Create a new version of paste:

http://co.water.usgs.gov/nawqa/hpgw/factsheets/DENNEHYFS1.html
http://en.wikipedia.org/wiki/Environmental_risks_of_the_Keystone_XL_pipeline

{{merge-to|Keystone Pipeline|Pipeline transport|discuss=Talk:Environmental risks of the Keystone XL pipeline#Merge discussion |date=February 2013}}
{{copy edit|date=April 2012}}
[[File:Ogallala Aquifer - Keystone XL.png|thumb|300px|Proposed Keystone XL Pipeline route and saturated thickness map of the Ogallala Aquifer]]
The '''Keystone XL Pipeline''' ([[TransCanada Corporation|TransCanada]]) is a proposed addition to the [[Keystone Pipeline]] that would primarily carry dilute bitumen ([[dilbit]]) from the [[Athabasca oil sands]] in Alberta, Canada, to refineries in the [[Foreign Trade Zone]] of [[Port_Arthur,_Texas#Economy|Port Arthur]], [[Texas]]. The pipeline addition would consist of 36-inch diameter pipes buried four feet underground; it would extend over 1,700 miles and carry up to 830,000 barrels per day (bpd).<ref>{{cite web|last=US Department of State|title=Final Environmental Impact Statement for the Proposed Keystone XL Project|url=http://www.keystonepipeline-xl.state.gov/clientsite/keystonexl.nsf/03_KXL_FEIS_Executive_Summary.pdf?OpenFileResource|accessdate=17 October 2011}}</ref> 

[[Petrochemical]] contamination is the primary concern raised by the planned extension; its planned route over the [[Ogallala Aquifer]] makes Keystone XL a source of concern for government agencies as well as the American public.<ref>{{cite web|last=Visconti|first=Grace|title=Keystone XL Pipeline Project Threatens Ogallala Aquifer|url=http://digitaljournal.com/article/311242|publisher=Digitaljournal.com|accessdate=17 October 2011}}</ref><ref>{{cite web|last=Johanns|first=Mike|title=Keystone XL Pipeline|url=http://johanns.senate.gov/public/?p=trans|accessdate=17 October 2011}}</ref><ref>{{cite web|last=Parfomak|first=Paul|title=Keystone XL Pipeline Project: Key Issues|url=http://www.fas.org/sgp/crs/misc/R41668.pdf|work=Congressional Research Service|publisher=[[Federation of American Scientists]] (FAS)|accessdate=18 October 2011}}</ref>A significant [[Oil spill|spill]] would have negative consequences for nearby [[surface water]], shallow [[groundwater]], and [[wetlands]]--and would expose local plant- and animal populations to known health hazards. The Ogallala Formation underlies about 80 percent of the High Plains and is the principal geologic unit forming an aquifer system that supplies about 30% of all groundwater drawn for irrigation in United States and provides drinking water for 1.9 million people who live within the aquifer boundary.<ref name="dennehy">{{Cite web
| url=http://co.water.usgs.gov/nawqa/hpgw/factsheets/DENNEHYFS1.html
| author=Dennehy, K.F.
| year=2000
| title=High Plains regional ground-water study: U.S. Geological Survey Fact Sheet FS-091-00
| publisher=[[United States Geological Survey|USGS]]
| accessdate=2008-05-07
}}</ref> >The region accounts for 19% of wheat-, 19% of cotton-, 15% of corn-, 3% of sorghum-, and 18% of cattle production in the United States.<ref name="dennehy" /> Contamination of the Ogallala Aquifer would be economically-, agriculturally-, and ecologically catastrophic. To properly [[risk assessment|assess the risk]]  to the Ogallala Aquifer, a step-wise process following [[hazard (risk)|hazard identification]], [[exposure assessment]], and [[uncertainty]] is outlined.

On November 11, 2011 the [[United States Department of State]] decided to delay its decision on the trans-boundary project, citing mounting concerns about the sensitive [[Sand Hills (Nebraska)|Sand Hills]] (Nebraska) area and the Ogallala Aquifer.<ref>{{cite web|last=[[US State Department]] |title=Keystone XL Pipeline Project Review Process: Decision to Seek Additional Information|url=http://www.state.gov/r/pa/prs/ps/2011/11/176964.htm|accessdate=22 November 2011}}</ref><ref>{{cite web|last=Broder, John|first=Frosch, Dan|title=U.S. Delays Decision on Pipeline Until After Election|url=http://www.nytimes.com/2011/11/11/us/politics/administration-to-delay-pipeline-decision-past-12-election.html|publisher=New York Times|accessdate=22 November 2011}}</ref> 

On February 17, 2013 an estimated 40,000 protesters gathered at the National Mall in Washington, D.C., calling on President Barack Obama to reject the planned pipeline extension.<ref name=NBC>{{cite web|last=Rafferty|first=Andrew|title=Thousands rally in D.C. against Keystone Pipeline|url=http://usnews.nbcnews.com/_news/2013/02/17/16996283-thousands-rally-in-dc-against-keystone-pipeline|work=NBC News|publisher=National Broadcast Company|accessdate=21 February 2013}}</ref>  He is expected to decide the fate of the pipeline after recently-confirmed Secretary of State John Kerry completes a review of the project.<ref name=NBC />  

==Hazard identification== <!-- Hazard identification is the proper wording in risk assessment -->
Because the [[solvent]] fraction of dilbit typically comprises [[volatile]] [[aromatics]] like [[naptha]] and [[benzene]], reasonably rapid carrier [[vapourisation]] can be expected to follow an above-ground spill--ostensibly enabling timely intervention by leaving only a [[viscous]] residue that is slow to migrate. Effective protocols to minimize exposure to [[petrochemical]] vapours are well-established, and oil spilled from the pipeline would be unlikely to reach the [[aquifer]] unless incomplete remediation were followed by the introduction of another carrier (e.g., a series of torrential downpours). 

The Keystone XL extension is designed to be buried under four feet of soil, which will hinder post-spill vapourisation of the carrier fraction. Diluent and bitumen will migrate at different rates, depending on the temperature- and composition of the surrounding soils, but separation will take place more slowly as the aromatics diffuse through sediment rather than through air. 

The introduction of [[benzene]] and other volatile organic compounds (collectively [[BTEX]]) to the subterranean environment compounds the threat posed by a pipeline leak. Particularly if followed by rain, a pipeline breach would result in BTEX [[dissolution (chemistry)|dissolution]] and [[chemical equilibrium|equilibration]] of benzene in water, followed by [[percolation]] of the admixture into the aquifer. Benzene can cause many [[benzene#Health effects|health problems]] and is [[carcinogenic]] with EPA [[Maximum Contaminant Level]] (MCL) set at 5 μg/L for [[potable water]].<ref>{{cite web|last=EPA|title=Basic Information about Benzene in Drinking Water|url=http://water.epa.gov/drink/contaminants/basicinformation/benzene.cfm}}</ref> Although it is not well studied, single benzene exposure events have been linked to acute carcinogenesis.<ref>{{cite journal|last=Calabrese|first=EJ|coauthors=Blain, RB|title=The single exposure carcinogen database: assessing the circumstances under which a single exposure to a carcinogen can cause cancer|journal=Toxicological Sciences|year=1999|volume=50|issue=2|pages=169–185}}</ref> Additionally, the exposure of livestock, mainly cattle, to benzene has been shown to cause many health issues, such as [[neurotoxicity]], fetal damage and fatal poisoning.<ref>{{cite web|last=Pattanayek, M. and DeShields, B.|title=Characterizing Risks to Livestock from Petroleum Hydrocarbons|url=http://ipec.utulsa.edu/Conf2003/Papers/pattanayek_deshields_29.pdf|publisher=Blasland, Bouck, and Lee, Inc.|accessdate=2011-11-13}}</ref>

The entire surface of an above-ground pipeline can be directly examined for material breach. Pooled petroleum is unambiguous, readily spotted, and indicates the location of required repairs. Because the effectiveness of remote inspection is limited by the cost of monitoring equipment, gaps between [[sensors]], and data that requires interpretation, leaks in buried pipe are more likely to go undetected

Pipeline developers do not always prioritise effective surveillance against leaks. Buried pipes draw fewer complaints. They are [[insulated]] from extremes in [[ambient]] temperature, they are shielded from [[ultraviolet rays]], and they are less exposed to [[photodegradation]]. Buried pipes are isolated from airborne debris, [[electrical storms]], [[tornadoes]], [[hurricanes]], [[hail]], and [[acid rain]]. They are protected from nesting birds, [[rutting]] mammals, and wayward buckshot. Buried pipe is less vulnerable to accident damage (e.g., [[automobile accidents|automobile collisions]]) and less accessible to [[vandals]], [[saboteurs]], and [[terrorists]].

==Exposure==
Previous work<ref name = "stansbury">{{cite web|last=Stansbury|first=John|title=Analysis of Frequency, Magnitude and Consequence of Worst-Case Spills From the Proposed Keystone XL Pipeline|url=http://watercenter.unl.edu/downloads/2011-Worst-case-Keystone-spills-report.pdf}}</ref> has shown that a ‘worst-case exposure scenario’ can be limited to a specific set of conditions. Based on the advanced detection methods and pipeline shut-off [[Standard operating procedure|SOP]] developed by TransCanada, the risk of a substantive or large release over a short period of time contaminating groundwater with benzene is unlikely.<ref name = "potential">{{cite web|last=US State Dept|title=POTENTIAL RELEASES FROM PROJECT CONSTRUCTION AND OPERATION AND ENVIRONMENTAL CONSEQUENCE ANALYSIS|url=http://www.keystonepipeline-xl.state.gov/clientsite/keystonexl.nsf/19_KXL_FEIS_Sec_3.13_Potential_Releases.pdf?OpenFileResource|accessdate=2 November 2011}}</ref> Detection, shutoff, and remediation procedures would limit the dissolution and transport of benzene. Therefore the exposure of benzene would be limited to leaks that are below the [[Detection limit|limit of detection]] and go unnoticed for extended periods of time.<ref name=stansbury/> Leak detection is monitored through a [[SCADA]] system that assesses pressure and volume flow every 5 seconds. A pinhole leak that releases small quantities that cannot be detected by the SCADA system (<1.5% flow) could accumulate into a substantive spill.<ref name=potential/> Detection of pinhole leaks would come from a visual or [[olfactory]] inspection, aerial surveying, or mass-balance inconsistencies.<ref name=potential/> It is assumed that pinhole leaks are discovered within the 14 day inspection interval, however snow cover and location (e.g. remote, deep) could delay detection. Benzene typically makes up 0.1 – 1.0% of oil and will have varying degrees of [[volatility]] and dissolution based on environmental factors. 

Even with pipeline leak volumes within SCADA detection limits, sometimes pipeline leaks are misinterpreted by pipeline operators to be pump malfunctions, or other problems. The [[Enbridge]] Line 6B [[Enbridge oil spill|crude oil pipeline failure]] in [[Marshall, Michigan]] on July 25, 2010 was thought by operators in Edmonton to be from column separation of the dilbit in that pipeline. The leak in wetlands along the Kalamazoo River was only confirmed 17 hours after it happened by a local gas company employee in Michigan.

[[File:Benzene Transport to Groundwater from Oil Spill.pdf|thumb|300px|Scenario for benzene leaching to groundwater]]

===Spill frequency-volume===
Although the [[Pipeline and Hazardous Materials Safety Administration]] (PHMSA) has standard baseline incident frequencies to estimate the number of spills, TransCanada altered these assumptions based on improved pipeline design, operation, and safety.<ref name=potential/> Whether these adjustments are justified is debatable as these assumptions resulted in a nearly 10-fold decrease in spill estimates.<ref name=stansbury/> Given that the pipeline crosses 247 miles of the Ogallala Aquifer,<ref>{{cite web|last=US State Dept|title=Environmental Analysis: Water Resources|url=http://www.keystonepipeline-xl.state.gov/clientsite/keystonexl.nsf/09_KXL_FEIS_Sec_3.3_Water_Resources.pdf?OpenFileResource|accessdate=2 November 2011}}</ref> or 14.5% of the entire pipeline length, and the 50-year life of the entire pipeline is expected to have between 11 – 91 spills,<ref name=stansbury/> approximately 1.6 – 13.2 spills can be expected to occur over the aquifer. An estimate of 13.2 spills over the aquifer, each lasting 14 days, results in 184 days of potential exposure over the 50 year lifetime of the pipeline.
In the reduced scope ‘worst case exposure scenario,’ the volume of a pinhole leak at 1.5% of max flow-rate for 14 days has been estimated at 189,000 barrels or 7.9 million gallons of oil.<ref name=stansbury/> According to PHMSA’s incident database,<ref>{{cite web|last=PHMSA|title=Incident Statistics|url=http://www.phmsa.dot.gov/hazmat/library/data-stats/incidents|accessdate=2 November 2011}}</ref> only 0.5% of all spills in the last 10 years were >10,000 barrels. This suggests that an accumulated leak is unlikely to release 189,000 barrels.

===Benzene fate and transport===
Benzene is considered a light [[aromatic hydrocarbon]] with high solubility and high volatility. It is unclear how temperature and depth would impact the volatility of benzene, so assumptions have been made that benzene in oil (1% weight by volume) would not volatilize before equilibrating with water.<ref name=stansbury/> 
Using the octanol-water partition coefficient and a 100-year precipitation event for the area, a worst-case estimate of 75&nbsp;mg/L of benzene is anticipated to flow toward the aquifer.<ref name=stansbury/> The actual movement of the [[Plume (hydrodynamics)|plume]] through [[groundwater]] systems is not well described, although one estimate is that up to 4.9 billion gallons of water in the Ogallala Aquifer could become contaminated with benzene at concentrations above the MCL.<ref name=stansbury/> The Final Environmental Impact Statement from the State Department does not include a quantitative analysis because it assumed that most benzene will volatilize.<ref name=potential/>

===Previous dilbit spill remediation difficulties===
One of the major concerns about dilbit is the difficulty in cleaning it up.<ref>[http://www.loe.org/shows/segments.html?programID=12-P13-00027&segmentID=1 "Kalamazoo River Spill Yields Record Fine"], ''[[Living on Earth]]'', July 6, 2012. Lisa Song, a reporter for Inside Climate News, interviewed by Bruce Gellerman. Retrieved 2013-01-01.</ref>  Enbridge's Line 6B, a 30 inch crude oil pipeline, ruptured in Marshall, Michigan on July 25, 2010, mentioned above, spilled at least 843,000 gallons of dilbit.<ref>http://www.ntsb.gov/doclib/reports/2012/PAR1201.pdf</ref> After detection of the leak, booms and vacuum trucks were deployed. Heavy rains caused the river to overtop existing dams, and carried dilbit 30 miles downstream before the spill was contained.  Remediation work collected over 1.1 million gallons of oil and almost 200,000 cubic yards of oil-contaminated sediment and debris from the Kalamazoo River system. However, oil was still being found in affected waters in October of 2012.<ref>[http://www.epa.gov/enbridgespill/ "More Work Needed to Clean up Enbridge Oil Spill in Kalamazoo River"], US EPA, October 3, 2012.</ref>

==Assumptions and uncertainties==
Of the two reports that have examined the potential for benzene to contaminate the Ogallala Aquifer, one assumes the quantity released is insignificant and the persistence minimal,<ref name=potential/> while the other assumes a high amount released with high persistence,<ref name=stansbury/> There are speculations concerning the corrosiveness of dilbit - especially when pumped at 158<sup>o</sup>F,<ref>{{cite web|last=Swift et al|first=Anthony|title=Tar Sands Pipelines Safety Risks|url=http://www.nrdc.org/energy/files/tarsandssafetyrisks.pdf|accessdate=2 November 2011}}</ref> the detection and shutdown time, and the assumptions for spill frequency-volume.<ref name=stansbury/> However, TransCanada has offered to comply with 57 special conditions set forth by the PHMSA and claim to have superior pipelines compared to those documented in the past.<ref>{{cite web|last=US State Department|first=Appendix U|title=PHMSA Special Conditions|url=http://www.keystonepipeline-xl.state.gov/clientsite/keystonexl.nsf/FEISAppendix_U_PHMSA-Special-Conditions.pdf?OpenFileResource|accessdate=17 November 2011}}</ref>

==References==
{{Reflist|35em}}

==External links==
*[http://www.guardian.co.uk/environment/2012/nov/14/al-gore-climate-change-transcript?intcmp=239 Al Gore's views on climate change, extreme weather and Keystone XL – full transcript | Environment | guardian.co.uk]—[[Guardian.co.uk]], Wednesday 14 November 2012

[[Category:Oil pipelines in Canada]]
[[Category:Oil pipelines in the United States]]
[[Category:Environmental issues in Canada]]
[[Category:Environmental issues in the United States]]
[[Category:Environmental issues with petroleum]]