Containment Ponds Research Articles

Eco-efficiency analysis of water distribution system flushing into a containment Pond

For a salt or other conservative contaminant contamination event in a water distribution system, opening fire hydrants to flush the system is currently an accepted decontamination method. However, all the contaminated flushed water is discharged to the local surroundings of the fire hydrants and imposes an environmental impact. Another system decontamination alternative can be using a containment pond to catch the contaminated water. To reduce environmental impacts of flushing salt from a water distribution system a comparative life cycle assessment study has been performed for both conventional flushing and for flushing contaminated water into a containment pond. This was performed using SimaPro software for both of these decontamination options and the impacts have been assessed using the IMPACT 2002+ methodology. The results show that environmental impacts can be reduced by 25% for rural areas, 69% for urban roads, 61% for urban lawns, and 64% for mixed land use. In addition, a sensitivity analysis reveals the two most sensitive variables resulting in the finding that a 10% change in the time needed for system decontamination led to a 10% change in environmental impact and a 10% change in the area of land exposed to contaminated water discharge led to an 8% change in environmental impact.

Feasibility of an environmentally friendly method of contaminant flushing in water distribution systems using containment ponds

Abstract Water distribution system flushing is one way to get rid of contamination. In conventional flushing, all the contaminated water is discharged to the environment, thereby harming it. A new method is proposed here as an alternative solution, in which a containment pond lined with impermeable material will be constructed in a suitable place within the municipality. Network modelling was performed to investigate the feasibility of the new method. It was found that (1) the proposed flushing method can successfully reduce environmental impacts compared to hydrant flushing only, (2) a containment pond cannot clear the system periphery away from the containment pond, (3) the best location of a containment pond is not always at the furthest location from the source reservoir, and (4) for some systems, some pond locations might be better from an economic perspective, while other locations will be better environmentally.

Eco-Efficiency Analysis of Water Distribution System Flushing into a Containment Pond

Eco-Efficiency Analysis of Water Distribution System Flushing into a Containment Pond

Trace elements in groundwater near an abandoned mine tailings dam and health risk assessment (NE Zimbabwe)

Groundwater from shallow hand-dug wells at an abandoned gold mine tailings dam was characterised for selected physicochemical parameters during dry and wet seasons of 2018 and 2019. Health risk exposure of the local population (adults and children) through ingestion and dermal exposure was assessed. Groundwater quality parameters were lower than international drinking water quality guidelines (p < 0.05). The parameters were significantly influenced by season of the year (As, Cl−, SO42−), nature (As, Cd, Cl−, Fe, NO3−, SO42−), depth (Cd, Cl−, Fe, Ni, SO42−) and direction of the well (Cu, Cl−, Fe, NO3−, Pb, SO42−) (p < 0.05) relative to the tailings dam. Groundwater did not pose non-carcinogenic risk due to studied trace elements. However, arsenic had the potential to cause medium to high cancer risk to the local population. We propose re-vegetation of the tailings dam, diversion of surface tailings drainage to a containment pond and the provision of continuous piped water supplies.

Arsenic as a contaminant of struvite when recovering phosphorus from phosphogypsum wastewater

BackgroundPhosphogypsum is a waste product from production of phosphorus and is stored in a containment pond. Phosphogypsum wastewater still contains a usable amount of phosphorus. In addition to phosphorus, this water contains a small amount of arsenic, which prevents direct use of this water in agriculture. MethodRecycling of phosphorus from phosphogypsum wastewater was performed by struvite (NH4MgPO4•6H2O), precipitation. Arsenostruvite (NH4MgAsO4•6H2O) has always occurred naturally in the presence of struvite. The properties of arsenostruvite in comparison with struvite were monitored. The effect of selected reductants (SnCl2, ascorbic acid, K2S2O5) on the potential of reducing the concentration of As in the struvite crystallized from phosphogypsum wastewater, was monitored. FindingsWhen recovering phosphorus from phosphogypsum wastewater in the form of struvite the results showed that a ratio of As to P was lower by 50% compared to the original wastewater. K2S2O5 proved to be the most effective reducing agent for reducing the arsenic content of the product, but it was still not sufficient for the product to be used as a fertilizer without any further treatment.

Seasonal Activity and Diets of Bats at Uranium Mines and Adjacent Areas near the Grand Canyon

Little information exists on the habitat use and feeding ecology of insectivorous bats in arid ecosystems, especially at and near uranium mines in northern Arizona, within the Grand Canyon watershed. In 2015–2016, we conducted mist-netting, nightly acoustic monitoring (>1 year), and diet analyses of bats, as well as insect sampling, at 2 uranium mines (Pinenut and Arizona 1) with water containment ponds. Because of physical barriers and limited general access to areas within the mine yard, mist-netting was limited to outside of the perimeter fence and away from the containment ponds. Mist-netting also occurred at 2 nearby sites that served as proxies to the mines. Bats captured directly at the mines included one pregnant Antrozous pallidus and 3 adult male Parastrellus hesperus. At the proxy sites, we captured 45 individuals identified as A. pallidus, Corynorhinus townsendii, Eptesicus fuscus, Euderma maculatum, Lasionycteris noctivagans, Myotis californicus, Myotis ciliolabrum, P. hesperus, and Tadarida brasiliensis. The nightly and seasonal presence of bats, as shown through acoustic recordings at each mine, coincided with the seasonal migratory and hibernation behaviors of the bat species. Statistical comparisons of acoustic recordings with precipitation data collected over one year show that seasonal monsoon rains generally had a negative effect on the nightly activity and presence of bats. Diets of P. hesperus from both mines were comprised mostly of coleopterans but also included smaller volumes of Hymenoptera, Hemiptera, Lepidoptera, Diptera, and Neuroptera. The diet of A. pallidus was comprised solely of Coleoptera. Diets of bat species from the proxy sites were characteristic of their known feeding ecology, which ranged from the consumption of soft-bodied insects (e.g., moths) by C. townsendii to the consumption of hard-bodied insects (e.g., beetles) by E. fuscus. Ultimately, the increased knowledge of the natural history of bats through multiple methods of data collection allows for a better understanding of complex arid ecosystems. It also provides resources needed for the management of habitat associated with alternative energy, such as uranium mining.

Waste Containment Ponds Are a Major Source of Secondary Organic Aerosol Precursors from Oil Sands Operations.

The surface mining and bitumen extraction of oil sands (OS) generates over one million barrels of heavy oil each day in the Alberta Oil Sands Region of Canada. Recent observations suggest that emissions from OS development contribute to secondary organic aerosol (SOA) formation, but the chemical composition, mass fluxes, and sources of those emissions are poorly delineated. Here, we simulated OS extraction and used comprehensive two-dimensional gas chromatography to quantify and characterize direct air emissions, bitumen froth, residual wastewater, and tailings components, ultimately enabling fate modeling of over 1500 chromatographic features simultaneously. During the non-ice cover season, tailings ponds emissions contributed 15 000-72 000 metric tonnes of hydrocarbon SOA precursors, translating to 3000-13 000 tonnes of SOA, whereas direct emissions during the extraction process itself were notably smaller (960 ± 500 tonnes SOA yr-1). These results suggest that tailings pond waste management practices should be targeted to reduce environmental emissions.

Inventing Tomorrow by Laura Nix (review)

Film Review: Inventing Tomorrow 151 Inventing Tomorrow A film directed by Laura Nix (2018) Associate Producers: Elease Lui Stemp and Ann Rogers Fishbowl Films, 1 hour 45 minutes https://www.inventingtomorrowmovie.com Increasingly, we see young climate activists highlighted in the news, and rightly so, for their actions are important and significant. This film is about some less-sung stories of six young heroes working in diverse countries to improve the environmental conditions of their cities through the application of science. Across four countries—from a small Indonesian island to the cities of Hilo, Hawaii; Bangalore, India; and Monterrey, Mexico—we see not only the toxic world young people are inheriting, but also the resolve and dedication they bring to tackling these problems. In the words of Sahithi Pingali, a young scientist from Bangalore: “You see the same issues repeated across the world. It’s inevitably our job as the next generation to tackle this. The people who are approaching this through the eye of science are the people who can fix it and are going to fix it.” This film will appeal to Science, Technology, Engineering, and Math (STEM) and environmental educators in both secondary and higher education contexts. It will also appeal to faculty interested in environmental studies, critical sustainability studies, and the sociology of youth empowerment, youth activism, and youth agency. The film is accompanied by free educator guides and youth biographies accessible from the film’s website. Working through separate vignettes in each of four countries, young people converge at the Intel International Science and Engineering Fair (ISEF), the “science fair of science fairs” in Los Angeles, California. Youth come from a variety of circumstances—from Monterrey youth who will be the first in their family to go to university and who must work long hours while in high school to support their families, to youth from the relative affluence of a suburb of Bangalore who are raised with an acute awareness of the disproportionate effects a wealthy lifestyle can bring to the environment. The environmental issues youth address are also diverse. In Indonesia, two young women devise a filtration system to mitigate the impacts of mining for tin, which is being harvested for cell phones and other technological devices and releases lead into the water. In Hilo, a third-generation Hawaiian investigates the spread of arsenic from a 28-year-old industrial containment pond that released its toxic waters after two tsunamis hit. In Bangalore, a small team explores how technology can be used to monitor water quality in what is known as the “Silicon Valley of India,” where contaminated lakes catch fire and foamy detergent water that is released into lakes eventually makes its way across highways as bubbly clouds the size of small cars. In Monterrey, three youth from one of the most industrialized cities of Mexico, tackle issues of air pollution—an issue made more salient after one of their uncles died of respiratory disease—through toxin-absorbing photovoltaic paints. Film Review: Inventing Tomorrow 152 This film’s primary story is about science as a tool for empowerment and action, with youth taking on the problems they see in their communities and receiving recognition and supports to advance their work. The film shows a sense of purpose as well as resolve in the face of some of the most grueling aspects of science, including when adult judges circulate during the ISEF fair, asking hard questions with poor language translators. Other themes, more subtly presented, include differences in educational equity between the global north and global south, transnational experiences of education between Los Angelinos and Monterrey youth, and many poignant moments that show the importance of cultural and intergenerational values in shaping young people’s approach to the application of science. Inventing Tomorrow shows the victories of science, with the young woman from Bangalore winning awards at ISEF and pursing solutions at the University of Michigan with graduate students and faculty in environmental engineering. I cannot help but also feel the disappointment for those who did not win at ISEF, from Monterrey and Indonesia, and to reflect on the extreme challenges youth face in advocating for change against nearly every barrier imaginable—ageism...

Environmental Health Assessment Using Sentinel Species near Placencia Lagoon, Belize

Unexplained bird deaths discovered around Placencia Lagoon, Belize over a 2-year period sparked an investigation into the environmental health of the lagoon and two of its major tributaries. In this study, conducted from January 23 to February 28, 2018, we assessed avian health within two commercial aquaculture facilities, each with a substantial outflow into the lagoon; a shrimp farm and a tilapia farm. Birds were chosen as our study subjects not only because of previous bird deaths, but also as sentinel species to assess overall possible contamination. Both facilities had previously been affected by die-offs of their cultivated product. The variety of sampled bird species, both year-round and winter residents, fed on small fish, airborne insects, mud-dwelling invertebrates and/or plant material, i.e. seeds and fruits, thereby sampling air, soil and water as possible bioaccumulation vectors. We trapped birds in, or nearby outflow containment ponds which emptied into the lagoon. Additionally, we assessed avian health at two reference locations on Placencia Penninsula, not known for avian health problems. Birds from multiple families representing different ecological niches were captured using two net types. We conducted standard ornithological assessments, measured hematocrit, made an evaluation of ectoparasite load and types, and for shorebirds, examined fecal swabs for parasites. Measured values were compared to published data and a previously established database from data collected elsewhere in the Caribbean. For each of the major sites, an extensive period of evaluation was later followed with a shorter, second evaluation at each location. Except for a single, second-year, Brown Pelican (Pelicanus occidentalis) evaluated one day at the close of the study, 257 birds were found to be healthy on all parameters including hematocrit and parasite load. We observed that the pelican had not been present previously and inferred that its health problems were acquired at another site. This conclusion was corroborated by the concurrent discovery of dead or dying pelicans along the Belize coast near the end of this investigation.

Metabarcoding of Environmental DNA Samples to Explore the Use of Uranium Mine Containment Ponds as a Water Source for Wildlife

Understanding how anthropogenic impacts on the landscape affect wildlife requires a knowledge of community assemblages. Species surveys are the first step in assessing community structure, and recent molecular applications such as metabarcoding and environmental DNA analyses have been proposed as an additional and complementary wildlife survey method. Here, we test eDNA metabarcoding as a survey tool to examine the potential use of uranium mine containment ponds as water sources by wildlife. We tested samples from surface water near mines and from one mine containment pond using two markers, 12S and 16S rRNA gene amplicons, to survey for vertebrate species. We recovered large numbers of sequence reads from taxa expected to be in the area and from less common or hard to observe taxa such as the tiger salamander and gray fox. Detection of these two species is of note because they were not observed in a previous species assessment, and tiger salamander DNA was found in the mine containment pond sample. We also found that sample concentration by centrifugation was a more efficient and more feasible method than filtration in these highly turbid surface waters. Ultimately, the use of eDNA metabarcoding could allow for a better understanding of the area’s overall biodiversity and community composition as well as aid current ecotoxicological risk assessment work.

Pre-mining trace element and radiation exposure to biota from a breccia pipe uranium mine in the Grand Canyon (Arizona, USA) watershed.

The risks to wildlife and humans from uranium (U) mining in the Grand Canyon watershed are largely unknown. In addition to U, other co-occurring ore constituents contribute to risks to biological receptors depending on their toxicological profiles. This study characterizes the pre-mining concentrations of total arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), mercury (Hg), nickel (Ni), selenium (Se), thallium (Tl), U, and zinc (Zn); radiation levels; and histopathology in biota (vegetation, invertebrates, amphibians, birds, and mammals) at the Canyon Mine. Gross alpha levels were below the reporting limit (4 pCi/g) in all samples, and gross beta levels were indicative of background in vegetation (<10-17 pCi/g) and rodents (<10-43.5 pCi/g). Concentrations of U, Tl, Pb, Ni, Cu, and As in vegetation downwind from the mine were likely the result of aeolian transport. Chemical concentrations in rodents and terrestrial invertebrates indicate that surface disturbance during mine construction has not resulted in statistically significant spatial differences in fauna concentrations adjacent to the mine. Chemical concentrations in egg contents and nestlings of non-aquatic birds were less than method quantification limits or did not exceed toxicity thresholds. Bioaccumulation of As, Pb, Se, Tl, and U was evident in Western spadefoot (Spea multiplicata) tadpoles from the mine containment pond; concentrations of As (28.9-31.4μg/g) and Se (5.81-7.20μg/g) exceeded toxicity values and were significantly greater than in tadpoles from a nearby water source. Continued evaluation of As and Se in biota inhabiting and forging in the mine containment pond is warranted as mining progresses.

E&amp;P Notes (December 2015)

E&amp;P Notes Study Finds Surface Spills a Higher Risk to Groundwater Than Fracturing Trent Jacobs, JPT Senior Technology Writer Researchers at Yale University who analyzed groundwater wells in the Marcellus Shale area have determined that hydraulic fracturing is highly unlikely to be a direct source of contamination. The 3-year study, published in the Proceedings of the National Academy of Sciences, also found that well casing failures and produced water containment ponds did not impact the groundwater samples taken during the study. The researchers concluded that the samples that tested positive for some of the same organic chemical compounds used in drilling and completion operations, but not in dangerous concentrations, resulted from accidental spills on the surface. Statistics Point to Water Injection as Cause of Earthquakes, But Understanding Why Remains a Geological Puzzle Stephen Rassenfoss, JPT Emerging Technology Senior Editor A surge in earthquakes tightly clustered in southern Kansas that followed the large increase in produced water injections prompted the state to cut the daily limits on disposal wells in that area to see if that will help solve the problem. Based on 3 months of reduced injections through mid-September, “the results were encouraging,” said Shelby Peterie, a research geophysicist at the Kansas Geological Survey. Her presentation at the Society of Exploration Geophysicists’ annual meeting in New Orleans in October showed there has been a reduction in the intensity of the earthquakes reported, but not the number of them. From Air to Sea: Introducing Crew Resource Management to the Offshore Industry Trent Jacobs, JPT Senior Technology Writer Despite a number of recent and high-profile jetliner crashes, commercial aviation has entered into a new era of safety. Seven of the past 10 years have seen the fewest fatal accidents in the industry’s nearly 7-decade history and this year is on track to be the safest yet. Aside from the significant improvements made in aircraft reliability, much of the progress has been attributed to the communication and operational training program known as crew resource management (CRM). The basic principle of CRM is to encourage key personnel to speak up when they detect problems or notice mistakes while maintaining the hierarchy of authority. Air Gun Inventor Creates A Lower Pressure Option Stephen Rassenfoss, JPT Emerging Technology Senior Editor More than 50 years after inventing the air gun, Stephen Chelminski is working on a new version of the industry standard designed to be more in tune with the current needs of the industry and its regulators. While the components used would be familiar to anyone who has worked with an air gun, it has a fatter shape and produces sounds in a lower range. If it were a horn, it would be a tuba and a standard air gun would be a trumpet. The goal is to reduce the energy emitted to produce the lower frequency range that is useful for seismic, while decreasing the emission of frequencies said to cause trouble for marine life. “Something like 3% to 6% of the energy from an air gun is turned into useful energy for seismic. The rest is wasted,” said Chelminski, chief executive officer of Chelminski Research, during an interview at the recent Society of Exploration Geophysicists’ (SEG) annual meeting in New Orleans. Drilling Competition Offers Real-World Skills Challenge Stephen Rassenfoss, JPT Emerging Technology Senior Editor Vimlesh Bavadiya is leading a team of engineering students at the University of Oklahoma (OU) to repeat its victory in SPE’s Drillbotics competition next year. The competition to build the best automated drilling machine was created to provide engineering students with a dose of real-world experience, where teamwork is required to attack a complex challenge when time and money are limited, the rules change, and in the end, things break. “It was a very difficult path. But it was very good,” Bavadiya said, summing up the experience of the five-member team that won the first ever Drillbotics competition, which was created by the SPE Drilling Systems Automation Technical Section.

Maintenance Dredging at Port of Townsville

The Port of Townsville conducts regular annual maintenance dredging to maintain depths of its harbor basin and approach channels for the navigational safety of the vessels against the natural accumulation of marine sediments. In addition to the regular maintenance dredging, the port undertakes emergency dredging in cases where large quantities of sediments are mobilized and deposited in port waters by cyclone or major flood events. The maintenance dredging material derived from the port may be disposed at sea or on land in accordance with relevant state and commonwealth regulations. For the land disposal, the dredged mud slurry is hydraulically placed into containment ponds and left to undergo sedimentation and self-weight consolidation to form fill material for land reclamation. This paper provides an overview of the maintenance dredging at the Port of Townsville and emphasis on maintenance dredging requirements, sediment quality, bathymetry, dredging methods used, and dredged material disposal options.

Fracking's Future in a Coal Mining Past: Subjectivity Undermined

AbstractThis paper presents initial research on a community of renters in Southwestern Pennsylvania whose homes are adjacent to a hydraulic fracturing site and containment pond. The community is nestled in a rural section of the county where abandoned and working coal mines are neighbors to fracking's new industrial process of energy extraction, which residents describe as moving in like “aliens.” Most have family members who work(ed) in the coal industry, and the identity that emerges from their community of practice, and the attendant institutions and structures that shape their commentary of complaint and benefit are fundamentally informed by factors associated with labor. Coal miners are a more localized, populous, networked labor force with deep roots in the area, while the fracking‐related labor is diffuse, disaggregated, and transient. Residents seek ways to frame their concerns and articulate their unease from a position as outsiders, and while buy‐in on jobs as a natural outcome of the natural gas industry is high despite evidence to the contrary, critiques about health and the environment are tentative.

An Instantaneous Unit Hydrograph for Estimating Runoff from Windrow Composting Pads

Abstract. Compost pads are frequently constructed employing open windrows over a porous sand and crusher-run aggregate surface supported by compacted finer textured subsoil with limited infiltration capacity. A MatLab-Simulink ® compartmental dynamic model was developed with the goal of linearizing the system and developing an instantaneous rainfall-runoff unit hydrograph. The MatLab-Simulink model was verified with a HYDRUS 2D ® model before developing the unit hydrograph. Infiltration rate and percolation through the crusher-run media were measured using double ring infiltrometers. We compared the containment pond stage predictions from the HYDRUS and Matlab-Simulink compartmental models to the observed pond stage and found R 2 values greater than 0.9, Nash-Sutcliffe statistics greater than 0.9, and Root-mean-square-errors (RMSE) less than 1% of the full pond volume on 16 storms occurring from 23 December 2010 to 21 June 2011). A continuous simulation over the calibration period (23 Dec. 2010 to 30 Jan. 2011) revealed good agreement of Matlab-Simulink and observed pond volume. Running the simulation between 10 April 2012 and 21 June 2011 suggested that an unmodeled compost absorption effect might be significant particularly in the summer period, along with evaporation and seepage losses. The Matlab-Simulink compartment model appeared to capture the physical runoff process occurring on the pad, except for the impact of the compost material itself. A transfer function for each linearized model made possible the determination of the impulse response at several linearized conditions. The instantaneous unit hydrograph is the impulse response at the appropriate linearization. From these analyses, we proposed an instantaneous unit hydrograph for similarly constructed windrow compost pads and believe the approach to be relevant to any site where surface and subsurface flow processes are reasonably well defined.

Role of Mixing Energy in the Flocculation of Mature Fine Tailings

High-molecular-weight polymer flocculants are used for accelerated dewatering of mature fine tailings (MFTs) to reclaim the land occupied by containment ponds. Two anionic polymers were used to flocculate an MFT sample containing 98% by weight of fines smaller than 44 μm in diameter, with 85% of this fraction being clay minerals. The polymer solutions and polymer-treated MFT followed the Herschel-Bulkley and Bingham equations of state, respectively. The coupling of shear thinning and structural breakdown of the flocculated MFT gave rise to cavern formation during mixing. The mixing energy input for a series of MFT flocculation tests, in which other conditions were held constant, was proportional to the mixing time. The mixing tools used for the flocculation process were a Rushton turbine (RT), a pitched-blade turbine (PBT), a vane, and hydrofoil impellers. The flocculation outcome was evaluated on the basis of the amount of water released and the capillary suction test time (CST). The CST of the treated M...

Aplicación del permanganato potásico para la eliminación de cianuros de cobre en aguas residuales de la planta de lixiviación en una mina de oro (I)

The use of cyanide in the hydrometallurgical and chemical industries has led to the emergence of a major environmental problem due to its high toxicity. The wastewater generated at these plants is hazardous to the environment and therefore must be managed properly. For this purpose, they undergo detoxification processes after lodes from the plant are accumulated in waste-resistant containment ponds that mast be waterproof to prevent environmental disasters from leakages or massive flood. This work shows the results obtained in laboratory tests carried out with plant waters and demonstrates the efficacy of potassium permanganate as an oxidant of cyanide wastewater from a gold hydrometallurgical plant. In the process the destruction of the copper cyanide complexes in solution is achieved and copper metal ions are eliminated through precipitation mostly as hydroxide.

Effects of Lime-Clay Modification on the Consolidation Behavior of the Dredged Mud

A series of laboratory tests was performed to evaluate the effect of clay fabric, altered due to the addition of hydrated lime into slurry, on the primary and secondary consolidation behavior of dredged mud samples. In this research, the seepage-induced consolidation test is proposed as a technique to determine the threshold value of lime, below which maximum flocculation of the clay particles takes place. A series of oedometer tests was conducted on lime treated samples in both normally consolidated (NC) and artificially over- consolidated (OC) states. The results obtained in NC range showed that both the coefficient of consolidation and compression index increased as the lime content increased. Under the same value of effective stress, with varying the amount of lime, the compression index increased and secondary compression index reduced, resulting in a gradual reduction of Calpha/Cc value. The laboratory results show that in the OC state and with surcharging, both the secondary compression index and recompression index reduced when the percentage of lime increased. However, it was observed that the surcharging effort has less impact on secondary compression as the percentage of lime increased. This study may encourage an innovative ground improvement technique, in which dredged mud slurry can be mixed with lime prior to discharging into a containment pond in order to optimize the effectiveness of preloading on the dredged mud layer.

Oil field-produced water discharges into wetlands: Benefits and risks to wildlife

Wyoming is one of a few states that allow the discharge of produced water from oil fields into surface waters for beneficial use by livestock and wildlife. Oil field discharges of produced water create wetlands that provide habitat for aquatic migratory birds and other wildlife. Wetlands surveyed in Wyoming from 1996 to 1999 showed that inefficient oil-water separation contributed to the discharge of oil into some wetlands receiving produced water. Over 62% of the sites surveyed had inadequate measures to exclude wildlife, particularly migratory birds, from entering skim pits used to separate oil from produced water. The risk of oil discharges into wetlands can be reduced significantly by proper maintenance of equipment used to separate oil from produced water; immediate removal of oil from production skim pits or tanks to prevent overflow into the receiving wetlands; installation of secondary or tertiary containment ponds or tanks to capture any oil accidentally discharged from the primary or secondary pits or tanks; or construction of wetland-based treatment systems for removing metals, radionuclides, and hydrocarbons from the produced water prior to discharge into natural wetlands. Wildlife mortality in skim pits can be prevented using closed containment systems, eliminating pits or keeping oil off open pits or ponds, or using effective and proven wildlife exclusionary devices.

The Potential for Carbon Dioxide Sequestration in Oil Sands Processing Streams

Abstract The consolidated tailings (CT) process involves chemical amendments to combine the clays and fines in oil sands mature fine tailings or thickened tailings with the coarser sand components to create a nonsegregating tailings (NST) mixture that will rapidly consolidate. Over the years, several amendment chemicals have proved useful in controlling the fluid tailings properties so that they may support sand loading and remain non-segregating. Suncor has several years of commercial-scale operating experience with gypsum as the CT process aid and in the years leading up to the commercialization of the CT process at Suncor, carbon dioxide was also investigated as a CT process aid. With the concerns over carbon dioxide related to the Kyoto Protocol, the extent to which carbon dioxide is trapped and chemically sequestered in the CT process has been investigated. The mechanism by which carbon dioxide addition affects the strength of the mature fine tailings or fluid tailings componentas been investigated, and the potential for carbon dioxide sequestration has been quantified. Depending upon the availability of gypsum as a CT or NST additive, carbon dioxide could beuseful alternative. Introduction Water-based extraction of bitumen from the Athabasca oil sands deposit results in the generation of a large amount of waste tailings. The tailings comprise slow settling fine clays with release water that is recycled for bitumen extraction, and a sand component that is generally used to create containment for the fluid fine ailings waste streams. The accumulated slowly settling fine claysare termed mature fine tailings (MFT) and settle to 30 to 45 wt﹪ after several years. Since approximately one barrel of fine tailings is generated from the production of 1 barrel of crude oil equivalent, over 1B m3 of MFT are currently impounded in containment ponds. Government regulations mandate that the containment ponds eventually be reclaimed to a natural landscape. The poor settling behaviour of fine tailings is a consequence of high concentrations of bicarbonate ion in the water, residual bitumen, and fine clays. Viable reclamation options that have been investigated in the industry involve some form of chemical manipulation using coagulants or polymeric flocculants to increase the dewatering rate, leaving behind a geotechnically stable deposit(1). The most successful strategy to date is the consolidated tailings (CT) process, which has been implemented by Suncor Energy Inc. using gypsum (CaSO4.2H2O) as a coagulant. The CT process can not only help deal with the accumulated MFT but, with thickeners to create an MFT analog at the end of pipe, it can also be used to prevent accumulation of fluid fine tailings or MFT. The making of a suitable CT mixture involves creation of a nonsegregating mixture of sand, clay, and water; rapid initial settling (water release) of the mixture; and ultimate consolidation of the mixture. Extensive studies by Scott et al.(1) have demonstrated that there is a wide range of sand-to-fines ratios, solids contents, and gypsum addition levels where these criteria are met.