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​Transmission Line Reintegration

​Sammamish-Maple Valley Line #1

Monroe Novelty Hill Line #1

​The Sammamish-Maple Valley and Monroe-Novelty Hill transmission lines were returned to BPA in August 2018 after the end of a 50-year lease. The two transmission lines are undergoing improvements through reintegration projects to bring them in line with BPA’s safety, reliability and cost management standards.  As part of its 2018-2023 Strategic Plan, BPA is employing industry best practices to continue to meet customer needs efficiently and responsively by providing safe and reliable transmission.

The reintegration projects include:

  • Transmission tower hardware replacements
  • Right-of-way (ROW) safety and reliability inspections
  • Danger tree trimming/clearing for ROW vegetation management
Q1: What changes will I see in my neighborhood or community?

A1: There are a few things that you may notice BPA doing to the transmission lines during the course of the reintegration.
·         Some of the towers will have hardware replaced. These include replacing non-ceramic insulators with BPA standard equipment.
·         Right-of-way safety and reliability inspections and patrols. This usually occurs in the fall and winter using BPA trucks or occasionally all-terrain vehicles or aircraft.
·         Increased clearing of vegetation and trees that pose a threat to safety and reliability within the ROW.

Q2: What are BPA’s standards and/or policies on right-of-ways, land use, and vegetation clearing?

A2: BPA’s “Lands and Community” webpage provides a wide range of information about these topics. The Vegetation Management page goes into further detail about “Danger Trees” that have the potential of coming in contact with power lines.

Q3: Why can’t the transmission lines be relocated or buried underground?

A3: The answer is cost – to relocate the lines would require building all new transmission towers and power lines. The steel lattice structures to support the lines would cost approximately $800 thousand per mile to construct. Additionally, relocation of the lines would also involve:
·         Purchasing land or land rights and associated costs
·         Removal of the old lines and associated costs

Burying the line would impact its reliability because of the time required to access lines buried underground. Burying the transmission line would also require similar expenses to relocating it:
·         The cost would range from $8 million to $12 million per mile, or ten to 15 times the cost of the existing structure.
·         Increased maintenance costs would occur because of the difficulty of accessing buried lines.

Q4: Why do we perform vegetation management in our transmission corridors?

A4: The primary reason BPA performs vegetation management is to ensure its ability to safely provide reliable power throughout the Northwest. When trees or tall brush come in contact with transmission lines they can disrupt the flow of electricity. For instance, during a storm or high winds, trees or tree limbs can fall into transmission lines, knocking out power to communities. Second, the electricity can “arc” or “flashover” from wires, through the air, to trees, other vegetation or equipment up to 15 feet away. These “arc” events can cause fires, injuries or even fatalities to anyone nearby.
The largest blackout in U.S. history was caused by trees coming into contact with high-voltage lines in 2003. The blackout affected almost 55 million people and took nearly two weeks for all power to be restored. The economic and security impact of the blackout was so great that it resulted in legal requirements to minimize the risk of this happening again.
·         Vegetation Management
·         Lands and Communities 

Q5: Why does BPA cut down trees instead of trimming them like other utilities do?

A5: BPA and utilities each manage problem trees and vegetation to the same federal standards, but how those standards are implemented are based on a complex combination of safety, reliability and cost control considerations.

Safety is of the utmost importance but there are other factors to consider as well. Some of the questions included in the decision making process are: What is the voltage capacity of the line? How far can a line sway at high temperatures/capacities? How fast can the surrounding vegetation grow? How tall can the surrounding vegetation grow? How often can the vegetation be trimmed and/or cleared? How much will it cost to trim vs. clear? What, if any, alternatives are there?

BPA is dedicated to delivering safe, low-cost reliable power to the region and maintains nearly 15,000 miles (24,000 km) of transmission lines in seven states. To ensure that vegetation can be managed while still meeting this goal, BPA sets standards to balance the need for safety and reliability with ROW aesthetics and being a good neighbor. A local utility may be able to manage their lines by trimming trees more often because of the lower cost of maintaining a smaller transmission system. BPA’s transmission system is simply too large to allow for regular tree trimming; the cost involved would be  unsustainable and work against BPA’s goals of providing reliable transmission and competitive power products and services.

In short, BPA uses a complex formula to consider multiple variables and compares this against industry standards to arrive at a decision that maintains the balance of being a good neighbor while providing safe, reliable and low-cost power to the Pacific Northwest.

Q6: Are there more aesthetically pleasing transmission towers that could be installed?

A6: There are only two other options available that are more aesthetically pleasing:  either single pole steel towers or underground construction. Unfortunately, both are very expensive. Single pole steel structures would increase the cost of construction from $800 thousand to nearly $1.2 million per mile. Burying the line would cost 10-15 times that of typical steel lattice construction. These expenses would be in addition to the cost of removing the existing structure(s). See question three (above) for more details on the costs of burying transmission lines.

Q7: What about damages to my yard, parks, or trails from utility trucks and equipment?

A7: Letters are sent to landowners prior to work. There will be door-to-door notification prior to tree work. BPA is committed to being a good neighbor. Ruts caused by BPA equipment will be mitigated where possible and restored where they occur. These mitigation and restoration projects occur at no cost to the landowner.