03 Sep
CORE is planning to rebuild the existing Roxborough to Timber Mill 115-kilovolt (kV) transmission line in Douglas County, Colorado. The project will rebuild approximately 11 miles of existing transmission facilities in two segments: Roxborough Substation to Sedalia Substation, and Sedalia Substation to the New Timber Mill Substation. The work will occur within the existing 75-foot transmission line right-of-way.
Construction is anticipated to begin in September 2026 and continue through June 2027. The project includes removal of existing transmission poles and installation of new transmission structures, along with replacement of conductors and overhead shield wire. The rebuilt line will consist of a combination of wood and steel structures.
Much of the existing transmission infrastructure was originally constructed in the 1970s and is approaching the end of its useful service life. Rebuilding the line will replace aging facilities, improve system reliability and resiliency, and help ensure continued safe and dependable electric service for CORE members for decades to come.
To support construction activities, temporary access may be required in certain locations. These temporary access areas are intended solely to facilitate safe construction and restoration activities associated with the transmission line rebuild. They are not related to any other current or proposed projects in the area.
Residents may notice construction crews, equipment, and vehicles accessing the transmission line corridor and approved temporary access routes during construction. CORE and its contractors will work to minimize impacts to neighboring properties and will restore temporarily disturbed areas following construction, as appropriate.
This project is intended to improve the reliability and resiliency of the electric transmission system serving CORE members while continuing to utilize the existing transmission corridor.
Learn more about CORE’s system improvement projects here.