BILLINGS, Mont. (AP) -- Phillips 66 is removing an oil pipeline from beneath a popular southeast Montana river after the line had to be abandoned because it was increasingly exposed by erosion.
A section of the Bighorn River southeast of Billings could be closed for two days, if necessary, in early January while the 8-inch pipeline is removed, Montana Fish Wildlife and Parks said Friday. The 10-mile stretch is widely known for its high-quality trout fishing.
The planned removal comes in the wake of a break in an Exxon Mobil Corp. pipeline last year beneath the Yellowstone River near Laurel. That rupture spilled an estimated 63,000 barrels of crude into the flooding river and contaminated 70 miles of riverbank.
On the Bighorn, state biologists have seen Phillips 66's Seminoe pipeline become exposed during periods of high water, said Fish, Wildlife and Parks spokesman Bob Gibson. It's now buried beneath an estimated 3 to 5 feet of gravel.
"Like a lot of the older pipelines around here, it wasn't buried real deep," Gibson said. "This was one that was considered at risk, and there were times it was exposed. This is good — getting it proactively and replacing it before it pops."
Phillips 66 spokesman Dean Acosta said Friday that a new section of pipeline has been installed deeper beneath the river and the line is now operational.
Phillips 66, which was spun off from ConocoPhillips this year, initially will try to pull the old pipeline out using equipment staged on the riverbank. If that doesn't work, the river will be closed while the company builds a temporary pad on the river to support excavating equipment that will dig the line from the riverbed, Gibson said.
The closure would cover a section of river between the Three Mile and Bighorn fishing access sites. The timing was coordinated with fly-fishing groups to minimize disruption, Gibson said.
Since Exxon Mobil's Silvertip pipeline spill in July 2011, regulators and companies inspected pipeline water crossings across Montana and in parts of Wyoming. Those revealed widespread erosion that had left many lines at risk.
Damon Hill with the Pipeline and Hazardous Materials Safety Administration said an inspection found a "very minimum amount of cover" over the Seminoe pipeline.
Acosta said the company had been planning pipeline surveys in the region prior to Silvertip and completed that work in the weeks immediately after the accident. He said the surveys assessed the depth of cover beneath the larger of the company's river crossings, with the information used to guide pipeline improvements.
"Phillips 66 has a very comprehensive monitoring plan for all of our crossings," Acosta said.
Crews drilled 40 feet beneath the riverbed to install the replacement line and protect it from future erosion. That's similar to work done by Exxon Mobil to restores its pipeline beneath the Yellowstone.