BPA wants to rebuild and harden a 3-mile 115kV transmission line

Unplanned transmission outages are extremely troublesome for the power system and a power line in Benton County, WA, US, has experienced 15 of them over the past five years. To fix the issue, Bonneville Power Administration (BPA) is proposing to rebuild the 115-kV transmission line to ensure unplanned outages in the Tri-Cities area are less likely to occur.

Of the 15 outages, six were resolved by dispatchers who were able to remotely reclose breakers to restore service without investigation or repairs but five of these outages occurred during peak loading periods in the spring and summer. If BPA takes no action, it said the outages could increase in frequency and result in longer, more widespread power interruptions to customers in the area.

BPA said it needs the new lines because it has obligations to ensure that its transmission system is safe, reliable, and has sufficient capability to serve its customers and prevent overloading under certain outage conditions of other transmission lines. In addition, the area is seeing load growth and the new line would ensure that electricity can be reliably delivered to the new customers in the area, it said.

The existing transmission line is a single-circuit line consisting of wood H-frame and monopole structures. The new line would be a 115kV double-circuit transmission line (i.e., two transmission lines on the same structure) on steel monopole structures, increasing the capacity of the grid.

Along the existing transmission line corridor, the work would include replacing all existing conductor, H-frame wood pole structures, wood monopoles, selected steel structures, and hardware. Rebuilding the transmission line would also require equipment upgrades at BPA’s Richland Substation and White Bluffs Substation, and city of Richland’s Thayer Drive, Stevens Drive, and First Street substations.

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To facilitate the removal of the existing White Bluffs to Richland No. 1 transmission line, the proposed work would take place at the substations and each structure located along the transmission line. The design of new steel monopoles versus wood-pole transmission line would reduce the total number of structures along the transmission line corridor. Some structures would be installed in the same place as the existing transmission structures; however, alternative locations would be required to accommodate new steel monopoles.

All structures, regardless of their placement, would be expected to remain in the existing established transmission line right-of-way (ROW) or additional easement would be obtained.

Estimated cost of the project is between $15 million and $21 million.

BPA is conducting an environmental review to understand the potential environmental impacts of this proposal, as required by law. As part of this process, BPA may prepare an environmental assessment (EA). If BPA determines that an EA should be prepared, the EA would analyse the Richland Substation to Stevens Drive Transmission Line Rebuild, as well as a no-action alternative in which BPA does not rebuild the line.

The EA would also describe anticipated impacts to natural and human resources and identify mitigation measures to help avoid or minimize impacts. During this process, BPA will work with landowners, Tribes, Federal, State, and local agencies, and interest groups.

Public comments are open until April 26.

Originally published on Power-Grid International.