345kV substation and station expansion
Completed December 2020
Engineer, Procure, Construct
Mortenson was chosen by AEP as the engineering, procurement, and construction contractor on a new greenfield 345kV substation to support the interconnection of a new wind generation project.
The station was designed with four breakers, 17 disconnect switches, 12 CCVTs, two metering PTs, three metering CTs, three ground switches, two Power PTs, a control enclosure, and two A-frame dead end structures with the ability to add multiple expansions in the future.
The transmission line work consisted of cutting into the existing North Edinburg-Rio Hondo transmission line with two dead-end structures and one single pole tangent structure. OPGW modifications were made to the existing line as well.
A significant challenge Mortenson faced on this project was the combination of high-water tables and abnormally high wind conditions. The day the contract was signed, the site experienced a 13-inch rain event that made the already-high water table even higher. To combat the rain, the team elevated the access road by one foot, built temporary “spur” roads, and placed matting for transmission line structure installation access.
In addition, the station was designed to elevate the ten-acre pad site five feet with imported fill. The team coordinated day and night shifts to combat the ever-changing weather conditions and meet the aggressive project schedule.
Through close coordination, constant communication, and an unwavering focus on the end goal, the Bonilla Interconnect project transformed from a dirt pad in September 2019 to an energized station in January 2020.
In August of 2020, AEP contracted Mortenson to expand the Bonilla Switchyard in a project known as the West Raymond Expansion.
The expansion facilitated the connection of a second, new wind farm to the grid. The project consisted of removing several piers from Phase 1 of the project and expanding on the existing A-Frame structures, as well as installing two new 345kV breakers, switches, and metering equipment.
With the existing station being currently energized, the team closely coordinated with AEP to secure outages to safely complete the work by December 2020.
