User:Oceanflynn/sandbox/Oil sands tailings ponds

From Wikipedia, the free encyclopedia
Jump to: navigation, search

Oil sands tailings ponds are engineered dam and dyke systems that contain solvents used in the separation process as well as residual bitumen, salts and soluble organic compounds, fine silts and water.[1] Large volumes of tailings are a byproduct of bitumen extraction from the oil sands and managing these tailings is one of the most difficult environmental challenges facing the oil sands industry.[1] Tailings ponds are engineered dam and dyke systems that contain solvents used in the separation process as well as residual bitumen, salts and soluble organic compounds, fine silts and water.[1]

Components of oil sands tailings ponds[edit]

The concentrations of chemicals may be harmful to fish and oil on the surface harmful to birds.[2] These settling basins were meant to be temporary. A major hindrance to the monitoring of oil sands produced waters has been the lack of identification of individual compounds present. By better understanding the nature of the highly complex mixture of compounds, including naphthenic acids, it may be possible to monitor rivers for leachate and also to remove toxic components. Such identification of individual acids has for many years proved to be impossible but a breakthrough in 2011 in analysis began to reveal what is in the oil sands tailings ponds.[3] Ninety percent of the tailings water can be reused for oil extraction.[1]

Size and scope[edit]

By 2009 as tailing ponds continued to proliferate and volumes of fluid tailings increased, the Alberta Energy Resources Conservation Board issued Directive 074 to force oil companies to manage tailings based on new aggressive criteria.[4] The Government of Alberta reported in 2013 that tailings ponds in the Alberta oil sands covered an area of about 77 square kilometres (30 sq mi).[1]

Regulations and oversight[edit]

The Tailings Management Framework for Mineable Oil Sands is part of Alberta’s Progressive Reclamation Strategy for the oil sands to ensure that tailings are reclaimed as quickly as possible.[4]


Reduction and reclamation[edit]

Suncor invested $1.2 billion in their Tailings Reduction Operations (TROTM) method [5] that treats mature fine tails (MFT) from tailings ponds with chemical flocculant, an anionic Polyacrylamide, commonly used in water treatment plants to improve removal of total organic content (TOC), to speed their drying into more easily reclaimable matter. Mature tailings dredged from a pond bottom in suspension were mixed with a polymer flocculant and spread over a "beach" with a shallow grade where the tailings would dewater and dry under ambient conditions. The dried MFT can then be transported to reclaimed in place or moved to another location for final reclamation. Suncor hoped this would reduce the time for water reclamation from tailings to weeks rather than years, with the recovered water being recycled into the oil sands plant. Suncor claimed the mature fines tailings process would reduce the number of tailing ponds and shorten the time to reclaim a tailing pond from 40 years at present to 7–10 years, with land rehabilitation continuously following 7 to 10 years behind the mining operations.[6] For the reporting periods from 2010 to 2012, Suncor had a lower-than-expected fines capture performance from this technology.[4] Syncrude used the older composite tailings (CT) technology to capture fines at its Mildred Lake project. Syncrude had a lower-than-expected fines capture performance in 2011/2012 but exceeded expectations in 2010/2011.[4] Shell used atmospheric fines drying (AFD) technology combined "fluid tailings and flocculants and deposits the mixture in a sloped area to allow the water to drain and the deposit to dry" and had a lower-than-expected fines capture performance.[4]

Suncor's Wapisiw Lookout[edit]

By 2010 Suncor had transformed their first tailings pond, Pond One, into Wapisiw Lookout, the first reclaimed settling basin in the oil sands. In 2007 the area was a 220-hectare pond of toxic effluent but several years later there was firm land planted with black spruce and trembling aspen. Wapisiw Lookout represents only one percent of tailings ponds in 2011 but Pond One was the first effluent pond in the oil sands industry in 1967 and was used until 1997. By 2011 only 65 square kilometres were cleaned up and about one square kilometre was certified by Alberta as a self-sustaining natural environment. Wapisiw Lookout has not yet been certified. Closure operations of Pond One began in 2007. The jello-like mature fine tails (MFT) were pumped and dredged out of the pond and relocated to another tailings pond for long-term storage and treatment. The MFT was then replaced with 30 million tonnes clean sand and then topsoil that had been removed from the site in the 1960s. The 1.2 million cubic meters of topsoil over the surface, to a depth of 50 centimetres, was placed on top of the sand in the form of hummocks and swales. It was then planted with reclamation plants.[7][8][9]

Syncrude's Sandhill Fen project[edit]

In 2008 Syncrude Canada Ltd. began construction of Sandhill Fen project, a 57-hectare research watershed- creating a mix of forest and wetland- on top of sand-capped composite tailings at its former 60-metre deep East Mine.[10]

End Pit Lakes[edit]

The Pembina Institute suggested that the huge investments by many companies in Canadian oil sands leading to increased production results in excess bitumen with no place to store it. It added that by 2022 a month’s output of waste-water could result in a 11-feet deep toxic reservoir the size of New York City’s Central Park [840.01 acres (339.94 ha) (3.399 km²)].[11]

The oil sands industry may build a series of up to thirty lakes by pumping water into old mine pits when they have finished excavation leaving toxic effluent at their bottoms and letting biological processes restore it to health. It is less expensive to fill abandoned open pit mines with water instead of dirt.[12] In 2012 the Cumulative Environmental Management Association (CEMA) described End Pit Lakes (EPL)[13] as

An engineered water body, located below grade in an oil sands post-mining pit. It may contain oil sands by-product material and will receive surface and groundwater from surrounding reclaimed and undisturbed landscapes. EPLs will be permanent features in the final reclaimed landscape, discharging water to the downstream environment.

— CEMA 2012

CEMA acknowledged that the "main concern is the potential for EPLs to develop a legacy of toxicity and thus reduce the land use value of the oil sands region in the future." Syncrude Canada was planning the first end pit lake in 2013 with the intention of "pumping fresh water over 40 vertical metres of mine effluent that it has deposited in what it calls 'base mine lake.'" David Schindler argued that no further end pit lakes should be approved until we "have some assurance that they will eventually support a healthy ecosystem." There is to date no “evidence to support their viability, or the ‘modelled’ results suggesting that outflow from the lakes will be non-toxic."[12]

Research[edit]

In March 2012 an alliance of oil companies called Canada’s Oil Sands Innovation Alliance (COSIA) was launched with a mandate to share research and technology to decrease the negative environmental impact of oil sands production focusing on tailings ponds, greenhouse gases, water and land. Almost all the water used to produce crude oil using steam methods of production ends up in tailings ponds. Recent enhancements to this method include Tailings Oil Recovery (TOR) units which recover oil from the tailings, Diluent Recovery Units to recover naphtha from the froth, Inclined Plate Settlers (IPS) and disc centrifuges. These allow the extraction plants to recover well over 90% of the bitumen in the sand.

In January 2013, scientists from Queen's University published a report analyzing lake sediments in the Athabasca region over the past fifty years.[14] They found that levels of polycyclic aromatic hydrocarbons (PAHs) had increased as much as 23-fold since bitumen extraction began in the 1960s. Levels of carcinogenic, mutagenic, and teratogenic PAHs were substantially higher than guidelines for lake sedimentation set by the Canadian Council of Ministers of the Environment in 1999. The team discovered that the contamination spread farther than previously thought.[15]

See also[edit]

References[edit]

  1. ^ a b c d e "Fact Sheet Tailings" (PDF), Government of Alberta, September 2013, retrieved 12 April 2014 
  2. ^ Tailings Ponds: What they're made of, Suncor 
  3. ^ Rowland SJ, Scarlett AG, Jones D, West CE, Frank RA., Diamonds in the Rough: Identification of Individual Naphthenic Acids in Oil Sands Process Water. Journal=Environmental Science & Technology 45: 3154–3159.Year=2011, doi:10.1021/es103721b 
  4. ^ a b c d e 2012 Tailings Management Assessment Report: Oil Sands Mining Industry (PDF), Calgary, Alberta: Energy Resources Conservation Board (ERCB), June 2013, retrieved 12 April 2014 
  5. ^ Ali, Zulfiqar (9 November 2011), Planning, Construction and Operational Challenges of Suncor’s 1st Sand Dump (PDF), Vancouver, BC, retrieved 12 April 2014 
  6. ^ "Suncor speeds tailings-pond reclamation". Oil & Gas Journal. Houston: PennWell Corporation. 23 October 2009. Retrieved 23 October 2009. 
  7. ^ Wapisiw Lookout Reclamation, nd, retrieved 11 August 2014 
  8. ^ Vanderklippe, Nathan (23 September 2010), Suncor scores environmental first, Wapisiw Lookout, Alberta: The Globe and Mail, retrieved 12 April 2014 
  9. ^ Schor, Elana (16 August 2011), Reclaimed Dump Sparks Oil Sands Sustainability Debate, New York Times, retrieved 12 April 2014 
  10. ^ Howell, David (22 September 2014), Q & A: Syncrude scientist talks about wetlands reclamation research, Fort McMurray, Alberta: Edmonton Journal, retrieved 22 September 2014 
  11. ^ van Loon, Jeremy (22 November 2013), Toxic Lakes From Tar-Sand Projects Planned for Alberta, Bloomberg Markets, retrieved 12 April 2014 
  12. ^ a b Vanderklippe, Nathan (3 October 2012), Ambitious plans for oil sands would create lakes from waste, Calgary, Alberta: The Globe and Mail, retrieved 12 April 2014 
  13. ^ CEMA Delivers Oilsands Mine End Pit Lake Guidance Document, Fort McMurray, Alberta: Cumulative Environmental Management Association (CEMA), 4 October 2012, retrieved 12 April 2014 
  14. ^ Kurek, J.; =Kirk, J.L.; Muir, D.C.G.; Wang, X.; Evans, M.S.; Smol; J.P. (2013). "Legacy of a half century of Athabasca oil sands development recorded by lake ecosystems" (PDF). Proceedings of the National Academy of Sciences of the United States of America. National Academy of Sciences of the United States of America: 1–6. Retrieved 9 January 2013. 
  15. ^ Austen, Ian (7 January 2013). "Oil Sand Industry in Canada Tied to Higher Carcinogen Level". The New York Times. 

Further reading[edit]

External links[edit]


Category:Bituminous sands Category:Petroleum industry Category:Unconventional oil