Extending foundations to protect transmission structures
Basin Electric transmission systems maintenance crews modify high-risk transmission structures standing in water.
Basin Electric Power Cooperative
- August 29, 2010
When the LOS-to-Watertown transmission line running from the Leland Olds Station near Stanton, ND, to Watertown, SD, was built in the 1970s, the land was bone dry. That has changed with time. Today, that same stretch of land, which runs 283 miles and includes 1,370 towers, is soaked and many of the transmission structures are standing in water.
Dave Tokach, designer III, said one of the biggest concerns with that is during the winter months, ice forms around and through the structure. "The movement of the ice bends and breaks the steel," he said. That's why a project is currently under way to extend the concrete foundations to protect the structures in deep enough water to put them at risk. Over the years, Transmission System Maintenance line crews with support from engineering and construction have done extensive work to protect and repair these structures.
 |
 |
|
|
One of the towers along the LOS-to-Watertown |
The same tower after work is complete. It includes |
Basically, according to Tokach, dirt is pushed out toward the structure to form a road to it. Fill dirt is also placed around the structure and protected from erosion with riprap. "The bracing steel members are removed, and the concrete foundations are extended to above the water line," Tokach said. "Finally, new bracing steel is placed on the now shorter leg extensions." He added that all the work is done without taking the line out of service.
Before any of the work could be done, Basin Electric needed to get a permit from the U.S. Corp of Engineers and consulted with the U.S. Fish and Wildlife, North Dakota Game and Fish, South Dakota Department of Game, Fish and Parks, and various county engineers.
Tokach said the work started in 1999 and Basin Electric engineers, Right of Way, Environmental, Transmission System Maintenance crews and contractors are in the process of completing the third series of repairs. There are about 119 towers in water and crews have built embankments and extended foundations on 33 of them. "With completion of this work, all high-risk structures will have been modified. TSM crews will continue to inspect them as more may need to be modified in the future," Tokach said.
Headquarters
1717 East Interstate Avenue
Bismarck, ND 58503-0564 USA
Phone: 701.223.0441
Basin Electric Power Cooperative will provide cost-effective wholesale energy along with products and services that support and unite rural America.
