- Terrebonne to Bayou Vista Transmission Upgrade
This initiative was a collaborative effort between Entergy Louisiana and CLECO Power LLC to replace aging power infrastructure with new facilities hardened to withstand extreme weather events such as hurricanes. The project spanned 36 miles, with the Entergy portion beginning at the preexisting Terrebonne substation on the eastern edge. Entergy’s portion runs 24 miles through the heart of Louisiana’s bayou system to a point at Bayou Boeuf near Amelia, La., where it dead-ends at the CLECO utility structures. CLECO’s portion of the project includes the remaining 12 miles of new 230-kV transmission line, along with related interconnections, eventually culminating at CLECO’s Bayou Vista substation.
Our team was part of the comprehensive systemwide capital program to improve reliability throughout southeast Louisiana. Known challenges included the route through the heart of the bayous of Southern Louisiana, which are among the most ecologically diverse and fragile ecosystems in North America. Home to a broad and unique array of wildlife, pristine wetlands, cypress forests and fantastic array of plant species, the transmission construction project required planning and management with the utmost care and sensitivity.
As program manager and engineer-procure-construct (EPC) contractor, we began with a detailed environmental assessment. This formed the foundation of a plan to minimize disturbance of the tightly interwoven ecosystems.
Construction required extraordinary planning and schedule coordination. Due to right-of-way constraints in two residential subdivisions, mile and half-mile segments of the existing Terrebonne-Greenwood-Humphrey 115-kV H-frames had to be rebuilt as new monopole structures next to new monopole structures supporting the Terrebonne to Bayou Vista line, creating a section of back-to-back vertically configured circuits within the existing right of way.
The Terrebonne substation required significant upgrades. As a brownfield effort, a new 230-kV, 5-breaker-ring buss was constructed with an ultimate layout at the Terrebonne station expanded to a 6-breaker buss. To allow for additional bay construction at the Terrebonne station, three existing lines had to be rerouted. The substation upgrades required the team to work at interconnecting substations times, requiring precise outage scheduling for interconnections to keep power to Entergy’s customers. This work was necessary to install advanced controls and communications equipment in interconnected substations to improve instantaneous communication for power flow variances. The outages required precise scheduling of crews and placement of equipment to minimize duration.
- Engineer-procure-construct project delivery
- Program management
- Environmental assessment
- Minimal disturbance of vegetation and wildlife, including zero long-term environmental impact on wildlife and wetlands
- Helicopter lifts for each pole location, requiring planning for traffic control, environmental disturbance, weight limits
- Crew transport coordination for helicopter lifts and air boat travel
- Avoidance of eagle nests
- Careful planning for bridge weight restrictions
- Pipeline and rail crossing coordination
- Safety protections to guard against alligators, snakes and other swamp inhabitants