BISMARCK, N.D. (AP) — Enbridge Inc., one of western North Dakota's major oil shippers, is asking state and federal regulators for permission to build a new oil pipeline beneath Lake Sakakawea.
The lake is the Missouri River's largest reservoir. The request comes six months after an Exxon Mobil Corp. pipeline beneath the Yellowstone River, a Missouri tributary, ruptured and leaked more than 63,000 gallons of crude.
The Yellowstone joins the Missouri River about 20 miles southwest of Williston, N.D. The Yellowstone pipeline leak occurred near Laurel, Mont., more than 300 miles to the southwest.
Members of North Dakota's Public Service Commission said Wednesday they would scrutinize the request closely. The commission is in charge of determining the pipeline's route and specifics about how it will be built.
Other oil pipelines have been built beneath the lake without incident, commissioners said.
"Water is the one liquid more precious than oil to any state, ours included," Commissioner Kevin Cramer said. "There is great care and caution that is taken, and appropriately so."
In a regulatory filing, an Enbridge vice president, Mark Sitek, said the pipeline would carry up to 60,000 barrels of oil daily, or more than 2.5 million gallons. It would cost $136 million to build. Enbridge wants to start operations by the end of 2013.
The 12-inch pipeline would run for 36 miles from Enbridge's Beaver Lodge pumping station southeast of Tioga to a location east of Watford City, in McKenzie County.
Oil production is booming in the region, and the project will give producers easier access to pipeline shipping and reduce truck traffic, said Katie Haarsager, an Enbridge spokeswoman in Minot, N.D.
Enbridge is capable of shipping 235,000 barrels of oil daily. North Dakota's current production is just over 500,000 barrels a day, according to the state Department of Mineral Resources.
The federal Bureau of Land Management is conducting an environmental review for federal agencies with land along the pipeline's proposed route, said Lowell Hassler, an agency natural resource specialist in Lewiston, Mont.
Haarsager said the company's proposal includes a 2.1-mile section of pipeline beneath the lake. It is likely to be buried 50 to 150 feet beneath the riverbed, she said.
She said a horizontal directional drilling process, similar to one used in oil production, would be used to bore a hole in the earth and literally pull the pipe through. The pipeline's walls will also be thicker than a conventional pipeline, in part because of the location beneath the lake, she said.
Cramer said the Exxon Mobil pipe was buried only a few feet beneath the Yellowstone's riverbed. Last spring's rushing river waters, caused by plentiful spring rain and melting snow, eroded the channel and exposed the pipe, making it vulnerable to damage.
"Sakakawea is a reservoir," Cramer said. "It does not have the same speed of flow that a swelling river would have, like Yellowstone."