Modelling and field measurements of water percolation through an experimental soil cover on mine tailings

1995 ◽  
Vol 32 (4) ◽  
pp. 601-609 ◽  
Author(s):  
Mark R. Woyshner ◽  
Ernest K. Yanful
Keyword(s):  
Mine Tailings ◽  
Soil Cover ◽  
Water Saturation ◽  
Field Measurements ◽  
Degree Of Saturation ◽  
Hydrologic Processes ◽  
Water Percolation ◽  
High Degree ◽  
Experimental Soil ◽  
Varved Clay

A composite soil cover constructed on acid-producing tailings was evaluated for its ability to retain a high degree of water saturation and low hydraulic conductivity. The cover consisted of a 60 cm thick, compacted, nearly saturated, varved clay placed between two sand layers, each 30 cm thick. A final 10 cm thick gravel layer was placed on the upper sand layer to minimize erosion. The Hydrologic Evaluation of Landfill Performance (HELP) model and a finite-element flow model (SEEP/W) were applied, and the results corroborated with field measurements of percolation and soil-water content. Modelling predictions indicate that 4% of precipitation will percolate through the cover and that the intermediate clay layer will retain a high degree of saturation after a 20 year simulation. Four years of field monitoring also indicate that 4% of precipitation percolates through the cover and that the clay retains its high saturation. These results suggest that a properly designed and constructed soil cover can be effective in reducing acid production in reactive mine tailings. Key words : acid-producing tailings, soil cover, water saturation; capillary barrier, hydrologic processes.

scholarly journals Measurement of unsaturated meltwater percolation flux in seasonal snowpack using self-potential

2021 ◽  
pp. 1-16
Author(s):  
Wilson S. Clayton
Keyword(s):  
Method Development ◽  
Water Saturation ◽  
Field Measurements ◽  
Time Domain Reflectometry ◽  
Electrode Spacing ◽  
Glacier Mass Balance ◽  
Wetting Front ◽  
Electrical Field Strength ◽  
Water Redistribution ◽  
Self Potential

Abstract This paper presents a feasibility study of in situ field measurements of unsaturated meltwater percolation flux within the vertical profile of a snowpack, using the self-potential (SP) method. On-site snowmelt column tests calibrated the SP measurements. The SP data measured electrical field strength with an electrode spacing of 20 cm, and coincident water saturation (Sw) measurements using time domain reflectometry allowed calculation of SP-modeled vertical percolation flux (qsp), expressed as Darcy velocity. The results reflected transient diurnal snowmelt dynamics, with peak flux lagging arrival of a saturation wetting front. Peak daily qsp was 60 to >300 mm d−1, whereas daily snowmelt was 20–50 mm w.e. Surface refreezing events appeared to cause upward flow, possibly representing water redistribution toward the freezing boundary. Calculated fluxes were comparable to actual fluxes, although average errors ranged from −15 to +46% compared to average of melt expected from surface energy-balance and ablation stake measurements. By advancing method development to measure unsaturated meltwater percolation flux in snowpacks this study creates opportunities to study fundamental snowmelt processes, may improve mathematical modeling and may supplement glacier mass-balance studies and studies of snowmelt interactions with avalanches, groundwater and surface water.

Field evidence of resuspension in a mine tailings pond

2001 ◽  
Vol 38 (4) ◽  
pp. 796-808 ◽  
Author(s):  
Celestina Adu-Wusu ◽  
Ernest K Yanful ◽  
Mohammed H Mian
Keyword(s):  
Shear Stress ◽  
Mine Tailings ◽  
Critical Shear Stress ◽  
Field Measurements ◽  
Shear Stresses ◽  
Wind Speeds ◽  
Tailings Pond ◽  
Field Evidence ◽  
Water Cover ◽  
Solubility Of Oxygen

Flooding of tailings under shallow water covers is an effective method of decommissioning potentially acid generating mine tailings. The low diffusivity and solubility of oxygen in water are attractive features of this technology. However, wind-induced waves can resuspend flooded tailings and expose them to greater contact with dissolved oxygen, thereby increasing the potential for oxidation and acid generation. Field measurements of wind activity and waves under different water cover depths and associated resuspension for a mine tailings pond in Ontario are presented and discussed. The results show that wind speeds greater than 8 m/s above water covers that are shallower than 1 m create waves of height greater than 10 cm and bottom shear stresses greater than 0.2 Pa. Under these conditions the critical shear stress of the mine tailings was exceeded, resulting in erosion and subsequent resuspension.Key words: mine tailings, water cover, wind-induced waves, resuspension, wind speed, shear stress.

Hydrothermal Field Experiment Simulating Steel Canister Embedded in Expansive Clay - Physical Behavior of the Clay

1991 ◽  
Vol 257 ◽  
Author(s):  
Roland Pusch ◽  
Ola Karnland ◽  
Alain Lajudie ◽  
Rosemarie Atabek
Keyword(s):  
Field Experiment ◽  
Physical Properties ◽  
Mineral Composition ◽  
Water Saturation ◽  
Expansive Clay ◽  
Physical Behavior ◽  
Gas Formation ◽  
Aluminum Compounds ◽  
Short Test ◽  
High Degree

ABSTRACTField heat experiments with kaolinite/smectite clay surrounding heaters in boreholes were conducted for 0.7 and 4 years with temperatures up to 170-180°C. The short test gave a high degree of water saturation even in the hottest part (> 75 %) and almost no change in physical properties and mineral composition. The long test gave a dry inner zone of claystone, indicating gas formation, and rich precipitation of silica/aluminum compounds and sulphate minerals. Brittleness characterized the hot parts and stiffening occurred also in the colder parts due to precipitation of silica and aluminum.

Improvement of Properties of the Argillaceous Soils when Using Additives "Chimston" in Combination with Inorganic Astringent

2019 ◽  
Vol 945 ◽  
pp. 136-140 ◽  
Author(s):  
Anna Ivanovna Trautvain ◽  
Andrey Akimov ◽  
E. Yakovlev
Keyword(s):  
Soil Compaction ◽  
Mechanical Characteristics ◽  
Soil Stabilization ◽  
Water Saturation ◽  
Water Repellent ◽  
Chemical Additives ◽  
Key Characteristics ◽  
Stabilized Soil ◽  
High Degree ◽  
Production Company

Paper observes research of the mechanical characteristics of the stabilized soil with different «Chimston» additives. Current work focuses on the application of the «Chimston-1» and «Chimston-2» produced by Zipo research and production company. Stabilized soil is based on local soils: argillaceous sand ground and sand clay. Chemical additives are mixed with water according to the manufacture’s recommendations. Amount of the «Chimston-1» is 0.07% of the soil. Amount of the «Chimston-2» is 0.01% of the cement. During the research plasticize effect is studied, based on maximum density and optimal humidity. Water saturation, mechanical strength under tension in bending and compression. It is established, application of the "Chimson" additives allow to increase key characteristics of the stabilized soil without increasing of the cement. «Chimston-1» additive has strongly pronounced plasticize effect which allow to increase soil compaction and decrease optimal humidity. Additive "Chimston-2" is a water repellent with a high degree of efficiency with soil stabilization.

Effects of capillary number, Bond number, and gas solubility on water saturation of sand specimens

2013 ◽  
Vol 50 (2) ◽  
pp. 133-144 ◽  
Author(s):  
Bruce L. Kutter
Keyword(s):  
Capillary Number ◽  
Water Saturation ◽  
Fluid Pressure ◽  
Infiltration Rate ◽  
Capillary Forces ◽  
Bond Number ◽  
Pore Fluid ◽  
Degree Of Saturation ◽  
Fluid Viscosity ◽  
Viscous Forces

To better understand how to prepare completely water-saturated specimens or centrifuge models from dry sand, the mechanisms of the infiltration and filling of pores in sand are studied. Complete saturation has been shown by others to be especially important in studies involving the triggering of liquefaction. This paper discusses how the degree of saturation obtained during infiltration increases with the “Bond number”, Bo (ratio of body forces and capillary forces), and the “capillary number”, Ca (ratio of viscous forces and capillary forces), as well as the solubility of gas bubbles in the pore fluid. Bo is varied by changing the particle size, fluid density, and centrifugal acceleration. Ca is varied by changing the fluid viscosity and infiltration rate. The dissolution of gas is encouraged by replacing pore air by CO2 (56 times more soluble in water than N2), by de-airing the liquid prior to infiltration or by increasing the pore fluid pressure after infiltration. Infiltration experiments performed at 1g and in a centrifuge are presented. A new technique for measuring the degree of saturation is also presented. Quantitative pressure–saturation relations are presented for different gasses, illustrating the importance of replacement of air by CO2. Spinning a specimen in a centrifuge during infiltration is also useful for speeding up the saturation process and for achieving higher degrees of saturation.

Some insights into the performance of an experimental soil cover near London, Ontario

1999 ◽  
Vol 36 (5) ◽  
pp. 846-860 ◽  
Author(s):  
Paul H Simms ◽  
Ernest K Yanful
Keyword(s):  
Liquid Flow ◽  
Laboratory Tests ◽  
Soil Cover ◽  
Unsaturated Flow ◽  
Capillary Barrier ◽  
Saturated Liquid ◽  
Sandy Gravel ◽  
Flow Modelling ◽  
Protection Layer ◽  
Experimental Soil

An experimental soil cover constructed near London, Ontario, 23.2 m × 15.2 m in plan area, has been monitored for 2 years for percolation and water-content data. The cover was a multilayer system consisting of a compacted till barrier soil placed between evaporation and drainage barriers of sandy gravel. Half of the cover was capped with coarse stone to prevent erosion and the other half was covered with topsoil to facilitate revegetation. High percolation rates and substantial desiccation of the barrier soil were reported under the topsoil protection layer. Unsaturated-saturated liquid and vapour flow modelling shows that the topsoil may act as a capillary barrier to infiltration, thereby promoting desiccation of the underlying compacted till. Percolation through the cover was measured using lysimeters filled with 5-16 cm (2-6 in.) diameter stone placed directly underneath the compacted till. Though the field lysimeters report water and laboratory tests show no evidence of flow partitioning between coarse stone and gravel, two-dimensional unsaturated-saturated liquid flow modelling of the lysimeter-cover interaction predicts that the lysimeters should not report significant water. Phenomena not simulated by the modelling, which include macrostructure flow in the barrier soil, trickle flow in the coarse stone, and vapour diffusion, are investigated and discussed. Consideration of vapour flow yields results that are inconsistent with the predictions of the liquid flow modelling. Key words: capillary barrier, lysimeters, soil covers, unsaturated flow, vapour flow.

scholarly journals THE EQUILIBRIUM BETWEEN CYTOCHROME OXIDASE AND CARBON MONOXIDE

1957 ◽  
Vol 40 (4) ◽  
pp. 593-608 ◽  
Author(s):  
George Wald ◽  
David W. Allen
Keyword(s):  
Carbon Monoxide ◽  
Cytochrome Oxidase ◽  
Hill Equation ◽  
Bohr Effect ◽  
Degree Of Saturation ◽  
Percentage Saturation ◽  
Equilibrium Function ◽  
Hyperbolic Equilibrium ◽  
High Degree ◽  
The Hill

An evolution argument which attempted to trace the development of hemoglobins from such respiratory pigments as cytochrome oxidase presupposed that the latter possesses, in addition to its high affinity for oxygen, an approximately hyperbolic equilibrium function, and little if any Bohr effect (decline in affinity for oxygen with rise in acidity). Since cytochrome oxidase, unlike hemoglobin, is irreversibly oxidized by oxygen, the present experiments examine its combination with carbon monoxide, with which, like hemoglobin, it yields a true equilibrium. In all known hemoglobins the form of the equilibrium function and the vigor of the Bohr effect are similar with carbon monoxide and with oxygen, so that observations involving the former gas are relevant to the relations of the latter. The equilibrium function of cytochrome oxidase with carbon monoxide—percentage saturation vs. partial pressure of CO—is slightly inflected (in the Hill equation n = 1.26; for a hyperbola, n = 1). No Bohr effect is present in the range of pH 7–8. The pressure of carbon monoxide at which half-saturation occurs (p50) is about 0.17 mm. at 10–13°C. The affinity for carbon monoxide is therefore higher than commonly supposed. These properties are consistent with the evolution argument. They are important also for the physiological functioning of cytochrome oxidase, the nearly hyperbolic equilibrium function facilitating a high degree of saturation, and the lack of Bohr effect making this enzyme impervious to hyperacidity. The slight inflection of the equilibrium function shows that the Fe-porphyrin units of cytochrome oxidase interact to a degree, hence that the enzyme must contain more than one such unit per molecule. It is suggested that in cytochrome oxidase two Fe-porphyrin groups may unite with one oxygen in the manner Fe++-O2-Fe++; and that the evolution of hemoglobins proceeded over a first stage in which the hemes were separated so that each combines with only one molecule of oxygen, so tending to remain reduced; to a further stage in which the separated hemes interact through the protein to facilitate one another in combining with oxygen.

Arsenic mobility in weathered gold mine tailings under a low-organic soil cover

2017 ◽  
Vol 76 (22) ◽  
Author(s):  
Stephanie L. DeSisto ◽  
Heather E. Jamieson ◽  
Michael B. Parsons
Keyword(s):  
Mine Tailings ◽  
Soil Cover ◽  
Organic Soil ◽  
Gold Mine ◽  
Arsenic Mobility ◽  
Gold Mine Tailings
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