We provided design and construction support services for the rebuilding of a 138-kV transmission line, replacing 5.6 miles of existing single conductor with new bundled conductor on one circuit of the double circuit line.

The project was necessary to meet reliability objectives, relieve overloading and provide adequate transmission capacity for contingency conditions after the loss of a section of line in 2021 had caused two other sections to be loaded to 106% and 104%, respectively, of their emergency ratings.

In addition to rebuilding the line to meet current standards, we coordinated with the owner’s partners on the inspection of the existing tap and created stringing charts. When materials were delayed due to vendor constraints, we engineered a workaround that allowed construction to begin on schedule.

Project Challenges

Vegetation management: The existing line did not have existing right-of-way, and overgrown vegetation was present along the entire route. We analyzed safe distances from the cable to the existing vegetation and preserved historically maintained trees. The vegetation management plan was reviewed by the owner’s management and municipal officials.

Lake routing: About 0.9 mile of the existing line crosses a lake, which created challenges for permit coordination, helicopter construction, municipal approvals and on-call engineering support during construction of foundations due to poor soil conditions.