Jun. 9--It might take weeks to determine how to fix a natural-gas pipeline that ruptured Sunday beneath the Yellowstone River near Laurel, an official said Monday.

The 8-inch-diameter line, servicing Montana-Dakota Utilities customers north of the Yellowstone River, including those in Billings, burst Sunday about 1:40 p.m., shooting a geyser of natural gas upward from the river's surface.

Emergency workers evacuated Riverside Park and other areas along the river to be safe. Highway 212 from Thiel Road to Interstate 90 was closed temporarily.

The line belongs to the Williston Basin Interstate Pipeline Co., an MDU Resources Group subsidiary. Spokesman Tim Rasmussen said the company doesn't know what caused the pipe to burst. Gas lines are buried several feet below water bodies for protection. Sunday's rupture blew a section of the pipe to the river's surface.

"What we've got to do is investigate the procedure to remove the pipeline and evaluate the cause," Rasmussen said. "We want to assure the safety of our crew and the safety of the public."

The company isn't sure if the pipe beneath the river will need to be completely replaced or can be repaired.

The 8-inch pipeline was actually a backup for a 16-inch natural-gas line, Rasmussen said. But because of increasing demand in the Billings area, the smaller line was doing more than part-time work. Initial reports indicated that the line served the CHS oil refinery in Laurel. The line served CHS, Rasmussen said, but the refinery wasn't its only customer.

Because of the 16-inch line's presence, natural-gas service in the Billings area wasn't affected, Rasmussen said.

The rupture and the subsequent gas release probably didn't affect Yellowstone River wildlife, said Bob Gibson of the state Department of Fish, Wildlife and Parks. Natural gas bubbles into Montana rivers and streams ordinarily in other parts of the state without harming trout.

The Williston Basin Interstate Pipeline system is a vast array of more than 3,200 miles of high-pressure pipe servicing Montana, Wyoming and the Dakotas.

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