Marion-Red Bluff 230kV Line

The Marion-Red Bluff 230kV Line transmission project includes constructing a new approximately 50-mile 230kV line by rebuilding existing 69kV and 115kV transmission lines as double circuits via new and existing right of way, where applicable. Some of the new line will be new 230kV single circuit construction via new right of way.

Santee Cooper transmission planning assessments have identified thermal loading and voltage violations under contingency conditions in the eastern region of the transmission system that are mitigated by the addition of a Marion-Red Bluff 230kV Line. These thermal loading exceedances do not meet the transmission system planning performance requirements under NERC Reliability Standard TPL-001-5 or Santee Cooper’s internal planning criteria. Potential violations may occur as early as June of 2027. 

In addition, Santee Cooper’s plans to retire Winyah Generating Station requires additional thermal and voltage support in this area through transmission reinforcements to mitigate potential widespread low voltage conditions under contingency conditions. The thermal and voltage violations described above could pose serious risk to the transmission system reliability in the area and result in the need to curtail large amounts load if this line is not constructed. To provide the necessary thermal loading relief and voltage support to the transmission system, Santee Cooper proposes the construction of the Marion-Red Bluff 230kV Line. This 230kV line will also provide an additional source for a highly concentrated load area of the Santee Cooper system that continues to see significant load growth.

Santee Cooper plans to utilize approximately 40-miles of existing right of way to minimize environmental and cost impacts. Utilizing existing right of way also allows for older 69kV and 115kV lines to be upgraded to current design standards, increasing resiliency during extreme weather events. Approximately 10-miles of new right of way will need to be acquired for the construction of the 230kV Line. Santee Cooper is conducting routing analyses and will coordinate public meetings prior to choosing a final route.

In double circuit 230-69kV and 230-115kV line rebuild sections, old wooden poles will be replaced with single pole steel structures. The new 230kV single circuit section will be using single pole steel structures.

In June 2023, we contacted property owners by letter to make them aware of the upcoming survey and lidar activities across the existing right of way. We will be sending out information cards to landowners in November 2023 for information regarding the new right of way to be acquired. We will be coordinating the first public meeting on Dec. 12, 2023.

You can contact us at santeecoopermb@powereng.com.