Exxon Pipeline Oil Spill Cleanup Efforts Widening

An additional 80 people were heading to the Exxon Mobil Corp. (XOM) pipeline spill site Monday as the effort to clean the oil spilled from its Silvertip pipeline widened, Exxon said.

With the addition, about 200 people are working to repair the damage from the estimated 1,000 barrels of oil the pipeline spilled into the Yellowstone River late Friday. Exxon said most of the oil fell along the shoreline within about 10 miles of the spill site, but has reconnaissance planes flying about 144 miles downstream to check for damage.

The leak from the 12-inch pipeline, originally reported Saturday, caused the temporary evacuation of some area residents. Local officials have said that flooding has hampered the cleanup work, and that some of the leaked oil could reach the Missouri River, of which the Yellowstone is a tributary.

The cause of the leak is still under investigation, Exxon said.

The incident comes on heightened concerns about pipeline safety stemming from natural-gas pipeline explosions across the U.S., and from a major spill in July 2010, in which 20,000 barrels of oil escaped from an Enbridge Energy Partners LP (EEP) pipeline in Michigan. The cause of the spill remains a mystery.

Exxon said its pipeline met "all regulatory requirements" and was inspected in December. The U.S. Pipeline and Hazardous Materials Safety Administration audited the pipeline's integrity management program in June, Exxon added.

PHMSA has sent agents to help with the investigation but has so far not issued information.

The Silvertip pipeline runs from Silver Tip, Mont., to Billings, and usually moves about 40,000 barrels of crude oil a day.

-By Ben Lefebvre, Dow Jones Newswires; 713-547-9201; [e-mail]; and Angel Gonzalez, Dow Jones Newswires; 713-547-9214; [e-mail]