What an Underground Keystone XL Spill Would Mean for Nebraska Groundwater

Aug. 2, 2017, 6:45 a.m. ·

One of the biggest concerns cited by Nebraskans and landowners along the pipeline route is potential contamination of the groundwater and soil. (Photo by Ariana Brocious, NET News)

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Next week, Nebraska’s Public Service Commission will hear arguments on all sides of the Keystone XL Pipeline debate. One of the biggest concerns cited by Nebraskans and landowners along the pipeline route is potential contamination of the groundwater and soil. As part of our reporting project, On the Line: Keystone in Nebraska, NET News explores what a spill could mean.

Most of Nebraska’s drinking and irrigation water comes from groundwater supplies. The proposed Keystone XL pipeline will be buried underground. And pipelines can leak. So to get an idea of what would happen with an underground oil spill, I talked to Doug Hallum, a survey hydrogeologist with the UNL Conservation and Survey Division in North Platte.

“We run into people fairly routinely who think that if you contaminate one part of the High Plains Aquifer that the entire aquifer is contaminated and that's just not the case,” Hallum said.

In general, Hallum said, underground oil spills stay fairly close to where they occurred, trapped in layers of sediment and water. He said the fine sand along the pipeline’s path would slow the movement of contaminants. And, oil and water don’t mix well, at least at first.

“If it does reach the groundwater, petroleum is going to have a tendency to float and slowly dissolve. The water will break down some of the petroleum and dissolve certain contaminants that will then begin moving in the groundwater, which is a slow movement as well,” Hallum said.

Hallum said in the event of a major spill, cleanup efforts would remove as much oil from the site as possible quickly, before it can spread. The Keystone XL pipeline has been through state and federal environmental reviews. TransCanada spokesman Matthew John said the company is going above and beyond to make this the safest pipeline in the United States. In the event of a spill, he said, “the number one thing in any crude oil response is speed. That's being able to respond and deploy the appropriate cleanup materials rapidly.”

Tim Cornwell is chairman of the Nance County Board of Supervisors, which was among several counties on the pipeline route to pass a resolution in support of the pipeline in May. He said his board weighed the environmental and safety concerns but has faith in TransCanada’s construction.

“There's a spiderweb of pipelines across our county already,” Cornwell said, “and this one being new and built with the latest technology seemed like it would be a relatively safe bet compared to a lot of the others that have been in the ground for 30 to 40 to 50-plus years.” He said the projected tax revenues were a big part of the board’s support for Keystone XL.

“Economic growth in a rural community is pretty hard to come by, other than farming and ranching. You don't get those opportunities all the time,” Cornwell said.

But many landowners are concerned. Byron Steskal lives in Holt County, in northeastern Nebraska. His farm near Atkinson is on the proposed pipeline route.

“We're in the Sandhills and we're over the Ogallala aquifer, which we rely on to grow our crops, drink ourselves, our cattle, our livestock. That's our lifeblood to survival,” Steskal said. He and his friend Calvin Dobias, another area farmer and rancher, said they’re worried about erosion and spills from the pipeline contaminating their water supply.

“It's not the whole thing we're against,” Dobias said, “it's tar sands oil is what we're more against than crude oil or other oils because of the materials that are in the oil to get it to go through the pipes.”

“What we're afraid of is if it leaks and gets in our groundwater,” Steskal said. “We're talking about tar sands, carcinogenic, benzene, xylene and all these other cancer-causing agents.”

The material that will move through the pipeline, called diluted bitumen, is a mix of heavy oil sands and lighter liquids, including benzene and xylene, to make it flow. Hydrogeologists say in the event of an underground spill, those lighter carcinogenic chemicals could contaminate the groundwater, while the heavy bitumen will likely stay in place if not excavated as part of a cleanup.

“I don't know if it would actually sink in the aquifer. With all the sand grains and the water that's already present, it's probably going to have a hard time moving very far at all,” said Jared Trost, a USGS hydrologist who works at a crude oil research site in Bemidji, Minnesota. In 1979, a pipeline there ruptured, spilling more than 10,000 barrels of oil, about a quarter of which was left underground. Since the 80s, USGS has been using the site to study groundwater contamination. Trost said in the last forty years, the oil and the groundwater contamination plume it created have only spread about 500 feet from the original spill site.

“So that was a big deal and that changed a lot how spill sites were managed. They realized they could leave material in the ground and there would be a stable plume reached, eventually, under the right conditions,” Trost said.

Trost said they’ve also learned more about how microbes naturally break down those compounds underground. While not all aquifers are the same as the Bemidji site, it offers an example of what might happen in the case of a slow undetected leak on the Keystone XL pipeline. But according to a 2016 report by the National Academy of Sciences, there are no quantitative field studies on the biodegradation of diluted bitumen. John Stansbury, an environmental and water resources engineering professor at UNL, says TransCanada hasn’t studied this possibility in Nebraska.

“TransCanada did no analysis of the potential plumes and therefore the impacts of a spill to the groundwater,” Stansbury said. He said TransCanada’s environmental assessment significantly underestimates the likely frequency and volume of spills from the pipeline, and how long it would take to detect a leak. Stansbury and other hydrogeologists agree that if a spill occurs, it will likely only affect a small part of the aquifer. But even with thorough cleanup, residual contamination will take a long time to break down.

“Decades. And lots of decades,” Stansbury said. “So that portion of the aquifer will essentially just be ruined for the foreseeable future.”

This story is part of our reporting project, On the Line: Keystone in Nebraska. Tomorrow, NET News looks at the economic impact and jobs created by the pipeline. For more reporting on the Keystone XL Pipeline, visit netnebraska.org/keystone.