A pair of pipeline leaked and spilled oilfield wastewater into a tributary of the Missouri River and over some pastureland last week in North Dakota. State Health Department environmental scientist Bill Suess said that on Tuesday, the cleanup was ongoing at the two sites where produced water leaked.
Produced water is a byproduct of oil production that contains saltwater and oil, and sometimes chemicals from hydraulic fracturing operations. The health officials do not yet know what caused the pipeline to spill oilfield wastewater.
"We still don't know what happened," Suess said.
The first spill was reported on July 14 that 21,000 gallons of oilfield wastewater leaked from an underground pipeline and into an unnamed tributary of the Missouri River. The second spill leaked more than 12,000 gallons of oilfield wastewater, impacting an unknown amount of pastureland near Epping.
Both spills were reported by Polar Midstream, a unit of Summit Midstream Partners LLC. Based on samples that were collected, investigators don't think the spill reached the river, and the produced water in the tributary was being pumped out and "flushed" with fresh water, Suess said.
"We are focused on remediation," said company vice president Zak Covar.