There are a number of tradeoffs when it comes to installing 115 kV transmission lines underground. While every project is unique, with undergrounding, the most significant tradeoff is cost – which is in the order of 10x more expensive than installing overhead lines. When PGE invests in equipment upgrades, the Oregon Public Utility Commission will review those expenditures to determine if they were reasonable and prudent because they result in price increases to all PGE customers. For this project, PGE is working within existing public right of way. To underground, PGE would want a dedicated easement to protect underground facilities along this corridor in order to protect customers from the prospect of paying for the lines to be buried, and then potentially paying to relocate them should future public works projects so require. Some of the tradeoffs when it comes to undergrounding transmission lines are: The need for more easements. Undergrounding transmission lines usually involves burying large vaults at regular intervals, in addition to the cables and conduits. More vegetation removal. To prevent roots from intruding into the electrical conduits in a transmission corridor, limited vegetation is allowed to grow above the lines and in the surrounding area. Longer construction times, more heavy equipment and impacts to vegetation and roads. More extensive maintenance inspections. Underground transmission lines can require patrolling to assess changes in soil depth, cover type, vegetation and other variables that can impact the ability of the line to effectively dissipate heat. They are more susceptible to water ingress, which can lead to equipment degradation and faults that in turn require more significant repairs. Lengthier problem-solving and repair process. If lines are damaged or experience a fault, the process of identifying the issue, accessing it and repairing it requires more time, resources and heavy equipment, leading to longer outages. Supply chain challenges. The cables and hardware used for underground transmission are often designed based on the unique soil and operating conditions, which can affect their availability for installation and repairs.