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Runoff from an abandoned pit that was used to store oil drilling mud and fluids nearly 50 years ago is eroding into the Little Missouri River south of Medora, the Department of Mineral Resources says. (Photo courtesy of the North Dakota Department of Mineral Resources)

Abandoned oil waste pit eroding into river near Medora

A long-abandoned pit formerly used to store oil drilling mud and fluids is eroding into the Little Missouri River in western North Dakota, reports the Forum News Service (FNS).

The waste pit, last used about 50 years ago, is now threatening to contaminate downstream drinking water. State officials are developing a cleanup plan, and Department of Mineral Resources Director Lynn Helms told a legislative committee that the pit is “priority one” on a list of old and abandoned site reclamation.

Earlier this year, lawmakers approved the appropriation of $1.5 million for abandoned well site cleanup. While officials had known about the pit for years, the erosion wasn’t discovered until potential reclamation sites were prioritized after the funding was approved.

As reported by the FNS, the 100-by-50-foot waste pit was created by Amerada Petroleum Corp. in 1966, but it was abandoned that same year when the nearby well came up dry. Cody VanderBusch, a reclamation specialist, said that whatever liquid that was in the unlined pit was likely either disposed of or absorbed into the ground. “You’re dealing with oil and probably salt, so it’s going to be toxic to plant life and it could be toxic to aquatic life. It just depends upon the quantities,” he said.

The North Dakota Department of Health has not tested water quality at the site, though an environmental assessment has been made. Officials suspect a small amount of the soil may have eroded into the Little Missouri River, which flows into the drinking water supplied by the Missouri River. The cleanup plan will likely involve excavating the contaminated soil and reinforcing the river bank.

Reserve pits such as this one were “phased out” in 2012, Oil and Gas Division spokeswoman Alison Ritter told the FNS. The change was prompted by spring flooding the year prior which some of the pits to overflow. According to Ritter, dry rock cuttings must be disposed of in a drilling pit or special waste landfill and the drilling muds and fluids must be separated onsite before being stored or shipped away. She added that oil and gas development isn’t allowed that close to waterways anymore, either. Five other sites have been identified for the legacy site reclamation program.

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