Post-closure investigation of engineered test covers on acid-generating waste rock at Whistle Mine, Ontario

Adu-Wusu, Celestina; Yanful, Ernest K.

doi:10.1139/t06-132

Cited by 18 publications

(7 citation statements)

References 10 publications

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“…The saturated hydraulic conductivity (K sat ) of the sandy silt material was measured in the laboratory to be 6 · 10 -8 m/s using both the fixed wall and flexible wall apparatus (ASTM 5084-00). This value was similar to in situ values measured using a Guelph Permeameter (Meiers 2002;Adu-Wusu and Yanful 2005). The unsaturated hydraulic conductivity function was derived from the measured K sat and the Fredlund and Xing (1994) functions.…”

Section: Soil Datasupporting

confidence: 81%

“…According to model predictions, the actual and potential evaporation were the same in the fall and spring months, with actual evaporation in the summer being 74% of potential evaporation. This would indicate a saturated soil surface during the fall and spring months, consistent with increased percolation and soil water storage trends in both the model results and measured data (Adu-Wusu and Yanful 2005).…”

Section: Evaporationsupporting

confidence: 77%

“…The unsaturated hydraulic conductivity function was derived from the measured K sat and the Fredlund and Xing (1994) functions. The K sat of the GCL specified by the manufacturer was 5 · 10 -11 m/s, however, as modeling progressed, this value was increased by two orders of magnitude to account for GCL deterioration resulting from freeze-thaw effects (Adu-Wusu and Yanful 2005). Samples of the GCL were excavated and tested in the laboratory for their hydraulic conductivity.…”

Section: Soil Datamentioning

confidence: 99%

“…In situ field hydraulic conductivity tests measured using the Guelph permeameter (Meiers 2002) on the sandy silt barrier gave hydraulic conductivity values ranging from 4.7 · 10 -8 m/s to 7.9 · 10 -7 m/s. Also post monitoring excavation of the barrier revealed a badly fractured barrier and the presence of sand and gravel lenses with estimated average hydraulic conductivity of 1.5 · 10 -4 m/s (Adu-Wusu and Yanful 2005). The SWCC used for the sandy silt barrier was measured in the laboratory on intact and homogeneous samples, which would be different and would not account for the imperfections present in the field.…”

Section: Tp#3-sandy Silt Barriermentioning

confidence: 99%

“…The manufacturer's hydraulic conductivity value of 5 · 10 -11 m/s was increased by two orders of magnitude to 7 · 10 -9 m/s to account for the increase in hydraulic conductivity of the GCL as a result of freeze-thaw effects (Adu-Wusu and Yanful 2005). Samples of the GCL were recovered from the field in 2004 and the average hydraulic conductivity measured in the laboratory was 5.0 · 10 -9 (Adu-Wusu and Yanful 2005). Hence model predictions of percolation were compared to field percolation measured through the GCL barrier in the period 2003-2004.…”

Section: Tp#1-gcl Barriermentioning

confidence: 99%

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Prediction of the water balance of two soil cover systems

et al. 2006

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Soil cover systems are widely used for containment of municipal solid waste, hazardous and mine waste, with the objective of limiting the ingress of precipitation and oxygen. The ability to predict their long-term performance is crucial, as their failure would result in the release of contaminants to the environment. However, monitoring covers over the long term to derive the information needed to aid in design is impractical and there are no large-scale covers that have been in use for a long enough period to generate the data needed. Numerical models have been particularly useful as design tools. To improve their reliability these models may be calibrated to field data and then used to make long-term predictions of cover performance. The field performance of two resistive test soil covers on a 20% sloping waste rock platform is predicted using the two-dimensional soil-atmosphere model Vadose/W. Input data for the model included soil, climate and vegetation data obtained either in the field or laboratory. Model results were compared to field data to assess the validity of the program. The model reasonably simulated field response patterns for soil water storage and suction. Divergence between field performance data and model predictions were significantly influenced by snowmelt, interflow and flow through preferential pathways.

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Section: Soil Datasupporting

confidence: 81%

Section: Evaporationsupporting

confidence: 77%

Section: Soil Datamentioning

confidence: 99%

Section: Tp#3-sandy Silt Barriermentioning

confidence: 99%

Section: Tp#1-gcl Barriermentioning

confidence: 99%

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Prediction of the water balance of two soil cover systems

et al. 2006

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Geräteausstattung von Abdichtungsschichten aus zwei verschiedenen Zusatzstoffen (Grünlauge und Bentonit) auf Geschiebemergel für die Rekultivierung von sulfidischen Bergbauabfällen

Nigéus,

Maurice,

Lindblom

2023

Mine Water Environ

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In Sweden, a dry cover solution is commonly used to stop sulfide oxidation and the production of acid rock drainage from unattended sulfidic mine waste. Recycling a non-hazardous industrial residue, such as green liquor dregs (GLD) generated during pulp production, in this cover solution is beneficial for both the mining industry where there is a great need for cover materials and the pulp production industry. The objectives of this field study were to install and evaluate the instrumentation of sealing layers made of GLD- and bentonite-amended till, and to evaluate the practical aspects of two different methods of installation: monitoring wells and pits. This practical field study demonstrated that it is difficult to properly seal the drill holes after installing the probes in observation wells and suggests that a better (easier and less costly) alternative for future instrument installation in a sealing layer might be to excavate a pit in the protective layer after installation of the soil cover and then drill the probes into the sealing layer from that pit.

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Monitoring and Modeling of Sand-Bentonite Cover for ARD Mitigation

Qin

Yanful

2007

Water Air Soil Pollut

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This paper deals with field measurements and hydraulic, oxygen transport and geochemical speciation modeling undertaken to evaluate the performance of a sand-bentonite test cover overlying a 20% sloping waste rock platform. A pit run (gravelly sand) layer protected the sand-bentonite layer. The study site was the Whistle Mine near Capreol, Ontario, Canada. The purpose of the study was to evaluate a number of test covers and select a final cover for the decommissioning of 7 million tonnes of acid-generating waste rock at the site. The sand-bentonite test plot and a control plot consisting of waste rock without cover were monitored over 3 years for water content, suction, soil temperature, gaseous oxygen concentrations, and water percolation. Air temperature, rainfall, snow pack and potential evaporation were also monitored. Finite element modeling showed very good agreement between modeled and measured cumulative precipitation, daily potential evaporation and cumulative evaporation, and to a lesser extent, the cumulative water percolation through the test cover. Due to construction difficulties in the field, the back of the waste rock platform was not covered with the test cover. This resulted in oxygen ingress from the back side of the waste rock.Oxygen transport modeling showed that if the entire waste rock pile had been covered, the daily oxygen flux would have been reduced by 90% to only 0.003 g/m 2 /day. Such low oxygen flux would minimize sulphide oxidation and hence acid generation in the waste rock. Aqueous equilibrium speciation modeling suggested that the concentrations of sulphate SO 2À 4 À Á , iron (Fe), and aluminum (Al) in percolate water in contact with waste rock were controlled by secondary minerals such as gypsum, alunite, and ferrihydrite.

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Post-closure investigation of engineered test covers on acid-generating waste rock at Whistle Mine, Ontario

Cited by 18 publications

References 10 publications

Prediction of the water balance of two soil cover systems

Prediction of the water balance of two soil cover systems

Geräteausstattung von Abdichtungsschichten aus zwei verschiedenen Zusatzstoffen (Grünlauge und Bentonit) auf Geschiebemergel für die Rekultivierung von sulfidischen Bergbauabfällen

Monitoring and Modeling of Sand-Bentonite Cover for ARD Mitigation

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