In January 2012, Congress tasked the Secretary of Transportation to “determine whether any increase in the risk of release exists for pipelines transporting diluted bitumen.”1 In response to the congressional request, the U.S. Department of Transportation (USDOT) asked the National Academies of Sciences, Engineering, and Medicine (the Academies) to study the likelihood of release of diluted bitumen from crude oil transmission pipelines. The Academies released a report in 2013 concluding that “[t]he committee does not find any causes of pipeline failure unique to the transportation of diluted bitumen.”2 Following the 2013 release of Effects of Diluted Bitumen on Crude Oil Transmission Pipelines, Congress subsequently charged USDOT to “investigate whether the spill properties [of diluted bitumen] differ sufficiently from other liquid petroleum products to warrant modifications to the spill response plans, spill preparedness, or cleanup regulations and report on those findings to the House and Senate Committees on Appropriations within 180 days of enactment.”3
USDOT returned to the Academies in 2014 with a request to form an ad hoc committee to help address this concern. Specifically, this committee was taskedi to review the available literature and data to examine the current state of knowledge, and to identify the relevant properties and characteristics of the transport, fate, and effects of diluted bitumen and commonly transported crude oils when spilled in the environment from U.S. transmission pipelines. Based on a comparison of the relevant
i The committee’s full statement of task can be found in Box 1-1.
properties of diluted bitumen and of a representative set of crude oils that are commonly transported via pipeline, the committee was asked to determine whether the differences between properties of diluted bitumen and those of other commonly transported crude oils warrant modifications to the regulations governing spill response plans, preparedness, and cleanup.
In order to answer the questions outlined in the statement of task, the committee analyzed information in a variety of forms. Part of the committee’s data gathering included hearing presentations, meeting with stakeholders, and reviewing the literature. A detailed list of the individuals the committee met with can be found in the Acknowledgments section of this report. In the early phases of the study, an opportunity for public comment was provided. After considering all of the available data and information, the history of the study, and the sponsor’s request, the committee focused on environments that would most likely be affected by an oil spill from a transmission pipeline–that is, the contiguous U.S., including the near-shore coastline with far offshore not being considered. The report also focuses on spills from transmission pipelines and does not explicitly address other modes of transportation (e.g., rail, barge, truck, and tanker). It is likely that many of the topics covered in this report, and many of the conclusions and recommendations, will be applicable to these other transportation modes because many aspects of environmental impact are independent of mode of transportation.
The committee’s task requires a comparison between diluted bitumen and “crude oils commonly transported in U.S. transmission pipelines.” After an analysis of the total volumes of crude oil transported by U.S. pipelines (see Chapter 1), a set of light and medium crudes was chosen as representative of those “commonly transported” and likely to be encountered in a response scenario. The committee’s approach is described in greater detail in Chapter 1.
The starting point for assessing the Chemical and Physical Properties of Crude Oils (Chapter 2) was the intrinsic complexity of crude oils as mixtures of hydrocarbons with diverse structures and widely varying molecular weights. Mixtures of these compounds combine to make up the bulk properties of any particular crude oil. The bitumen fraction, in particular, is associated with reservoirs of recalcitrant and immobile crude oils. Unconventional extraction methods are required to access bitumen
reservoirs and addition of a diluent is needed to transport the bitumen product through unheated transmission oil pipelines. In comparison to other commonly transported crude oils, many of the chemical and physical properties of diluted bitumen, especially those relevant to environmental impacts, are found to differ substantially from those of the other crude oils. The key differences are in the exceptionally high density, viscosity, and adhesion properties of the bitumen component of the diluted bitumen that dictate environmental behavior as the crude oil is subjected to weathering (a term that refers to physical and chemical changes of spilled oil).
Immediately following a spill, the Environmental Processes, Behavior, and Toxicity of Diluted Bitumen (Chapter 3) are similar to those of other commonly transported crudes. Beginning immediately after a spill, however, exposure to the environment begins to change spilled diluted bitumen through various weathering processes. The net effect is a reversion toward properties of the initial bitumen. An important factor is the amount of time necessary for the oil to weather into an adhesive, dense, viscous material. For any crude oil spill, lighter, volatile compounds begin to evaporate promptly; in the case of diluted bitumen, a dense, viscous material with a strong tendency to adhere to surfaces begins to form as a residue. For this reason, spills of diluted bitumen pose particular challenges when they reach water bodies. In some cases, the residues can submerge or sink to the bottom of the water body. Importantly, the density of the residual oil does not necessarily need to reach or exceed the density of the surrounding water for this to occur. The crude oil may combine with particles present in the water column to submerge, and then remain in suspension or sink.
These factors are important to consider for Spill Response Planning and Implementation (Chapter 4). Spills of diluted bitumen into a body of water initially float and spread while evaporation of volatile compounds may present health and explosion hazards, as occurs with nearly all crude oils. It is the subsequent weathering effects, unique to diluted bitumen, that merit special response strategies and tactics. For example, the time windows during which dispersants and in situ burning can be used effectively are significantly shorter for diluted bitumen than for other commonly transported crudes. In cases where traditional removal or containment techniques are not immediately successful, the possibility of submerged and sunken oil increases. This situation is highly problematic for spill response because (1) there are few effective techniques for detection, containment, and recovery of oil that is submerged in the water column, and (2) available techniques for responding to oil that has sunk to the bottom have variable effectiveness depending on the spill conditions.
When Comparing Properties Affecting Transport, Fate, Effects, and Response (Chapter 5), several key properties emerge. Figure S-1 illustrates the properties relevant to transport, fate, and effects and the
potential environmental outcomes following a crude oil spill. Based on the similarities and differences between diluted bitumen (in pipeline and weathered forms) and other commonly transported crudes, the comparative levels of concern associated with these properties are highlighted. The majority of the properties and outcomes that differ from commonly transported crudes are associated not with freshly spilled diluted bitumen, but with the weathering products that form within days after a spill. Given these greater levels of concern for weathered diluted bitumen, spills of diluted bitumen should elicit unique, immediate actions in response.
Based on the differences identified previously, a review of the Regulations Governing Spill Response Planning (Chapter 6) was conducted. Of particular focus was Part 194 of the Pipeline and Hazardous Materials Safety Administration (PHMSA) regulations, which governs the planning of responses to spills from transmission pipelines. In addition, because the scope of the task was broadly defined to address “regulations governing spill response plans, spill preparedness, or cleanup,” relevant U.S. Environmental Protection Agency (USEPA) and U.S. Coast Guard (USCG) regulations were reviewed, primarily for comparison to PHMSA regulations. It is clear that PHMSA takes a substantially different approach from USEPA and USCG when setting expectations for and reviewing spill response plans. Notably, PHMSA reviews plans for completeness in terms of the regulatory requirements only, while USEPA and USCG review plans for both completeness and adequacy for response. Broadly, regulations and agency practices do not take the unique properties of diluted bitumen into account, nor do they encourage effective planning for spills of diluted bitumen.
In light of the aforementioned analysis, comparisons, and review of the regulations, it is clear that the differences in the chemical and physical properties relevant to environmental impact warrant modifications to the regulations governing diluted bitumen spill response plans, preparedness, and cleanup. The concern associated with these differences is summarized in Figure S-1 for both diluted bitumen and weathered diluted bitumen. Each property that is relevant to environmental transport, fate, and effects is identified with the potential outcomes and a qualitative level of concern compared to other commonly transported crudes. The most notable changes observed are in the comparison between diluted bitumen and weathered diluted bitumen. For example, the level of concern goes from the same to more (or less) concern between the weathered and non-weathered material for ten of the properties in Figure S-1 and all techniques identified in Figure S-2.
FIGURE S-2 Response operations: diluted bitumen relative to commonly transported crude oils. Acronym: VOCs: volatile organic compounds.
Diluted bitumen has unique properties, differing from those of commonly transported crude oils, which affect the behavior of diluted bitumen in the environment following a spill. This behavior differs from that of the light and medium crudes typically considered when planning responses to spills. Of greatest significance are the physical and chemical changes that diluted bitumen undergoes during weathering. A more comprehensive and focused approach to diluted bitumen across the oil industry and the relevant federal agencies is necessary to improve preparedness for spills of diluted bitumen and to spur more effective cleanup
and mitigation measures when these spills occur. The recommendations presented here are designed to achieve this goal.
Recommendation 1: To strengthen the preparedness for pipeline releases of oil from pipelines, the Part 194 regulations implemented by PHMSA should be modified so that spill response plans are effective in anticipating and ensuring an adequate response to spills of diluted bitumen. These modifications should
- Require the plan to identify all of the transported crude oils using industry-standard names, such as Cold Lake Blend, and to include safety data sheets for each of the named crude oils. Both the plan and the associated safety data sheets should include spill-relevant properties and considerations;
- Require that plans adequately describe the areas most sensitive to the effects of a diluted bitumen spill, including the water bodies potentially at risk;
- Require that plans describe in sufficient detail response activities and resources to mitigate the impacts of spills of diluted bitumen, including capabilities for detection, containment, and recovery of submerged and sunken oil;
- Require that PHMSA consult with USEPA and/or USCG to obtain their input on whether response plans are adequate for spills of diluted bitumen;
- Require that PHMSA conduct reviews of both the completeness and the adequacy of spill response plans for pipelines carrying diluted bitumen;
- Require operators to provide to PHMSA, and to make publicly available on their websites, annual reports that indicate the volumes of diluted bitumen, light, medium, heavy, and any other crude oils carried by individual pipelines and the pipeline sections transporting them; and
- Require that plans specify procedures by which the pipeline operator will (i) identify the source and industry-standard name of any spilled diluted bitumen to a designated Federal On-Scene Coordinator, or equivalent state official, within 6 hours after detection of a spill and (ii) if requested, provide a 1-L sample drawn from the batch of oil spilled within 24 hours of the spill, together with specific compositional information on the diluent.
Recommendation 2: USEPA, USCG, and the oil and pipeline industry should support the development of effective techniques for detection, containment, and recovery of submerged and sunken oils in aquatic environments.
Recommendation 3: USEPA, USCG, and state and local governments should adopt the use of industry-standard names for crude oils, including diluted bitumen, in their oversight of oil spill response planning.
Recommendation 4: USCG should revise its oil-grouping classifications to more accurately reflect the properties of diluted bitumen and to recognize it as a potentially nonfloating oil after evaporation of the diluent. PHMSA and USEPA should incorporate these revisions into their planning and regulations.
Recommendation 5: NOAA should lead an effort to acquire all data that are relevant to advanced predictive modeling for spills of diluted bitumen being transported by pipeline.
Recommendation 6: USEPA, USCG, PHMSA, and state and local governments should increase coordination and share lessons learned to improve the area contingency planning process and to strengthen preparedness for spills of diluted bitumen. These agencies should jointly conduct announced and unannounced exercises for spills of diluted bitumen.
Recommendation 7: USEPA should develop a standard for quantifying and reporting adhesion because it is a key property of fresh and weathered diluted bitumen. The procedure should be compatible with the quantity of the custodial sample collected by pipeline operators.
Although many differences between diluted bitumen and commonly transported crudes are well established, there remain areas of uncertainty that hamper effective spill response planning and response to spills. These uncertainties span a range of issues, including diluted bitumen’s behavior in the environment under different conditions, its detection when submerged or sunken, and the best response strategies for mitigating the impacts of submerged and sunken oil. These research priorities, discussed in Chapter 7, apply broadly to the research community.
Major topics for future research include
- Transport and fate in the environment,
- Ecological and human health risks of weathered diluted bitumen,
- Detection and quantification of submerged and sunken oil,
- Techniques to intercept and recover submerged oil on the move, and
- Alternatives to dredging to recover sunken oil.