Reconstruction of 64 miles of existing 69kV transmission line
Engineer, Procure, Construct
AEP selected Mortenson to engineer, procure, and construct the reconstruction of 64 miles of existing 69kV transmission line in southern Texas. The existing structures removed consisted of both single pole and H-frame wood pole construction, mostly installed in 1928, including about 20 miles of distribution underbuild.
The transmission line construction was performed during six separate outage windows spanning over fourteen months. While the transmission facilities were being reconstructed, distribution underbuild remained energized and reconstructed. The new transmission line was updated to 138kV class, and the structures included spun concrete tangent poles as well as custom steel structures mounted on drilled pier foundations for angles and dead-end structures.
New conductor and OPGW were strung on all structures utilizing 795 ACSS Drake conductor and 48 count OPGW. As part of the distribution underbuild rework, customers were managed and notified to decrease impacts to homes and businesses.
Setting of the transmission line structures, pulling conductor, installing distribution lines, and demolishing the existing transmission line were all scopes self-performed by Mortenson.
The project traversed different types of terrain, including agricultural areas, brush land, and urban environments. With one section built directly in front of a high school, the team completed construction with no public safety incidents. All this was achieved while removing many brittle structures from the early 1900s and oftentimes during night shifts, navigating water, sewer, electrical, and live distribution in residential areas.
In addition to engineering, procuring, and constructing, Mortenson also managed the supplemental right-of-way acquisition process for the project.
Tremendous and detailed communication between AEP, Mortenson, trade partners, and the local community was essential to the success of the transmission line rebuild throughout its entirety, along with thorough planning from preconstruction through to project finalization.
The project commenced in late 2018 and was completed in spring of 2021.
