The investigation into last month's oil pipeline spill in the Yellowstone River will be stalled until at least next fall because the most critical piece of evidence—the failed segment of pipe—can't be safely retrieved from the river until after snow-melt flooding is over, according to the pipeline's owner.
The 193-mile Poplar Pipeline, meanwhile, could be repaired and re-opened as soon as March 31, according to Bill Salvin, spokesman for Bridger Pipeline LLC, which owns the ruptured oil line.
The company is preparing to install a replacement pipe segment that would cross the Yellowstone deeper below the riverbed, though it wasn't immediately clear what the depth would be. The Poplar was eight feet under the river in late 2011, but at the time of the spill, river forces had eroded away all of that cover in places.
The Poplar breach has renewed concerns about the safety of oil pipelines that cross rivers and other bodies of water in more than 18,000 places nationwide. Many of them are buried just a few feet below the water—and it's increasingly clear that pipelines should be installed much deeper.
Under a Jan. 23 corrective action order from federal regulators, Bridger must subject the replacement pipe to hydrostatic pressure testing and carry out a restart plan that has been approved by the Pipeline and Hazardous Materials Safety Administration. When the Poplar resumes carrying crude oil across Montana, it must operate at reduced pressure.
The order also gave Bridger 45 days to complete a battery of tests and failure analysis on the broken pipe. With the river still covered in ice, Bridger will seek an extension of that requirement until conditions allow for safe removal of the pipe, said Salvin, the Bridger spokesman. He said the pipe will likely to stay in the river until after the Yellowstone's seasonal flooding, which can last into August.
Last week, Montana's Department of Environmental Quality formally notified Bridger that the spill violated state water quality standards, that the company must reimburse the state for its emergency response efforts, and that it must conduct extensive testing and complete corrective actions to remediate damage from the spill once the ice melts. The DEQ's Feb. 12 letter also noted that it "will be seeking to negotiate with Bridger to enter into a settlement to address final compliance and penalties."
Salvin said the company expected the DEQ notice. "Nothing in there was a surprise to us," he said.
When the Poplar broke in eastern Montana on Jan. 17, about 30,000 gallons of crude oil spilled into the Yellowstone and contaminated the drinking water for residents of nearby Glendive. Oil recovery was hampered by a thick layer of ice at the rupture site and for several miles downstream.
Subsequent sonar testing showed that about 110 feet of the pipeline were completely exposed along the bottom of the river. In one area, river scour had whisked away a foot of earth underneath the pipe, leaving it unsupported and especially vulnerable to damage for 22 feet.
The company said the Poplar was still buried at least eight feet under the river bottom in September 2011, when it was last checked. Bridger planned to check the depth of cover again in September 2016. While the rupture's cause will not be known until testing is completed, it's likely that the pipeline's exposure was a factor.
This case and several other recent spills—including ExxonMobil's 2011 pipeline spill into the Yellowstone—have involved pipelines that were uncovered after floods and natural forces scoured away the earth that was covering them.
To address that concern, PHMSA also required Bridger to replace the Poplar pipeline crossings at the Yellowstone and Poplar rivers using "horizontal directional drilling."
That technique involves drilling a tube-like opening for the pipeline tens of feet below the bottom of the riverbed. Bridger will construct a 6,000-foot pipe segment on land, and then place it under the Yellowstone river through the drilled opening.
TransCanada, the company behind the controversial Keystone XL pipeline, plans to use horizontal directional drilling where the pipeline would cross the Yellowstone and in some other places. The pipeline would carry Canadian tar sands and would cross nearly 2,000 rivers, streams and reservoirs in Montana, South Dakota and Nebraska, according to one estimate.
The Poplar segment that leaked was installed by digging a trench in the riverbed, laying the pipe and then covering it with earth. It's a method that's been used extensively in the industry, but many now consider trenched pipeline crossings to be more susceptible to river scour and other hazards.