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Lesser Slave River No.124 AB
Canada

A lower crustal perspective on the stabilization and reactivation of continental lithosphere in the western Canadian shield


Author(s): Flowers, R. M.

Year: 2005

Abstract:
New geochronological, thermochronological, geological and isotopic data from an extensive (> 20,000 km²) exposure of high-pressure granulites (0.8 to > 1.5 GPa, >750 ⁰C) in the East Lake Athabasca region of the Snowbird tectonic zone provide important constraints on the stabilization, reactivation and exhumation of continental lithosphere in the western Canadian Shield. The exhumed lower crust of this craton comprises several disparate domains that preserve a complex record of tectonic, magmatic and metamorphic processes from formation to exhumation. U-Pb zircon geochronology documents two episodes of metamorphic zircon growth at 2.55 Ga and 1.9 Ga, linked with two high-pressure granulite facies assemblages preserved in Chipman domain mafic granulites. The intervening 650 m.y. of relative quiescence implies a period of lithospheric stability during which the granulites continued to reside in the deep crust. Disruption of the stable Archean craton at 1.9 Ga broadly coincides with the assembly of the Laurentian supercontinent. The correlation of 1.9 Ga mafic magmatism and metamorphism in the Chipman domain with contemporaneous mafic magmatism along > 1200 km strike-length of the Snowbird tectonic zone indicates that regional asthenospheric upwelling was an important aspect of this reactivation event. (cont.) UL-Pb (titanite, apatite, rutile), ⁴⁰Ar/³⁹Ar (hornblende, muscovite, apatite) and (U-Th)/He (zircon, apatite) thermochronometry documents the cooling history of domains in the East Lake Athabasca region during the 200 m.y. multistage history of unroofing following 1.9 Ga metamorphism. Linkage of reconstructed temperature-time histories with existing pressure-temperature-deformation paths reveals spatial and temporal heterogeneity in exhumation patterns, with domain juxtaposition during episodes of unroofing separated by intervals of crustal residence. Low temperature (U-Th)/He zircon and apatite dates are the oldest reported for terrestrial rocks, and confirm the protracted residence of rocks at shallow (< [or equal to] 2 km) crustal depths following the re-attainment of a stable lithospheric configuration in the western Canadian shield at ca. 1.7 Ga. by Rebecca M. Flowers. Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2005. "September 2005." Includes bibliographical references.

A study to evaluate the performance of reclamation soil covers placed over an oil sands fluid coke deposit


Author(s): Fenske, D.

Year: 2012

Abstract:
Coke, a by-product of petroleum extraction from oil sands, is considered a potential energy source and must be stored within the reclaimed landscape in a manner that allows it to be recovered in the future. Syncrude Canada constructed two instrumented watersheds at the Mildred Lake Settling Basin (tailings management facility) to study the effects of coke in the environment. The watersheds consisted of a “shallow” and a “deep” cover system with nominal thicknesses of 35cm and 100cm, overlying an approximate 5 m thick coke deposit. The two reclamation soil covers were constructed using peat-mineral mix placed over secondary (glacial till). The global objective of this research program was to evaluate the preliminary performance for each of the soil covers with respect to the available water holding capacity (AWHC). The specific objectives were to: a) install additional instrumentation to supplement the existing instrumented watersheds; b) characterize the properties of the covers on each watershed; and c) develop a preliminary, one-dimensional water balance for each watershed. Existing instrumentation on each cover (installed by others) included: a meteorological station; automated soil stations to monitor suction, water content and temperature; and, lysimeters to collect net percolation. Additional instrumentation was installed during this research program to track vertical and horizontal variations in soil conditions and included: access tubes for monitoring water content; temperature sensors; gas sampling points; and, standpipe piezometers to determine depth to the water table. The instrumentation generally performed well, with the exception of the lysimeters which did not appear to measure net percolation accurately. Through the measurement of soil parameters, interpretation of field monitoring data and laboratory testing, the covers were characterized for their relative ability to store water for plant growth. A water balance was determined for each watershed. Evaluation of the covers indicated that neither the deep nor the shallow covers were successful at storing sufficient water necessary for plant growth under dry conditions. However, the deep cover performed better than the shallow cover based on the overall cover performance, likely due to its higher AWHC.

Baseline hydrogeological regime at the intermediate scale AOSTRA Underground Test Facility


Year: 1992

Abstract:
This report presents the baseline hydrogeological regime of formation waters in the Phanerozoic sedimentary succession in an area of approximately 4000 km� (5x8 townships) surrounding the Alberta Oil Sands Technology and Research Authority (AOSTRA) Underground Test Facility (UTF) near Fort McMurray in northeast Alberta. The study was prompted by the AOSTRA plans to expand the Underground Test Facility to a pilot operation. As part of this expansion, it is envisaged to dispose of residual waters by on-site deep well injection. Environment Canada and the Alberta Research Council initiated in 1990 a collaborative study on the effects of deep injection of residual water at the UTF site, with data support and cooperation from AOSTRA. The evaluation of the effects of deep injection of residual water is based on predictive modeling, which requires knowledge of the initial baseline hydrogeological conditions. Previous regional-scale studies of the hydrogeological regime in the sedimentary succession in northeast Alberta are too coarse for the resolution needed for predictive modeling at the UTF site. On the other hand, the data are very scarce and incomplete at the local scale. Thus, an intermediate-scale hydrogeological study is required for the identification and characterization of the hydrostratigraphic units at the UTF site, which form the content of this report. The intermediate-scale hydrostratigraphy around the UTF site is less complex than at the regional scale because of the absence of Lower Elk Point Group halite beds and of extensive pre-Cretaceous erosion of Devonian strata. The sedimentary succession can be broadly divided into four main flow units (aquifers) separated by three barriers (aquitards or aquicludes). The flow of formation waters in the lowermost unit, the Winnipegosis-Basal aquifer, is regional in nature. The formation waters are very saline, with depth related trends. The halite and shale Prairie-Watt Mountain aquiclude separates this aquifer from the Beaverhill Lake aquifer above, which exhibits local flow regime characteristics. The formation water salinity is much fresher, and the flow directions are toward the northeast where the formation waters discharge at outcrop along the Athabasca River and its tributaries. The McMurray-Wabiskaw aquifer also has local flow-regime characteristics, being controlled by the topography and physiography of the area. The bitumen-saturated sands at the McMurray Formation seem to form a strong barrier, separating the flow systems in the Beaverhill Lake below and McMurray-Wabiskaw above, respectively. The shale Clearwater aquitard, overlying the McMurray-Wabiskaw aquifer, appears to be a strong barrier to flow. However, its integrity in places may be questionable because of recent and present-day erosion. The post-Clearwater aquifers of Grand Rapids and Pleistocene strata are of limited extent, with paleo-valleys cutting down in places into the Clearwater aquitard.

Controls on the spatial distribution of soil moisture and solute transport in a sloping reclamation cover


Year: 2008

Abstract:
A detailed field study was conducted to map the spatial distribution of soil moisture and salt transport within a sloping clay-rich reclamation cover overlying a saline-sodic shale overburden landform. The soil moisture data suggest that: lower-slope positions are wetter in spring due to the down-slope movement of surface run-off; infiltration occurs via preferential flow paths while the ground is frozen; and, interflow occurs along the cover–shale surface when the ground thaws. Soil moisture conditions also remain wetter in lower-slope positions throughout the summer and fall. Salt transport from the shale into the overlying cover is affected predominantly by soil moisture conditions and lateral groundwater flux. Quasi one-dimensional modelling of in situ profiles of pore-water Na+ concentration demonstrate that: (i) increased soil moisture conditions in lower-slope positions accelerate salt transport into the cover through diffusion; (ii) snow melt infiltration water bypasses the soil matrix higher in the cover profile; (iii) drier conditions in the mid- and upper-slope positions limit salt transport through diffusion; (iv) advection accelerates upward salt transport in lower-slope positions; and, (v) interflow and (or) deep percolation are key mechanisms mitigating vertical salt movement in lower- and upper-slope positions.

Depositional facies and carbonate diagenesis of the downslope reefs in the Nisku Formation (U. Devonian), central Alberta, Canada


Author(s): Anderson, J. H.

Year: 1985

Abstract:
The Nisku Formation (Frasnian) in Alberta was deposited during four stages of basin infill, corresponding to deposition of the Lobstick, Bigoray, Cynthia, and Wolf Lake members. Stages are regionally correlatable, and are bounded by shaly carbonates. Lobstick and Bigoray carbonates were deposited on a ramp in moderate water depths. Rises in sea level resulted in the backstepping of Bigoray carbonate deposition higher onto the ramp and the formation of a shelf margin. Coral mounds formed downslope in water depths of around 50 m. Argillaceous carbonates of the Cynthia and Wolf Lake members infilled the basin between the reefs. Reefs average 2 km in diameter and 100 m in thickness, and exhibit an overall shoaling-upward sequence. The tops of some reefs were subaerially exposed, resulting in the formation of shallow meteoric lenses and minor calcite dissolution and cementation. Reef growth was terminated by drowning. Marine diagenesis included micritization and extensive cementation by Mg-calcite with inclined extinction. Calcic dolomite formed penecontemporaneously with deposition at the tops of the reefs. Following deposition and through the Mississippian, the reefs were buried to depths of 0.5 to 1 km. Stabilization of marine precipitates and precipitation of minor amounts of calcite cement occurred in seawater modified during burial at elevated temperatures. An active hydrologic system developed during the Pennsylvanian and through the Early Cretaceous in response to the westward tilting of the craton. Replacement of limestone by fabric-selective and nonfabric-selective dolomite and calcite dissolution occurred at depths of 0.5 to 1 km and temperatures around 5(DEGREES)C. Magnesium was derived from updip migrating, burially modified seawater. Mass balance calculations indicate that insufficient connate fluid existed in the basin, and in order to dolomitize the reefs and platforms, regional recharge of seawater must have occurred. Thermal convection is proposed as the driving mechanism for this recharge. Baroque dolomite, calcite, and anhydrite formed during deep burial from saline brines during the Late Cretaceous and Early Tertiary. Carbon isotopic data indicate a rock-buffered carbon system. Progressively later calcites and dolomites are depleted in ('18)O and enriched in ('87)Sr because of increasing burial temperatures and increasing reaction of detrital silicates. The susceptibility of these carbonates to burial modification is attributed to deposition in a downslope setting with little early meteoric alteration.

Effects of climate variability and change on surface water storage within the hydroclimatic regime of the Athabasca River, Alberta, Canada


Author(s): Walker, G. S.

Year: Submitted

Abstract:
Warmer air temperatures projected for the mid-21st century under climate change are expected to translate to increased evaporation and a re-distribution of precipitation around the world, including in the mid-latitude, continental Athabasca River region in northern Alberta, Canada. This study examines how these projected changes will affect the water balance of various lake sizes. A thermodynamic lake model, MyLake, is used to determine evaporation over three theoretical lake basins – a shallow lake, representative of perched basins in the Peace-Athabasca Delta near Fort Chipewyan; an intermediate-depth lake representative of industrial water storage near Fort McMurray; and a deep lake representative of future off-stream storage of water by industry, also near Fort McMurray. Bias-corrected climate data from an ensemble of Regional Climate Models are incorporated in MyLake, and the water balance is completed by calculating the change in storage as the difference between precipitation and evaporation. Results indicate that evaporation and precipitation are projected to increase in the future by similar magnitudes, thus not significantly changing the long-term water balance of the lakes. However, intra-annual precipitation and evaporation patterns are projected to shift within the year, changing seasonal water level cycles, and the magnitudes and frequencies of extreme 1-, 3- and 5-day weather events are projected to increase. These results demonstrate that future climate change adaptation and mitigation strategies should take into account increases in intra-annual variability and extreme events on water levels of lakes in mid-latitude, interior hydroclimatic regimes.

Effects of oil sands related aquatic reclamation on yellow perch (Perca flavescens). II. Chemical and biochemical indicators of exposure to oil sands related waters


Year: 1999

Abstract:
Adult yellow perch (Perca flavescens) were stocked into experimental ponds designed to emulate possible aquatic reclamation alternatives of the oil sands mining industry. After 5 and 11 months, mixed-function oxygenase (MFO) activity, liver conjugation enzymes, bile polycyclic aromatic hydrocarbon (PAH) equivalents, and plasma sex steroids were measured. Liver MFO activity and bile PAH equivalent concentration were closely correlated and showed the highest levels in the experimental ponds but also demonstrated a gradient of exposure among reference locations. Levels of steroid hormones in fall-captured fish did not show major differences among sites. However, during winter, yellow perch from three sites, including the experimental ponds, showed low levels of sex steroids in both males and females. Multivariate regressions showed no relationship between steroid hormone concentrations and gonad size or fecundity. Similarly, steroid hormones did not parallel the gradient of exposure as measured by MFO and bile PAH metabolites. Gonad size and fecundity also were not directly correlated with the gradient of exposure observed in this study. Although MFO activity and bile PAH equivalents were good indicators of exposure to oil sands related waters, they were not predictive of physiological endpoints, suggesting that the latter were influenced primarily by ecological and not by chemical factors.

Energy and water exchange from a saline-sodic overburden restoration cover Fort McMurray, Alberta


Author(s): Carey, S. K.

Year: 2006

Abstract:
The Canadian oil sand mining industry takes responsibility for restoring mining areas to an equivalent level that existed before mining occurred. During this process, the surface-vegetation-atmosphere continuum is dramatically altered, creating few similarities to the boreal forest that existed prior to mining. Using the eddy covariance method, a study of the integrated salt and water balance of a saline-sodic overburden pile at Syncrude Canada Ltd.'s Mildred Lake mine north of Fort McMurray, Alberta was undertaken in order to measure the surface energy balance for three summers (2003 - 2005) with different climatic and phenological conditions. The objective of this study was to document how evapotranspiration and energy partitioning varied inter-annually during the growing season atop the restoration cover and to relate the portioning of energy at the surface to environmental and physiological variables. The paper described the site and measurement specifics and also presented the results and discussion. Results were organized under the following topics: climate; soil moisture and suction; leaf area index and vegetation; surface energy balance; evapotranspiration; and controls on evapotranspiration. It was concluded that results from this study have important implications for recovery strategies, as the availability water for plant growth, the movement and migration of salts and percolating water for deep drainage all depend on accurate quantification of evapotranspiration. 9 refs., 1 tab

Hydrological modelling of reconstructed watersheds using system dynamics


Author(s): Elshorbagy, A., & Jutla A.

Year: 2006

Abstract:
The mining of oil sands in the sub-humid region of Northern Alberta, Canada causes large-scale landscape disturbance, which subsequently requires extensive reclamation to re-establish the surface and subsurface hydrology. The reconstructed watersheds examined in this study are located at the Syncrude Canada Limited mine site, 40 km North of Fort McMurray, Alberta, Canada. The three experimental reconstructed watersheds, with nominal soil thicknesses of 1.0 m, 0.50 m and 0.35 m comprised a thin layer of peat (15-20 cm) over varying thicknesses of secondary (till) soil, have been constructed to cover saline sodic overburden and to provide sufficient moisture storage for vegetation while minimizing surface runoff and deep percolation to the underlying shale overburden. In order to replicate the hydrological behavior, assess the sustainability, and trace the evolution over time of the reclaimed watersheds, a suitable modeling tool is needed. In this research, a model is developed using the system dynamics approach to simulate the hydrological processes in the three experimental reconstructed watersheds and to assess their ability to provide the various watershed functions. The model simulates the vertical and lateral water movement, surface runoff and evapotranspiration within each watershed. Actual evapotranspiration, which plays an important role in the hydrology of the Canadian semi-arid regions, is simulated using an indexed soil moisture method. The movement of water within the various soil layers of the cover is based on parametric relationships in conjunction with conceptual infiltration models. The feedback relationships among the various dynamic hydrologic processes in the watershed are captured in the developed System Dynamic Watershed Model (SDWM). Most hydrological models are evaluated using runoff as the determining criterion for model calibration and validation, while accounting for the movement of moisture in the soil as a water loss. Since one of the primary objectives of a reconstructed watershed is to maintain the natural flora and fauna, it is important to recognize that soil moisture plays an important role in assessing the performance of the reconstructed watersheds. In turn, soil moisture becomes an influential factor for quantifying the health of the reconstructed watershed. The developed model has been calibrated and validated with data for two years (2001-2002), upholding the sensitive relationship between soil moisture and runoff. Accurate calibration of the model based on simulations of soil moisture in the various soil layers improves its overall performance. The model was subsequently used to simulate the three sub-watersheds for five years, with changing the calibrated model parameters to use them as indicators of watershed evolution. The simulated results were compared with the observed values. The results of the study illustrate that all three watersheds are still evolving. Failure to identify a unique parameter set for simulating the watershed response supports the hypothesis of watershed evolution. Soil moisture exchange between the till and peat layers changed with time in all of the watersheds. There was also a modest change in the water movement from the till to shale layers in each of the sub-watersheds. Vegetation is increasing in all of watersheds although there is an indication that one of the sub-watersheds may be sustaining deep rooted vegetation. The results demonstrate the successful application of the system dynamics approach and the developed model in simulating the hydrology of reconstructed watersheds and the potential for using this approach in assessing complex hydrologic systems. Degree:

Long term prediction of vegetation performance on mined sands


Author(s): Bliss, L. C.

Year: 1977

Abstract:
This project on the \"Long Term Prediction of Vegetation Performance On Mined Sands\" (V.E.6.1) was undertaken to provide management with answers on the predictive ability to maintain different kinds of vegetation on raw sands. The research was designed as an integrated, multi-disciplinary program that would concentrate on the role of water stress in a dynamic soil-plant-atmosphere system of a planted grass cover and a natural Jack pine forest. To date only the latter project has been initiated because of the lack of funding and approval to work on the GCOS dike in 1975. This and the Syncrude dyke represent the worst (driest) environmental situation and therefore revegetation of other sand deposits should be more easily accomplished. The Richardson Fire Tower site was chosen because of the representativeness of its Jack pine - lichen woodland on deep sands, a forest type so characteristic of northeastern Alberta. The results of the first full year show that climatically this southwest-facing sand slope warms more rapidly in spring than do level sites at Mildred Lake and Fort McMurray and that the 1976 summer was above normal for temperature. Precipitation was near normal based upon the 1941 - 1970 period. Of the >60 days of precipitation, over 60% were 4 mm or less and thus little if any water entered the soil due to tree, lichen, and litter interception. Both needle duff and lichens provide a significant barrier to surface evaporation compared with open sand. Resistance to evaporation is 2 to 3 times greater with a lichen cover than with litter. The soils are very porous which is advantageous for water entrance, thus preventing erosion but porosity is a disadvantage in maintaining higher water levels near the soil surface for plant growth. These soils recharge during snowmelt in late March - early April; little runoff occurs and over the summer soil water drawdown takes place. Soil moisture content (volume basis) is generally 8 - 15% near the surface in spring, but by late September is 1 - 3% at all depths. Xylem water potentials, a measure of tree water content, were never very low (mean maximum at dawn -5 to -7 atm. and mean minimum at midday -11 to -14 atm.) which reflect a year of average precipitation with frequent light rains and periodic heavier storms. Transpiration and stomatal closure were controlled largely by vapour pressure deficits. Jack pine avoided spring drought by remaining dormant when air and needle temperatures were above freezing, yet when soils were still frozen. Although Jack pine did not show indications of severe drought in a relatively moist summer, it did develop xylem water potentials of -16 to -18 atm., values which are probably detrimental to many of the species being used in revegetation trials on the dike (Bromus inermis, Phleum pratense, and species of Agropyron). This means that potential species must be drought hardy and tested under laboratory rather than only under field conditions to determine their survival under severe drought conditions that may occur but once in 30 to 50 years. The studies of mycorrhizae show that a large number of species of fungi infect the roots of Jack pine and that the infecting flora from disturbed soils (old burns) is quite different from that of undisturbed forests. Since mycorrhizae are critical for the proper growth and survival of pines, care in innoculating tree seedlings with the proper species is essential. The energy and water balance mathematical model predicts the heat and water status of the Jack pine forest. Examination of the model outputs suggests that late season resistance to water uptake occurs because of increased root resistance in autumn. If this is confirmed with further experimental data, and model runs, it means that fall droughts may be especially critical because of the reduced ability of the trees to absorb water through their roots. A second field season coupled with the laboratory studies to determine lethal and sublethal levels of water stress in Jack pine will provide the added inputs to the models necessary for predicting tree response to severe climatic stress. These data, gathered in a highly integrated manner, will permit the calculation of tree survival on sands, be they dikes or other kinds of mined sand, in terms of soil water content and tree density (including crown extent) in relation to the exceptional dry year that may occur once in 30 to 50 years. Data from field trials of grasses or woody species, without supporting measurements of plant physiological responses to environmental conditions cannot provide this essential predictive tool for management unless the one in 30 to 50 year drought cycle is encountered. It is for this reason that modelling of the data in order to predict plant response to unusual environmental conditions becomes so useful. In summary, this study should be able to provide sufficient data to determine whether or not an open stand of Jack pine or similar conifer is the desired end point in maintaining vegetation at a low maintenance cost on sands, the result of open pit mining of the oil sands.

Migration of inconnu (Stenodus leucichthys) and burbot (Lota lota), Slave River and Great Slave Lake, June 1994 to July 1995


Year: 1996

Abstract:
To determine the timing of movements and relative abundance of burbot, Lota lota, and inconnu, Stenodus leucichthys, on the lower Slave River north of the 60th parallel, we sampled on a regular basis using gillnets from June to November, 1994. Movement patterns in time and space in the Slave River and Great Slave Lake were determined by radio-tagging 24 inconnu and 16 burbot in the fall of 1994. Tracking was carried through the fall of 1994 through to July 1995. Inconnu entered the Slave River system from Great Slave Lake in August and attained peak catch-per-unit-effort (CPUE) during the first two weeks of September. By November they had left the system. Burbot CPUE did not increase substantially, therefore, no discemable pattern of movement was recognized from catches. Radio-tagged inconnu stayed in the Fort Smith area of the river until late October when they migrated out of the system into Great Slave Lake. Migrations in Great Slave Lake appeared to be geographically extensive. From January to the end of August 1995, all inconnu were captured or detected by radio telemetry in Great Slave Lake, only. No inconnu were detected or captured in the Slave River. Extensive floy- tagging programs conducted by the Department of Fisheries and Oceans corroborate these observations for inconnu in Great Slave Lake. Burbot appeared to be relatively sedentary and probably escaped detection by residing in deep holes of the river and the river delta. These movement patterns signify that inconnu may transfer contaminants over a large area including Great Slave Lake whereas burbot would concentrate contaminants locally in the lower Slave River and its delta.

Oil sands sludge dewatering by freeze-thaw and evapotranspiration


Year: 1993

Abstract:
The dewatering of oil sands sludge is a major technological, economical, and environmental challenge to the oil sands industry of northeastern Alberta. Sludge is a mixture of small mineral particles (less than 44 µm in diameter), residual bitumen from the extraction process, and water. Sludge consolidates at the bottom of tailings ponds to approximately 30% solids in 2 years and will remain at this level of solids and water indefinitely. At 30% solids, sludge acts as a liquid; unstable and extremely low in strength. Approximately 25 million cubic metres of sludge at 30% solids are produced each year by the two operating extract ion plants owned by Syncrude Canada Ltd. and Suncor Inc. More than 500 million cubic metres of sludge have been produced over the first 20 years these plants have operated. The experiments detailed in this report show that it was possible to increase the solids content of sludge to 50% solids by adding three parts sand (tailings sand) to one part sludge. At 505 solids, the sand-sludge mixture was semi-plastic, but extremely weak. One thousand parts per million of lime were needed to keep the sand from segregating from the sludge. Drainage of sand-sludge mixtures, even under the pressure of self-consolidation, was slow and uneconomical. The sand-sludge mixture had to be dewatered to 85% solids content before its shear strength was sufficiently high to support machine traffic or the overboarding of more sand-sludge mixture. At 85% solids, the sand-sludge mixture had a shear strength in excess of 100 kPa. Freezing and thawing sludge (without sand) caused the solids content to increase from 30% to 50%. Another 10% increase in solids content was achieved by several more cycles of freezing and thawing. At 50% solids, sludge was semi-plastic. Ditches or grooves ploughed into the sludge remained, but the shear strength was very low (less than 2 kPa). Sludge without sand needed at least 80% solids to have sufficient shear strength (more than 100 kPa) to support machinery traffic or sludge overboarding. If snow was removed from the surface periodically, the sludge froze to 165 cm depth in one winter in Mildred Lake, the Syncrude Canada Ltd. plant and mine site, approximately 40 km north of fort McMurray, Alberta. If the snow cover was left in place, freezing was restricted to 30cm. Laboratory and pilot-plant experiments showed that the amount of sludge that could be frozen in one winter could be increased by freezing the sludge in thin layers. Using this technique, a layer only a few centimetres deep was deposited and left to freeze for a day or two; as soon as it was frozen, a second layer was deposited. Layered freezing was also slightly more effective at dewatering sludge than freezing a pool of sludge from the top down. The water released from the sludge during the thaw period rose almost immediately to the sludge surface. Surface water had to be drained away to allow further dewatering, either by evaporation or vegetation-controlled evapotranspiration. Standing water on the sludge surface prevented the establishment and growth of adapted vegetation by floating seeds, making the rooting medium unstable, or inhibiting oxygen flux to the root zone. If the water was removed, two species of plants—reed canary grass and western dock—were well adapted to the sludge environment and capable of removing enough water from the sludge to dry it to 80% solids. Reed canary grass was the best adapted plant to both sludge and sand-sludge mixtures. Furthermore, reed canary grass grew from small sections of its own rhizome, known as sprigs. Starting plants on sludge with sprigs of reed canary grass may allow for large scale (hundreds of hectares) dewatering by vegetation. Sprigs were easy to spread, not subject to movement by wind or small amounts of water, and fast to establish new plants. Sludge at 50% solids that was planted to reed canary grass was dewatered to 80% solids in one growing season. At 80% solids the sludge had a shear strength of 120 kPa and could support machine traffic of any kind or the overboarding of several metres of liquid sludge. However, the rapid removal of surface water and the quick establishment of a dense plant community were essential. Otherwise, dewatering during the summer months was minimal, less than a 5% increase in solids from May to October. Sand-sludge mixtures were also dewatered by freezing and thawing. A 1 year dewatering cycle that included freezing and thawing and summer evaporation, but no plant controlled evapotranspiration, increased the solids content of a 2-m deep sand-sludge mixture from 50% to 80% solids. Reed canary grass and western dock also grew well on sand-sludge mixtures and aided in dewatering, if the surface water was removed.

Planning for Canada's future oil sands pit lakes: An overview of the COSIA demonstration pit lakes project


Author(s): Vandenberg, J. A.

Year: 2014

Abstract:
Pit lakes are one of the most visible legacies of open pit mining that result from permanent modifications to pre-mining topography, hydrology and hydrogeology. The extraction of the non-traditional hydrocarbon resource bitumen from Alberta’s Athabasca Oil Sands using truck-and-shovel techniques will result in the development of 35 pit lakes within the next 50 years. These will be large permanent basins with surface areas ranging from 0.2 to 35 km2 and depths ranging from 5 to 42 m. Only one lake, Syncrude’s Base Mine Lake, presently exists. Stakeholders and regulators are concerned that concentrations of constituents such as naphthenic acids, PAHs, ammonia and chloride in lake water will impair the environmental function and social utility of these lakes. However, numerical models have predicted that, within a decade or two of filling, these lakes will become relatively benign systems with the capacity to sustain aquatic ecosystems and to be fully integrated within the Athabasca watershed. To improve our understanding of oil sands pit lake functions, a consortium of oil sands producers called Canada’s Oil Sands Innovation Alliance (COSIA) is considering developing a state-of-the-art research facility with three to four demonstration pit lakes, a dozen experimental ponds, and a smaller mesocosm and microcosm facility. The proposed demonstration pit lakes will be approximately 200 m in diameter and 20 m deep, will be constructed using oil sands waste materials and process waters representing proposed closure strategies, and will be monitored regularly for at least a decade. The DPL Project will include funding for external researchers (both Canadian and international) to conduct publishable research on specific knowledge gaps. On a global scale, this will be one of the first research initiatives from the petroleum-, metals-, coal-, uranium-, diamond-, or aggregate-mining sectors to physically test pit lake predictions on this scale in advance of lake formation. This presentation will review the content and status of the COSIA Demonstration Pit Lakes Project, and will highlight potential research opportunities.

Potential impacts of beaver on oil sands reclamation success - an analysis of available literature


Year: 2013

Abstract:
The North American beaver (Castor canadensis) is a large semi-aquatic rodent that has played a central role in shaping the Canadian boreal landscape, and colonial Canadian history. Exploitation of North American beaver populations to supply the European hat industry spurred the westward expansion of European explorers and traders into the continental interior. With intensive unregulated harvest, beavers virtually disappeared across much of their range; though populations are recovering, the species is only about 10% as abundant as it was before the fur trade took its toll. As a result, much of the recent ecological history of the Canadian boreal forest has occurred in the absence of this keystone ecosystem engineer, and the ecological state that we perceive as natural is in many regions quite different than it was a century ago. Beavers, while playing an important role in structuring streams and wetlands by altering vegetation communities and water flow patterns, may also affect human structures. In the mineable oil sands region of northeastern Alberta, much of the landscape will be impacted by mining. Mine sites will have to be reclaimed, and those reclaimed sites will consist of engineered landforms (including water bodies and waterways); the long-term hydrological and ecological function of those sites may be vulnerable to beaver activity. In an effort to determine if approaches exist that could manage the risk of beavers colonizing and negatively impacting reclaimed sites, we performed an extensive literature search and analysis. Our objective was to examine characteristics of beaver ecology that might potentially impact reclamation plans, and to identify possible methods to mitigate those impacts. We also include information on traditional use, historical abundance, and current abundance in the mineable oil sands region to provide important historical and ecological context. Although beavers inhabit a range of aquatic habitats, the focus of our review is on watercourses that could be dammed by beavers. Of the aquatic habitats which will be constructed during reclamation, these systems are probably the most vulnerable to impacts from beaver activity. Note, however, that inlet and outflow streams from lakes may be vulnerable to beaver activity, which could impact the performance of constructed lakes in a variety of ways. Beavers alter stream form and function, create wetlands, and change vegetation patterns. The most important predictor of beaver occurrence is stream gradient, with low gradients being associated with higher beaver activity. Stream depth and width, soil drainage, and stream substrate are also important. Although beavers may also respond to vegetation factors, such as tree or shrub species and density, hydrological factors are more important predictors of beaver occupancy of a site. The primary forage preferred by beavers includes deciduous tree and shrub species. Aspen (Populous tremuloides) is the species most preferred by beaver, and is a common component of reclamation plantings and natural recolonization of reclamation sites in the oil sands region. Beavers are central-place foragers, meaning foraging is concentrated around a central home base. They typically harvest deciduous trees and shrubs up to 60 m or more from the water, but most harvest occurs less than 30 to 40 m from the water’s edge. Predation (and predation risk) restricts the size of beavers’ foraging areas, and may also regulate their population size. Management of wolf populations to limit predation on caribou in northeastern Alberta may have significant indirect effects on beaver abundance and distribution by releasing them from predation pressure. The boreal forest ecosystem of Canada evolved over millennia with the beaver as a keystone species altering hydrological systems, creating vast areas of wetlands and beaver meadows, changing vegetation communities and modifying geomorphological processes. Reclamation of functional ecosystems in the region must therefore integrate beavers and their engineered structures. The most ecologically- and cost-effective approach is to design reclaimed areas with the objective of including beaver, but directing beaver activity to areas away from vulnerable reclamation structures. Ecological function requires the presence of beaver on the post-reclamation landscape, and the species is important to First Nations peoples and other trappers in the area. Although beaver abundance can be expected to increase in the area after reclamation, their activities will result in the replacement of existing vegetation with species of lower nutritional quality to beaver (conifer trees). This is expected to result in a beaver population decline and then stabilization over time. With beavers an integral component of the functional landscape, it is important to create “beaver exclusion zones” to ensure that the impact of the species is diverted to areas where beaver activity does not damage reclamation structures. There are very few existing studies of beaver impacts to reclaimed areas. Incorporating ecologically-based strategies for keeping beaver density low in sensitive areas at the outset of a reclamation project, and then monitoring the effectiveness of that strategy, is the best advice that can be derived from our analysis of the existing literature. Beavers could be discouraged from settling at a site by creating streams with steep gradients (>10%) that are wide and deep enough to ensure substantial water flows, are armoured with rock or cobble bottoms, and are bordered by coniferous tree species and/or grass and sedge species. Trees should be planted at high density to prevent growth of shrubs and deciduous trees in the understory, as these are preferred by beaver. Deciduous vegetation should not be planted during reclamation near sites where beavers are to be excluded, and it may be necessary to remove existing deciduous trees and shrubs and replace them with conifers, grasses and sedges in these areas. Although planting specific types of vegetation may be used to discourage beavers from settling a certain area in the short term, natural succession could eventually result in other vegetation communities attractive to beavers. Therefore, unless long-term vegetation management is envisioned, reclamation plans should not rely on using vegetation to dissuade beaver activity in sensitive areas alone, though this approach may be used in combination with other methods, especially in the few decades immediately following reclamation. Note that the goal is to plan for a maintenance-free environment in which ongoing beaver control is unnecessary, and the use of multiple strategies in tandem to guide beaver activity is more likely to achieve this goal. More active, maintenance-intensive techniques could be used to limit the damage caused by beaver dams to sensitive areas. These techniques include lethal (e.g., kill trapping or shooting) and nonlethal (e.g., relocation) methods to reduce population density. However, these methods require constant effort, and can be expensive. Another approach is to manipulate water flow through existing beaver dams using pipe drainage systems; this allows the beaver dam to stay in place, while reducing the risk that it will trap enough water to be dangerous if the dam should fail. Again, however, these drainage systems require long-term maintenance. One approach may be more sustainable in the long term and require less maintenance: minimize or maximize water flow through engineered channels, as beavers are less likely to use very low-flow and very high-flow watercourses. Note that beavers may still affect these channels, especially when population densities are high or other habitat is unavailable; however, the probability of beavers affecting very low-flow or high-flow channels is lower than for watercourses with more moderate flows. Creating several dispersed low-flow channels may make an area less desirable to beavers compared to a single moderate flow channel. Similarly, multiple low- to moderate-flow channels could be created, with some having characteristics that attract beavers (“decoys”) and others that do not (“exclusions”), allowing water flow to continue through some channels even in the presence of beavers. “Pre-dam” fences can be installed on decoy streams to create a structure to encourage beavers to occupy a site where damage is not a concern. Discharge could be controlled by regulating water flow through exclusion streams that are not dammed, or by installing flow devices though dams on decoy streams. A similar approach might be used on culverts that allow streams to flow beneath roadways; flow devices could be used proactively at these sites, and/or oversized culverts could be installed to allow maintenance of the natural width of the stream channel and reduce the noise of running water, which attracts beaver activity. Although many different landforms on the reclaimed landscape may be vulnerable to beaver activity, a few are considered critical areas where beaver impacts must be controlled, including the outlets of lakes, side-hill drainage systems, and constructed peatlands. Beaver activity at the outlet of constructed lakes could cause instability in containment structures, negatively affect littoral and riparian zones around the lake, and increase the probability of catastrophic outburst flooding. Damming of side-hill drainage systems could cause stream avulsion and routing of water flow into a new pathway not engineered for a stream, causing increased erosion. Flooding of constructed peatlands could convert them to open-water systems, thereby subverting their intended ecological function. These critical areas should be protected from beaver activities, while other areas should be designed to accommodate this important species. In practice, several different approaches – tailored to specific situations and landforms – will be necessary to develop and implement plans that accommodate beavers as a part of the post-reclamation landscape. As so few data exist to inform effective reclamation in the presence of beavers, all of the methods we suggest carry an unknown degree of risk. This risk can be decreased in the future by adapting methods based on observed effectiveness. We recommend implementing a research and adaptive management program on the influence of beavers on reclamation within the context of oil sands reclamation in northeast Alberta. Lack of existing information, particularly in northeast Alberta, illustrates the need to implement research that documents the positive and negative influence of beavers on reclamation sites and tests alternative methods to prevent negative and support positive influences. Otherwise reclamation strategies will be ad-hoc and tenuous, with a mixed success rate. A research and monitoring program would ideally contribute to a standardized strategic approach to mitigating negative beaver influences on reclamation of watercourses in the oil sands region. Beavers are, to a certain extent, unpredictable. No single approach will guarantee that a site will be unaffected by beaver activity. We suggest that multiple management approaches be simultaneously implemented at sites that are particularly vulnerable or critical for the functioning of the reclaimed landscape (e.g., outlet streams from constructed lakes). It is impossible to predict all eventualities, as the character of the reclaimed landscape will change over time due to successional processes, fire, global climate change, and resource extraction. The information we provide is the best available based on limited current knowledge, and provides the best chance for minimizing risk while accommodating this keystone species. Ultimately, the presence of beavers on reclaimed oil sands leases will increase biodiversity, enhance ecosystem goods and services, and assist in developing ecosystems that are consistent with natural systems in the boreal region.

Potential impacts of beaver on oil sands reclamation success–an analysis of available literature


Year: 2013

Abstract:
The North American beaver (Castor canadensis) is a large semi-aquatic rodent that has played acentral role in shaping the Canadian boreal landscape, and colonial Canadian history. Exploitation of North American beaver populations to supply the European hat industry spurred the westward expansion of European explorers and traders into the continental interior. With intensive unregulated harvest, beavers virtually disappeared across much of their range; though populations are recovering, the species is only about 10% as abundant as it was before the furtrade took its toll. As a result, much of the recent ecological history of the Canadian boreal forest has occurred in the absence of this keystone ecosystem engineer, and the ecological state that we perceive as natural is in many regions quite different than it was a century ago. Beavers, while playing an important role in structuring streams and wetlands by altering vegetation communities and water flow patterns, may also affect human structures. In the mineable oil sands region of northeastern Alberta, much of the landscape will be impacted by mining. Mine sites will have to be reclaimed, and those reclaimed sites will consist of engineered landforms (including water bodies and waterways); the long-term hydrological and ecological function of those sites may be vulnerable to beaver activity. In an effort to determine if approaches exist that could manage the risk of beavers colonizing and negatively impactingreclaimed sites, we performed an extensive literature search and analysis. Our objective was to examine characteristics of beaver ecology that might potentially impact reclamation plans, and to identify possible methods to mitigate those impacts. We also include information on traditional use, historical abundance, and current abundance in the mineable oil sands region to provide important historical and ecological context. Although beavers inhabit a range of aquatic habitats,the focus of our review is on watercourses that could be dammed by beavers. Of the aquatic habitats which will be constructed during reclamation, these systems are probably the most vulnerable to impacts from beaver activity. Note, however, that inlet and outflow streams fromlakes may be vulnerable to beaver activity, which could impact the performance of constructed lakes in a variety of ways. Beavers alter stream form and function, create wetlands, and change vegetation patterns. The most important predictor of beaver occurrence is stream gradient, with low gradients being associated with higher beaver activity. Stream depth and width, soil drainage, and stream substrate are also important. Although beavers may also respond to vegetation factors, such astree or shrub species and density, hydrological factors are more important predictors of beaver occupancy of a site.The primary forage preferred by beavers includes deciduous tree and shrub species. Aspen(Populous tremuloides) is the species most preferred by beaver, and is a common component of reclamation plantings and natural recolonization of reclamation sites in the oil sands region. Beavers are central-place foragers, meaning foraging is concentrated around a central home base. They typically harvest deciduous trees and shrubs up to 60 m or more from the water, but mostharvest occurs less than 30 to 40 m from the water’s edge. Predation (and predation risk) restricts the size of beavers’ foraging areas, and may also regulate their population size. Management of wolf populations to limit predation on caribou in northeastern Alberta may have significant indirect effects on beaver abundance and distribution by releasing them frompredation pressure.The boreal forest ecosystem of Canada evolved over millennia with the beaver as a keystone species altering hydrological systems, creating vast areas of wetlands and beaver meadows,changing vegetation communities and modifying geomorphological processes. Reclamation offunctional ecosystems in the region must therefore integrate beavers and their engineered structures. The most ecologically- and cost-effective approach is to design reclaimed areas withthe objective of including beaver, but directing beaver activity to areas away from vulnerablereclamation structures. Ecological function requires the presence of beaver on the post-reclamation landscape, and the species is important to First Nations peoples and other trappers in the area. Although beaver abundance can be expected to increase in the area after reclamation, their activities will result in the replacement of existing vegetation with species of lower nutritional quality to beaver (conifer trees). This is expected to result in a beaver population decline and then stabilization over time. With beavers an integral component of the functional landscape, it is important to create “beaver exclusion zones” to ensure that the impact of thespecies is diverted to areas where beaver activity does not damage reclamation structures.There are very few existing studies of beaver impacts to reclaimed areas. Incorporating ecologically-based strategies for keeping beaver density low in sensitive areas at the outset of a reclamation project, and then monitoring the effectiveness of that strategy, is the best advice thatcan be derived from our analysis of the existing literature. Beavers could be discouraged from settling at a site by creating streams with steep gradients (>10%) that are wide and deep enoughto ensure substantial water flows, are armoured with rock or cobble bottoms, and are bordered byconiferous tree species and/or grass and sedge species. Trees should be planted at high density to prevent growth of shrubs and deciduous trees in the understory, as these are preferred by beaver. Deciduous vegetation should not be planted during reclamation near sites where beavers are to be excluded, and it may be necessary to remove existing deciduous trees and shrubs and replace them with conifers, grasses and sedges in these areas. Although planting specific typesof vegetation may be used to discourage beavers from settling a certain area in the short term,natural succession could eventually result in other vegetation communities attractive to beavers. Therefore, unless long-term vegetation management is envisioned, reclamation plans should notrely on using vegetation to dissuade beaver activity in sensitive areas alone, though this approachmay be used in combination with other methods, especially in the few decades immediately following reclamation. Note that the goal is to plan for a maintenance-free environment in whichongoing beaver control is unnecessary, and the use of multiple strategies in tandem to guidebeaver activity is more likely to achieve this goal. More active, maintenance-intensive techniques could be used to limit the damage caused bybeaver dams to sensitive areas. These techniques include lethal (e.g., kill trapping or shooting)and nonlethal (e.g., relocation) methods to reduce population density. However, these methodsrequire constant effort, and can be expensive. Another approach is to manipulate water flowthrough existing beaver dams using pipe drainage systems; this allows the beaver dam to stay in place, while reducing the risk that it will trap enough water to be dangerous if the dam shouldfail. Again, however, these drainage systems require long-term maintenance.One approach may be more sustainable in the long term and require less maintenance: minimize or maximize water flow through engineered channels, as beavers are less likely to use very low-flow and very high-flow watercourses. Note that beavers may still affect these channels,especially when population densities are high or other habitat is unavailable; however, the probability of beavers affecting very low-flow or high-flow channels is lower than forwatercourses with more moderate flows. Creating several dispersed low-flow channels maymake an area less desirable to beavers compared to a single moderate flow channel. Similarly, multiple low- to moderate-flow channels could be created, with some having characteristics thatattract beavers (“decoys”) and others that do not (“exclusions”), allowing water flow to continuethrough some channels even in the presence of beavers. “Pre-dam” fences can be installed ondecoy streams to create a structure to encourage beavers to occupy a site where damage is not aconcern. Discharge could be controlled by regulating water flow through exclusion streams that are not dammed, or by installing flow devices though dams on decoy streams. A similar approach might be used on culverts that allow streams to flow beneath roadways; flow devices could be used proactively at these sites, and/or oversized culverts could be installed to allowmaintenance of the natural width of the stream channel and reduce the noise of running water,which attracts beaver activity.Although many different landforms on the reclaimed landscape may be vulnerable to beaver activity, a few are considered critical areas where beaver impacts must be controlled, includingthe outlets of lakes, side-hill drainage systems, and constructed peatlands. Beaver activity at the outlet of constructed lakes could cause instability in containment structures, negatively affectlittoral and riparian zones around the lake, and increase the probability of catastrophic outburstflooding. Damming of side-hill drainage systems could cause stream avulsion and routing ofwater flow into a new pathway not engineered for a stream, causing increased erosion. Floodingof constructed peatlands could convert them to open-water systems, thereby subverting theirintended ecological function. These critical areas should be protected from beaver activities,while other areas should be designed to accommodate this important species.In practice, several different approaches – tailored to specific situations and landforms – will benecessary to develop and implement plans that accommodate beavers as a part of the post-reclamation landscape. As so few data exist to inform effective reclamation in the presence ofbeavers, all of the methods we suggest carry an unknown degree of risk. This risk can bedecreased in the future by adapting methods based on observed effectiveness. We recommend implementing a research and adaptive management program on the influence of beavers onreclamation within the context of oil sands reclamation in northeast Alberta. Lack of existing information, particularly in northeast Alberta, illustrates the need to implement research thatdocuments the positive and negative influence of beavers on reclamation sites and testsalternative methods to prevent negative and support positive influences. Otherwise reclamationstrategies will be ad-hoc and tenuous, with a mixed success rate. A research and monitoring program would ideally contribute to a standardized strategic approach to mitigating negativebeaver influences on reclamation of watercourses in the oil sands region. Beavers are, to a certain extent, unpredictable. No single approach will guarantee that a site willbe unaffected by beaver activity. We suggest that multiple management approaches besimultaneously implemented at sites that are particularly vulnerable or critical for the functioning of the reclaimed landscape (e.g., outlet streams from constructed lakes). It is impossible topredict all eventualities, as the character of the reclaimed landscape will change over time due tosuccessional processes, fire, global climate change, and resource extraction. The information weprovide is the best available based on limited current knowledge, and provides the best chancefor minimizing risk while accommodating this keystone species. Ultimately, the presence of beavers on reclaimed oil sands leases will increase biodiversity, enhance ecosystem goods andservices, and assist in developing ecosystems that are consistent with natural systems in the boreal region.

Regional geology and hydrostratigraphy in northeast Alberta


Year: 1991

Abstract:
The Alberta Oil Sands Technology and Research Authority (AOSTRA) is currently planning to expand the Underground Test Facility (UTF) near Fort McMurray in northeast Alberta to a commercial size operation. As part of this expansion, it is envisaged to dispose of produced residual waters by on-site deep well injection. Selection of a disposal zone is currently under way. The upgrading of the UTF operations provides an opportunity for monitoring possible environmental effects related to the deep disposal of waste water resulting from the in situ extraction of bitumen from oil sands. With this in mind, and the additional objective of developing strategies for similar future activities, Environment Canada and the Alberta Research Council initiated a collaborative study of the effects of deep waste injection at the UTF site, with data support and cooperation from AOSTRA. The evaluation of the effects of deep injection of waste water is based on predictive modelling, which requires knowledge of the initial baseline hydrogeological conditions. Because the data are very scarce and incomplete at the local scale, a regional-scale hydrogeological study is required for the identification and characterization of the hydrostratigraphic units at the UTF site. For this purpose, a regional-scale study area is defined in northeast Alberta between latitudes 55�N and 58�N, and longitudes 110�W to 114�W (Tp 70-103, R 1-26, W4 Mer). The first step in the hydrogeological characterization is the description of the geology and the delineation of the hydrostratigraphy, which form the content of this progress report. The geology and hydrostratigraphy of the Phanerozoic sedimentary rocks in northeast Alberta are extremely complex due to various depositional, salt dissolution and erosional events. The shales interbedded with sandstones, red beds and evaporitic units of the Lower Elk Point Subgroup (Lower Devonian) overlying the impervious crystalline Precambrian basement from a dominantly aquiclude system at the base of the succession. The overlying carbonates of the Winnipegosis aquifer are separated from the mainly carbonate Beaverhill Lake aquifer system by the halite and shale of the Prairie-Watt Mountain aquiclude system. The argillaceous Ireton aquitard separates the Beaverhill Lake and Grosmont-Wabamun aquifer systems. All the Devonian strata have been eroded and subcrop at the sub-Cretaceous unconformity. They are overlain by the succession of the McMurray, Clearwater and Grand Rapids formations of the Lower Cretaceous Mannville Group. These are defined as weak aquifer-aquitards because of a complex combination of interbedded sands, shales and oil sands. The Colorado aquitard system (mainly shales with a few sandy units) lies at the top of the hydrostratigraphic succession. The hydrogeological characterization (porosity and permeability, formation pressure, and chemistry of formation waters) of the hydrostratigraphic units identified in this progress report will form the subject of the next research stage.

Regional-scale subsurface hydrogeology in northeast Alberta


Year: 1993

Abstract:
The hydrogeological regime of formation waters in the Phanerozoic sedimentary succession was determined for a region defined as Tp 70-103 W4 Mer (55-58 degrees;N latitude and 110-114 degrees;W longitude) in northeast Alberta, covering most of the Athabasca Oil Sand Deposit. The study was based on information from 12,479 wells, 3187 analyses of formation water, 2531 drillstem tests and 452,030 core analyses. Data management and processing were carried out using the INGRES Data Base Management System and specially designed software developed at the Alberta Geological Survey. The regional geology was synthesized in terms of definable stratigraphic successions, and 26 individual units were characterized by structure top and isopach maps. The hydrostratigraphy was developed through several iterations starting from the stratigraphy and lithology of the strata. Complex groups of aquifers and/or aquitards exhibiting generally common overall characteristics were grouped into hydrostratigraphic systems. Thirteen hydrostratigraphic units were identified in the Phanerozoic succession. The hydrogeological regime in aquifers was described using isopach, salinity distributions and freshwater hydraulic-head distributions. Cross-formational flow was evaluated using plots of pressure variation with depth in selected wells. Because the study area is situated at the feather edge of the Alberta Basin, topography and physiographic features exert a strong influence on the flow regime within most aquifers. In the most general sense, fluid flow is to the northeast toward the edge of the basin. Areas of high topography, such as the Birch and Pelican mountains, act as local recharge areas, introducing fresh meteoric water to aquifers unprotected by significant confining strata. The valleys of the Athabasca River system represent discharge areas for aquifers at outcrop or subcropping near them. The salinity of formation waters generally increases with depth. This is the result of a combination of factors like temperature, hence solubility increase with depth, dissolution of deep Devonian evaporitic beds, and dilution near the surface by meteoric water introduced by local flow systems. In terms of flow regime and overall characteristics, the hydrostratigraphic units can be grouped into pre-Prairie Formation aquifers, Beaverhill Lake-Cooking Lake aquifer system, Grosmont-to-Wabamun aquifers, and Cretaceous aquifers. The aquifers below the Prairie evaporite exhibit regional flow-regime characteristics. Overall high formation water salinity is associated with the proximity of Elk Point Group evaporites. The Beaverhill Lake-Cooking Lake aquifer system has hydrogeological characteristics consistent with an intermediate-to-local flow regime. Within subcrop and outcrop areas, local physiographic influences are superimposed over a regional northeastward flow trend. The Grosmont aquifer and Winterburn-Wabamun aquifer system may act locally as a 'drain' for aquifers in hydraulic continuity above and below. The flow of formation waters is generally to the northwest, towards discharge at outcrop along the Peace River. The Cretaceous aquifers are characterized by low salinity and local flow regime.The synthesis of this vast amount of information on the hydrogeological regime of formation waters in northeast Alberta was carried out under a jointly funded research project by the Alberta Research Council and Environment Canada.

Size distribution of the macroinvertebrate community in a freshwater lake


Year: 1989

Abstract:
Macroinvertebrates were collected every 2 wk for 18 wk from three depth zones in a deep lake in Alberta. Unionid clams comprised 80% of the total macroinvertebrate biomass and were excluded from initial analyses. The seasonal average size-spectrum for the littoral zone community was bimodal with peaks in the 8–16 and 256–512 mg weight-classes; size-spectra for the sublittoral and profundal communities were unimodal with peaks in the 8–16 and 16–32 mg weight-classes, respectively. Slopes of the normalized size-spectra for the littoral, sublittoral, profundal and whole-lake communities were not significantly different from −1.0, −1.0, 0.0, and −1.0, respectively. These results suggest that biomass is evenly distributed across logarithmically even size-classes for the average macroinvertebrate community in the littoral zone, sublittoral zone, and on a whole-lake basis. The biomass peak for unionids (16.4–32.8 g weight-class) was 10–30 times greater than biomass peaks for the remaining macroinvertebrates. The slopes of normalized size-spectra for the littoral zone and whole-lake were changed significantly when unionids were included; however, unionids presumably play a minor role in the macroinvertebrate community because they are an energy sink in the present context. Despite wide seasonal variation, average normalized size-spectra based on samples collected at 4- and 6-wk intervals were very similar to those based on nine biweekly collections.

Status of the pygmy whitefish (Prosopium coulteri) in Alberta


Author(s): Mackay, W. C.

Year: 2000

Abstract:
Pygmy whitefish are a glacial relict species that are known from two watersheds in Alberta. A total of eight specimens have been collected in Alberta: Two from Waterton Lake and six from four localities in upper Athabasca River as far downstream in Whitecourt. In other jurisdictions sch as BC and the NWT, pygmy whitefish are found in cold deep lakes similar to Waterton Lake. The species has also been reported from the Saskatchewan portion of Lake Athabasca. Little is known of the biology of pygmy whitefish in river systems except that they are found in relatively cold, fast mountain streams.

Sulfur compounds in oils from the western Canada tar belt


Year: 1976

Abstract:
Sulfur compounds in the gas oil fractions from two bitumens (Athabasca oil sand and Cold Lake deposit), a heavy oil (Lloydminster) from Cretaceous reservoirs along the western Canada sedimentary basin, and a Cretaceous oil from a deep reservoir that may be mature (Medicine River) are investigated. The gas oil distillates were separated to concentrates of different hydrocarbon types on a liquid adsorption chromatographic column. The aromatic hydrocarbon types with their associated sulfur compounds were resolved by gas chromatographic simulated distillation and then by gas solid chromatography. Some sulfur compounds were further characterized by mass spectrometry. The predominant sulfur compounds in these fractions are alkyl-substituted benzo- and dibenzothiophenes with short side chains which have few dominant isomers.

The Baptiste Lake Study : Technical Report


Year: 1987

Abstract:
The primary purposes of the Baptiste Lake Study, carried out between March, 1976 and March, 1979 were to determine the trophic status of the lake, and to develop and employ methods for assessing the impact of existing or future shoreline and watershed development on that status. In order to determine the trophic status of the lake an intensive limnological study was undertaken; the latter included weekly observations of phytoplankton carbon fixation, phytoplankton standing crop, taxonomic changes and changes in the physico-chemical environment. In order to assess existing cultural impacts to the lake, the sedimentary record was analyzed to determine any historical changes in the fertility of the system. In order to predict the effect of future development, a detailed nutrient budget was constructed for the lake and a comparative nutrient loading analysis undertaken. Baptiste Lake drains a large watershed and, as such, has a large external loading of nutrients. Prior to European settlement this loading, primarily from a boreal mixed-wood forest, was large enough to ensure that the lake was in a eutrophic condition. This interpretation has been confirmed by the sediment core analysis. The clearing and conversion of forested land to agricultural use has had a measurable impact on stream nutrient loadings, the net result of which has been to elevate the trophic status of the lake to a more eutrophic condition. By comparison, the estimated nutrient loadings from cottages were relatively small, although the question of nutrient bio-availability was not assessed in this study. The average total phosphorus (TP) export coefficient for forested lands was 0.14 kg ha-1 yr-1 , and that from agricultural land was 0.27 kg ha-1 yr-1 • These data are similar to the mean coefficients presented by the US EPA (1974) and Uttormark (1974). The average total nitrogen (TN) export coefficient for forested land was 2.50 kg ha-1 yr-1 and for agricultural land 2.13 kg ha-1 yr-1 ; these differences between land use types were not statistically significant. These coefficients are lower than those measured in many other locations, and the TN pools differ significantly in composition. The TN loads were primarily composed of organic nitrogen (approximately 75% for agricultural streams and 90% for forested streams). The TN:TP ratios in both stream basin types were high and suggest phosphorus deficiency, however, inorganic N:P ratios were below 7.2 and suggest nitrogen deficiency. This conundrum will remain until some understanding of the bio-availability of the organic nitrogen component is attained. The atmospheric input of nutrients was measured in devices similar to those described by Likens et al. (1979) for the Hubbard Brook Study. The annual input of TP was estimated at 30.4 mg -2 -1 m yr , which is lower than that occurring in many other regions. Most of the deposition occured during spring, sunmer, and autumn, with little input over winter. Groundwater flows into the lake were estimated by a mathematical model developed by Crowe and Schwartz (1981). They estimated that approximately 13% of the annual hydraulic loadings could be derived from groundwater. However, because of the diversity of hydrostratigraphic. units surrounding the lake basin, each with different hydrochemical characteristics, we did not attempt to estimate nutrient loading from this source. Direct evidence for groundwater seepage into the lake was produced as a result of discrete chemical testing in the north basin. Baptiste Lake has one seasonally stratified basin, and one temporarily stratified basin. The lake is partially meromictic as a result of incomplete spring mixing, and displays many of the characteristics of the classical eutrophic system. Hypolimnetic oxygen depletion occurred in the deep, southern basin and this resulted in a large accumulation of nutrients in the hypolimnion, presumably from sediment release. TP concentrations exceeded 500 mg m-3 near the bottom in late summer and this hypolimnetic pool probably enriched surface waters as the thermocline was depressed. Heavy blue-green algal blooms occurred during late summer, with peak surface chlorophyll ! concentrations observed in the high hundreds of mg m- a, The shallow, northern basin stratified for approximately three months each summer; this was also accompanied by oxygen depletion and nutrient accumulation. Isothermal conditions developed by late August in this basin so that the hypolimnetic nutrient supply enhanced the summer blue-green bloom, as opposed to enhancing the autumn pulse of phytoplankton as occurred in the southern basin. The seasonal pattern of phytoplankton succession is similar to that described for eutrophic systems by Reynolds (1982). The open water season lasts approximately six months, extending from late April to early November. The spring diatom assemblage is dominated by Stephanodiscus astraea, with the pyrrhophyte Peridinium !Q.. ·making brief but important contributions to the biomass during May. An unidentified unicellular blue-green, now believed to be broken colonies of Microcystis aeruginosa, was also significant. An early sunmer minimum during June was characterized by a mixed conmunity which included ~- astraea, several cyanophytes, and the cryptophyte Cryptomonas ovata. The cyanophytes dominated from early July to mid-September, however, there was a shift from domination by Anabaena circinalis and Microcystis aeruginosa to Gomphosphaeria naegelianum and Aphanizomenon flos-aguae in August. The large pyrrhophyte Ceratium hirundinella was also present during July and August and was extremely important in terms of total cell volumes. During the month of October, the phytoplankton was again dominated by the diatoms Melosira granulata and Stephanodiscus astraea, but also included the cryptophyte Cryptomonas ovata. The annual carbon fixation rate was determined by the radiocarbon method and estimated at approximately 302.5 g c m- 2 yr-1 • Most photosynthetic activity was concentrated in.the open water season, although some under-ice activity was recorded in late March as the photoperiod increased Extreme spatial heterogeneity, or patchiness, was observed in surface chlorophyll ~distributions in Baptiste Lake. The degree of patchiness increased as the concentration increased, and these data pointed out the importance of statistical sampling design in the accurate trophic assessment of productive lakes.

The environmental hydrogeology of the oil sands lower Athabasca area, Alberta


Author(s): Miall, A. D.

Year: 2013

Abstract:
Shallow fresh groundwater and deep saline groundwater are used together with surface water in the extraction of bitumen from the Athabasca Oil Sands both in the surface mining and in situ operations. However, increasing efficiencies in processing technologies have reduced water use substantially, and currently at least 75% of the water used in most operations is recycled water. Much concern has been expressed regarding contamination of surface waters by seepage from tailings ponds, but hydrogeological studies indicate that this is not happening; that seepage capture design is effective. Oil sands mining and in situ project licensing and operation regulations include Environmental Impact Assessments that mandate considerable hydrogeological measurement and monitoring work. However, little of this is independently evaluated for accuracy or synthesized and interpreted for the public. Recent changes in Alberta environmental regulation, including the establishment of the Alberta Environmental Monitoring Management Board (in October 2012) are expected to bring new transparency to environmental management of Oil Sands operations.

The Laurentide and Innuitian Ice Sheets During the Last Glacial Maximum


Year: 2002

Abstract:
Abrupt temperature changes in the northern North Atlantic occurred frequently throughout the last glaciation as shown by proxy records from Greenland ice-cores, deepsea cores, and Norway speleothems. Many of these variations occurred in irregular sawtooth cooling cycles which sometimes ended with the deposition of thick layers of ice-rafted debris (IRD) in the deep ocean that are known as Heinrich events. The lithologies of most of the IRD deposits are consistent with widespread surges of the Laurentide Ice-Sheet that may have resulted from the accumulation of deformable sediments in portions of the ice-sheet bed. An alternative conceptual model proposed here to explain the sawtooth coolings and the surges involves repetitive jökulhlaups from a Hudson Bay lake dammed by ice at the mouth of Hudson Strait. The slow sawtooth coolings may be explained by storm track diversion due to progressive coverage of the lake by icebergs, and the surges by abrupt losses of water pressure and buttressing ice-shelves at all ice-sheet fronts in the lake when the ice-dams failed.

Use of traditional ecological knowledge in environmental assessment of uranium mining in Saskatchewan


Year: 1999

Abstract:
Use of traditional ecological knowledge (TEK) is now a requirement of many environmental review panels. It was in the remit for investigation into uranium mining in northern Saskatchewan, but there was a mismatch between the narrow, often technical treatment of TEK and the broader, more cultural comments of the Dene Aboriginal intervenors. It is essential to recognize when a development proposal's planning needs and social issues exceed the scope of environmental assessment (EA). TEK can relate to EA on three levels; detailed information from local people on the environment and wildlife; gaining insight in to socio-cultural effects of a project; and changes to a landscape or a people's relationship with it that may threaten deep identification with their environment. The last may not be a part of an ordinary EA.

Use of traditional ecological knowledge in environmental assessment of uranium mining in the Athabasca Saskatchewan


Year: 1999

Abstract:
Use of traditional ecological knowledge (TEK) is now a requirement of many environmental review panels. It was in the remit for the investigation into uranium mining in northern Saskatchewan, but there was a mismatch between the narrow, often technical, treatment of TEK and the broader, more cultural comments of the Dene Aboriginal intervenors. It is essential to recognize when a development proposal's planning needs and social issues exceed the scope of environmental assessment (EA). TEK can relate to EA on three levels: detailed information from localpeople on the environment and wildlife; gaining insight in to socio-cultural effects of a project; and changes to a landscape or a people's relationship with it that may threaten their deep identification with their environment. The last may not be a part of an ordinary EA.

Water use in Canada's oil-sands industry: The facts


Author(s): Lunn, S.

Year: 2013

Abstract:
Canada's oil-sands industry is often perceived as having poor environmental performance. One focus area is the use of water for oil-sands production. Bitumen from oil sands is produced by surface mining or by in-situ thermal extraction. Both technologies are water-based. The oil-sands deposits are situated in northern Alberta, where the river basins have 87% of the provincial average annual water supply but only have 13% of the demand. Oil-sands operators have made significant progress in improving freshwater use productivity (intensity), and water use represents a small percentage of natural supply. For in-situ production, the 2010 freshwater use productivity for the industry was 0.43 units of freshwater per unit of bitumen produced. As an example of continuous improvement, the Imperial Oil Cold Lake in-situ oil-sands operation has improved freshwater use productivity by 90% since 1985 through produced-water recycling and the use of deep saline groundwater. The in-situ oil-sands industry will remain a relatively small water user into the future (2030) using an estimated 0.04 to 0.09% of available supply from the three river basins where it is situated. For oil-sands mining, most of the source water comes from the Athabasca River. The average water-use productivity for oil-sands production between 2006 and 2011 was 2.5 units of Athabasca River water per unit of bitumen and synthetic crude oil produced (3.6 for all freshwater sources). In 2011, the oil-sands mining industry used 0.54% of the annual Athabasca River flow and 3% of the lowest 2011-2012 winter weekly flow. For growth forecasts to 2030, it is estimated that the oil-sands mining industry will require 1.4% of the average annual flow of the Athabasca River. Overall, by 2030, it is projected that the entire oil-sands industry will use less than 0.4% of Alberta's average annual water supply to produce 80% of Canada's total oil production.

Wind-wave-induced suspension of mine tailings in disposal ponds - a case study


Year: 1991

Abstract:
Linear wave theory and wave hindcasting are applied to derive an expression for the depth of water needed to prevent the wind-wave-induced suspension of sediments in mine tailings ponds. The depth is expressed as a function of four factors: the threshold velocity, the wind velocity, the fetch over which the wind blows, and a factor based on the statistical distribution of wave heights. This study was motivated by the need to determine the thickness of water required to prevent the suspension of sludge solids in existing and proposed tailings ponds at Syncrude Canada Ltd.'s oil sands plant. Although data relevant to this problem are used to provide a specific example, the results are applicable whenever sediment suspension is caused by fetch-limited, deep water, wind waves. The results should be of particular use when the available data set is limited, e.g., for proposed tailings ponds. Key words: linear wave theory, wave hindcasting, wind-wave-induced suspension, threshold velocity, sludge capping, reclamation ponds, mine tailings ponds.