Commonwealth Associates, Inc. was hired by Avista Corporation (Avista) to design the replacement of the distribution portion of the Ninth & Central Substation due to its age, condition, and inability to be maintained. Avista had begun an in-house design to rebuild the substation, but due to the retirement of their lead designer, they were unable to complete the design in a timely fashion. Thus, Commonwealth was asked to complete the design for the project. Commonwealth was responsible for the physical and electrical design, while Avista provided drafting and civil engineering support.
Commonwealth’s work included finishing the design and setting a new standard for open-air distribution racks. Commonwealth completed the design of two distribution transformer lineups. Each transformer lineup had one 115 kV circuit breaker, a 30 MVA transformer, three feeders with a main and auxiliary bus configuration, and a tie between the two sets of feeders. Avista had never used a main and auxiliary bus design on their distribution racks before. Commonwealth was responsible for adapting this new operating philosophy to their standard rack design.
Challenges that Commonwealth overcame during this project included working with a design that was partially complete when Commonwealth was hired by Avista, which required Commonwealth to assess how complete the design was in order to finish the project. An additional challenge was picking up the design of a completely new operating philosophy for Avista’s distribution racks mid-stream and conforming it to existing practices. Commonwealth often interacted with Avista employees to identify and solve issues, coordinate work, and keep the project moving forward. Having offices at Avista was beneficial to facilitate the interaction of Commonwealth and Avista and the coordination of the project. The project was completed successfully and under budget.