HELENA, Mont. - About 40 Montana landowners have reported contamination of their property by crude oil spilled from a ruptured Exxon Mobil pipeline into the flood-swollen Yellowstone River over the weekend, the company said on Wednesday.
As the scope of property damage came into sharper relief, Montana's governor accused Exxon of underestimating how much oil spewed into the one of America's most pristine rivers 150 miles downstream from Yellowstone National Park.
"This cleanup would go a lot better if we could get accurate information from Exxon Mobil," Governor Brian Schweitzer told Reuters, expressing frustration at what he characterized as the company's changing story in recent days.
Citing disparities in accounts of how long it took to stop the leak, he disputed Exxon's assertion that up to 1,000 barrels, or 42,000 gallons, of oil had spilled from the time of the rupture until the company had completely sealed off the broken pipeline.
Schweitzer, in a letter to the company, also demanded it preserve all documents and evidence related to the spill, and asked that government representatives observe all work on the pipeline.
The company told reporters in a conference call that it stood by its original spill estimate. Exxon Mobil Pipeline President Gary Pruessing said the actual amount of escaped oil was likely closer to 750 barrels than 1,000.
The company initially said it took roughly 30 minutes to shut off all the valves necessary to keep oil in the line from draining into the river once the pipe had burst. But documents released late on Tuesday by the U.S. Transportation Department put the interval between the rupture and complete shutdown at 56 minutes, nearly double the time.
"Now it ran nearly twice as long but the amount of oil dumped into the river is the same? Maybe we aren't smart enough to do their math," Schweitzer said by telephone. "The timeline is double what they initially said, but they're still confident in their estimate about how much oil spilled? ... I have a $2 calculator; they can have it when I'm finished with it."
Pruessing acknowledged the company earlier had cited a pipeline shut-off time of about 30 minutes, but said its spill volume estimates were based on the "actual" time of 49 minutes that it reported to the Transportation Department.
Either way, he said, the spill estimate stands.
The Transportation Department said surveillance flights over the spill zone as recently as Sunday revealed "oil deposits as far as 240 miles downstream" in Terry, Montana.
Pruessing, however, said Exxon's best information had confirmed oil-fouled shoreline extending just 25 miles downstream, with most of the contamination between the rupture site near the town of Laurel and Billings to the northeast.
He said the company had received about 90 calls to a special telephone hotline set up in the aftermath of the spill, with 36 to 40 of those coming from landowners reporting that their property had been tainted by oil.
But Pruessing said the company lacked an estimate for how much acreage was involved.
About 350 personnel have been assigned to spill response teams so far, most of them walking the river banks with oil-absorbent pads to blot up as much crude as possible, he said, adding that was a sufficient number for the time being.
The so-called Silvertip pipeline normally carries about 40,000 barrels of crude per day from the Montana-Wyoming border north to Billings, connecting to two of the state's three major refineries. The line burst on Friday night at a point where it crosses the Yellowstone beneath the riverbed at Laurel.
The cause of the accident is under investigation, and Pruessing said the damaged pipe remains under 18 feet of water raging through the Yellowstone after a spring season of heavy rains and runoff from record snowmelt in the mountains.
Investigators have focused on the possibility that high water washed away some of the riverbed around the buried pipe, exposing it to debris carried downstream.
Pruessing said restoration of the severed pipeline is not expected for at least two weeks and that cleanup from the spill remained the company's chief concern.
Exxon said it briefly shut down the pipeline in May when officials in Laurel raised concerns about erosion from flood waters but reopened it after a safety review concluded the line was sufficiently covered.
(Additional reporting by Laura Zuckerman and Anna Driver; Writing by Steve Gorman; Editing by Cynthia Johnston)