LAUREL — In just three years, the 100-yard stretch of the Yellowstone River south of town has claimed two pipelines, parts of a public park and a city water plant.
A few months ago, the ExxonMobil pipeline was at least 5 feet below the riverbed but was scoured bare by spring runoff. The Yellowstone seems to be carving a deeper channel, leaving the arteries of industry exposed.
“Obviously this is something the entire industry is watching,” said Lani Jordan of CHS Inc., whose Laurel refinery is a rock skip away from the July 1 ExxonMobil pipe burst and the 2009 burst of a Montana-Dakota Utilities natural gas line. “We try to do things in a safe way.”
The ExxonMobil rupture dumped as much as 42,000 gallons of crude into the Yellowstone, sending oil as far downstream as Terry, according to federal investigators.
CHS also has a pipeline beneath the river at this location. The pipelines were placed in the same trench in the 1990s, Jordan said, meaning that the CHS pipeline is in close proximity to the ruptured ExxonMobil pipe. A third pipe in the trench, operated by ConocoPhillips, was shut down two years ago after the Wyoming crude that fed it began to run out, according to the company.
The federal Pipeline and Hazardous Materials Safety Administration on Tuesday ordered ExxonMobil to bore a new pipeline route deep beneath the riverbed to avoid future run-ins with the Yellowstone.
“That would have been the plan regardless of the order,” said Alan T. Jeffers, an ExxonMobil spokesman.
After high spring runoff exposed the Montana-Dakota Utilities natural gas line in June 2009, that company chose to bore 30 to 50 feet beneath the riverbed when replacing its line, said Tim Rasmussen, an MDU spokesman.
Similar to speculation surrounding the ExxonMobil break, when the MDU pipeline burst, there was talk that a large object being pushed down the riverbed by the Yellowstone’s current possibly smashed into the pipe. But, investigators ultimately concluded that no large object was needed to break the 8-inch gas line.
“Water pressure from high-volume flows during that time of year, that was determined to be the cause,” Rasmussen said.
MDU’s gas pipelines are in a redundant loop, so customers never lost service, Rasmussen said. That fall, over a couple of days, the company drilled horizontally beneath the river and installed a new line.
ExxonMobil said it does not know when the ruptured Silvertip pipeline will be replaced and will use truck or train to deliver oil to its refinery until the 40,000-barrels-per-day pipeline is fixed.
CHS has also turned to boring deep below water bodies, Jordan said.
“Right now, the major crossings in Montana have been bored — directional drilled — so they’re way, way under the riverbed,” he said.
When the Yellowstone River, now racing by at 56,000 cubic feet per second, loses its runoff punch, CHS will review its options in Laurel, Jordan said.
In the Billings and Laurel area, there is a loose web of oil and gas lines that cross beneath the Yellowstone River at least 10 times, according to the U.S. Department of Transportation’s National Pipeline Mapping System. Most of the lines were installed by trench, years before directional boring made threading pipes deep below the river possible. Trenched pipelines are in compliance if they’re 48 inches below the riverbed.
While the Pipeline and Hazardous Materials Safety Administration ordered ExxonMobil to bore beneath the river when replacing its ruptured pipe, the same demand was not made to other pipeline operators along the Yellowstone.
Those companies were advised to be aware of possible risks posed by the flooding Yellowstone.