Challenges and Lessons Learned on a 200-Mile 500kV Electrical Transmission Line Construction Project
Since 2009, Southern California Edison has been building the Tehachapi Renewable Transmission Project (TRTP), a 220-mile, 500kV transmission line to bring renewable wind power from the Tehachapi Mountains to the population centers of Los Angeles, Orange, Riverside, and San Bernardino Counties. The beginning of the project coincided with adoption of the 2009 CGP, ensuring many lessons would be learned about implementation of the new construction storm water requirements over the course of the project.
Segments 6 and 11 of the TRTP traverse the Angeles National Forest, an area characterized by steep topography, often heavily vegetated, and largely undisturbed areas between the San Gabriel Valley and Antelope Valley.
Traditionally, linear construction projects have managed storm water runoff (including post construction final stabilization) and habitat restoration as two separate scopes of work. Typically the final stabilization scope of work is implemented by the general construction contractor in order to expeditiously relieve them of their SWPPP responsibilities under the California Storm Water Construction General Permit. Habitat restoration activities are then performed by a specialty contractor who is brought on board after the main construction work is completed. However, regulatory overlap by different State, Federal and local government agencies (State Water Resources Control Board, California Department of Fish and Wildlife, Army Corps of Engineers, Angeles National Forest, and some local governments) now mandate integration of requirements during all phases of construction, especially during the final phases. Often, the integration requirement can limit flexibility, increase cost and complicate compliance. Knowing the potential challenges for a project of this magnitude, a programmatic, site by site approach to cooperatively manage all environmental requirements for the 200-plus towers was implemented. The solutions identified by the project team presented many unique solutions and efficiencies that can benefit other California projects.
This technical paper explores the challenges of utility construction in steep and remote areas, coupled with the various regulatory requirements that impacted the project. Detailed discussion of the line between construction and restoration activity, permitting approach, and lessons learned through collaboration between the BMP Design Team and the Restoration Team will be addressed.