Federal Regulations Should Be Strengthened to Prepare for Potential Spills of Diluted Bitumen, Which Pose Unique Environmental Concerns


WASHINGTON -- The U.S. Department of Transportation (DOT) needs to modify its regulations and planning in order to strengthen preparedness for accidental spills of diluted bitumen from pipelines, says a new report from the National Academies of Sciences, Engineering, and Medicine. Diluted bitumen, a type of crude oil made from bitumen extracted from tar sands, has properties that warrant special preparations to limit environmental damage in the event of a spill, said the committee that conducted the study and wrote the report.


“The recommendations set forth in our report represent a practical and pragmatic approach to mitigating the unique concerns associated with spills of diluted bitumen,” said committee chair Diane McKnight, professor of civil, environmental, and architectural engineering and a fellow of the Institute of Arctic and Alpine Research at the University of Colorado.


Bitumen is a heavy and dense crude oil that is extracted from tar sands in Canada. It is mixed with lighter oils and transported through pipelines in this diluted form. Diluted bitumen has been transported by pipeline in the U.S. for more than 40 years, but the amount has increased recently as a result of improved extraction technologies and production and exportation by Canada. Both new and existing pipelines are being proposed and developed to accommodate this increased production.


An Academies study released in 2013 found that diluted bitumen is no more likely than other crude oils to be accidentally released from a pipeline. As a follow-up to that study, Congress and DOT further directed the Academies to investigate whether, if a spill occurs, the properties of diluted bitumen differ enough from other types of oil to warrant changes to preparedness or cleanup regulations or to spill response plans. 


Such changes in regulations and planning are warranted, the new report says. While immediately following a spill, diluted bitumen behaves similarly to other crude oils immediately following a spill, exposure to the environment induces rapid physical and chemical changes known as “weathering” that are unique to diluted bitumen. Within days, diluted bitumen starts to turn into a heavy, viscous, sediment-laden residue that cannot easily be recovered using traditional response techniques. The residue has a strong tendency to adhere to surfaces, and it poses particular challenges if it is spilled into a body of water, because the residues can submerge or sink to the bottom.


The way diluted bitumen changes after weathering calls for greater concern compared with commonly transported crude oils and special response strategies and tactics, the report says. Currently, the regulations and practices of DOT’s Pipeline and Hazardous Materials Safety Administration (PHMSA) do not take the unique properties of diluted bitumen into account, nor do they encourage effective planning for spills of diluted bitumen. A more comprehensive and focused approach is needed to improve preparedness for spills of diluted bitumen and to spur more effective cleanup and mitigation measures when spills do occur.


The report recommends that PHMSA modify its Part 194 regulations so that spill response plans can effectively anticipate and ensure an adequate response to spills of diluted bitumen. For example, PHMSA should:

§  require response plans to describe activities and resources to mitigate impacts of spills of diluted bitumen, including capabilities to detect, contain, and recover submerged and sunken oil;

§  consult with the U.S. Environmental Protection Agency (EPA) and/or the U.S. Coast Guard (USCG) to obtain their input on whether response plans are adequate for spills of diluted bitumen; and

§  require response plans to describe procedures by which, if a spill occurs, pipeline operators will inform a designated federal or state official of the source and industry-standard name of any spilled diluted bitumen within six hours. If requested, they will provide a sample of the oil and information on the specific composition of the diluent within 24 hours.


PHMSA, together with the U.S. Environmental Protection Agency), the U.S. Coast Guard, and state and local governments should take advantage of the Area Response Planning process to increase coordination and share lessons learned in order to strengthen preparedness for spills of diluted bitumen.


In addition, EPA, USCG, and the oil and pipeline industry should support the development of effective, environmentally friendly techniques to detect, contain, and recover submerged and sunken oils in aquatic environments. USCG should revise its oil-grouping classification system to more accurately reflect the properties of diluted bitumen and to recognize it as a potentially nonfloating oil. And NOAA should lead an effort to acquire all relevant data that could aid advanced predictive modeling for spills of diluted bitumen being transported by pipeline.


Although many differences between diluted bitumen and other crude oils are well-established, some remaining areas of uncertainty hamper effective responses to spills, the report says. Further research is needed in a range of areas, including the ecological and human health risks posed by weathered diluted bitumen, techniques to intercept and recover submerged oil in moving water, and alternatives to dredging to recover sunken oil.


The study was sponsored by the U.S. Department of Transportation.  The National Academies of Sciences, Engineering, and Medicine are private, nonprofit institutions that provide independent, objective analysis and advice to the nation to solve complex problems and inform public policy decisions related to science, technology, and medicine.  The Academies operate under an 1863 congressional charter to the National Academy of Sciences, signed by President Lincoln.  For more information, visit http://national-academies.org.  A committee roster follows.



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Copies of Spills of Diluted Bitumen from Pipelines: A Comparative Study of Environmental Fate, Effects, and Response are available from the National Academies Press on the Internet at http://www.nap.edu or by calling 202-334-3313 or 1-800-624-6242. Reporters may obtain a copy from the Office of News and Public Information (contacts listed above).


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Division on Earth and Life Studies

Board on Chemical Sciences and Technology


Committee on the Effects of Diluted Bitumen on the Environment: A Comparative Study



Diane M. McKnight1 (chair)

Professor of Civil, Environmental, and Architectural Engineering, and



University of Colorado



Michel C. Boufadel

Professor and Director

Center for Natural Resources Development and Protection

Department of Civil and Environmental Engineering

New Jersey Institute of Technology



Merv Fingas

Independent Consultant

Edmonton, Alberta



Stephen K. Hamilton

Professor of Ecosystem Ecology and Biogeochemistry

W.K. Kellogg Biological Station

Michigan State University

Hickory Cornes


Orville Harris


O.B. Harris LLC

Missouri City, Texas


John M. Hayes2

Scientist Emeritus

Woods Hole Oceanographic Institution (retired)

Berkeley, Calif.


Jacqueline Michel


Research Planning Inc.

Columbia, S.C.


Carys Mitchelmore

Associate Professor

Center for Environmental Science

Chesapeake Biological Laboratory

University of Maryland



Denise J. Reed

Chief Scientist

Water Institute of the Gulf

Baton Rouge, La.


Robert M. Sussman


Sussman and Associates

Washington, D.C.


David L. Valentine

Professor of Earth Science and Biology

Department of Earth Science

University of California

Santa Barbara




Douglas Friedman

Study Director



1Member, National Academy of Engineering

2Member, National Academy of Sciences