Southern Cross Transmission Line

Location: East Texas, Louisiana, Mississippi

Client: Pattern Power Development

Completion Date: 2012

Burns & McDonnell evaluated substation sites, identified routes and routing corridors, evaluated multiple Mississippi River crossings and conducted a preliminary corridor assessment for Pattern Power Development's proposed 350-mile Southern Cross 500-kV AC/DC transmission line project. The line will transfer renewable energy from wind-rich portions of Texas to the Southeast. Burns & McDonnell evaluated system needs, established schedules and cost estimates, identified a routing corridor, sited converter stations, and initialized OneTouchPM for data collaboration.

Available aerial photography in conjunction with field reconnaissance helped identify constraints, develop routes for the 500-kV AC portions of the project in Texas and Mississippi, and to develop a 20-mile-wide routing corridor for the 500-kV DC portion of the project. Geographic information system (GIS) technology was used to identify and map constraints and routes and was shared with Pattern via OneTouchPM. Information was collected on existing utility corridors, land use, floodplains, cultural resources, threatened and endangered species, parks, wetlands, cities, state and federal properties, and residential and commercial developments.

Several sites were evaluated based on engineering and environmental criteria for use as the Rusk County Substation. Routes in Texas were then identified from this site to the Texas border and evaluated based on locally important environmental and social issues, as well as engineering criteria, and a preferred route was recommended to Pattern. Several converter station sites near the Texas border were proposed based on the location of the route.

Burns & McDonnell then identified several route alternatives from a siting area for the converter station in Mississippi to the Union, West Vernon and Wolf Creek substations. A document was prepared describing the alternatives and identifying potential constraints associated with each route. Data was collected for potential converter station sites in Mississippi, but a preferred site has yet to be determined.

Burns & McDonnell identified a 20-mile wide routing corridor in Louisiana and Mississippi that will accommodate two to three routes. The corridors were identified to minimize impacts to macro-constraints such as cities, lakes, state and federal lands, the Mississippi River, and other local, state and federal constraints. Pattern then requested Burns & McDonnell to identify, evaluate and coordinate with the U.S. Army Corps of Engineers (USACE) regarding potential crossings of the Mississippi River. Burns & McDonnell identified and evaluated seven crossings. The crossings were evaluated based on potential cultural, wetland, biological, routing, engineering and right-of-way/landowner impacts. Two crossings were retained for further evaluation with USACE. Meetings with USACE helped determine permitting requirements and potential schedule concerns with regard to the Mississippi River crossing.

  • Transmission line routing
  • GIS mapping
  • Site evaluation
  • Corridor identification and analysis
  • Environmental analysis
  • Alternatives analysis
  • Cultural resource assessment
  • Threatened and endangered species assessment
  • Preliminary right-of-way assessment

The Southern Cross 500-kV AC/DC project would extend approximately 350 miles across Texas, Louisiana and Mississippi. A short portion of 500-kV AC line will run from a proposed substation site in Rusk County, Texas, east to a new AC-DC converter station near the Texas / Louisiana border. The 500-kV DC portion of the project will extend from the converter station site east through Louisiana and western Mississippi, terminating at a proposed converter station site in west-central Mississippi. Three 500-kV AC transmission lines would then extend from the converter station northeast to Tennessee Valley Authority's Union Substation, east to Southern Company's West Vernon Substation in extreme western Alabama, and southeast to Entergy's Wolf Creek Substation.