Geochemical Stability of Oil Sands Tailings in Mine Closure Landforms

Oil sands surface mining in Alberta has generated over a billion cubic metres of waste, known as tailings, consisting of sands, silts, clays, and process-affected water that contains toxic organic compounds and chemical constituents. All of these tailings will eventually be reclaimed and integrated into one of two types of mine closure landforms: end pit lakes (EPLs) or terrestrial landforms with a wetland feature. In EPLs, tailings deposits are capped with several metres of water while in terrestrial landforms, tailings are capped with solid materials, such as sand or overburden. Because tailings landforms are relatively new, past research has heavily focused on the geotechnical and biogeochemical characteristics of tailings in temporary storage ponds, referred to as tailings ponds. As such, the geochemical stability of tailings landforms remains largely unknown. This review discusses five mechanisms of geochemical change expected in tailings landforms: consolidation, chemical mass loading via pore water fluxes, biogeochemical cycling, polymer degradation, and surface water and groundwater interactions. Key considerations and knowledge gaps with regard to the long-term geochemical stability of tailings landforms are identified, including salt fluxes and subsequent water quality, bioremediation and biogenic greenhouse gas emissions, and the biogeochemical implications of various tailings treatment methods meant to improve geotechnical properties of tailings, such as flocculant (polyacrylamide) and coagulant (gypsum) addition.

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METHANE EBULLITION CAN INFLUENCE INTERNAL MASS LOADING IN OIL SANDS END PIT LAKES

10.1130/abs/2019am-334343 ◽

2019 ◽

Author(s):

Daniel Francis ◽

◽

Matthew B.J. Lindsay ◽

Lee Barbour

Keyword(s):

Oil Sands ◽

Internal Mass ◽

Mass Loading ◽

Pit Lakes ◽

Methane Ebullition

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Quantification of methane sources in the Athabasca Oil Sands Region of Alberta by aircraft mass balance

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-7361-2018 ◽

2018 ◽

Vol 18 (10) ◽

pp. 7361-7378 ◽

Cited By ~ 17

Author(s):

Sabour Baray ◽

Andrea Darlington ◽

Mark Gordon ◽

Katherine L. Hayden ◽

Amy Leithead ◽

...

Keyword(s):

Mass Balance ◽

Oil Sands ◽

Surface Mining ◽

Open Pit ◽

Emission Rates ◽

Athabasca Oil Sands ◽

Emissions Inventory ◽

Athabasca Oil Sands Region ◽

Major Surface ◽

Tailings Ponds

Abstract. Aircraft-based measurements of methane (CH4) and other air pollutants in the Athabasca Oil Sands Region (AOSR) were made during a summer intensive field campaign between 13 August and 7 September 2013 in support of the Joint Canada–Alberta Implementation Plan for Oil Sands Monitoring. Chemical signatures were used to identify CH4 sources from tailings ponds (BTEX VOCs), open pit surface mines (NOy and rBC) and elevated plumes from bitumen upgrading facilities (SO2 and NOy). Emission rates of CH4 were determined for the five primary surface mining facilities in the region using two mass-balance methods. Emission rates from source categories within each facility were estimated when plumes from the sources were spatially separable. Tailings ponds accounted for 45 % of total CH4 emissions measured from the major surface mining facilities in the region, while emissions from operations in the open pit mines accounted for ∼ 50 %. The average open pit surface mining emission rates ranged from 1.2 to 2.8 t of CH4 h−1 for different facilities in the AOSR. Amongst the 19 tailings ponds, Mildred Lake Settling Basin, the oldest pond in the region, was found to be responsible for the majority of tailings ponds emissions of CH4 (> 70 %). The sum of measured emission rates of CH4 from the five major facilities, 19.2 ± 1.1 t CH4 h−1, was similar to a single mass-balance determination of CH4 from all major sources in the AOSR determined from a single flight downwind of the facilities, 23.7 ± 3.7 t CH4 h−1. The measured hourly CH4 emission rate from all facilities in the AOSR is 48 ± 8 % higher than that extracted for 2013 from the Canadian Greenhouse Gas Reporting Program, a legislated facility-reported emissions inventory, converted to hourly units. The measured emissions correspond to an emissions rate of 0.17 ± 0.01 Tg CH4 yr−1 if the emissions are assumed as temporally constant, which is an uncertain assumption. The emission rates reported here are relevant for the summer season. In the future, effort should be devoted to measurements in different seasons to further our understanding of the seasonal parameters impacting fugitive emissions of CH4 and to allow for better estimates of annual emissions and year-to-year variability.

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Using carbon-14 and carbon-13 measurements for source attribution of atmospheric methane in the Athabasca Oil Sands Region

10.5194/acp-2021-622 ◽

2021 ◽

Author(s):

Regina Gonzalez Moguel ◽

Felix Vogel ◽

Sébastien Ars ◽

Hinrich Schaefer ◽

Jocelyn Turnbull ◽

...

Keyword(s):

Oil Sands ◽

Surface Mining ◽

Atmospheric Methane ◽

Source Attribution ◽

Athabasca Oil Sands ◽

Ch4 Emissions ◽

Athabasca Oil Sands Region ◽

Carbon 14 ◽

Isotopic Characterization ◽

Tailings Ponds

Abstract. The rapidly expanding and energy intensive production from the Canadian oil sands, one of the largest oil reserves globally, accounts for almost 12 % of Canada’s greenhouse gas emissions according to inventories. Developing approaches for evaluating reported methane (CH4) emission is crucial for developing effective mitigation policies, but only one study has characterized CH4 sources in the Athabasca Oil Sands Region (AOSR). We tested the use of 14C and 13C carbon isotope measurements in ambient CH4 from the AOSR to estimate source contributions from key regional CH4 sources: (1) tailings ponds, (2) surface mines and processing facilities, and (3) wetlands. The isotopic signatures of ambient CH4 indicate that the CH4 enrichments measured at the site were mainly influenced by fossil CH4 emissions from surface mining and processing facilities (53 ± 18 %), followed by fossil CH4 emissions from tailings ponds (36 ± 18 %), and to a lesser extent by modern CH4 emissions from wetlands (10 < 1 %). Our results confirm the importance of tailings ponds in regional CH4 emissions and show that this method can successfully separate wetland CH4 emissions. In the future, the isotopic characterization of CH4 sources, and measurements from different seasons and wind directions are needed to provide a better source attribution in the AOSR.

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A Review about the Sustainability of Pit Lakes as a Rehabilitation Factor after Mine Closure

Materials Proceedings ◽

10.3390/materproc2021005052 ◽

2021 ◽

Vol 5 (1) ◽

pp. 52

Author(s):

Chara Sakellari ◽

Christos Roumpos ◽

Georgios Louloudis ◽

Eleni Vasileiou

Keyword(s):

Water Management ◽

Dynamic Systems ◽

Surface Mining ◽

Research Problem ◽

Mining Activities ◽

Mine Closure ◽

Mine Water Management ◽

Pit Lakes ◽

Challenging Research ◽

Mining Regions

At the end of surface mining activities, the remnant voids are of great concern regarding rehabilitating the final open pits. The investigation of the sustainability of pit lakes in post-mining regions constitutes a challenging research problem. This paper aims to highlight the effectiveness of pit lakes as a rehabilitation factor. In this framework, several cases worldwide and in Greece were examined in detail and evaluated. The results indicate that mine pit lakes must be evaluated as dynamic systems, natural or artificial, which demand rational mine water management to ensure their sustainability. Specifically in Greece, it is of great importance during the transition to the post-lignite era.

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Effects of Calcium and Aluminum on Particle Settling in an Oil Sands End Pit Lake

Mine Water and the Environment ◽

10.1007/s10230-021-00808-9 ◽

2021 ◽

Author(s):

Kai Wei ◽

Heidi L. Cossey ◽

Ania C. Ulrich

Keyword(s):

Surface Water ◽

Oil Sands ◽

Surface Mining ◽

Pit Lake ◽

Particle Settling ◽

Pit Lakes ◽

Fine Tailings ◽

High Turbidity ◽

Fluid Fine Tailings ◽

Al Treatment

AbstractSurface mining of oil sands ore in Alberta, Canada has generated fluid fine tailings (FFT) that must be reclaimed. End pit lakes (EPLs), which consist of thick deposits of FFT capped with water, have been proposed for FFT reclamation, and Base Mine Lake (BML) is the first full-scale demonstration EPL. However, FFT particle settling and resuspension contributes to high turbidity in the BML water cap, which may be detrimental to the development of an aquatic ecosystem. This study investigated the effect of Ca and Al treatments on turbidity mitigation. The initial turbidity was reduced from 20 NTU to less than 2 NTU in BML surface water treated with 54 mg/L of Ca or 1.1 mg/L of Al. At a concentration of 1.1 mg/L, Al reduced the initial turbidity to a greater extent, and in a shorter time, than 54 mg/L of Ca. Further, resuspended Al-treated FFT particles were 100–700 nm larger in diameter, and thus resettled faster than the resuspended untreated or Ca-treated FFT particles. The final turbidity values 21 days after resuspension of untreated and 1.7 mg/L Al-treated FFT particles in fresh BML surface water were 20.5 NTU and 2.5 NTU, respectively. Thus, Al treatment may be effective in mitigating turbidity in BML through both Al-induced coagulation and self-weight settling of the resuspended Al-treated FFT particles.

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Temperature, Precipitation, and Lightning Modification in the Vicinity of the Athabasca Oil Sands

Earth Interactions ◽

10.1175/2011ei412.1 ◽

2011 ◽

Vol 15 (32) ◽

pp. 1-14 ◽

Cited By ~ 4

Author(s):

Daniel M. Brown ◽

Gerhard W. Reuter ◽

Thomas K. Flesch

Keyword(s):

Boreal Forest ◽

Oil Sands ◽

Waste Heat ◽

Surface Mining ◽

Open Pit ◽

Athabasca Oil Sands ◽

Open Pit Mines ◽

Lightning Strikes ◽

The Past ◽

Tailings Ponds

Abstract The Athabasca oil sands development in northeast Alberta, Canada, has disturbed more than 500 km2 of boreal forest through surface mining and tailings ponds development. In this paper, the authors compare the time series of temperatures and precipitation measured over oil sands and non–oil sands locations from 1994 to 2010. In addition, they analyzed the distribution of lightning strikes from 1999 to 2010. The oil sands development has not affected the number of lightning strikes or precipitation amounts but has affected the temperature regime. Over the past 17 years, the summer overnight minimum temperatures near the oil sands have increased by about 1.2°C compared to the regional average. The authors speculate that this is caused by a combination of the industrial addition of waste heat to the atmosphere above the oil sands and changing the surface type from boreal forest to open pit mines with tailings ponds.

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The Right and the Good: Communicating Environmental Issues

Earth Common Journal ◽

10.31542/j.ecj.180 ◽

2014 ◽

Vol 4 (1) ◽

Author(s):

Goldwin Edison McEwen

Keyword(s):

Oil Sands ◽

Environmental Issues ◽

Natural World ◽

Critical Areas ◽

Pros And Cons ◽

Global Concern ◽

The Right ◽

Duty To Inform ◽

Tailings Ponds

What we see is partially dependent on what we are shown. As communicators, we have a duty to inform and educate and lead. As environmental communicators we have the privilege of explaining how the various parts of our natural world work, individually, in unison, and in relationship to people. By examining two specific areas of growing global concerns, this paper provides an analytic tool and starts a discussion as to what should be guiding decisions concerning major environmental questions. The first growing global concern discussed is tailings ponds in Northern Alberta’s oil sands. The second is the large bodies of air pollution in Asia. In both cases, (Good) short term decisions that benefit a few have led to large environmental concerns. Should humanity be worried about our future? Could (Right) long-term, sustainable, and inclusive decisions lead to more manageable environmental challenges? To be a communicator in the real world it is important to know and differentiate between the Good and the Right. Good and Right communications in environmental issues support daily or frequent acts concerning any or all of three critical areas: sustainability, conservation, and climate change. Questions are addressed. Where are people now with respect to environment, how did we get here, and what are the pros and cons of changing from Good to Right solutions? By looking at one individual’s choice, readers see that Good and Right decisions do not have to be mutually exclusive.

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Quantification of Methane Sources in the Athabasca Oil Sands Region of Alberta by Aircraft Mass-Balance

10.5194/acp-2017-925 ◽

2017 ◽

Author(s):

Sabour Baray ◽

Andrea Darlington ◽

Mark Gordon ◽

Katherine L. Hayden ◽

Amy Leithead ◽

...

Keyword(s):

Mass Balance ◽

Oil Sands ◽

Surface Mining ◽

Open Pit ◽

Emission Rates ◽

Athabasca Oil Sands ◽

Emissions Inventory ◽

Athabasca Oil Sands Region ◽

Major Surface ◽

Tailings Ponds

Abstract. Aircraft-based measurements of methane (CH4) and other air pollutants in the Athabasca Oil Sands Region (AOSR) were made during a summer intensive field campaign between August 13 and September 7 2013, in support of the Joint Canada–Alberta Implementation Plan for Oil Sands Monitoring. Chemical signatures were used to identify CH4 sources from tailings ponds (BTEX VOC's), open-pit surface mines (NOy and rBC) and elevated plumes from bitumen upgrading facilities (SO2 and NOy). Emission rates of CH4 were determined for the five primary surface mining facilities in the region using two mass balance methods. Emission rates from source categories within each facility were estimated when plumes from the sources were spatially separable. Tailings ponds accounted for 45 % of total CH4 emissions measured from the major surface mining facilities in the region while emissions from operations in the open pit mines accounted for ~ 50 %. The average open pit surface mining emission rates ranged from 1.2 to 2.8 tonnes of CH4 hr−1 for different facilities in the AOSR. Amongst the 19 tailings ponds, Mildred Lake Settling Basin, the oldest pond in the region, was found to be responsible for the majority of tailings ponds emissions of CH4 (> 70 %). The sum of measured emission rates of CH4 from the five major facilities, 19.2 ± 1.1 tonnes CH4 hr−1, was similar to a single mass balance determination of CH4 from all major sources in the AOSR determined from a single flight downwind of the facilities, 23.7 ± 3.7 tonnes CH4 hr−1. The measured hourly CH4 emission rate from all facilities in the AOSR is 48 ± 8 % higher than that extracted for 2013 from the Canadian Green House Gas Reporting Program, a legislated facility-reported Emissions Inventory, converted to hourly units. The measured emissions correspond to an emissions rate of 0.17 ± 0.01 Tg CH4 yr−1, if the emissions are assumed temporally constant, an uncertain assumption. The emission rates reported here are relevant for the summer season. In future, effort should be devoted to measurements in different seasons to further our understanding of seasonal parameters impacting fugitive emissions of CH4 and to allow better estimates of annual emissions and year to year variability.

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