YANKTON, S.D. (AP) - Crews are expected to begin working this week to bury pipe for the TransCanada Keystone oil pipeline 60 feet below the bed of the Missouri River at Yankton.

The project of 4-6 weeks will involve nearly a half-mile of 30-inch pipe.

The TransCanada underground pipeline will run from Canada through the eastern Dakotas and Nebraska to refineries in Illinois and Oklahoma.

Some pipe is already in place in northeast South Dakota.

Rather than wait for the pipeline to reach the southeast part of the state, TransCanada officials decided to move ahead and lay the pipeline underneath the Missouri River at Yankton, said spokesman Jeff Rauh.

"It's out of sequence (to work at Yankton), but the crews with the expertise and equipment were available," he said.

A sensor will detect the depth and location of a drillhead as it goes from the South Dakota side under the riverbed to Nebraska, said Steve Craycroft, a member of a consulting firm working with the project.