Analyses of water diversion along inclined covers with capillary barrier effects

2009 ◽  
Vol 46 (10) ◽  
pp. 1146-1164 ◽  
Author(s):  
M. Aubertin ◽  
E. Cifuentes ◽  
S. A. Apithy ◽  
B. Bussière ◽  
J. Molson ◽  
...  
Keyword(s):  
Climatic Conditions ◽  
Water Infiltration ◽  
Water Diversion ◽  
Key Factors ◽  
Capillary Barrier ◽  
Fine Grained ◽  
Barrier Effects ◽  
Fine Grained Soil ◽  
Cover Systems ◽  
Recharge Rates

Various types of cover systems can be used to control water infiltration into waste disposal sites. One promising option is to combine different types of soil to create a layered cover with capillary barrier effects (CCBE). A CCBE basically involves the placement of a relatively fine-grained soil, which acts as a water-retention layer, over a coarser capillary break material. On slopes, a CCBE promotes lateral water diversion. Inclined CCBEs, however, are relatively complex, as their behaviour is influenced by numerous factors. In this paper, the authors present the key results obtained from a numerical investigation into the response of steeply inclined CCBEs. The study evaluates the behaviour of covers under dry and humid climatic conditions. After a review of the physical processes and background studies, the paper presents simulation results that demonstrate the effect of key factors on the diversion length of covers, including layer thicknesses, material properties, and recharge rates. The results shown here indicate that increasing the thickness of the cover may improve its efficiency, but only up to a certain maximum beyond which the gain becomes minimal. These results should be of help to those involved in the design of inclined CCBEs.

Insulation covers with capillary barrier effects to control sulfide oxidation in the Arctic

2020 ◽  
Author(s):  
Vincent Boulanger-Martel ◽  
Bruno Bussière ◽  
Jean Côté
Keyword(s):  
Sulfide Oxidation ◽  
Climatic Conditions ◽  
Degree Of Saturation ◽  
The Arctic ◽  
Capillary Barrier ◽  
Suitable Material ◽  
Experimental Cell ◽  
Fine Grained ◽  
Barrier Effects ◽  
Term Performance

Insulation covers can be used for the reclamation of tailings storage facilities located in the Arctic. However, this approach can be vulnerable to changes in climatic conditions as its long-term performance is strictly based on controlling the temperature of tailings. A more robust alternative could be the use of insulation covers with capillary barrier effects because they control both the tailings temperature and oxygen flux. This study assesses the potential for an insulation cover with capillary barrier effects using laboratory tests and a field experimental cell. Material characterization indicated that the fine-grained compacted waste rock is a suitable material for constructing a moisture-retaining layer. A 2-m-thick field experimental cell was constructed in which temperatures and unfrozen volumetric water contents were monitored for 3.5 years. Results showed thaw depths periodically reaching the reactive tailings and temperatures at the tailings-cover interface greater than 0 °C for 39 to 57 days each year. The degree of saturation in the moisture-retaining layer was almost always greater than 80-85% when temperatures at the tailings-cover interface exceeded 0 °C. Yearly oxygen fluxes passing through the moisture-retaining layer were calculated to be less than 2 mol/m<sup>2</sup>/yr, thus confirming the effectiveness of the cover as an oxygen barrier.

scholarly journals Shrub vegetation shores strengthening and protection in Kalachevsky district of Volgograd area

2021 ◽  
Vol 25 (3) ◽  
pp. 65-72
Author(s):  
A.S. Solomentseva ◽  
Keyword(s):  
Surface Runoff ◽  
Climatic Conditions ◽  
Forest Stands ◽  
Effective Measure ◽  
Rosa Canina ◽  
Fine Grained ◽  
Fine Grained Soil ◽  
Subsurface Runoff ◽  
Protective Forest

The critical abrasion situation manifests itself on the coastal part of the Kalachevsky district due to the increasing anthropogenic load. The most important element of the complex of measures to combat silting of reservoirs and coastal abrasion, as well as an effective measure to strengthen the banks is forest vegetation. The objectives of the research were to study the soil, forest and climatic conditions of the object under study, to develop an assortment of shrubs and features of the formation of protective forest stands, as well as criteria for selecting an adapted assortment of tree and shrub vegetation and methods of caring for the soil and plantings. During the research, the most promising types of shrubs for creating upper protective forest stands were identified: Ligustrum vilgare L., Berberis vulgaris L., Cotoneaster lucidus Schltdl., Amelanchier Medik., Ribes aureum Pursh., Rosa canina L. It was found that the useful role of forest stands is manifested in their ability to convert surface runoff into subsurface runoff, to clean surface stock water from fine-grained soil, to weaken the speed of movement and to extinguish the energy of waves, binding the soil with roots. Recommendations are given for the creation and placement of anti-abrasion plantings, depending on the steepness and height of the slope. It is stated that one of the main measures for the care of the aboveground part of the plantings is the pruning of the crown, carried out taking into account the biological characteristics of their growth and development, including the removal of dry and damaged branches, thinning of the crown, preservation of the previously given crown size, rejuvenation of the crown. It is recommended to place shrubs depending on the landscape, soil and climatic conditions and features of abrasive processes in areas of constant, periodic, episodic flooding and strong moderate and weak flooding of the coastline.

scholarly journals Field monitoring and model predicted water balance of monolithic cover

2021 ◽  
Vol 337 ◽  
pp. 04009
Author(s):  
Md Jobair Bin Alam ◽  
Asif Ahmed ◽  
Md Aminul Islam ◽  
Naima Rahman ◽  
Md Sahadat Hossain
Keyword(s):  
Water Balance ◽  
Climatic Conditions ◽  
Soil Water Storage ◽  
Soil Parameters ◽  
Fine Grained ◽  
Future Performance ◽  
Fine Grained Soil ◽  
Actual Field ◽  
Field Water Balance

The use of the evapotranspiration cover for landfill is increasing because of its long-term enhanced performance. However, the performance of evapotranspiration cover primarily depends on the onsite geo-climatic conditions. Therefore, field verification of cover performance through constructed test plots is required before actual implementation. Additionally, numerical modeling and comparison with field results are necessary for future performance prediction. The objective of this study was to simulate the water balance hydrology of evapotranspiration cover using the code SEEP/W. Drainage lysimeter was constructed with fine-grained soil and native vegetation. Field water balance data from the lysimeter were obtained through instrumentation. Onsite climatological data, laboratory and field investigated soil parameters and actual field studied plant parameters were used as model input. Based on one year’s simulation, it was observed that the code nearly captured the seasonal variations in the water balance quantities measured in the field. Surface runoff was reasonably predicted in the model where precipitation intensity appeared to be responsible to some extent. Evapotranspiration was slightly overpredicted and the fluctuation in soil water storage was similar to the field results. The model predicted annual percolation was approximately 45 mm, which is under-predicted than the actual field measured annual percolation of 62 mm.

Evaluation of alternative cover systems using GIS

2001 ◽  
Vol 7 (4) ◽  
pp. 343-355
Author(s):  
Julie Coonrod ◽  
John Stormont ◽  
Lisa Vantassell
Keyword(s):  
New Mexico ◽  
Soil Cover ◽  
Performance Criteria ◽  
Capillary Barrier ◽  
Waste Containment ◽  
Fine Grained ◽  
Native Soil ◽  
Cover Systems ◽  
Gis Environment ◽  
Cover Thickness

Abstract Geographic Information Systems (GIS) can be used to determine and display the depths of native soil covers required for waste containment sites. Readily available data for the State of New Mexico are used in a GIS environment to determine the required depth of two separate cover systems. The depth of an evapotranspirative (ET) soil cover is determined using the available water capacity of the soil and the amount of dormant precipitation. The thickness of a capillary barrier cover system is determined using unsaturated hydraulic parameters, the amount of dormant precipitation, and an iterative numerical model. A difference map showing the savings using a capillary barrier instead of an ET cover is then created. The use of a capillary barrier in areas with fine-grained soils can decrease the necessary soil cover thickness by 90 cm of soil. The computed cover thickness compare well with those determined using Hydrologic Evaluation of Landfill Performance (HELP) (Schroeder et al., 1994), a model commonly used in New Mexico to determine if alternative cover systems can meet the required performance criteria.

Field investigation of a suction break designed to control slope-induced desaturation in an oxygen barrier

2011 ◽  
Vol 48 (1) ◽  
pp. 53-71 ◽  
Author(s):  
Abdelkabir Maqsoud ◽  
Bruno Bussière ◽  
Michel Aubertin ◽  
Michel Chouteau ◽  
Mamert Mbonimpa
Keyword(s):  
Water Distribution ◽  
Water Saturation ◽  
Field Measurements ◽  
Field Investigation ◽  
Climatic Conditions ◽  
Water Infiltration ◽  
Barrier Effects ◽  
Hydraulic Behaviour ◽  
Novel Approach ◽  
Zone Of Influence

Covers with capillary barrier effects (CCBEs) can be used as oxygen barriers to limit gas flux into waste disposal sites. Laboratory and field measurements show that the hydraulic behaviour of such a layered cover system is influenced by its slope geometry and gravity drainage, which can result in local desaturation that may be detrimental to cover performance. Such desaturation can be minimized by placing a suction break in the moisture-retaining layer of the inclined cover. This novel approach was applied in the field to an existing inclined CCBE. The three-layer cover was then subjected to different boundary conditions to evaluate the influence of the suction break on hydraulic behaviour. Volumetric water content and suction measurements demonstrated that a zone of water saturation and low suction was created upslope of the suction break under natural climatic conditions. The hydrological behaviour close to the suction break was not significantly affected by a forced drought of 78 days (without water infiltration). The results also reveal that the suction break had a relatively limited upslope zone of influence (typically less than 10 m). The monitoring results are confirmed by geophysical measurements used to characterize water distribution in the inclined CCBE.

scholarly journals Valorisation of Partially Oxidized Tailings in a Cover System to Reclaim an Old Acid Generating Mine Site

Minerals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 987
Author(s):  
Gabrielle Dublet-Adli ◽  
Thomas Pabst ◽  
Gudny Okkenhaug ◽  
Christian Sætre ◽  
Anna M. Vårheim ◽  
...  
Keyword(s):  
Capillary Barrier ◽  
Wetting And Drying ◽  
Barrier Effects ◽  
Cover Systems ◽  
Control Column ◽  
Geochemical Behaviour ◽  
Long Term Performance ◽  
Term Performance ◽  
Leachate Water

The reclamation of acid-generating mine tailings typically involves building cover systems to limit interactions with water or oxygen. The choice of cover materials is critical to ensure long-term performance, and partly determines the environmental footprint of the reclamation strategy. The objective of this research was to evaluate if tailings pre-oxidized on-site could be used in cover systems. Column experiments were performed to assess the effectiveness of a cover with capillary barrier effects (CCBE), where the moisture retention layer (MRL) was made of pre-oxidized tailings with little to no remaining sulfides (LS tailings). The columns were submitted to regular wetting and drying cycles, and their hydrological and geochemical behaviour was monitored for 510 days. The LS tailings showed satisfying hydrological properties as an MRL and remained saturated throughout the test. The concentrations of Cu in the drainage decreased by more than two orders of magnitude compared to non-covered tailings. In addition, the pH increased by nearly one unit compared to the control column, and Fe and S concentrations decreased by around 50%. Despite these improvements, the leachate water remained acidic and contaminated, indicating that acid drainage continued to be generated despite a hydrologically efficient CCBE.

scholarly journals Numerical study of the application of capillary barrier systems for prevention of rainfall-induced slope instabilities

2020 ◽  
Vol 195 ◽  
pp. 01027
Author(s):  
Riccardo Scarfone ◽  
Simon J. Wheeler ◽  
Colin C. Smith
Keyword(s):  
Numerical Study ◽  
Slope Instability ◽  
Degree Of Saturation ◽  
Atmospheric Conditions ◽  
Capillary Barrier ◽  
Fine Grained ◽  
Suction Control ◽  
Fine Grained Soil ◽  
Improved Stability ◽  
Slope Instabilities

Slope instability is often caused by decreases in suction due to heavy and prolonged rainfall. In this study, the application of capillary barrier systems (CBSs) for suction control and slope stabilization purposes (i.e. reducing the risk of rainfall-induced slope instabilities) is analysed, due to their capacity to limit the percolation of water into the underlying soil. The behaviour of two slopes was studied numerically: a bare slope made of fine-grained soil and the same slope covered by a capillary barrier system. The time evolution of suction in the slopes subjected to realistic atmospheric conditions was studied by performing numerical finite element analyses with Code_Bright. In particular, multi-phase multi-physics thermo-hydraulic analyses were performed, modelling the soil-atmosphere interaction over periods of many years. Suction and degree of saturation distributions obtained from these analyses were then exported to the software LimitState GEO, which was used to perform limit analysis to assess the stability of the slopes. The CBS was able to limit the percolation of water into the slope and was shown to be effective in increasing the minimum values of suction attained in the underlying ground, resulting in improved stability of the slope.

scholarly journals Influence of freeze–thaw cycles on the performance of covers with capillary barrier effects made of crushed rock–bentonite mixtures to control oxygen migration

2016 ◽  
Vol 53 (5) ◽  
pp. 753-764 ◽  
Author(s):  
Vincent Boulanger-Martel ◽  
Bruno Bussière ◽  
Jean Côté ◽  
Mamert Mbonimpa
Keyword(s):  
Mine Drainage ◽  
Mine Waste ◽  
Effective Diffusion ◽  
Crushed Rock ◽  
Capillary Barrier ◽  
Freeze Thaw ◽  
Fine Grained ◽  
Barrier Effects ◽  
Attractive Option ◽  
Oxygen Migration

In temperate climates, covers with capillary barrier effects (CCBEs) are being used successfully to prevent oxygen fluxes from reaching covered potentially acid mine drainage (AMD) generating mine tailings. In northern climates, the more attractive option for mine site reclamation is insulation covers, which are designed to keep reactive materials frozen. This article suggests that CCBEs can simultaneously control oxygen migration and mine waste temperature to inhibit AMD generation. However, in northern conditions, where natural fine-grained materials needed for the CCBE moisture-retaining layer are not always available, soil–bentonite mixtures could be used instead. This laboratory study assessed — using instrumented columns — the effects of freeze–thaw cycles on the performance of three CCBEs made with crushed rock–bentonite mixtures. An oxygen diffusion test was developed to determine the effective diffusion coefficient of oxygen (De) and its sensitivity to freeze–thaw cycles. The results show good initial performance for the saturated CCBEs. However, the tested CCBEs are significantly affected by freeze–thaw cycles and have limited oxygen-limiting ability.

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