Study calls for stronger rules to prepare for potential dilbit spills

The US Department of Transportation should modify its regulations and planning to strengthen preparedness for accidental spills of diluted bitumen, or dilbit, from pipelines, a new report from the National Academies of Science, Engineering & Medicine (NASEM) recommended.

Its findings came on Dec. 8 as the US Department of State continued to consider applications from other pipelines to transport dilbit from Alberta into the US following President Barack Obama’s denial of a cross-border permit to TransCanada Corp. for its proposed Keystone XL project (OGJ Online, Nov. 6, 2015).

DOT and Congress requested the study in 2013 as a follow-up to one that found that dilbit is no more likely than other heavy oils to be accidentally released from a pipeline (OGJ Online, June 25, 2013).

They asked what were then known as the National Academies to investigate whether, if a spill occurs, dilbit’s properties sufficiently differ from other oils’ characteristics to warrant changes to preparedness or cleanup regulations and to spill response plans.

Such changes are warranted, the committee concluded. It said that while dilbit behaves similarly to other crude oils immediately following a spill, exposure to the environment induces rapid physical and chemical changes known as “weathering,” which are unique to dilbit.

Becomes heavy residue

Within days, dilbit starts to turn into a heavy, viscous, sediment-laden residue that cannot be recovered easily using traditional response techniques, the report said. The residue strongly tends to adhere to surfaces, and poses particular challenges if it is spilled into a body of water because the residues can submerge or sink to the bottom, it indicated.

The report said these changes after weathering call for greater concern compared with commonly transported crude oil and special response strategies and tactics. Regulations and practices at the US Pipeline & Hazardous Materials Safety Administration (PHMSA) do not currently take dilbit’s unique properties into account, nor do they encourage effective planning for dilbit spills, it said as it called for a more comprehensive and focused approach.

It specifically called on PHMSA to modify its Part 194 regulations so that spill response plans can effectively anticipate and ensure more effective cleanup and mitigation measures when spills occur by:

• Requiring response plans to describe activities and resources to mitigate impacts of dilbit spills, including capabilities to detect, contain, and recover submerged and sunken oil.

• Consulting with the US Environmental Protection Agency and the US Coast Guard (USCG) to obtain their input on whether response plans are adequate for dilbit spills.

• Requiring 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 dilbit within 6 hr. If requested, they also should provide a sample of the oil and information on its specific composition within 24 hr.

PHMSA, together with EPA, USCG, and state and local governments, should take advantage of the Area Response Planning Process to increase coordination and share lessons learned to strengthen preparedness for dilbit spills, the report said.

EPA, USCG, and the oil and pipeline industry should support development of effective, environmentally friendly techniques to detect, contain, and recover submerged and sunken oils in aquatic environments, it urged.

It recommended that USCG revise its oil-grouping classification system to more accurately reflect dilbit properties and recognize it as a potential nonfloating oil, and called on the National Oceanic and Atmospheric Administration to lead an effort to recover all relevant data which could facilitate advanced protective modeling for dilbit spills from pipelines.

Although many differences between dilbit and other crudes are well established, some remaining areas of uncertainty hamper effective spill responses, the report said. Further research is needed, including the ecological and human health risks weathered dilbit may pose, techniques to intercept and recover submerged oil in moving water, and alternatives to dredging to recover sunken oil.

“The recommendations set forth in our report represent a practical and pragmatic approach to mitigating the unique concerns associated with spills of [dilbit],” said Diana M. McKnight, a professor of civil, environmental, and architectural engineering at the University of Colorado at Boulder who chaired the committee.

Contact Nick Snow at

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