Big Stone South to Ellendale, 345-Kv Power Transmission Line
Milbank, S.D., to Ellendale, N.D.
Award of Merit 

Owner: Otter Tail Power
Partners: Montana Dakota Utilities
Lead Design Firm: Power Engineers
Prime Contractor: Brink Constructors Inc.
Environmental Engineer: HDR
Construction Management: Beste Consulting
Civil Construction General Contractor: Tri-State Drilling
Subcontractors: A&I Services; Dahn Construction; Fiber Network Solutions; KLJ; Power Consulting Associates; Webster Scale; Winco Powerline Services

This project installed a 163-mile-long, 345-kV extra high-voltage power transmission line from South Dakota to North Dakota. Designed to withstand harsh elements, the power line features monopole tubular steel on concrete drilled-pier foundations with a bundle twisted-pair 477-T2 ACSR conductor. The footprint was minimized on landowners’ fields, while the route avoided buildings and excessive tree removal and minimized obstruction of crop land. 

The project included acquisition of land easements and environmental protection work and access through soft, swampy areas that required interlocking matting tools for ground stabilization. The contractor worked with a Native American tribe to find a path through areas of cultural significance and performed work during the winter to preserve grasslands. The twisted-pair conductor self-dampens to minimize galloping and allows the twisted pair to “dance” in the wind, helping them resist the formation of ice.

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