ExxonMobil recently released an update to the estimated amount of oil spilled into the Yellowstone River when the Silvertip Pipeline ruptured during the summer. Initially the put the spill at 1,000 barrels of oil (42,000 gallons), but have revised that figure and given a new estimate of 1,509 barrels (63,378 gallons).
Al Jeffers, the media relations manager for the oil major said, "What we've done today is we've informed the various regulators, the EPA, MDEQ, and the Pipeline and Hazardous Materials Safety Administration of a revised estimate of 1,509 barrels."
The initial estimate was given so that regulating agencies could devise an appropriate plan of action.
"We brought in a lot of people in a hurry to try and respond as quickly as possible and get this spill cleaned up," had the estimate been given as 1,500 barrels the approach to the situation would have been no different assured Jeffers.
The problem was that a detailed analysis of the spill couldn’t be undertaken until the broken pipeline was fully extracted. "You'll recall a few months ago we were able to remove it from the river and we were able to see that it severed completely-- and that's not typical of a pipeline break. Usually, there is some sort of fissure or crack that will obviously let the oil escape a lot slower, and that was the reason for the lower estimate. Once we realized that the pipeline had severed completely-- probably in a very quick way-- that led us to make some assumptions about the volume spilled, to increase that estimate.
Joao is a writer for Oilprice.com