Field Experiments to Test the Elevated Water Table Concept Combined with a Desulfurized Tailings Cover Layer

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.

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Elevated Water Table with Monolayer Covers

Hard Rock Mine Reclamation ◽

10.1201/9781315166698/-8 ◽

2020 ◽

pp. 187-202

Author(s):

Thomas Pabst

Keyword(s):

Water Table ◽

Elevated Water Table ◽

Elevated Water

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Three-dimensional hydrogeological modeling to assess the elevated-water-table technique for controlling acid generation from an abandoned tailings site in Quebec, Canada

Hydrogeology Journal ◽

10.1007/s10040-017-1713-y ◽

2018 ◽

Vol 26 (4) ◽

pp. 1201-1219 ◽

Cited By ~ 13

Author(s):

Marie-Pier Ethier ◽

Bruno Bussière ◽

Stefan Broda ◽

Michel Aubertin

Keyword(s):

Water Table ◽

Three Dimensional ◽

Acid Generation ◽

Elevated Water Table ◽

Elevated Water

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

Canadian Geotechnical Journal ◽

10.1139/cgj-2018-0875 ◽

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.

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

Hydrology and Earth System Sciences ◽

10.5194/hess-14-2207-2010 ◽

2010 ◽

Vol 14 (11) ◽

pp. 2207-2217 ◽

Cited By ~ 94

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.

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Surface and subsurface flow effect on permanent gully formation and upland erosion near Lake Tana in the Northern Highlands of Ethiopia

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-7-5235-2010 ◽

2010 ◽

Vol 7 (4) ◽

pp. 5235-5265 ◽

Cited By ~ 16

Author(s):

T. Y. Tebebu ◽

A. Z. Abiy ◽

H. E. Dahlke ◽

Z. M. Easton ◽

A. D. Zegeye ◽

...

Keyword(s):

Water Table ◽

Crop Yields ◽

Gully Erosion ◽

Rill Erosion ◽

Grazing Land ◽

Lake Tana ◽

Erosion Rates ◽

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 lowers crop yields, reduces 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 of 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 estimates 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 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 quick bird 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 between 2007 and 2008 was 530 t ha-1yr-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 inter-rill erosion rates in a nearby section of the watershed, gully erosion rates were approximately 20 times the measured rill and inter rill 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 facilitates the slumping of gully walls, which causes widening and up-migration on the hillside.

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617 Effects of Nitrogen, Potassium, and Irrigation on Postharvest Pitting of White Grapefruit

HortScience ◽

10.21273/hortsci.34.3.554a ◽

1999 ◽

Vol 34 (3) ◽

pp. 554A-554

Author(s):

Huating Dou ◽

Peter Petracek ◽

Mohamed Ismail ◽

Ashok Alva ◽

David Calvert

Keyword(s):

Soil Moisture ◽

Water Table ◽

Field Experiments ◽

Water Relation ◽

Factorial Combination ◽

Irrigation Regimes ◽

Available Soil Moisture

Effects of N, K, and water relation on the incidence and severity of postharvest pitting in white grapefruit were evaluated in two field experiments. In the first experiment, a factorial combination of 3 N (56, 168, and 336 kg·ha–1) and 3 K (52, 156, and 312 kg·ha–1) rates were used with three broadcast applications per year. In the second experiment, there were two irrigation regimes (at 30% and 60% depletion of available soil moisture, ASM, content) with three subtreatments of variable N and K rates (Kg·ha–1) at 56: 52; 112: 104, and 336: 312 kg·ha–1. The fruit were harvested three times each season, waxed with shellac wax, and stored at 70°F for evaluation of pitting. The pitting incidence was lower at the optimal N and K rates than that at the low or high rates. The irrigation at 30% ASM significantly reduced pitting incidence. The higher incidence of pitting was found in an area in the grove with higher water table. This study suggested that effects of water may play an important role on peel physiology and pitting.

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