of a capillary barrier at the interface to the second basal layer (LB2). The capillary barrier prevents water from entering the deeper layer under unsaturated conditions and diverts the seepage water according to the slope inclination. With higher saturation, the capillary barrier breaks down and water reaches the highly conductive deeper layer. This highlights the importance of the capillary barrier effect for the prevention or activation of different flow pathways under variable hydrological conditions.

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Capillary Barrier Effect from Underlying Coarser Soil Layer

Cited by 182 publications

References 13 publications

Feasibility study of a new unsaturated three-layer landfill cover system

Feasibility study of a new unsaturated three-layer landfill cover system

Engineering Bioretention for Treatment of Urban Storm Water Runoff

Impacts of a capillary barrier on infiltration and subsurface stormflow in layered slope deposits monitored with 3-D ERT and hydrometric measurements

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