Oxygen diffusion and consumption in low-sulphide tailings covers

2009 ◽  
Vol 46 (4) ◽  
pp. 454-469 ◽  
Author(s):  
Isabelle Demers ◽  
Bruno Bussière ◽  
Mamert Mbonimpa ◽  
Mostafa Benzaazoua
Keyword(s):  
Water Table ◽  
Oxygen Diffusion ◽  
Mine Drainage ◽  
Effective Diffusion ◽  
Single Layer ◽  
Attractive Alternative ◽  
Sulphide Tailings ◽  
Elevated Water ◽  
Acid Mine Drainage Generation ◽  
Cover Thickness

Acid-generating tailings can be reclaimed using oxygen barrier covers in humid climates, such as in Quebec. A single-layer low-sulphide tailings cover is an attractive alternative to traditional water covers to maximize the impoundment’s storage capacity. Low-sulphide tailings can serve as a moisture-retaining material to limit oxygen diffusion, and their residual sulphides can consume the diffusive oxygen that still gets through the cover. A laboratory experiment using instrumented columns was initiated to confirm the efficiency of a low-sulphide tailings monolayer cover placed over acid-generating tailings to reduce the oxygen flux reaching the reactive tailings. Oxygen concentration profiles were measured over the thickness of the cover and oxygen fluxes were calculated to evaluate the effect of three parameters on these fluxes: water table level, cover sulphide content, and cover thickness. Oxygen fluxes at the bottom of the low-sulphide tailings cover layer, calculated using oxygen gradient and estimated effective diffusion coefficient and predicted using Vadose/W, were lower than 1.5 mol·m−2·year−1. These results suggest that a low-sulphide tailings cover with an elevated water table can reduce oxygen migration and potentially limit acid mine drainage generation.

Laboratory study of low-sulfide tailings covers with elevated water table to prevent acid mine drainage

2020 ◽  
Vol 57 (12) ◽  
pp. 1998-2009
Author(s):  
Nicolas J. Rey ◽  
Isabelle Demers ◽  
Bruno Bussière ◽  
Mamert Mbonimpa
Keyword(s):  
Water Table ◽  
Mine Drainage ◽  
Degree Of Saturation ◽  
Water Table Level ◽  
Elevated Water Table ◽  
Oxygen Migration ◽  
Elevated Water ◽  
Oxygen Ingress ◽  
Sulfide Tailings ◽  
Cover Thickness

The use of monolayer covers combined with an elevated water table (EWT) is a promising reclamation method that relies on the low gas-diffusivity of water to limit oxygen ingress into potentially acid-generating tailings. A monolayer cover is installed over the sulfidic material and the water table level is controlled to maintain the tailings close to saturation. A protocol including laboratory columns was conducted to evaluate the sensitivity of the technique to parameters including cover thickness, water table level, and the presence of an anti-evaporation layer. Two types of desulfurized tailings were evaluated: silty tailings from Westwood mine and sandy tailings from Goldex mine. Data used to evaluate the covers performances included volumetric water content, suction, oxygen concentrations, and oxygen consumption. Results showed that both cover materials could be used to maintain the reactive tailings at a degree of saturation ≥90% when the EWT level was maintained at a maximum distance of 1 m below the tailings surface. The finer Westwood material showed a better capacity for limiting oxygen migration through the cover, with a maximum flux of 5.7 mol·m−2·year−1 measured near the cover base.

Preventing Acid Mine Drainage with an Elevated Water Table: Long-Term Column Experiments and Parameter Analysis

2010 ◽  
Vol 213 (1-4) ◽  
pp. 437-458 ◽  
Author(s):  
Mariam Ouangrawa ◽  
Michel Aubertin ◽  
John W. Molson ◽  
Bruno Bussière ◽  
Gérald J. Zagury
Keyword(s):  
Acid Mine Drainage ◽  
Water Table ◽  
Mine Drainage ◽  
Parameter Analysis ◽  
Column Experiments ◽  
Acid Mine ◽  
Elevated Water Table ◽  
Elevated Water

In situ evaluation of performance of reclamation measures implemented on abandoned reactive tailings disposal site

2018 ◽  
Vol 55 (12) ◽  
pp. 1742-1755 ◽  
Author(s):  
Marie-Pier Ethier ◽  
Bruno Bussière ◽  
Michel Aubertin ◽  
Abdelkabir Maqsoud ◽  
Isabelle Demers ◽  
...  
Keyword(s):  
Water Table ◽  
Mine Drainage ◽  
Current System ◽  
Field Investigation ◽  
Performance Criteria ◽  
Disposal Site ◽  
Tailings Disposal ◽  
Water Table Level ◽  
Evaluation Of Performance ◽  
Elevated Water

The abandoned Manitou mine site produced acid mine drainage for decades. One of the site’s tailings storage facilities (TSF 2) was reclaimed in 2009 using an elevated water table combined with a monolayer cover made of low-sulphur tailings. A field investigation was undertaken from 2012 to 2015 to verify the performance of the reclamation technique in stemming the production of contaminants. This verification is based on two main criteria, i.e., the minimum water table level and maximum oxygen flux reaching the Manitou tailings. Thirteen monitoring stations were installed in TSF 2. The hydrogeological behavior and oxygen migration were investigated at each station by measuring volumetric water content, suction, water table level, gaseous pore oxygen concentration, and oxygen consumption. Analyses of field data showed that the minimum water table level criterion was reached with the exception of a portion of TSF 2 during the summer months. Oxygen fluxes reaching the Manitou tailings were determined using numerical simulations and analytical solutions; their yearly mean was many times lower than maximum targets generally used on reclaimed tailings disposal areas. The current system met the targeted performance criteria over the studied period.

Evaluation of a single-layer desulphurized tailings cover

2013 ◽  
Vol 50 (7) ◽  
pp. 777-792 ◽  
Author(s):  
Bonnie Dobchuk ◽  
Craig Nichol ◽  
G. Ward Wilson ◽  
Michel Aubertin
Keyword(s):  
Oxygen Diffusion ◽  
Unsaturated Flow ◽  
Water Saturation ◽  
Effective Diffusion ◽  
Single Layer ◽  
High Water ◽  
Degree Of Saturation ◽  
Rate Coefficients ◽  
Oxygen Penetration ◽  
Oxygen Ingress

The potential effectiveness for long-term closure of a desulphurized tailings cover placed on reactive tailings at the Detour Lake Mine was assessed. The single-layer cover was aimed at reducing oxygen ingress using high water saturation to limit oxygen diffusion and consumption of oxygen in the cover by residual sulphide minerals. The cover was 1.0 to 1.5 m thick and met desulphurization targets, but was coarser grained than the design. One-dimensional unsaturated flow and oxygen diffusion modelling was used to predict water content profiles, depth of oxygen penetration, and diffusive oxygen fluxes. Effective diffusion and reaction rate coefficients estimated from field data matched laboratory measurements. Depth to water table was identified as the most important factor for reducing tailings oxidation. The deeper (4 m) water tables measured at the cover edges led to a lower degree of saturation and higher oxygen flux. Finer grain size and higher air-entry values in the cover materials helped maintain saturation, and a capillary break (fine over coarse) cover reduced oxygen fluxes to <5% of fluxes to uncovered tailings. The as-built cover (coarse over fine) reduced oxygen influx by at most 50% and as low as <1% of uncovered tailings.

Simulating the effect of climate change on the performance of a monolayer cover combined with an elevated water table placed on acid generating mine tailings

2021 ◽  
Author(s):  
Elodie Lieber ◽  
Isabelle Demers ◽  
Thomas Pabst ◽  
Émilie Bresson
Keyword(s):  
Climate Change ◽  
Water Table ◽  
Mine Drainage ◽  
Oxygen Flux ◽  
Climate Change Scenarios ◽  
Local Conditions ◽  
Elevated Water Table ◽  
Elevated Water ◽  
The Impact ◽  
Monolayer Cover

Several reclamation approaches were developed in the last decades to control acid mine drainage from tailings storage facilities, including the monolayer cover combined with an elevated water table. Its performance is dependent on water table elevation and tailings saturation, and is directly affected by climatic conditions, therefore climate change needs to be taken into account to design resilient reclamation systems. The objective of this research was to evaluate three approaches to simulate climate change and compare the impact on reclamation performance up to year 2100. Numerical simulations were calibrated using experimental field data and future weather conditions were established based on three climate change scenarios adapted for local conditions. Results showed that the projected impact of climate change varied depending on the approach used. Simpler and more conservative approaches indicated that reclamation would eventually fail following an increase of droughts during future summers. However, 80-year simulations showed that reclamation failures (evaluated as oxygen flux) could be limited to a few isolated summers and that a well-designed monolayer cover with elevated water table appeared to remain efficient in the long-term. Overall, the probability to exceed the oxygen flux target of 1 mol/m2/y did not exceed 2% for the simulated conditions.

scholarly journals Surface and subsurface flow effect on permanent gully formation and upland erosion near Lake Tana in the northern highlands of Ethiopia

2010 ◽  
Vol 14 (11) ◽  
pp. 2207-2217 ◽  
Author(s):  
T. Y. Tebebu ◽  
A. Z. Abiy ◽  
A. D. Zegeye ◽  
H. E. Dahlke ◽  
Z. M. Easton ◽  
...  
Keyword(s):  
Water Table ◽  
Gully Erosion ◽  
Grazing Land ◽  
Cross Sectional ◽  
Lake Tana ◽  
Erosion Rates ◽  
Remotely Sensed Imagery ◽  
Reservoir Siltation ◽  
Upland Erosion ◽  
Elevated Water

Abstract. Gully formation in the Ethiopian Highlands has been identified as a major source of sediment in water bodies, and results in sever land degradation. Loss of soil from gully erosion reduces agricultural productivity and grazing land availability, and is one of the major causes of reservoir siltation in the Nile Basin. This study was conducted in the 523 ha Debre-Mawi watershed south of Bahir Dar, Ethiopia, where gullies are actively forming in the landscape. Historic gully development in a section of the Debre-Mawi watershed was estimated with semi structured farmer interviews, remotely sensed imagery, and measurements of current gully volumes. Gully formation was assessed by instrumenting the gully and surrounding area to measure water table levels and soil physical properties. Gully formation began in the late 1980's following the removal of indigenous vegetation, leading to an increase in surface and subsurface runoff from the hillsides. A comparison of the gully area, estimated from a 0.58 m resolution QuickBird image, with the current gully area mapped with a GPS, indicated that the total eroded area of the gully increased from 0.65 ha in 2005 to 1.0 ha in 2007 and 1.43 ha in 2008. The gully erosion rate, calculated from cross-sectional transect measurements, between 2007 and 2008 was 530 t ha−1 yr−1 in the 17.4 ha area contributing to the gully, equivalent to over 4 cm soil loss over the contributing area. As a comparison, we also measured rill and interrill erosion rates in a nearby section of the watershed, gully erosion rates were approximately 20 times the measured rill and interrill rates. Depths to the water table measured with piezometers showed that in the actively eroding sections of the gully the water table was above the gully bottom and, in stable gully sections the water table was below the gully bottom during the rainy season. The elevated water table appears to facilitate the slumping of gully walls, which causes the gully to widen and to migrate up the hillside.

The effects of a permanently elevated water table in an acid sulphate soil on reed canary grass for combustion

2013 ◽  
Vol 375 (1-2) ◽  
pp. 149-158 ◽  
Author(s):  
Kenedy E. Epie ◽  
Seija Virtanen ◽  
Arja Santanen ◽  
Asko Simojoki ◽  
Frederick L. Stoddard
Keyword(s):  
Water Table ◽  
Reed Canary Grass ◽  
Acid Sulphate Soil ◽  
Acid Sulphate ◽  
Elevated Water Table ◽  
Canary Grass ◽  
Elevated Water

Spatial patterns of aerobic limit depth and oxygen diffusion rate at two peatlands drained for forestry in Alberta

1999 ◽  
Vol 29 (1) ◽  
pp. 53-61 ◽  
Author(s):  
U Silins ◽  
R L Rothwell
Keyword(s):  
Spatial Variability ◽  
Water Table ◽  
Spatial Patterns ◽  
Oxygen Diffusion ◽  
Diffusion Rate ◽  
Drainage Ditches ◽  
Soil Aeration ◽  
Rooting Zone ◽  
Capillary Zone ◽  
Oxygen Diffusion Rate

The spatial variability of soil aeration (aerobic limit depth and oxygen diffusion rate (ODR)) among different drainage ditch spacings and at various distances from drainage ditches was examined at two peatlands drained for forestry in north-central Alberta. Drainage lowered mean water table levels (p < 0.001) at both peatlands. Lower water table levels within drained areas were associated with greater aerobic limit depths (p < 0.001) and greater ODR (p < 0.001 at Saulteaux River; p < 0.027 at Wolf Creek) compared with undrained areas of both peatlands. Spatial patterns of aerobic limit depth and ODR indicated strong spatial variability of soil aeration in the immediate vicinity of drainage ditches. However, little sensitivity of soil aeration to different ditch spacings was evident. Potential effects of post-drainage subsidence on soil aeration was evident as increased distance of both the aerobic limit, and near-zero oxygen diffusion rates above the water table surface at both peatlands. One effect of post-drainage peatland subsidence may be to increase the thickness of the capillary zone above the water table. However, reduction of aeration within the rooting zone of peatland trees due to subsidence was not observed because of low water tables within the drained areas of both peatlands.

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