State regulators say a pipeline spill this week in McKenzie County caused 4,300 barrels or 181,000 gallons of saltwater to leak into farmland, though the company responsible says it believes that estimate is too high after further investigation at the site.
Tallgrass Energy said it provided the initial volume to the state Tuesday based off information from remote pipeline sensors, but workers at the site Wednesday indicated that the spill was actually smaller in size, company spokeswoman Phyllis Hammond said.
"We have a team on the ground now, so we should know more in the next day or two," she said.
Saltwater, also known as brine or produced water, can render land infertile when it leaks. The fluid comes to the earth's surface alongside oil and gas pumped at well sites, and it's typically transported to another well where it's injected back underground for permanent storage.
The leak occurred 1 mile southwest of Arnegard. The cause of the spill is not yet known, and the company told the state that it believes the line began leaking within the past couple days, said Karl Rockeman, director of the Division of Water Quality for the North Dakota Department of Environmental Quality.
Tallgrass has since shut down the pipeline.
"They began removing the produced water and looked to be starting excavation shortly once they've identified any other lines in the area," Rockeman said.
When saltwater spills occur, companies often haul out contaminated soil before replacing it. Rockeman said that seems to be Tallgrass's initial plan, and doing so will help the company assess how deep and far the fluid spread. Hammond, with Tallgrass, said the company was in touch with landowners in the area and would work with them to restore contaminated property.
The pipeline also leaked 1 barrel or 42 gallons of crude oil, according to the state. Rockeman said saltwater in pipelines generally includes a small amount of oil.
State inspectors from both Environmental Quality and the North Dakota Oil and Gas Division have visited the site. Rockeman said the spill does not appear to have impacted any surface water.
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