New transmission construction highlights BPA-DOE partnership

The construction of a new 230-kilovolt transmission line in southeast Washington State is the result of a valuable partnership between the Bonneville Power Administration and the U.S. Department of Energy's Richland Operations Office.

After more than seven years of discussion and work between BPA and DOE-Richland, construction crews broke ground March 20 on the new Midway-Ashe transmission line, which will span from Midway Substation to Ashe Substation, both located on the Hanford Site near Richland.

The new Midway-Ashe line will replace an existing 70-year-old line that DOE-Richland has operated for various nuclear projects since the 1940s. Through agreements with DOE-Richland, BPA has used the line since the early 1980s to provide backup service to Energy Northwest's Columbia Generating Station.  Once the new line is complete, it's estimated BPA will save approximately $600,000 to $700,000 in transmission operations expenses annually.

For years, the two agencies have agreed that a new line was needed for reliability, especially since DOE-Richland is on the verge of starting a vitrification plant; vitrification is a process that immobilizes nuclear waste  in the form of a glass-like solid. However, because the project crosses the Hanford Site, a protected superfund clean-up area, it took considerable time and coordination to incorporate environmental, cultural, and other unique considerations into the project's planning and design.

“We are excited to see years of hard work being realized out on the Hanford Reservation," says Amanda Williams, Midway-Ashe project manager. “This new transmission line will provide enormous benefits to reliability for both BPA and DOE-Richland."

BPA designed and is now building the new 18-mile double-circuit line that will better meet the needs of both BPA and DOE. One side of the new line will tie into the existing 8-mile-long Ashe Tap, providing a dedicated path to Ashe Substation. When completed, BPA will own and operate the new line's towers and the Midway-Ashe circuit, while DOE-Richland will own the second circuit that will replace their existing transmission line to supply power to the Hanford Site clean-up mission.

In addition to the new transmission line, crews are installing new bays at Midway Substation and new communications and line control equipment at both Midway and Ashe substations. BPA and DOE-Richland are each covering about 50% of the cost of construction.

The partnership between BPA and DOE-Richland has been valuable in managing and maintaining the old line over the years 

and in determining the best path forward for new-line construction. BPA's expertise in transmission line design and construction is of great benefit as is DOE-Richland's knowledge of the Hanford Site's unique challenges.

Officials estimate the new Midway-Ashe transmission line will take more than two years to complete and be fully operational in 2025.