The nation's first major dilbit spill occurred in July 2010, when a ruptured pipeline released a million gallons of dilbit into the Kalamazoo River. As the light, liquid chemicals in dilbit began evaporating, the heavy bitumen sank into the river. Nearly two and a half years later, Enbridge Inc., the Canadian company that owns the ruptured pipeline, is still struggling to clean up the Kalamazoo. The current cost of clean up exceeds $800 million.
The Enbridge accident showed what happens when dilbit spills into a river. But little is known about how dilbit might behave in an aquifer, said Wayne Woldt, a University of Nebraska-Lincoln professor who studies groundwater management.
Once an aquifer is contaminated, it's virtually impossible to restore it to its pristine condition, Woldt said. The extent of damage would depend on the size of the spill and on how the dilbit moves within the aquifer.
"Some say it would pollute the Ogallala aquifer a tremendous amount. Others say it wouldn't be a big deal. I don't know, because I haven't found the research that would answer this question," Woldt said. "I think we're all operating in a vacuum of information."
Woldt has tried without success since June 2011 to secure funding for a study modeling the effects of dilbit on the Ogallala aquifer.
Most Sensors Detect Only Major Pipeline Ruptures
TransCanada ran newspaper ads in Nebraska last summer assuring residents that the Keystone XL will be protected by 21,000 sensors that relay information to the company's control center once every five seconds. But a recent examination of PHMSA data by InsideClimate News showed that between 2002 and July 2012, only five percent of U.S. crude oil pipeline spills were detected by leak detection systems like those planned for the Keystone XL. Those systems detect major pipeline ruptures, not the "weeps and seeps" that can accumulate into large spills. That means the Keystone system is unlikely to detect spills smaller than hundreds of thousands of gallons per day.
The technology used on the Longhorn pipeline is more sophisticated. In addition to a standard leak detection system, hydrocarbon-sensing cables are attached to the pipeline's exterior, where they can trigger an alert if the pipeline's contents drip out. According to Longhorn, they can detect spills as small as three gallons a day.
Because external sensors are more expensive, they are used on less than one percent of the nation's oil pipelines. They're usually found on small stretches over sensitive river crossings, aquifers and other areas where an oil spill could be disastrous.
PHMSA requires operators to "have a means to detect leaks" on their pipelines, but it sets no standards for how effective the systems must be. The agency is in the midst of a two-year study on leak detection, but it could be years before the results are incorporated into regulations.
Weimer, the Pipeline Safety Trust director, said that while PHMSA supports advances in pipeline technology, the agency "is hesitant to ever tell the industry what kind of system they need to use." As a result, it takes a long time for new safety technologies to percolate through the industry.
Longhorn purchased its sensor cables from Houston-based Tyco Thermal. Ken McCoy, general manager of the group that designed the cable, said his product costs more per mile than the typical leak detection technology used for oil pipelines. He refused to compare prices directly but estimated that installing his company's sensors on 20 miles of the Keystone XL would raise the project's $5.3 billion price tag by less than 0.13 percent. He said that price includes the added cost of adapting the technology for Nebraska's high water table.
TransCanada has no plans to add external sensors. Howard, the company spokesman, said external sensing technology "is not the best method to use" on the Keystone XL, because it is "subject to localized conditions such as water table and soil conditions and therefore reliability and maintenance can be an issue."
TransCanada's concerns are valid but not insurmountable, said Richard Kuprewicz, a pipeline safety expert who is president of the consulting firm Accufacts, Inc. Kuprewicz has worked with TransCanada in the past, but is not involved with the Keystone XL.
TransCanada could choose from a variety of external sensors, including fiber optics or acoustic sensing technology, Kuprewicz said. Investing in these technologies might make good business sense if concerns about oil spills are holding up a multi-billion dollar project, he said. "If you can't solve a problem, either reroute the line, or come up with a solution that has a high degree of expectation it'll do its job."
Howard said TransCanada is involved in an industry research group that has undertaken a "multi-year effort to identify and quantify improved capabilities for the detection of small leaks," and that the design of Keystone XL "positions us well to leverage evolving technologies in the future."
Other safeguards on the Longhorn—including concrete caps and more frequent foot and aerial patrols—do not involve expensive technology.
Most of the 700-mile Longhorn pipeline route is inspected once a week, but the 19-mile section over Austin's aquifer is inspected every day.