Local media reports cite farmer Steve Jensen as saying the crude appeared to be coming from a rupture in an underground pipeline operated by Tesoro Corp.
The farmer noted that he had smelled the crude for days but it wasn’t until he began harvesting his wheat fields that he discovered the source of the smell, as his combine got caught up in crude spewing up to six inches above the ground.
Related article: How Our Inability to Calculate Risk Opened the Doors for Fukushima
The spill, discovered on 29 September and since contained, is one of the largest ever in the history of North Dakota. A total of 20,600 barrels of crude was leaked into the field, spreading over 7.3 acres. To put this into perspective, this leak is four times larger than a leak in Arkansas in late March that prompted the evacuation of 20 residences.
It took state authorities 12 days to report the spill after the farmer alerted them.
According to Tesoro Corp., no water sources were contaminated during the spill, but the fact that it went undetected long enough to spread so far, coupled with the 12-day reporting delay by officials, has raised more questions about leak detection policies.
"There are many questions to be answered on how it occurred and how it was detected and if there was anything that could have been done that could have made a difference," state Governor Jack Dalrymple told reporters.
"Initially, it was felt that the spill was not overly large," Dalrymple said. "When they realized it was a fairly sizable spill, they began to contact more people about it."
The spill gives more ammunition to watchdog groups who have been calling for more transparency and better leak detection processes for pipeline operators.
Earlier leaks in Kalamazoo and Arkansas were massive and caused by complete pipeline ruptures. These are rare incidents that account for less than 10% of leaks. But the small leaks--those that traditional pipeline detection systems don’t catch—account for more than 90% of US pipeline leaks.
According to a recent report from the U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration (PHMSA), the majority of leaks are smaller but can persist for months or even years, and those that are even reported are generally done so by people who have stumbled upon them by accident.
In this case, the leak was larger than the Arkansas leak, but also only detected by a farmer who stumbled upon it with his harvesting equipment—and now the land will not be usable for planting for years.
According to Adrian Banica, CEO of Synodon--which has developed advanced remote sensing leak detection systems--traditional leak detection systems are only able to detect high level leaks above 1% of the pipeline flow.
Furthermore, as the Department of Transportation has recently pointed out, these systems only detect a leak at best about 40% of the time, irrespective of how big the leak is.
“For catastrophic leaks, most pipelines use these flow meters which operate 24/7. But smaller leaks can only be detected by performing an above-ground survey either by foot patrol, vehicle or aircraft. The predominant technologies used would be sampling gas sensors, thermal cameras, laser detection or our remote sensing system,” Banica told Oilprice.com.
This article originally appeared at OilPrice.com. Copyright 2014.