Following the regrettable pipeline spill in Mayflower on March 29, ExxonMobil has been working with federal, state and local authorities to provide frequent updates on the status of the cleanup and response operations. The Unified Command Joint Information Center, which includes the EPA, Arkansas Department of Health, Faulkner County and ExxonMobil Pipeline Company, has provided a daily update and has worked to respond to a wide range of inquiries about the incident.
Greenpeace has raised a number of questions in a blog post entitled “14 Questions from an Oil Spill Expert.” Below are our responses:
1. Why did this pipeline rupture happen?
The results of an investigation will determine the cause. We are working with the regulator – the U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administration (PHMSA) – to investigate the cause of the rupture. We anticipate that the results of their investigation will be made public.
2 & 3. When was the last time Exxon or the Pipeline and Hazardous Materials Safety Administration (PHMSA) inspected the pipeline segment in question? What exactly were the results of the most recent inspection?
In February of this year, ExxonMobil Pipeline Company performed an in-line inspection of the Pegasus Pipeline in the area of the failure site. The final results from this inspection have not yet been issued by the vendor who performed the work.
Previous tests, which met all regulatory requirements, were performed in 2006 and 2010 and showed no areas of concern.
4. Exactly when did the leak detection system send an alarm?
At approximately 2:37 pm CDT on March 29, a low pressure alarm was received at ExxonMobil Pipeline Company’s Operations Control Center in Houston.
5. How long after the leak detection alarm did it take Exxon to shut down the flow through? It is inexcusable that 10,000+ barrels came out without the flow being suspended.
Within approximately 90 seconds after receiving the low pressure alarm, the controller in the Operations Control Center initiated a full shutdown of the pipeline. It took approximately 16 minutes to fully shut down all of the pumps on the pipeline and isolate the impacted segment of the pipeline by closing isolation valves. Oil in the pipeline between the closed isolation valves drained from the breach area. Emergency response personnel were on the ground in Mayflower within 30 minutes after the leak was detected and indicated that oil appeared to stop seeping from the pipe at 3 a.m. CDT on March 30.
The response to the spill is being managed by a Unified Command, which includes the EPA, Arkansas Department of Health, Faulkner County and ExxonMobil Pipeline Company. The Unified Command has estimated that approximately 5,000 barrels of oil were spilled, not the 10,000 barrels referenced in your question. In the initial hours after the response, ExxonMobil said a response for 10,000 barrels had been undertaken to ensure adequate resources were put in place.
We agree that it is a very regrettable accident, and have taken responsibility for the cleanup and apologized to the people of Mayflower.
6 & 7. When was the pipeline last pigged? (Pipeline Inspection Gauge = PIG) What was the last maintenance on this segment of the pipeline, e.g., replacement?
I noted earlier that we ran an in-line inspection in February of this year, but the final results of that inspection have not yet been released. The previous pipeline inspection gauge tool was run in July 2010. Tool run data showed no metal loss or deformation anomalies in the area of the failed pipe.
8. Dilbit pipelines run much hotter, and thus have more corrosion, and thus have 2-3 times the failure rate of normal crude pipelines. What additional design factors were incorporated into the Pegasus pipeline to accommodate this added risk?
I have seen Greenpeace and others repeatedly make inaccurate statements about temperatures and the corrosive nature of diluted bitumen, or dilbit, from oil sand sands production that are unsupported by scientific analysis. Numerous studies – from Canada’s CANMET national research institute, Alberta’s Energy Resources Conservation Board, the Battelle Memorial Institute and Penspen Integrity – have all shown that dilbit is no more corrosive than other crude oils.
In the case of Pegasus, diluent was added to the oil to meet pipeline viscosity requirements. Diluents are petroleum-based materials — typically naphtha, distillate and/or condensate. Once blended and mixed, the diluent will not separate from the oil to which it is added.
I’ll point out that the industry has shipped diluted bitumen by pipeline safely for more than 40 years. There haven’t been any cases of pipeline releases of dilbit caused by internal corrosion in all that time. Oil sands crude has the same chemical properties as other heavy crude oils from California, Mexico and Venezuela that have been successfully transported by pipeline in the U.S. for the last 40 years. In fact, the CANMET researchers mentioned above concluded that the dilbit samples they tested were actually less corrosive than several of the other heavy oils they studied.
9. Exactly which tar sands crude mixture was in the pipe?
The oil released in Mayflower, Arkansas was Wabasca Heavy, a conventionally produced heavy oil from Alberta.
Wabasca Heavy has an API gravity range of 18.5 – 21, which makes it similar to heavy crudes from Brazil, Colombia, Ecuador and Mexico. Other conventionally produced crudes such as San Joaquin (California) are heavier, with API gravity of 12.5 – 13.5. Typical oil sands crude has an API gravity of around 8.
10. Is an environmental damage assessment currently being conducted?
We are continually assessing the impact of the spill on the environment. A cleanup plan has been developed and endorsed by the Unified Command.
11. What amount of oil has been collected in the cleanup?
According to the Unified Command update on April 9, approximately 3,000 barrels of oil have been recovered.
12. Is Exxon prepared to pay local property owners for their losses, and to cover all cleanup costs?
Yes. ExxonMobil will pay for the cleanup and honor all valid claims.
13. How can the US public trust Exxon in operating a safe pipeline with tar sands oil in it?
Pipelines are the safest way to transport oil and natural gas, which are vital to our economy. According to the Association of Oil Pipe Lines, accidents are 1,000 times more likely to occur with a large truck, 13 times more likely to occur by barge, and five times more likely to occur by rail than they are on a pipeline. I addressed the question of oil sands corrosivity above in question 8, but I’ll also note that the Association of Oil Pipelines makes an obvious point on its website: “Pipeline operators don’t build multi-billion dollar assets to then destroy them with a corrosive product.”
14. Given Exxon’s professed commitment to the highest standards for its global oil production and transportation operations, how could this possibly happen, right under the watchful eye of Exxon management and federal regulators?
We truly regret the incident in Mayflower and we are sorry to the people who are affected. The cause of the spill will be determined by an investigation. Managing the risk to avoid these types of accidents is a critical element of operational integrity, and our employees and management are trained to identify hazards and assess risks. But in the rare instances when incidents do occur, it is important to make sure you have the competency and capability to respond quickly, which I think we demonstrated in this case.