As many as 1000 barrels of crude oil have been leaked into Montana’s Yellowstone River following a leak from an ExxonMobil Pipeline Company (EMPCo) pipeline.
Clean up activities are being concentrated in two zones a combined 19 miles downriver from the spill site, while reconnaissance and evaluation activities are underway in the second two zones, 222 miles from the spill site.
ExxonMobil found the leak from the 12 inch EMPCo crude pipeline early on Saturday morning. The pipeline runs only in Montana, from Silver Tip to Billings, the state’s biggest city.
The cause of the leak remains unclear, though ExxonMobil has established an investigation team to look into the incident.
ExxonMobil saying in a statement that the pipeline had met all regulatory requirements when it underwent its most recent inspection in December.
A field audit of the pipeline’s integrity management program was undertaken by US Department of Transportation Pipeline and Hazardous Materials Safety Administration in June, the company said.
EMPCo president Gary Pruessing told reporters during a Sunday conference call that the pipeline had been shut in May as a precaution as the river approached a high-water point, but that it was judged to be safe and turned back on.
“We had no indications that there were any issues with this pipeline,” he said.
The US oil company said it had slowed processing rates at its Billings refinery following the leak but did not expect supply disruptions in the area.
The company has contended most of the oil from the spill from the pipeline, which typically transports 40,000 barrels per day, is contained within a 10 mile area.
Daily aerial flights over the river are being undertaken to locate additional oil locations and monitor and direct cleanup activity, ExxonMobil said, with over 70 calls having been made to a community claims hotline.
On Sunday Montana Governor Brian Schweitzer questioned ExxonMobil’s contention that the spill into the Yellowstone, the longest undammed river in the United States, was concentrated within a 10-mile area.
“This is a lot of wild country, and they haven’t any idea whether it’s five miles, 50 miles or 100 miles, they’re guessing,” Schweitzer, a Democrat, told Reuters in a telephone interview.
A full assessment of the oil’s spread will not be possible until small boats can be deployed in the river, he said.
ExxonMobil said earlier that the river’s turbulence made it unsafe to use boats, but that the company had sent aircraft to view the spill.
ExxonMobil discovered the leak when a loss of pressure was detected on the pipeline, which dates from 1991, and within six minutes the line was shut off, company officials said.
Some residents were briefly evacuated as a precaution but were allowed to return home later.
ExxonMobil said more than 120 people were involved in the response and cleanup effort including its own regional response team, Environmental cleanup company Clean Harbours and additional contractors. A further 80 people are expected on site today.
An ExxonMobil spokesman, said in response to Schweitzer’s comments that the company made its assessment that the spill appeared to be confined to within a 10-mile area based on what it had observed and what was reported to it.
“The bulk of it appears to be in that area, but we’re continuing to look for oil along the river,” he said.
Schweitzer said he was concerned about damage from the spill to farm fields recently flooded when the Yellowstone overflowed, and to the state’s trout fishing industry.
ExxonMobil said it was working with local authorities to coordinate the cleanup, including the Environmental Protection Agency, the Montana Department of Environmental Quality, Montana Fish, Wildlife and Parks and International Bird Rescue.
Air monitoring has detected no threat to residents from the spill, EMPCo’s Pruessing said. Municipal water systems also have shown no signs of infiltration by the oil, he said.
The Billings Gazette on Sunday cited conflicting reports from ExxonMobil officials as to the extent of the leak. The paper carried pictures of absorbent bags piled along the side of a road running parallel to the river, ribbons of oil sticking to logs and one of a turtle stuck in oily mud.
The leak came one day after a Maryland jury awarded plaintiffs suing ExxonMobil $1.5 billion in damages for a 2006 leak at a gasoline station.
