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  • Oil Sands- Trailing Ponds

    by Sanjay Patel | No comment

    Published on June 4th, 2013

    Image and Reality – Tailings Ponds:

    Oil sands tailings ponds have received a great deal of media attention in connection with two types of environmental problems: how they impact ecosystems while active, and whether or when the land they occupy will be reclaimed. The media hype and distortion have had serious—and unfair—consequences for the industry’s image. This has made it difficult for those outside of the industry to gain a realistic insight into the relative importance of the various environmental issues linked to tailings ponds. The purpose of this report is to clarify the matter by providing crucial background information that, for a variety of reasons, including time, space, and other constraints, is customarily omitted from media reporting.

    In 2008, 1,600 ducks died after landing on syncrude’s aurora tailings pond, and separate studies in 2009 and 2010 revealed raised toxin levels in the athabasca river near oil sands operations and groundwater contamination. Complaints regarding reclamation surged in 2010, when the first pond was reclaimed, critics cried, “too little, too late.”

    This report will first discuss media reporting on tailings ponds, then provide background information about each topic, followed by a short description of what is currently being done to deal with environmental issues and what else must be done in the future. What emerges at the end is, predictably, a mixed bag: some concerns are fair, but others, although motivated by honest environmental concerns, are greatly exaggerated. For example, the bird affair would never have been so overblown if crucial statistics had been presented to the public to provide context. The jury is still out on the water contamination issue, since evidence is conflicting and additional scientific studies are needed to clarify matters. If contamination is occurring, operators will be required to take additional precautions, as new and stricter environmental regulations are already being enforced in Canada. Finally, the industry’s alleged passivity towards the reclamation issue is fueled by misconceptions about how tailings ponds work, and perhaps by ignorance of the sophisticated regulations that define (and enforce) when they must be abandoned.

    Tailings Ponds As Portrayed In The Media

    In April 2008, hundreds of ducks landed on Syncrude’s Aurora tailings pond, became coated in residual bitumen, and an estimated 1,600 died. Syncrude was found guilty of breaking provincial and federal wildlife laws for failing to deploy adequate deterrence measures to stop the birds from landing on the ponds, and was fined a total of $3 million in penalties. This was the highest total penalty ever imposed in Canada for an environmental offense. Thousands of photos and videos of the suffering ducks hit the newspapers and the Internet, and the tailings ponds became a focal point for oil sands critics. According to Prime Minister Stephen Harper, the dying ducks have tarred Alberta’s and Canada’s image. More recently, a 2010 investigation by Canadian Broadcasting Corporation (CBC) News revealed that a tailings pond belonging to CNRL was leaking, contaminating groundwater. First Nations leaders from the Fort MacKay reserve were featured in the report, and a band councillor expressed worry that animals used as traditional food sources could be drinking from the pond since there are no barriers to keep them away. The ERCB disputed this claim, but the report had made its impact.

    The issue of tailings ponds reclamation has been another controversial issue in the headlines. To date, only one tailings pond has been reclaimed, in 2010. One of the reasons why environmental critics target tailings ponds is the very visual way they impact the landscape. They are large and desolate, and remain like that for decades until the land they occupy is eventually reclaimed. Exactly how that will happen is something that continues to worry environmentalists, some of whom wonder whether the land will be lifeless for centuries to come.
    We will first look at what tailings ponds are and what problems are associated with them. Then we will see what must be done to ensure that the industry is environmentally responsible, and what is currently being done to reduce the environmental impact of tailings ponds.

    The Environmental Issues:

    Tailings ponds are an integral component of oil sands surface mining operations, but they are not required for in-situ extraction. Tailings are a leftover mixture of fine clay, sand, water, and residual bitumen after the bitumen is recovered from the oil sands in the extraction process. Approximately 12 to 14 barrels of water are needed to produce a barrel of bitumen in surface mining operations. All of this water and the solid waste from the extraction plants are pumped into man-made containment (tailings ponds) to settle solids from water. Heaviest material – mostly sand – settles to bottom and water rises to the top. Middle layer, – mature fine tailings (MFT) – made up of fine clay particles, remains suspended in water. Tailings are often deposited in discontinued mine pits, when they are available. This helps to minimize the environmental impact, since it reuses areas that have already been disturbed. When in-pit storage is not possible, compacted overburden and sands from tailings stream are used to create above ground ponds by forming dyke walls that are typically 50 to 70 meters high (Figure 1). Tailings ponds serve the dual purpose of storing water and tailings. Eventually the solids in suspension settle, which allows the water to be reused several times. However, not all of the water is recovered and recycled. Of the 12 to 14 barrels of water used, only 8 to 10 barrels are recycled from the tailings ponds and remaining 4 barrels of water remains trapped in fluid fine tailings. Because of this the fluid fine tailings are an essential part of water management because they retain so much water. The trapped water is replaced primarily with fresh water from the Athabasca River, with the remainder from site runoff and mine dewatering.

    The existence of tailings ponds can present three main types of risks to the environment: the possibility of birds landing on the ponds, river and ground water contamination, and land reclamation.

    First, tailings discharged in the ponds contain residual bitumen, which, over a period of time, accumulates and floats to the surface. Although some operators skim off and recover some of it, a film of bitumen is always present and poses a threat to any migrating bird that may land on the ponds.

    Second, after the water in the ponds has been used many times, the concentration of naphthenic acid and salts increases, and with it, its toxicity. Water in tailings ponds also contains several other harmful substances including benzene, phenols, toluene, polycyclic aromatic hydrocarbons, aluminum, arsenic, etc. that exceed ambient water quality guidelines (i.e., the Canadian Environmental Quality Guidelines for protection of aquatic life). However, this guideline is not directly applicable to the oil sands water, because the sensitive aquatic species that these guidelines are designed to protect do not live in the tailings ponds, and the water is not directly released to the environment except through seepage. Also, the toxicity of the water decreases slowly over time as organic compounds degrade, with some studies showing a much lower level of toxicity after about ten years. However, seepage from the tailings ponds could be a problem, particularly since several of the tailings ponds are very close to the Athabasca River. Seepage of these more heavily contaminated tailings into surface water and groundwater can have a serious impact on the environment.

    Third, there is the issue of when the land the ponds occupy can be reclaimed and returned to a condition similar to what it was before being used. Tailings ponds occupy a large area. It is estimated that every barrel of oil produced through surface mining generates one and a half barrels of fluid tailings. As mining operations expanded, it became necessary to build more and larger settling ponds. There are several oil sands tailings ponds, each close to 40-45 meters in height, covering a total area of 170 square kilometers. These ponds account for about 24 percent of the approximately 715 square kilometers of land that the industry has disturbed through oil sands mining, and they can have long lives as part of an active tailings management system, being used either for storage and recycling of water or for tailings deposits for 30 to 40 years.

    It is important to understand that reclamation is slow for good reasons. Although reclamation is planned for each pond when it is built, the actual reclamation process is initiated only after the pond has gone through its whole lifecycle, with no additional tailings being added and the residue left to settle. In tailings pond, the heaviest, coarser solids (mostly sand) sink to the bottom very quickly while water rises to the top, but a middle layer of MFT, which is comprised of about 70 percent water and 30 percent fine clay particles and has the consistency of yogurt, can take several decades to settle. Only when it does, can the excess water be removed, leaving the tailings to solidify and making reclamation possible.

    What Should Be Done, And What Is Being Done

    A number of mechanisms are already being used to prevent birds from landing on tailings ponds, and they have been in place for a number of years. Oil sands operators employ propane-fired cannons, scarecrows, decoy predators, and radar controlled laser deterrent systems. Their purpose is to warn or scare the birds (mostly waterfowl) away, and predict waterfowl patterns, but they do occasionally (rarely) land on the ponds. In the unfortunate 2008 incident at the Aurora pond, Syncrude had 18 gas-fired sonic cannons installed around it but they were not deployed, allegedly because of bad weather. This incident, which received extensive coverage in the media and seriously damaged the image of tailings ponds and the industry in general, was not deserving of the attention it received, as the number of dead birds was very low when put in context.

    Let’s consider the number of birds that die each year due to other forms of human intervention. According to studies cited by the American Bird Conservancy (ABC), thousands and thousands of birds die each year in the U.S. from collisions with wind turbines alone and, for all the casualties, wind power produced less than 3 percent of all U.S. electricity in 2011. To get an idea of the rate of mortality when birds collide with manmade structures in the U. S. alone, take a look at Table 1:

    Table 1: Bird Mortality Rate (U.S.)

    Collisions with Year of Estimate Mortality Estimate (Low) Mortality Estimate (High)
    Wind turbines 2009/10 100,000 (2010) 440,000 (2009)
    Towers 2008 4,000,000 50,000,000
    Power lines 2001 10,000,000 154,000,000
    Roads/vehicles 2005 10,700,000 380,000,000
    Urban light 2009 31,158,000 -
    Glass 2006 100,000,000 1,000,000,000
    (Source: American Bird Conservancy)

    According to the U.S. Department of Energy, 20 percent of all electricity will be generated by wind in 2030. When that happens, between 100,000 and 750,000 birds will be killed by wind turbines each year. In Alberta alone, hunters kill 125,000 ducks every year, and up to 80 million birds die each year in collisions with motor vehicles in North America. With the numbers put in context, we can say that Syncrude’s media punishment did not fit the crime.

    Oil Sands - Bird Deterrent Systems
    (Source: Shell Canada)

    In order to address the seepage and ground water contamination issue, ditches and wells are built with the aim of intercepting water leaking from ponds built in old pits as shown in Figure 1. Despite these precautions, there is always the risk of water escaping from the tailings ponds through groundwater because tailings pond walls are permeable by design and contaminants can migrate through the structure to a degree. Surface mine operators are currently required by the EPEA to report seepage rates. However, on this issue, both opponents and proponents of oil sands have different opinions about the current situation and its impact on the environment. But the latest reports issued by an independent oil sands advisory panel seem to indicate that we will have to wait a little longer to know exactly what is happening, and reserve judgment until further scientific analysis clarifies the true nature of the problem. The Alberta and federal governments commissioned the reports, after previous reports came to conflicting conclusions. Since 1997, the impact of oil sands exploration on water bodies has been monitored by the Regional Aquatics Monitoring Program (RAMP), a multi-stakeholder group governed by a committee including representatives from government, aboriginal communities, and industry, who claim that water bodies in the area show no significant changes in water quality. However, Dr. David Schindler of the University of Alberta and his team conducted their own study in 2010 and claimed that the oil sands industry releases the 13 elements considered priority pollutants under the U.S. Environmental Protection Agency’s Clean Water Act, via air and water, to the Athabasca River and its watershed. Confronted with the conflict between the claims of RAMP and Dr. Schindler’s group, the federal and Alberta governments commissioned independent advisory panels to try to clarify the matter. Their reports, issued in 2010 and 2011 respectively, argue that the level and quality of current federal and provincial monitoring is not sufficiently comprehensive, and that it must be improved in order for an adequate evaluation of the problem to be possible. According to Alberta’s expert panel, some of the contaminants found in the water almost certainly are not naturally occurring, but added that not enough research has been conducted on the level and source of the pollutants to be able to reach a definite conclusion. One important reason for the somewhat unsatisfactory nature of this report is that the interpretation of monitoring data is complicated by the fact that naturally occurring outcrops of bitumen continually release hydrocarbons and heavy metals into the Athabasca River. In summary, more work needs to be done before we reach a definite conclusion about the impact of oil sands development on the environment. The Canadian Minister of the Environment decided to establish a first class, state-of-the-art monitoring system for oil sands development. This monitoring program will be discussed further.

    Regarding the speed at which tailings ponds are being reclaimed, the industry could be criticized for 40 years of poor performance in addressing this issue, but this would be to state the problem in the wrong terms, since 40 years is the time it took for the first pond to be ready for reclamation. In September 2010, Suncor declared Pond 1 (Wapisiw Lookout), which in 1967 was the first tailings pond in oil sands to be created in Canada, to have solidified to a sufficient degree to allow the land to be reclaimed. Once complete, Wapisiw Lookout (formerly Pond 1) will be a 2.2 square kilometers area of mixed wood forest and a small wetland, supporting a variety of plants and wildlife. Wapisiw Lookout was a containment area for oil sands tailings between 1967 and 1997. A clearer description of the issue would address the need and urgency of pressing the industry to find quicker ways to achieve reclamation. This is particularly important since the future growth of oil sands exploration will require an increase in ponds capacity, although the tendency for future exploration to use primarily and increasingly in-situ methods (which do not require tailings ponds) will somewhat mitigate the problem.

    MFT takes many decades to firm up sufficiently for reclamation. The key to achieving speedy reclamation of tailing ponds is to find a way to solidify the problematic layer of MFT at a faster rate. It is only once these tailings have solidified and all water has been fully drained that the pond is ready to have its topsoil replaced in preparation for the planting of vegetables, trees, and shrubs. When the provincial government determines that an area has met its criteria for reclamation (the land must have been restored to a sustainable landscape), it is certified as reclaimed and officially returned to the province. After certification, ongoing assessment of the soil and vegetation is still necessary to ensure that reclamation was successful.

    A number of technologies have been developed since the industry started operations in the 1960s to reduce the environmental impact of tailings ponds. These technologies seek to reduce the volume of fine tailings and increase the rate of solidification. These include the use of mechanical centrifuges or thickeners, which reduce the water content of fine tailings, and the mixing of fine tailings with polymers, lime, or gypsum, which separate out the water from clay that would otherwise hold water. Some of these technologies are in the process of being tested, and a few of them have already been implemented.

    We do not have to rely on the goodwill of operators to reduce their environmental footprint, however, because environment regulation enforces it. In 2009, the ERCB issued Directive 074 on tailings ponds management, with performance criteria and clear enforcement actions should these criteria fail to be met. It requires operators to specify dates for construction, use, and closure of tailings ponds, and to file them with the ERCB, to reduce the accumulation of fine tailings, and to accelerate the reclamation of all new and existing tailings ponds. In addition, the directive requires that 50 percent of the clay and silt produced from the oil sands ore after July 2012 be removed from tailings ponds and made solid enough to support heavy equipment traffic. The ERCB monitors whether tailings ponds are abandoned by the date specified on the approved plans, and there is a provision to take action when they are not. Directive 074 is technically very challenging and only time will tell whether operators will succeed in achieving the goals. But strict environmental regulation in Canada has already motivated the major oil sands producers to join forces in an effort to advance tailings management technologies. In 2010, CNRL, Suncor, Imperial Oil, Syncrude, Teck Resources, Total E&P Canada, and Shell Canada announced plans to share both their research and current technologies. By working together, all operators will be able to lower costs, avoid penalties, and more quickly meet defined environmental goals.

    No industry can judiciously claim to have no impact on the environment, but hopefully this report has contributed to clarifying the extent of the environmental challenges facing the oil sands industry, and the degree to which the media have at times distorted these challenges, intentionally or unintentionally. One very positive aspect of producing oil from oil sands on Canadian soil is that additional monitoring can be implemented when necessary, and environmental regulations can be enforced to ensure that impact is minimized. It would be difficult to make this statement about many other oil-producing countries.

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