Lincoln County spokesman Stephen Malik said that the evacuation order was lifted shortly after 11:30 a.m. Thursday even though a fire was still burning at the plant.
"At this time they don't feel like there is really any credible threat of secondary explosions or anything like that," Malik said. "I don't think that they'll get into the actual facility itself until the fire is completely out."
No injuries were reported in the explosion Wednesday in Opal, a town of about 95 people about 100 miles northeast of Salt Lake City. All of Opal was evacuated.
Gas from the plant serves a huge number of customers across the West and as far east as Ohio, but the explosion came between the winter heating and summer cooling seasons, when demand is lower, officials said.
There was no immediate word on the cause of the explosion.
The blast was reported at about 2 p.m. Firefighters decided to let the fire burn off rather than try to put it out.
"It burned so hot you can't fight this thing," Malik said of the fire.
The explosion occurred in a cryogenic processing tower, which chills unrefined natural gas to remove impurities.
The fire was confined to the facility, and no structures in the town were affected, county officials said.
All employees at the gas processing plant were accounted for, said Tom Droege, a spokesman for Williams Partners LP of Tulsa, Okla., which operates the plant.
Williams paid the costs to lodge Opal residents at motels in Little America, about 25 miles east, and in Kemmerer, about 15 miles west.
The Opal plant removes carbon dioxide and other impurities from natural gas that comes from gas fields in the region. It can gather up to 1.5 billion cubic feet of gas a day, and it sends the refined product into pipelines that go to urban centers to the east, west and south. Lately, the plant has been handling about 1 billion cubic feet of natural gas a day, Williams said.
Williams has temporarily suspended collecting gas from surrounding areas and is looking for ways to resume production.
Regional pipelines converge at a major national hub in Opal, and it's the principal spot where prices are set for natural gas produced from the large gas fields in western Wyoming and the San Juan Basin in Utah. Government officials and industry insiders closely watch Opal hub prices to monitor trends in regional gas supply and demand.
Williams operates the Northwest Pipeline, which runs through Opal on its way to the Pacific Northwest.
Renny MacKay, spokesman for Gov. Matt Mead, said investigators would look into the cause of the explosion once the site was secured.
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