Belle Fourche Pipeline: The Oil Spill Regulators Say Could Have Been Prevented

The Facts

The Skunk Hill-to-Bicentennial segment of the Bicentennial Pipeline was approximately 58 miles long and six inches in diameter. It transported crude oil from the Skunk Hill station to the Bicentennial station and crossed beneath Ash Coulee Creek and the Little Missouri River while passing through the Little Missouri National Grassland.

According to the complaint, the segment could affect a High Consequence Area and was included in Belle Fourche’s written Integrity Management Plan.

The complaint says the pipeline’s average flow at the time was approximately 1,000 barrels per hour, or 24,000 barrels per day. It also says the pipeline crossed environmentally sensitive waterways and could affect a federally defined High Consequence Area.

The Warning Signs

The complaint’s account begins before the rupture itself. It alleges that the site was located in hilly, unstable terrain prone to slope failure and other mass movements.

There had allegedly been a landslide, slope failure, or other mass movement at the site in or before 2012. After that event, Belle Fourche replaced a section of pipeline in 2013 using horizontal directional drilling.

But the complaint alleges that the company did not obtain site-specific geotechnical information, such as soil borings, and did not conduct an adequate risk analysis addressing the known geological hazards.

According to the government’s allegations, that meant additional preventive measures — including potentially rerouting the pipeline — were not identified or taken.

The complaint alleges that the geological risk was known before the pipeline failed.

The Meter Problem

Belle Fourche used volume balancing to detect leaks on the segment. Incoming and outgoing volumes were compared using flow-meter data, with discrepancies indicating a possible leak. The flow data was transmitted in real time through a SCADA system to the company’s control room in Casper, Wyoming.

The complaint alleges that the Bicentennial Station flow meter was mis-calibrated from at least July 2016 and remained uncorrected as of December 1.

The government’s complaint provides an example: at an actual flow of 1,000 barrels per hour, the meter would read approximately 960 barrels per hour after the two errors were combined.

The Leak Signal

The complaint alleges that the meter problem did not fully explain the later change in the pipeline’s flow imbalance.

The complaint alleges that the sudden increase in the discrepancy between the Skunk Hill and Bicentennial measurements was indicative of a significant leak. It further alleges that Belle Fourche’s controller and a field employee attributed the discrepancy to the known meter calibration problem rather than treating it as a leak.

The complaint says the company continued operating the segment as usual until the morning of December 5.

The Spill

The complaint attributes the rupture to mass movement, which in ordinary terms, is a landslide. According to the government’s allegations, the force of that movement ruptured the pipeline and discharged approximately 14,400 barrels of crude oil.

The oil entered an unnamed tributary to Ash Coulee Creek, Ash Coulee Creek itself, the Little Missouri River, and adjoining shorelines.

The State’s claims allege that the spill caused water-quality violations in the affected waterways and groundwater, including visible oil and scum, sheens, and contamination that impaired designated uses.

A known geological hazard, a compromised measurement system, and a later leak signal became part of the same chain of events.

The Reporting Failure Allegation

The DOJ’s complaint alleges that Belle Fourche did not report the Ash Coulee Spill to the North Dakota Department of Environmental Quality until December 5, several days after the spill first occurred.

It further alleges that the report understated the spill’s volume and duration and failed to provide all relevant information required under North Dakota regulations.

The Environmental Claims

The federal complaint alleges that crude oil from the Ash Coulee Spill reached waters of the United States without authorization, forming the basis for Clean Water Act claims.

North Dakota separately alleged violations involving state water quality, discharge requirements, reporting, and disposal of crude oil. The complaint states that the affected waters and groundwater experienced violations of applicable numeric and narrative standards.

• Unnamed tributary to Ash Coulee Creek
• Ash Coulee Creek
• Little Missouri River
• Groundwater around and beneath the spill site

The State alleged that the spill produced visible sheens and other contamination and impaired beneficial uses of the affected waters.

What the Government Asked the Court to Do

The complaint sought a combination of monetary penalties, injunctive relief, remediation, and reimbursement of North Dakota’s response costs.

• Civil penalties associated with the alleged Clean Water Act and North Dakota environmental violations.
• Civil penalties and punitive damages associated with alleged federal pipeline-safety violations.
• Injunctive relief requiring measures to prevent future oil discharges and remediation of the Ash Coulee Spill.
• Reimbursement of NDDEQ’s response, administrative, and legal costs.

The complaint also requested other relief the court deemed appropriate.

The documented failure modes in this case point toward reforms that address not just the rupture, but the systems used to recognize and respond to foreseeable pipeline risks.

The source document for this investigation is attached below.